WO2018113294A1 - 一种转发报文的方法、设备及系统 - Google Patents

一种转发报文的方法、设备及系统 Download PDF

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Publication number
WO2018113294A1
WO2018113294A1 PCT/CN2017/094165 CN2017094165W WO2018113294A1 WO 2018113294 A1 WO2018113294 A1 WO 2018113294A1 CN 2017094165 W CN2017094165 W CN 2017094165W WO 2018113294 A1 WO2018113294 A1 WO 2018113294A1
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Prior art keywords
state
packet
bypass
primary
traffic
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PCT/CN2017/094165
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English (en)
French (fr)
Inventor
张耀坤
孙春霞
李娟�
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP17884866.9A priority Critical patent/EP3471343B1/en
Publication of WO2018113294A1 publication Critical patent/WO2018113294A1/zh
Priority to US16/360,897 priority patent/US10992570B2/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/06—Management of faults, events, alarms or notifications
    • H04L41/0654—Management of faults, events, alarms or notifications using network fault recovery
    • H04L41/0663—Performing the actions predefined by failover planning, e.g. switching to standby network elements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/28—Routing or path finding of packets in data switching networks using route fault recovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/2854—Wide area networks, e.g. public data networks
    • H04L12/2856—Access arrangements, e.g. Internet access
    • H04L12/2869—Operational details of access network equipments
    • H04L12/287—Remote access server, e.g. BRAS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/2854—Wide area networks, e.g. public data networks
    • H04L12/2856—Access arrangements, e.g. Internet access
    • H04L12/2869—Operational details of access network equipments
    • H04L12/2878—Access multiplexer, e.g. DSLAM
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/06—Management of faults, events, alarms or notifications
    • H04L41/0654—Management of faults, events, alarms or notifications using network fault recovery
    • H04L41/0668—Management of faults, events, alarms or notifications using network fault recovery by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/68—Pseudowire emulation, e.g. IETF WG PWE3
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/12—Avoiding congestion; Recovering from congestion
    • H04L47/125—Avoiding congestion; Recovering from congestion by balancing the load, e.g. traffic engineering

Definitions

  • the present application relates to the field of communications technologies, and in particular, to a method, device, and system for forwarding a message. More specifically, the present application relates to Pseudo Wire Redundancy technology.
  • the PW redundancy technology is based on the Pseudo Wire Emulation Edge-to-Edge (PWE3) system. It provides a carrier edge (Provider Edge, PE) in a dual-homing scenario of the Customer Edge (CE) device. The protection mechanism of the device or the Attachment Circuit (AC).
  • a PW redundancy group is formed by configuring a primary pseudowire (Pseudo Wire, PW) and a secondary PW.
  • the PW in the PW redundancy group can forward data traffic. However, only one PW can be used to forward data traffic. Normally, the primary PW forwards data traffic. When the primary PW fails, the data traffic is quickly switched to the backup PW for forwarding. When the primary PW is restored, the data traffic will be switched back to the primary PW for forwarding.
  • Virtual Private Wire Service Pseudo Wire is a specific implementation of PW redundancy technology.
  • the Virtual Private Wire Service can also be called a Virtual Leased Line (VLL).
  • VPWS refers to the Asynchronous Transfer Mode (ATM), Frame Relay (FR), Ethernet (Ethernet), and low-speed time division as much as possible in a Packet Switched Network (PSN).
  • ATM Asynchronous Transfer Mode
  • FR Frame Relay
  • Ethernet Ethernet
  • PSN Packet Switched Network
  • a Layer 2 service bearer technology that uses basic behaviors and features of services such as Time Division Multiplexing (TDM) circuits and Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH).
  • TDM Time Division Multiplexing
  • SONET Synchronous Optical Network
  • SDH Synchronous Digital Hierarchy
  • the primary PW and the backup PW in the VPWS PW implement redundancy protection.
  • the bandwidth resources of the PW redundancy group cannot be fully utilized.
  • the backup PW will be in a standby state, and the backup PW will not forward data traffic. Even if the bandwidth resource of the primary PW is insufficient, the bandwidth resources of the backup PW cannot be utilized.
  • the embodiment of the present application provides a method, a device, and a system for forwarding a message, so as to improve the redundancy protection function of the primary PW and the backup PW in the VPWS PW, and help improve the implementation of the VPWS PW. Bandwidth utilization.
  • the first aspect provides a method for forwarding a message, where the method is applied to a VPWS PW redundant network, where the VPWS PW redundant network includes a first PE device, a second PE device, and a third PE device.
  • a primary PW is established between the first PE device and the second PE device
  • a backup PW is established between the first PE device and the third PE device
  • the second PE device and the third A bypass pseudowire Bypass PW is established between the PE devices.
  • the method includes: the first PE device sends a first packet to the second PE device by using the primary PW.
  • the first packet is, for example, a PW status notification packet, and the label may be a label distribution protocol.
  • LDP distribution protocol
  • the first packet is used to request that the active PW is switched from an active Active state of the forwarding traffic to an equalized Balance state of the forwarding traffic, where the Balance state is used to indicate that the traffic is balanced. Way to forward traffic.
  • the first PE device further sends a second packet to the third PE device via the backup PW.
  • the second packet is, for example, a PW status notification packet, which may be an LDP packet, and the second packet.
  • the message is used to request that the backup PW be switched from the standby Standby state that does not forward traffic to the balanced Balance state of the forwarding traffic.
  • the first PE device receives, by the primary PW, a response packet from the second PE device, where the response packet is sent by the second PE device according to the first packet and the first The second message is determined.
  • the second packet is forwarded by the second PE device to the third PE device by using the bypass PW, and the response packet is used to indicate that the first packet and the first packet are agreed to.
  • Two message switching requests The first PE device switches the priority forwarding state of the first PE device relative to the primary PW by the active state of the forwarding traffic to the Balance state of the forwarding traffic according to the response packet, and the first The priority forwarding state of the PE device with respect to the backup PW is switched from a Standby state that does not forward traffic to a Balance state that forwards traffic.
  • the first PE device may determine the primary PW and the backup PW as a Balance state by negotiating with the second PE device and the third PE device to implement the primary PW and The traffic balance of the backup PW helps to improve the bandwidth utilization of the VPWS PW.
  • the method further includes: the first PE device receiving traffic from the first CE device. And the first PE device forwards the traffic from the first CE device to the second PE device and the third PE device by using the primary PW and the backup PW in the balance state according to the traffic balancing manner.
  • the method before the first PE device sends the first packet to the second PE device by using the primary PW, the method further includes: the first The PE device determines that the bandwidth usage rate of the traffic sent by the first PE device to the second PE device exceeds a predetermined threshold.
  • the VPWS PW can automatically select the redundant mode forwarding data traffic and the traffic balancing mode to forward the data traffic according to the bandwidth condition of the forwarding traffic.
  • the selection of the threshold is not limited, for example, using the rated bandwidth of the PW as a threshold or being configured by an operator.
  • the method before the first PE device sends the first packet to the second PE device by using the primary PW, the method further includes: the first The PE device determines that the first PE device sends a traffic to the second PE device for a predetermined period of time.
  • the data traffic is forwarded to the traffic balancing mode.
  • the method further includes that the first PE device determines that the fault detection message from the second PE device cannot be received within a predetermined period. Then, the first PE device switches the priority forwarding state of the first PE device relative to the primary PW from a Balance state to a Standby state, and sends a third packet to the second PE device, where the Three messages are used to request that the primary PW be The Balance state is switched to the Standby state. And the first PE device switches the priority forwarding state of the first PE device relative to the backup PW from a Balance state to an Active state, and sends a fourth packet to the third PE device, where the The fourth message is used to request that the backup PW be switched from the Balance state to the Active state.
  • the first PE device After determining that the primary PW or the second PE device is faulty, the first PE device performs the PW forwarding state switching to ensure that the service traffic is smoothly forwarded to avoid service interruption.
  • the method further includes that the first PE device determines that the fault detection message from the third PE device cannot be received within a predetermined period. Then, the first PE device switches the priority forwarding state of the first PE device with respect to the primary PW from the Balance state to the Active state, and sends a third packet to the second PE device, where the The three messages are used to request that the primary PW be switched from the Balance state to the Active state. And the first PE device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to a Standby state, and sends a fourth packet to the third PE device, where the The four message request will indicate that the backup PW is switched from the Balance state to the Standby state.
  • the first PE device After determining that the backup PW or the third PE device is faulty, the first PE device performs the PW forwarding state switching to ensure that the service traffic is smoothly forwarded to avoid service interruption.
  • the method further includes: the first PE device receiving a termination message from the second PE device and the third PE device, the termination message The text is used to indicate the termination of the Balance state of the Bypass PW. Then, the first PE device switches the priority forwarding state of the first PE device with respect to the primary PW from the Balance state to the Active state, and sends a third packet to the second PE device, where the The three messages are used to request that the primary PW be switched from the Balance state to the Active state.
  • the first PE device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to a Standby state, and sends a fourth packet to the third PE device, where the The four messages are used to request that the backup PW be switched from the Balance state to the Standby state.
  • the first PE device After determining the Bypass PW fault, the first PE device performs the PW forwarding state switching to ensure that the service traffic is smoothly forwarded to avoid service interruption.
  • a second aspect provides a method for forwarding a message, where the method is applied to a VPWS PW redundant network, where the VPWS PW redundant network includes a first PE device, a second PE device, and a third PE device.
  • a primary PW is established between the first PE device and the second PE device, and a backup PW is established between the first PE device and the third PE device, and the second PE device and the device are established.
  • a bypass pseudowire Bypass PW is established between the third PE devices.
  • the method includes: the second PE device receives, by the primary PW, a first packet from the first PE device, where the first packet is, for example, a PW status notification packet, which may be an LDP packet.
  • the first packet is used to request that the primary PW be switched from an active Active state of the forwarding traffic to an equalized Balance state of the forwarding traffic, where the Balance state is used to indicate that the traffic is forwarded in a traffic balanced manner.
  • the second PE device receives the second packet that is forwarded by the third PE device by using the bypass PW.
  • the second packet is, for example, a PW status notification packet, which may be an LDP packet.
  • the second packet is used to request that the backup PW be switched from a standby Standby state that does not forward traffic to an equalized Balance state of the forwarding traffic.
  • the second PE device generates a response message according to the first packet and the second packet, and the priority forwarding state of the second PE device relative to the primary PW is determined by the Active state of the forwarding traffic. Switch to forward traffic The balance state, and switching the priority forwarding state of the second PE device relative to the Bypass PW from the Bypass state to the Balance state.
  • the second PE device sends the response packet to the first PE device via the primary PW, and sends the response packet to the third PE device via the Bypass PW, the response packet.
  • the text is used to indicate that the handover request of the first packet and the second packet is agreed.
  • the second PE device may determine the primary PW and the Bypass PW as a Balance state by negotiating with the first PE device and the third PE device to implement the primary PW and The traffic balance of the backup PW helps to improve the bandwidth utilization of the VPWS PW.
  • the second CE device is dual-homed to the second PE device and the third PE device in the VPWS PW redundant network by using an MC-Trunk link.
  • the link between the CE device and the second PE device is a primary link
  • the link between the CE device and the third PE device is a backup link.
  • the method also includes the second PE device receiving traffic from the CE device via the primary link. Then, the second PE device forwards the traffic from the CE device to the first PE device and the third PE device via the primary PW and the bypass PW in the Balance state according to the traffic balancing manner.
  • the second PE device generates a response packet according to the first packet and the second packet, and compares the second PE device with respect to the second PE device.
  • the priority forwarding state of the primary PW is switched from the active state of the forwarding traffic to the Balance state of the forwarding traffic, and before the priority forwarding state of the second PE device with respect to the Bypass PW is switched from the Bypass state to the Balance state,
  • the method further includes: determining, by the second PE device, that the bandwidth usage of the outbound interface that the second PE device sends the traffic to the third PE device is less than a predetermined threshold.
  • the second PE device generates a response packet according to the first packet and the second packet, and compares the second PE device with respect to the second PE device.
  • the priority forwarding state of the primary PW is switched from the active state of the forwarding traffic to the Balance state of the forwarding traffic, and before the priority forwarding state of the second PE device with respect to the Bypass PW is switched from the Bypass state to the Balance state,
  • the method further includes: the second PE device determines that the bandwidth usage rate of the outbound interface that the second PE device sends the traffic to the third PE device is greater than or equal to a predetermined threshold, and the second PE device generates a reject packet. And sending, by the primary PW, the reject message to the first PE device and to the third PE device by using the Bypass PW, where the reject message is used to indicate that the first packet and the first message are different. The switching request of the second message.
  • the method further includes that the second PE device determines that the fault detection message from the first PE device cannot be received within a predetermined period. Then, the second PE device switches the priority forwarding state of the second PE device with respect to the primary PW from the Balance state to the Standby state, and sends a failure notification message to the first PE device, where the fault occurs.
  • the advertisement message is used to notify the first PE device of the fault discovered by the second PE device.
  • the second PE device switches the priority forwarding state of the second PE device with respect to the Bypass PW from the Balance state to the Bypass state, and sends a termination packet to the third PE device, where the termination message is sent.
  • the text is used to indicate the termination of the Balance state of the Bypass PW.
  • the second PE device performs the PW forwarding state switching after determining the primary PW fault, based on the foregoing implementation manner. Ensure that traffic is forwarded smoothly and business interruptions are avoided.
  • the method further includes that the second PE device determines that the fault detection message from the CE device cannot be received within a predetermined period. Then, the second PE device determines that the priority forwarding state of the second PE device relative to the primary PW is a Balance state, maintains a Balance state with respect to the primary PW, and does not send the first PE device to the first PE device. A message for switching the Balance state of the primary PW.
  • the second PE device After the second PE device determines that the PW forwarding state of the PW network is in the Balance state, the second PE device maintains the Balance state to ensure that the service traffic is smoothly forwarded and avoids the generation. Business disruption.
  • the method further includes that the second PE device determines that the fault detection message from the third PE device cannot be received within a predetermined period. Then, the second PE device switches the priority forwarding state of the second PE device with respect to the Bypass PW from the Balance state to the Bypass state, and sends a termination message to the first PE device, where the termination message is sent.
  • the text is used to indicate the termination of the Balance state of the Bypass PW.
  • the second PE device receives a third packet from the first PE device, where the third packet is used to request that the primary PW be switched from a Balance state to an Active state. And the second PE device switches the priority forwarding state of the second PE device relative to the primary PW from a Balance state to an Active state according to the third packet.
  • the second PE device After determining that the Bypass PW or the third PE device is faulty, the second PE device performs the PW forwarding state switching to ensure that the service traffic is smoothly forwarded to avoid service interruption.
  • a method for forwarding a message is provided, where the method is applied to a virtual private line service pseudowire VPWS PW redundant network, where the VPWS PW redundant network includes a first PE device, a second PE device, and Third PE device.
  • a primary PW is established between the first PE device and the second PE device, and a backup PW is established between the first PE device and the third PE device, and the second PE device and the device are established.
  • a bypass pseudowire Bypass PW is established between the third PE devices.
  • the method includes the third PE device receiving, by the backup PW, a first packet from the first PE device, where the first packet is, for example, a PW status notification packet, which may be an LDP packet.
  • the first packet is used to request that the backup PW be switched from a standby Standby state that does not forward traffic to an equalized Balance state of forwarding traffic.
  • the third PE device forwards the first packet to the second PE device via the Bypass PW.
  • the third PE device receives the response packet from the second PE device via the Bypass PW, and the response message is used to indicate that the handover request of the first packet is agreed.
  • the third PE device switches the priority forwarding state of the third PE device relative to the backup PW from a Standby state that does not forward traffic to a Balance state that forwards traffic according to the response packet, and The priority forwarding state of the third PE device with respect to the Bypass PW is switched from the Bypass state to the Balance state.
  • the third PE device may determine the backup PW and the Bypass PW as the Balance state by using the manner negotiated with the first PE device and the second PE device to implement the primary PW and The traffic balance of the backup PW helps to improve the bandwidth utilization of the VPWS PW.
  • the method before the third PE device forwards the first packet to the second PE device by using the Bypass PW, the method further includes: The third PE device determines that the bandwidth occupancy rate of the outbound interface that the third PE device sends the traffic to the second PE device is less than a predetermined threshold.
  • the method before the third PE device forwards the first packet to the second PE device by using the Bypass PW, the method further includes: The third PE device determines that the bandwidth usage rate of the outbound interface that the third PE device sends the traffic to the second PE device is greater than or equal to a predetermined threshold, and the third PE device generates a reject packet and uses the backup PW. Sending the reject message to the first PE device, where the reject message is used to indicate that the handover request is different from the second packet.
  • the method further includes: the third PE device determines that the fault detection message from the first PE device cannot be received within a predetermined period. Then, the third PE device switches the priority forwarding state of the third PE device with respect to the backup PW from the Balance state to the Standby state, and sends a failure notification message to the first PE device, where the fault occurs.
  • the advertisement message is used to notify the first PE device of the fault discovered by the third PE device.
  • the third PE device switches the priority forwarding state of the third PE device with respect to the Bypass PW from a Balance state to a Bypass state, and sends a termination packet to the second PE device, where the termination message is sent.
  • the text is used to indicate the termination of the Balance state of the BypassPW.
  • the third PE device After determining the backup PW fault, the third PE device performs the PW forwarding state switching to ensure that the service traffic is smoothly forwarded to avoid service interruption.
  • the method further includes: the third PE device determines that the fault detection message from the second PE device cannot be received within a predetermined period. Then, the third PE device switches the priority forwarding state of the third PE device with respect to the Bypass PW from the Balance state to the Bypass state, and sends a termination message to the first PE device, where the termination message is sent. The text is used to indicate the termination of the Balance state of the Bypass PW.
  • the third PE device receives a second packet from the first PE device, where the second packet is used to request that the backup PW be switched from a Balance state to an Active state or a Standby state. Then, the third PE device switches the priority forwarding state of the third PE device relative to the backup PW from the Balance state to the Active state or the Standby state according to the second packet.
  • the third PE device After the third PE device determines that the Bypass PW or the second PE device is faulty, the third PE device performs the PW forwarding state to ensure that the service traffic is smoothly forwarded and the service interruption is avoided.
  • a first PE device having a function of implementing behavior of the first PE device in the foregoing method.
  • the functions may be implemented based on hardware, or may be implemented based on hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the first PE device includes a processor and an interface configured to support the first PE device to perform a corresponding function in the above method.
  • the interface is configured to support communication between the first PE device and the second PE device and the third PE device, and send information or instructions involved in the foregoing method to the second PE device and the third PE device, or from the second The PE device and the third PE device receive information or instructions involved in the above method.
  • the first PE device can also include a memory for coupling with the processor that retains program instructions and data necessary for the first PE device.
  • a second PE device having a function of implementing behavior of the second PE device in the foregoing method.
  • the functions may be implemented based on hardware, or may be implemented based on hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the structure of the second PE device includes a processor and an interface configured to support the second PE device to perform the corresponding function in the above method.
  • the interface is configured to support communication between the second PE device and the first PE device and the third PE device, and send information or instructions involved in the foregoing method to the first PE device and the third PE device, or from the first The PE device and the third PE device receive information or instructions involved in the above method.
  • the second PE device can also include a memory for coupling with the processor that holds the necessary program instructions and data for the second PE device.
  • a third PE device having a function of implementing the behavior of the third PE device in the foregoing method.
  • the functions may be implemented based on hardware, or may be implemented based on hardware.
  • the hardware or software includes one or more modules corresponding to the functions described above.
  • the structure of the third PE device includes a processor and an interface configured to support the third PE device to perform the corresponding function in the above method.
  • the interface is configured to support communication between the third PE device and the first PE device and the second PE device, and send information or instructions involved in the foregoing method to the first PE device and the second PE device, or from the first The PE device and the second PE device receive information or instructions involved in the above method.
  • the third PE device can also include a memory for coupling with the processor that holds the necessary program instructions and data for the third PE device.
  • the first packet and the second packet carry a PW status code
  • the PW status code is used to indicate that the state of the PW is a Balance state.
  • a VPWS PW redundant network system comprising the first PE device of the fourth aspect, the second PE device of the fifth aspect, and the third PE of the sixth aspect device.
  • a computer storage medium for storing a program, code or instruction used by the first PE device, and the processor or the hardware device can perform the first of the above aspects when executing the program, code or instruction.
  • the function or step of the PE device is provided for storing a program, code or instruction used by the first PE device, and the processor or the hardware device can perform the first of the above aspects when executing the program, code or instruction.
  • the function or step of the PE device is provided for storing a program, code or instruction used by the first PE device, and the processor or the hardware device can perform the first of the above aspects when executing the program, code or instruction.
  • a computer storage medium for storing a program, code or instruction used by the second PE device, and the processor or the hardware device can perform the second of the above aspects when executing the program, code or instruction.
  • the function or step of the PE device is provided for storing a program, code or instruction used by the second PE device, and the processor or the hardware device can perform the second of the above aspects when executing the program, code or instruction.
  • a computer storage medium for storing a program, code or instruction used by the third PE device, and the third aspect of the foregoing may be completed when the processor or the hardware device executes the program, code or instruction.
  • the function or step of the PE device is provided for storing a program, code or instruction used by the third PE device, and the third aspect of the foregoing may be completed when the processor or the hardware device executes the program, code or instruction.
  • the function or step of the PE device is provided for storing a program, code or instruction used by the third PE device, and the third aspect of the foregoing may be completed when the processor or the hardware device executes the program, code or instruction.
  • the method, device, and system for forwarding a packet provided by the embodiment of the present application, by using the primary PW and the backup PW, respectively, send a request to the second PE device and the third PE device to switch to the Balance state.
  • Request message the second PE device receives two request messages via the primary PW and via the backup PW, the third PE device, and the Bypass PW; the second PE device will use the second request.
  • the priority forwarding state of the PE device with respect to the primary PW and the bypass PW is switched to a Balance state, and the first PE device and the third PE device are notified by a response packet;
  • the response packet switches the priority forwarding state of the first PE device with respect to the primary PW and the backup PW to a Balance state, and the third PE device sends the third PE device according to the response packet.
  • the priority forwarding state is switched to the Balance state with respect to the Bypass PW. Therefore, based on the redundancy protection function of the primary PW and the backup PW in the VPWS PW, the traffic balance between the primary PW and the backup PW is implemented, which helps to improve. Bandwidth utilization of VPWS PW.
  • FIG. 1 is a schematic structural diagram of a VPWS PW redundant network according to an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of another VPWS PW redundant network according to an embodiment of the present application.
  • FIG. 3 is a flowchart of a method for forwarding a message according to an embodiment of the present application
  • FIG. 4 is a schematic structural diagram of another VPWS PW redundant network according to an embodiment of the present application.
  • FIG. 5 is a flowchart of a method for processing a fault according to an embodiment of the present application.
  • FIG. 6 is a flowchart of another method for processing a fault according to an embodiment of the present application.
  • FIG. 7 is a flowchart of still another method for processing a fault according to an embodiment of the present application.
  • FIG. 8 is a flowchart of still another method for processing a fault according to an embodiment of the present application.
  • FIG. 9 is a flowchart of still another method for processing a fault according to an embodiment of the present application.
  • FIG. 10 is a flowchart of still another method for processing a fault according to an embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a first PE device according to an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of hardware of a first PE device according to an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a second PE device according to an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of hardware of a second PE device according to an embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of a third PE device according to an embodiment of the present application.
  • FIG. 16 is a schematic structural diagram of hardware of a third PE device according to an embodiment of the present application.
  • the embodiment of the present invention provides a method, a device, and a system for forwarding a packet, so as to improve the bandwidth utilization of the VPWS PW based on the redundancy protection function of the primary PW and the backup PW in the VPWS PW.
  • FIG. 1 is a schematic structural diagram of a VPWS PW redundant network according to an embodiment of the present application.
  • the VPWS PW redundant network includes a first PE device, a second PE device, and a third PE device.
  • the first PE device communicates with the second PE device and the third PE device respectively through a communication link.
  • a PW redundancy group is established between the first PE device and the second PE device and the third PE device, where the PW redundancy group includes a primary PW and a backup PW.
  • the primary PW is established between the first PE device and the second PE device, and the backup PW is established between the first PE device and the third PE device.
  • the process of establishing the primary PW and the backup PW may be implemented according to a corresponding standard formulated by the Internet Engineering Task Force (IETF), for example, a Request for Comments (RFC) 6718, and the application does not advance. Parallel description.
  • IETF Internet Engineering Task Force
  • RRC Request for Comments
  • a bypass pseudowire is established between the second PE device and the third PE device.
  • the Bypass PW may use an Inter-Chassis Backup Pseudo Wire (ICB PW) or a Dual Node Interconnection Pseudo Wire (DNI PW).
  • ICB PW Inter-Chassis Backup Pseudo Wire
  • DNI PW Dual Node Interconnection Pseudo Wire
  • the first PE device communicates with the first CE device over a communication link.
  • the first CE device may send data traffic to the PW redundancy group via the first PE device, or may receive data traffic from the PW redundancy group via the first PE device.
  • the communication link between the first CE device and the first PE device may be a physical link, or may be an aggregated link Ethernet (Eth-Trunk) chain composed of multiple physical links. road.
  • Et-Trunk aggregated link Ethernet
  • the network composed of the first PE device and the first CE device may be referred to as a local AC side network.
  • the second CE device is dual-homed to the second PE device and the third PE device in the VPWS PW redundant network by using a multi-chassis Trunk (MC-Trunk) link.
  • the MC-Trunk link can also be called an enhanced trunk (E-trunk).
  • the MC-Trunk link includes two member Eth-Trunk links. An Eth-Trunk link is disposed between the second CE device and the second PE device, and another Eth-Trunk link is disposed between the second CE device and the third PE device. between. On the MC-Trunk link, you need to configure the active/standby status of the two member Eth-Trunk links. As shown in FIG.
  • the Eth-Trunk link between the second CE device and the second PE device is determined to be a primary link, or an active Eth-Trunk link;
  • the Eth-Trunk link between the CE device and the third PE device is determined as a backup link or a standby Eth-Trunk link.
  • the network composed of the second PE device, the third PE device, and the second CE device may be referred to as a remote AC side network.
  • the CE device can be a switch or a router, and the PE device can be a router or a Layer 3 switch.
  • the VPWS PW redundant network shown in Figure 1 can be applied in a variety of scenarios.
  • the VPWS PW redundant network is applied to a Mobile Bearer Network.
  • a typical mobile bearer network is an Internet Protocol Radio Access Network (IP RAN).
  • IP RAN Internet Protocol Radio Access Network
  • the first CE device may be a Base Transceiver Station (BTS)
  • BSC Base Station Controller
  • Radio Network Controller Radio Network Controller
  • the RNC, the first PE device may be a base station side gateway (CSG), and the second PE device and the third PE device may be a base station controller side gateway (Radio Network Controller Site Gateway, RSG).
  • CSG base station side gateway
  • RSG Radio Network Controller Site Gateway
  • the VPWS PW redundant network is applied to a fixed network.
  • the first CE device and the second CE device may be a site on the user side, and the site may be located in a virtual private network (VPN), the first PE.
  • the device may be a Digital Subscriber Line Access Multiplexer (DSLAM), and the second PE device and the third PE device may be a Broadband Access Server (BAS).
  • DSLAM Digital Subscriber Line Access Multiplexer
  • BAS Broadband Access Server
  • the VPWS PW redundancy protection mechanism can operate in two modes: Master/Slave Mode and Independent Mode. Next, introduce the two working modes separately.
  • the first PE device determines the preferential forwarding status of the first PE device relative to the primary PW as an active state, and sends the information to the second PE device.
  • a PW status notification packet carrying an Active status code.
  • the priority forwarding state is used to indicate a forwarding state of the PW determined by the PE device.
  • the Active status code is used to indicate that the PW is an Active state for forwarding traffic. For example, according to RFC4447 or RFC6870 formulated by the IETF, the value of the Active Status Code is set to 0x00 (0x indicates hexadecimal).
  • the second PE device After receiving the PW status notification message carrying the active status code, the second PE device determines the priority forwarding status of the second PE device with respect to the primary PW as an active state, and sends the status to the first PE device. Returns the PW status notification packet carrying the Active status code. In this way, the first PE device and the second PE device both determine the priority forwarding state of the primary PW as the active state, and the priority forwarding states of the two ends of the primary PW are the same, so that the primary PW It is determined to be in the Active state. Moreover, the first PE device determines a priority forwarding state of the first PE device with respect to the backup PW as a standby state, and sends a PW status notification message carrying a Standby status code to the third PE device.
  • the Standby status code is used to indicate that the PW is a Standby state that does not forward traffic. For example, according to RFC4447 or RFC6870 formulated by the IETF, the value of the Standby status code is set to 0x20.
  • the third PE device determines the priority forwarding state of the third PE device with respect to the backup PW as a Standby state, and sends the status to the first PE device. Returns the PW status notification packet carrying the Standby status code. In this way, the first PE device and the third PE device both determine the priority forwarding state of the backup PW as a Standby state, and the priority forwarding states of the backup PWs are the same, so that the backup PW is the same.
  • the PW status notification packet may be a Label Distribution Protocol (LDP) packet.
  • LDP Label Distribution Protocol
  • the second CE device and the second PE device pass the Link Aggregation Control Protocol (LACP) packet, and the second CE device and the second PE device are The Eth-Trunk link is negotiated as the active link.
  • the second CE device and the third PE device negotiate an Eth-Trunk link between the second CE device and the third PE device as an alternate link by using an LACP packet.
  • the negotiation process between the PW side network and the remote AC side network is isolated from each other.
  • the first CE device and the second CE device can forward data traffic to each other through the primary PW and the primary link by using the foregoing negotiation process, where the forwarding path of the data traffic is: the first CE device- A PE device - a primary PW - a second PE device - a primary link - a second CE device.
  • the PW state of the PW network is determined by the Eth-Trunk link state of the remote AC network and the PW status notification message exchanged between the PW network. Specifically, the Eth-Trunk link between the second CE device and the second PE device is negotiated as the active link, and the Eth-Trunk link between the second CE device and the third PE device is negotiated as the backup. link. The first PE device determines that the local priority forwarding state is the active state, and sends a PW status notification message carrying the Active status code to the second PE device and the third PE device, respectively.
  • the local priority forwarding state determined by the second PE device is an active state, because the Eth-Trunk link between the second CE device and the second PE device is negotiated as the active link.
  • the second PE device compares the active status code of the PW status notification message with the local priority forwarding status, and is in an active state. Therefore, the second PE device compares the second PE device with respect to the second PE device.
  • the priority forwarding state of the primary PW is determined to be an active state, and a PW status notification message carrying an Active status code is sent to the first PE device. And because the Eth-Trunk link between the second CE device and the third PE device is negotiated as a backup device. With the link, the local preferential forwarding state determined by the third PE device is a Standby state.
  • the third PE device compares the active status code of the PW status notification message with the local priority forwarding status. Therefore, the third PE device preferentially forwards the second PE device with respect to the backup PW.
  • the status is determined to be in the Standby state, and the PW status notification message carrying the Standby status code is sent to the first PE device.
  • the first PE device compares the received PW status notification message carrying the Active status code, and compares the Active status code of the PW status notification message with the local priority forwarding status, which is an Active status. Therefore, the first PE device determines the priority forwarding state of the first PE device with respect to the primary PW as an active state. Thus, the primary PW is determined to be in an active state.
  • the first PE device notifies the packet according to the received PW status carrying the Standby status code, and compares the Active status code of the PW status notification message with the local priority forwarding status.
  • the first PE device determines a priority forwarding state of the first PE device with respect to the backup PW as a Standby state.
  • the backup PW is determined to be in the Standby state.
  • the first CE device and the second CE device can forward data traffic to each other through the primary PW and the primary link by using the foregoing negotiation process, where the forwarding path of the data traffic is: the first CE device- A PE device - a primary PW - a second PE device - a primary link - a second CE device.
  • the PW status notification packet may be an LDP packet.
  • only one PW is used to forward data traffic at any time.
  • multiple PWs can be set or multiple tunnels can be carried in one PW.
  • two PWs are disposed between the first PE device and the second PE device, one is a primary PW, and the other is a backup PW; correspondingly, the first PE device and the third PE device are Set two PWs, one for the main PW and the other for the backup PW.
  • Such an arrangement may enable the first PE device to simultaneously transmit data traffic to the second PE device and the third PE device based on different PW redundancy groups.
  • a PW is set between the first PE device and the second PE device, and the PW includes multiple tunnels; correspondingly, a first setting between the first PE device and the third PE device is set.
  • PW the PW includes a plurality of tunnels.
  • Such an arrangement may enable the first PE device to simultaneously transmit data traffic to the second PE device and the third PE device based on different tunnel redundancy groups.
  • two PWs in each PW redundancy group or two tunnels in each tunnel redundancy group are required to maintain one primary and one standby, and only one PW or one tunnel is used to forward data traffic. Real traffic balancing is not possible.
  • the embodiment of the present application provides a method for forwarding a packet, so as to implement the function of balancing traffic on the basis of the redundancy protection function of the primary PW and the backup PW in the VPWS PW, and improve the bandwidth utilization of the VPWS PW.
  • traffic balancing can also be referred to as load sharing. Traffic balancing is equivalent to load sharing without adding special instructions.
  • FIG. 3 is a flowchart of a method for forwarding a message according to an embodiment of the present application.
  • the method shown in FIG. 3 can be applied to the VPWS PW redundant network shown in FIG. 1 and FIG. 2, the VPWS PW redundant network includes a first PE device, a second PE device, and a third PE device, where the A primary PW is established between the PE device and the second PE device, and a backup PW is established between the first PE device and the third PE device, and the second PE device and the third PE device are The Bypass PW was established between.
  • the forwarding state of the VPWS PW redundant network shown in FIG. 1 the forwarding state of the VPWS PW redundant network is switched to the forwarding state shown in FIG. 2 by applying the method shown in FIG. 3.
  • the method includes:
  • the first PE device sends a first packet to the second PE device, where the first packet is used for The master PW is switched from the Active state to the Balance state.
  • the first PE device sends a second packet to the third PE device, where the second packet is used to request that the backup PW be switched from a Standby state to a Balance state.
  • the first CE device and the second CE device can mutually forward data traffic through the primary PW and the primary link through a negotiation process, and the data traffic forwarding path is : First CE device - first PE device - primary PW - second PE device - primary link - second CE device. That is, the state of the primary PW is an Active state in which data traffic is forwarded, and the state of the backup PW is a Standby state in which data traffic is not forwarded.
  • the first PE device sends the first packet to the second PE device by using the primary PW, where the first packet is used to request that the primary PW be switched from an active state to a Balance state.
  • the Balance state is used to indicate that data traffic is forwarded in a traffic-balanced manner.
  • the first packet is a PW status notification packet carrying a Balance status code.
  • the Balance status code is used to indicate that the PW is a Balance state for forwarding traffic. Since the current state of the primary PW is an active state, the Balance state code can be regarded as indicating that the primary PW is switched from an Active state to a Balance state.
  • the PW status notification packet may be an LDP packet.
  • the value of the Balance status code can be set, for example, to 0x30.
  • the first PE device sends the second packet to the third PE device via the backup PW, where the second packet is used to request that the backup PW be in a Standby state.
  • the Balance state is used to indicate that data traffic is forwarded in a traffic balanced manner.
  • the second packet is a PW status notification packet carrying a Balance status code.
  • the Balance status code is used to indicate that the PW is a Balance state for forwarding traffic. Since the current state of the backup PW is a Standby state, the Balance state code can be regarded as indicating that the backup PW is switched from the Standby state to the Balance state.
  • the PW status notification packet may be an LDP packet.
  • the value of the Balance status code can be set, for example, to 0x30.
  • the present embodiment does not limit the sequence of execution of S101 and S102. It should be understood that S101 may be performed before S102; S101 may also be executed after S102; S101 may also be executed simultaneously with S102.
  • the second PE device receives the first packet.
  • the third PE device receives the second packet.
  • the second PE device receives, by using the primary PW, a PW status notification message that carries a Balance status code from the first PE device.
  • the third PE device receives, by the backup PW, a PW status notification message carrying the Balance status code from the first PE device.
  • the third PE device forwards the second packet to the second PE device by using the Bypass PW.
  • the second PE device receives the second packet.
  • the third PE device is between the second PE device and the third PE device.
  • the bypass PW forwards the PW status notification message to the second PE device.
  • the second PE device receives the PW status notification message via the Bypass PW.
  • the second PE device generates a response packet according to the first packet and the second packet, and switches the priority forwarding state of the second PE device relative to the primary PW from an Active state to a Balance. State, And switching the priority forwarding state of the second PE device relative to the Bypass PW from the Bypass state to the Balance state.
  • the second PE device determines that both PW status notification messages carry a Balance status code to generate a response message, and the response is generated.
  • the message indicates that the switching request of the two PW status notification messages is agreed.
  • the PW status notification message is sent by the first PE device by using the primary PW, and the other PW status notification message is the first PE device.
  • the backup PW is sent by the second PE device and the Bypass PW.
  • the second PE device also switches the priority forwarding state of the second PE device with respect to the primary PW from the active state to the Balance state and the priority forwarding state of the second PE device to the BypassPW by Bypass The state is switched to the Balance state.
  • the beneficial effect that the second PE device switches the preferential forwarding state of the second PE device with respect to the bypass PW to the Balance state is that the second CE device sends data to the first CE device. After the traffic reaches the second PE device via the primary link of the remote AC side network, the data traffic may be equalized by the second PE device to the primary PW and the Bypass PW for transmission.
  • the second PE device sends the response packet to the first PE device by using the primary PW, and sends the response packet to the third PE device by using the Bypass PW, the response packet.
  • the text is used to indicate that the handover request of the first message and the second message is agreed.
  • the response message may be a PW status notification message carrying a Balance status code
  • the PW status notification message may be an LDP message.
  • the second PE device may copy the response message into two or directly generate two response messages, that is, obtain two PW status notification messages carrying a Balance status code. Therefore, the second PE device sends the response message to the first PE device via the primary PW and the response message to the third PE device via the Bypass PW.
  • the first PE device receives the response packet.
  • the first PE device switches the priority forwarding state of the first PE device relative to the primary PW from an Active state to a Balance state according to the response packet, and compares the first PE device with respect to the first PE device.
  • the priority forwarding state of the backup PW is switched from the Standby state to the Balance state.
  • the first PE device when the first PE device receives the response packet, the first PE device can confirm that the second PE device receives the first report sent by the first PE device by using the primary PW. And a second packet sent by the first PE device via the backup PW and the Bypass PW, and the second PE device has forwarded the priority status and location of the second PE device relative to the primary PW.
  • the priority forwarding state of the Bypass PW is switched to the Balance state. Therefore, the first PE device may switch the priority forwarding state of the first PE device relative to the primary PW from an Active state to a Balance state according to the response packet, and compare the first PE device with respect to the first PE device.
  • the priority forwarding state of the backup PW is switched from the Standby state to the Balance state.
  • the second PE device has switched the priority forwarding state of the second PE device relative to the primary PW from an Active state to a Balance state. Since the devices at both ends of the primary PW switch their own preferential forwarding state with respect to the primary PW to the Balance state, the primary PW is determined to be in the Balance state, and the corresponding handover is completed.
  • the third PE device receives the response packet.
  • the third PE device compares the third PE device with respect to the backup according to the response packet.
  • the PW priority forwarding state is switched from the Standby state to the Balance state, and the priority forwarding state of the third PE device relative to the Bypass PW is switched from the Bypass state to the Balance state.
  • the third PE device can confirm that the second PE device receives the first report sent by the first PE device by using the primary PW. And a second packet sent by the first PE device via the backup PW and the Bypass PW, and the second PE device has forwarded the priority status and location of the second PE device relative to the primary PW.
  • the priority forwarding state of the Bypass PW is switched to the Balance state. Therefore, the third PE device may switch the priority forwarding state of the third PE device relative to the backup PW from a Standby state to a Balance state according to the response message, and compare the third PE device with respect to the third PE device.
  • the priority forwarding state of the Bypass PW is switched from the Bypass state to the Balance state.
  • the second PE device has switched the priority forwarding state of the second PE device with respect to the Bypass PW from the Bypass state to the Balance state, and the first PE device has already performed the The priority forwarding state of a PE device relative to the backup PW is switched from the Standby state to the Balance state. Thereby, the backup PW and the Bypass PW are determined to be in a Balance state, and the corresponding handover is completed.
  • the forwarding state of the VPWS PW redundant network is as shown in FIG. 2.
  • the first PE device may perform traffic balancing calculation on the data traffic from the first CE device based on a hash algorithm.
  • the first PE device sends a part of the traffic of the data traffic to the second PE device by the primary PW, and reaches the second CE device via a primary link; the first PE device further Another portion of the traffic of the data traffic will be sent by the backup PW to the third PE device and to the second CE device via the Bypass PW, the second PE device, and the primary link.
  • the second PE device may perform traffic balancing calculation on the data traffic based on a hash algorithm.
  • the traffic reaches the first PE device via the primary PW, and another portion of the traffic reaches the first PE device via the Bypass PW, the third PE device, and the backup PW.
  • the calculation principle of the traffic balancing calculation is not limited.
  • the traffic may be allocated evenly, or the traffic may be allocated according to the bandwidth of two PWs, or the traffic may be allocated according to the service type of the traffic.
  • the first PE device sends a request message requesting to switch to the Balance state to the second PE device and the third PE device via the primary PW and the backup PW, respectively;
  • the second PE device is via the primary PW and via The backup PW, the third PE device, and the Bypass PW receive two request messages;
  • the second PE device switches the priority forwarding state of the second PE device with respect to the primary PW and the Bypass PW.
  • the first PE device compares the first PE device with respect to the primary PW according to the response packet
  • the priority forwarding state of the backup PW is switched to the Balance state
  • the third PE device switches the priority forwarding state of the third PE device with respect to the Bypass PW to a Balance state according to the response packet. Therefore, based on the redundancy protection function of the primary PW and the backup PW in the VPWS PW, the traffic balance between the primary PW and the backup PW is implemented, which helps improve the bandwidth utilization of the VPWS PW.
  • the first packet and the second packet carry a PW status code, where the PW status code is used to indicate that the status of the PW is a Balance state.
  • the first packet and the second packet may be LDP packets, where the LDP packet is used.
  • the PW status code carries a Balance status code, and the value of the Balance status code can be set, for example, to 0x30.
  • the method further includes: determining, by the first PE device, that the bandwidth usage of the first PE device to send traffic to the second PE device exceeds a predetermined threshold.
  • the PW forwarding mode of the VPWS PW has been negotiated as the scenario shown in FIG. 1, and the data traffic is forwarded through the active primary PW, and the backup PW is in the Standby state.
  • the first PE device can periodically detect the bandwidth usage of the outbound interface of the first PE device, and the outbound interface is used to connect to the primary PW, that is, the detection of the first PE device period. Traffic to the primary PW in the Active state. When the bandwidth occupancy exceeds a predetermined threshold, it indicates that the primary PW may be overloaded or congested.
  • the first PE device triggers execution of S101, that is, triggers the process shown in FIG. 3, based on the case where the bandwidth usage exceeds a predetermined threshold.
  • the VPWS PW can automatically select a redundant mode forwarding data traffic and a traffic balancing mode to forward data traffic according to the bandwidth condition of the forwarding traffic.
  • the selection of the threshold is not limited, for example, using the rated bandwidth of the PW as a threshold or being configured by an operator.
  • the method further includes: the first PE device determines that the first PE device sends a traffic to the second PE device for a predetermined period of time.
  • the PW forwarding mode of the VPWS PW has been negotiated as the scenario shown in FIG. 1, and the data traffic is forwarded through the active primary PW, and the backup PW is in the Standby state.
  • the first PE device triggers the execution of S101 after the predetermined time period elapses from the time when the first PE device sends the traffic to the second PE device, that is, the process shown in FIG. 3 is triggered.
  • the data traffic is forwarded to the traffic balancing mode.
  • the method further includes: determining, by the second PE device, that the bandwidth usage of the outbound interface that the second PE device sends the traffic to the third PE device is less than a predetermined threshold.
  • the PW link is carried on the physical link. Therefore, the physical link may also transmit non-PW traffic.
  • the non-PW traffic refers to traffic that is transmitted via a physical link carrying the PW link without being transmitted via the PW link.
  • the total bandwidth of the physical link is fixed. If the bandwidth of the non-PW traffic on the physical link is too high, the bandwidth of the PW link carried by the physical link is reduced. Therefore, even if there is no traffic on the PW link, the non-PW traffic overload of the physical link may occur, resulting in congestion or poor communication quality of the PW link.
  • the second PE device sends the second PE device to the second PE device and the third PE device before generating the response packet according to the first packet and the second packet.
  • the traffic on the physical link is detected, that is, the second PE device detects the bandwidth occupancy rate of the outbound interface that the second PE device sends the traffic to the third PE device.
  • the bandwidth usage of the outbound interface is less than a predetermined threshold
  • the bypass PW carried on the physical link between the second PE device and the third PE device has a remaining bandwidth carrying PW traffic. Based on the foregoing implementation manner, it helps to reduce the unsuccessful negotiation of the traffic balancing mode, and helps reduce the congestion of the link after switching to the traffic balancing mode.
  • the method further includes: determining, by the second PE device, that the bandwidth usage of the outbound interface that the second PE device sends the traffic to the third PE device is greater than or equal to a predetermined threshold, where The second PE device generates a reject message, and sends the reject message to the first PE device and the third PE device via the Bypass PW via the primary PW, where the reject message is used.
  • the indication disagrees with the first message And a switching request of the second message.
  • the reject packet when the bandwidth usage of the outbound interface of the second PE device is greater than or equal to a predetermined threshold, the reject packet is generated, and the first PE device and the third PE device are generated.
  • the notification is rejected.
  • the first PE device and the third PE device terminate the negotiation process of switching to the traffic balancing mode.
  • the acknowledgment message is a PW status notification message carrying a refusal status code
  • the PW status notification message may be an LDP message.
  • the value of the rejection status code can be set, for example, to 0x31.
  • the method further includes: determining, by the third PE device, that the bandwidth usage of the outbound interface that the third PE device sends the traffic to the second PE device is less than a predetermined threshold.
  • the method further includes: determining, by the third PE device, that the bandwidth usage of the outbound interface that the third PE device sends the traffic to the second PE device is greater than or equal to a predetermined threshold, where And the third PE device generates a reject message, and sends the reject message to the first PE device by using the backup PW, where the reject message is used to indicate that the second message is different from the handover request.
  • the third PE device based on the implementation manner of detecting the bandwidth occupancy rate of the interface with the second PE device, the third PE device receiving the message that the first PE device sends via the backup PW After the second packet, the bandwidth usage of the outbound interface that the third PE device sends the traffic to the second PE device is determined to be less than a predetermined threshold. If the third PE device determines that the bandwidth occupancy rate of the outbound interface that the third PE device sends the traffic to the second PE device is less than a predetermined threshold, step S105 is performed.
  • the third PE device determines that the bandwidth usage of the outbound interface that the third PE device sends the traffic to the second PE device is greater than or equal to a predetermined threshold, and the third PE device generates a reject packet, and the The backup PW sends the reject message to the first PE device.
  • the method shown in FIG. 3 will not perform the corresponding steps of S105-S112.
  • FIG. 4 is a schematic structural diagram of still another VPWS PW redundant network according to an embodiment of the present application.
  • FIG. 4 is a scenario diagram of a failure occurring based on the traffic balancing forwarding mode shown in FIG. Fault 1, Fault 2, Fault 3, Fault 4, Fault 5, and Fault 6 are shown in FIG. It should be understood that the scenario presented in FIG. 4 does not mean that the above six types of faults occur at the same time, but represents the location where the above six faults occur.
  • the next embodiment of the present application will discuss the processing of each fault. Moreover, the following embodiments only discuss the case where one type of failure occurs at the same time, and the case where two or more types of failures occur simultaneously is not discussed.
  • FIG. 5 is a flowchart showing a method of processing fault 1 in FIG. 4, and the method shown in FIG. 5 is a fault processing after fault 1 occurs in the case where the traffic balancing manner shown in FIG. 2 has been implemented.
  • the fault 1 refers to the fault of the primary PW between the first PE device and the second PE device.
  • the method includes:
  • the first PE device determines that the fault detection packet from the second PE device cannot be received within a predetermined period.
  • the data traffic sent from the first CE device to the second CE device, and the data traffic sent from the second CE device to the first CE device are all allocated to the primary PW and the backup PW in a traffic-balanced manner.
  • the first PE device may send a fault detection message to the second PE device by using the primary PW, and correspondingly, the second PE device may go to the primary PW through the primary PW.
  • the first PE device sends a fault detection message, that is, the first PE device and the second PE device send the fault detection message in both directions.
  • the fault detection message is used to indicate a fault of the PW link or the PE device.
  • the fault detection packet may be sent according to a predetermined time interval, and the fault detection packet may be a Bidirectional Forwarding Detection (BFD) packet. If the first PE device does not receive the fault detection message sent by the second PE device, the first device may determine that the primary PW or the second PE device is faulty. (This embodiment takes the failure of the primary PW as an example, and the failure of the second PE device can be referred to the subsequent embodiment).
  • BFD Bidirectional Forwarding Detection
  • the first PE device switches the priority forwarding state of the first PE device with respect to the primary PW from a Balance state to a Standby state, and sends a third packet to the second PE device, where the The three messages are used to request that the primary PW be switched from the Balance state to the Standby state.
  • the first PE device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to an Active state, and sends a fourth packet to the third PE device, where the The fourth message is used to request that the backup PW be switched from the Balance state to the Active state.
  • the first PE device After the first PE device fails to receive the fault detection message from the second PE device, the first PE device switches the priority forwarding state of the first PE device relative to the primary PW from the Balance state to the Balance state. a Standby state, and sending a third message to the second PE device via the primary PW.
  • the third packet may be a PW status notification message carrying a Standby status code, and the PW status notification message may be an LDP message, and the Standby status code is, for example, 0x20.
  • the first PE device also switches the priority forwarding state of the first PE device relative to the backup PW from the Balance state to the Active state, and sends the third PE device to the third PE device via the backup PW.
  • the fourth packet may be a PW status notification message carrying an Active status code, and the PW status notification message may be an LDP message, and the Active status code is, for example, 0x00.
  • the first PE device does not limit the execution sequence.
  • the S203 may be executed after the S202 is executed, or the S202 may be executed after the S203 is executed.
  • the third packet may not be received by the second PE device due to the failure of the primary PW. In this case, the first PE device still sends the third packet to reduce the complexity of performing the operation of the first PE device.
  • the third packet may also carry a fault code.
  • the third packet may be regarded as a combined packet of a handover packet and a fault notification packet.
  • the third packet may not use the PW status notification packet carrying the Standby status code, but the LDP packet carrying the fault status code.
  • the third PE device receives the fourth packet.
  • the third PE device switches the priority forwarding state of the third PE device relative to the backup PW from a Balance state to an Active state according to the fourth packet.
  • the third PE device receives the PW status notification message carrying the Active status code via the backup PW, and switches the backup PW from the Balance state to the Active state according to the PW status notification message.
  • the second PE device determines that the fault detection packet from the first PE device cannot be received within a predetermined period.
  • S206 and S201 do not limit the execution order, and all are triggered according to the fault detection message. After the failure of the primary PW, if the fault detection message is sent in both directions, the second PE device will not receive the fault detection message from the first PE device within a predetermined period. For the implementation of the fault detection message, see the above. The corresponding description of S201 is not described herein.
  • the PW link is a bidirectional link. Even if the PW link fails in a single direction, the PEs of both parties cannot receive the fault detection packet.
  • the first PE device and the second PE device send BFD packets to each other, assuming that the first PE device fails in the direction of the second PE device, and the first PE device arrives at the device. Normal communication in the direction of the first PE device.
  • the second PE device will not be able to receive the BFD packet from the first PE device, and the second PE device will set the port to the DOWN, so that the second PE device is no longer to the first PE.
  • the device sends BFD packets. Therefore, the first PE device cannot receive the BFD packet from the second PE device.
  • the second PE device switches the priority forwarding state of the second PE device with respect to the primary PW from a Balance state to a Standby state, and sends a fault notification message to the first PE device, where the fault occurs.
  • the advertisement message is used to notify the first PE device of the fault discovered by the second PE device.
  • the second PE device switches the priority forwarding state of the second PE device with respect to the Bypass PW from a Balance state to a Bypass state, and sends a termination packet to the third PE device, where the termination message is sent.
  • the text is used to indicate the termination of the Balance state of the Bypass PW.
  • the second PE device After the second PE device fails to receive the fault detection message from the first PE device, the second PE device switches the priority forwarding state of the second PE device relative to the primary PW from the Balance state to the Balance state. a Standby state, and sending a fault notification message to the first PE device via the primary PW.
  • the fault notification packet may be an LDP packet.
  • the second PE device also switches the priority forwarding state of the second PE device relative to the Bypass PW from a Balance state to a Bypass state, and sends a termination to the third PE device via the Bypass PW.
  • the termination message is a PW status notification message carrying a termination status code
  • the PW status notification message may be an LDP message
  • the termination status code is, for example, 0x32.
  • the fault notification message may not be received by the first PE device due to a failure of the primary PW.
  • the third PE device receives the termination packet.
  • the third PE device switches the priority forwarding state of the third PE device relative to the Bypass PW from a Balance state to a Bypass state according to the termination message.
  • the third PE device receives the PW status notification message carrying the termination status code via the Bypass PW, and forwards the priority status of the third PE device relative to the Bypass PW according to the PW status notification message. Switch from the Balance state to the Bypass state.
  • the forwarding mode of the VPWS PW redundant network is switched from the traffic balancing mode to the redundant protection mode. And because the primary PW fails, the data traffic forwarding path is: the first CE device - the first PE device - the backup PW - the third PE device - the Bypass PW - the second PE device - the primary link - the second CE device.
  • the VPWS PW redundant network may enter the traffic balancing mode again according to the implementation shown in FIG. 3.
  • FIG. 6 shows a flow chart of a method for processing fault 2 in FIG. 4, and the method shown in FIG. 6 is a fault processing after fault 2 occurs in the case where the forwarding mode of the traffic equalization shown in FIG. 2 has been implemented.
  • the fault 2 is that the backup PW between the first PE device and the third PE device is faulty.
  • the method includes:
  • the first device determines that the fault detection message from the third PE device cannot be received within a predetermined period.
  • the first device switches the priority forwarding state of the first PE device with respect to the primary PW from the Balance state to the Active state, and sends a third packet to the second PE device, where the third packet is used.
  • the request is to switch the primary PW from the Balance state to the Active state.
  • the first device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to a Standby state, and sends a fourth packet to the third PE device, where the fourth packet is sent.
  • the message is used to request that the backup PW be switched from the Balance state to the Standby state.
  • the third packet, and the fourth packet refer to the corresponding description of S201-S203 in the foregoing embodiment, and details are not described herein.
  • the first PE device does not limit the execution sequence when executing S302 and S303.
  • the S302 may be executed after S302 is executed first, or S302 may be executed after S303 is executed first, or may be performed at the same time.
  • the fourth packet may not be received by the third PE device due to a backup PW failure. In this case, the first PE device still sends the fourth packet to reduce the complexity of performing the operation of the first PE device.
  • the fourth packet may also carry a fault code.
  • the fourth packet may be regarded as a combined packet of a handover packet and a fault notification packet.
  • the fourth packet may not use a PW status notification message carrying a Standby status code, but an LDP message carrying a fault status code.
  • the second PE device receives the third packet.
  • the second PE device switches the priority forwarding state of the second PE device relative to the primary PW from a Balance state to an Active state according to the third packet.
  • the second PE device receives the PW status notification message carrying the Active status code via the primary PW, and switches the primary PW from the Balance state to the Active state according to the PW status notification message.
  • the third PE device determines that the fault detection packet from the first PE device cannot be received within a predetermined period.
  • the third PE device switches the priority forwarding state of the third PE device with respect to the backup PW from a Balance state to a Standby state, and sends a failure notification message to the first PE device, where the fault occurs.
  • the advertisement message is used to notify the first PE device of the fault discovered by the third PE device.
  • the third PE device switches the priority forwarding state of the third PE device with respect to the Bypass PW from the Balance state to the Bypass state, and sends a termination packet to the second PE device, where the termination packet is used. Instructing to terminate the Balance state of the Bypass PW.
  • the fault detection packet the fault notification packet, and the termination packet, refer to the corresponding descriptions of S206-S208 in the foregoing embodiment, and details are not described herein.
  • the second PE device receives the termination packet.
  • the second PE device switches the Bypass PW from a Balance state to a Bypass state according to the termination message.
  • the second PE device receives the PW status notification message carrying the termination status code via the Bypass PW, and forwards the priority status of the second PE device to the Bypass PW according to the PW status notification message. Switch from the Balance state to the Bypass state.
  • the forwarding mode of the VPWS PW redundant network is performed by the flow
  • the quantity equalization mode is switched to the redundancy protection mode.
  • the data traffic forwarding path is: the first CE device - the first PE device - the primary PW - the second PE device - the primary link - the second CE device.
  • the VPWS PW redundant network may enter the traffic balancing mode again according to the implementation shown in FIG. 3.
  • FIG. 7 shows a flowchart of a method for processing fault 3 in FIG. 4, and the method shown in FIG. 7 is a fault processing after fault 3 occurs in the case where the traffic balancing manner shown in FIG. 2 has been implemented.
  • the fault 3 is that the primary link between the second PE device and the second CE device is faulty.
  • the method includes:
  • the second PE device determines that the fault detection message from the second CE device cannot be received within a predetermined period.
  • the second CE device is dual-homed to the second PE device and the third PE device in the VPWSPW redundant network through an MC-Trunk link.
  • the Eth-Trunk link between the second CE device and the second PE device is negotiated as the active link and the second CE device is The Eth-Trunk link between the third PE devices negotiates as the standby link.
  • the data traffic sent from the first CE device passes through "first PE device - primary PW - second PE device - primary link” and "first PE device - backup PW” - the third PE device - the Bypass PW - the second PE device - the primary link "two paths are forwarded to the second CE device; the data traffic sent from the second CE device passes through the "primary link” Two paths of the second PE device - primary PW - first PE device and " primary link - second PE device - Bypass PW - third PE device - backup PW - first PE device" are forwarded to the first CE equipment.
  • the second PE device and the second CE device send a fault detection message to each other, and when the second PE device determines that the fault detection message from the second CE device cannot be received within a predetermined period, the The second device can determine that the primary link has failed.
  • the fault detection packet and the fault detection packet are described in the foregoing embodiment, and details are not described herein.
  • the second PE device determines that the priority forwarding state of the second PE device relative to the primary PW is a Balance state, maintains a Balance state with respect to the primary PW, and does not send the switch to the first PE device.
  • the second CE device determines that the fault detection message from the second CE device cannot be received within a predetermined period, correspondingly, the second CE device determines that the second period cannot be received from the second Fault detection packet of the PE device. In this way, the second CE device will trigger the active/standby switchover of the primary link and the standby link of the remote AC side network, thereby switching data traffic to the standby link.
  • the PW side network remains unchanged. . That is, the primary PW remains in an active state, and the backup PW remains in a Standby state.
  • the data traffic sent from the first CE device is sent to the second CE device via the “first PE device-primary PW-second PE device-Bypass PW-third PE device-standby link”.
  • the PW side network will follow the remote AC side.
  • the active/standby relationship of the network is switched. That is, the primary PW maintains a Standby state, and the backup PW remains in an Active state.
  • the data traffic sent from the first CE device is sent to the second CE device through the “first PE device-backup PW-third PE device-standby link”.
  • the primary PW and the backup PW are in a Balance state. Therefore, in the master/slave mode and the independent mode, the second PE device determines that the state of the primary PW is a Balance state, maintains the Balance state of the primary PW, and does not send the first PE device for switching the primary PW's Balance state message. In this way, the second PE device does not switch the Balance priority forwarding state of the second PE device with respect to the primary PW, and does not send any trigger packet to the first PE device.
  • the first PE device maintains the Balance priority forwarding state of the first PE device with respect to the primary PW and the Balance priority forwarding state of the backup PW, further causing the third PE device to maintain the third The Balance priority forwarding state of the PE device with respect to the backup PW.
  • the PW side network still maintains the traffic balance mode. For example, the data traffic sent from the first CE device passes through "first PE device - primary PW - second PE device - Bypass PW - third PE device - backup link" and "first PE device - backup PW" - The third PE device - the alternate link" two paths are forwarded to the second CE device.
  • FIG. 8 is a flowchart showing a method of processing the fault 4 in FIG. 4, and the method shown in FIG. 8 is a fault processing after the fault 4 occurs in the case where the forwarding mode of the traffic equalization shown in FIG. 2 has been implemented.
  • the fault 4 refers to the fault of the second PE device.
  • the method includes:
  • the first PE device determines that the fault detection packet from the second PE device cannot be received within a predetermined period.
  • the first PE device switches the priority forwarding state of the first PE device to the primary PW from a Balance state to a Standby state, and sends a third packet to the second PE device, where the third packet is sent.
  • the text is used to request that the primary PW be switched from the Balance state to the Standby state.
  • the first PE device switches the priority forwarding state of the first PE device to the backup PW from the Balance state to the Active state, and sends a fourth packet to the third PE device, where the fourth packet is used by the fourth packet.
  • the third PE device receives the fourth packet.
  • the third PE device switches the priority forwarding state of the third PE device relative to the backup PW from a Balance state to an Active state according to the fourth packet.
  • the second PE device cannot accept the third packet due to a fault, but in order to reduce the complexity of performing the operation of the first PE device, the first PE device still goes to the first The second PE device sends the third packet.
  • the third PE device determines that the fault detection message from the second PE device cannot be received within a predetermined period.
  • the second PE device and the third PE device send a fault detection message to each other via the Bypass PW, that is, the second PE device cycle is
  • the third PE device sends a fault detection message, and the third PE device periodically sends a fault detection message to the second PE device.
  • the fault detection message may be a BFD packet. If the third PE device does not receive the fault detection message sent by the second PE device via the Bypass PW within a predetermined period, the third device may determine the Bypass PW or the second The PE device is faulty. In this embodiment, the fault occurs on the second PE device. For the fault of the bypass PW, see the subsequent embodiment.
  • the third PE device forwards the priority status of the third PE device to the Bypass PW by The balance state is switched to the bypass state, and the termination message is sent to the first PE device, where the termination message is used to indicate that the Balance state of the Bypass PW is terminated.
  • the third PE device After the third PE device fails to receive the fault detection message from the second PE device within a predetermined period, the third PE device preferentially forwards the third PE device with respect to the bypass PW.
  • the state is switched from the Balance state to the Bypass state, and the termination message is sent to the first PE device via the backup PW.
  • the termination packet For the implementation of the termination packet, refer to the corresponding description in the foregoing S208, and details are not described herein.
  • the third PE device sends a termination message to the second PE device via the Bypass PW.
  • the termination message cannot be received by the second PE device due to the failure of the second PE device.
  • the third PE device sends the termination message to reduce the complexity of performing operations of the third PE device.
  • the first PE device determines, according to the termination packet, that the Bypass PW is switched from a Balance state to a Bypass state.
  • the subsequent data traffic is forwarded, which may reduce the possibility of packet loss.
  • the second CE device triggers the active/standby switchover of the primary link and the backup link of the remote AC side network, so that the data traffic is switched to the standby link.
  • the forwarding mode of the VPWS PW redundant network is switched from the traffic balancing mode to the redundant protection mode.
  • the data traffic forwarding path is: the first CE device - the first PE device - the backup PW - the third PE device - the backup link - the second CE device.
  • the VPWS PW redundant network may enter the traffic balancing mode again according to the implementation shown in FIG. 3.
  • FIG. 9 is a flowchart showing a method of processing the fault 5 in FIG. 4, and the method shown in FIG. 9 is a fault processing after the fault 5 occurs in the case where the forwarding mode of the traffic equalization shown in FIG. 2 has been implemented.
  • the fault 5 refers to the fault of the third PE device.
  • the method includes:
  • the first device determines that the fault detection message from the third PE device cannot be received within a predetermined period.
  • the first device switches the priority forwarding state of the first PE device with respect to the primary PW from the Balance state to the Active state, and sends a third packet to the second PE device, where the third packet is used.
  • the request is to switch the primary PW from the Balance state to the Active state.
  • the first device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to a Standby state, and sends a fourth packet to the third PE device, where the fourth packet is sent.
  • the message is used to request that the backup PW be switched from the Balance state to the Standby state.
  • the second PE device receives the third packet.
  • the second PE device switches the priority forwarding state of the second PE device relative to the primary PW from a Balance state to an Active state according to the third packet.
  • the third PE device cannot accept the fourth packet due to a fault, but in order to reduce the complexity of performing the operation of the first PE device, the first PE device still goes to the first The third PE device sends the fourth packet.
  • the second PE device determines that the fault detection from the third PE device cannot be received within a predetermined period. Test message.
  • the second PE device and the third PE device send a fault detection message to each other via the Bypass PW, that is, the second PE device cycle is
  • the third PE device sends a fault detection message, and the third PE device periodically sends a fault detection message to the second PE device.
  • the fault detection message may be a BFD packet. If the second PE device does not receive the fault detection message sent by the third PE device via the Bypass PW within a predetermined period, the second device may determine the Bypass PW or the third The PE device is faulty. In this embodiment, the third PE device is faulty.
  • the bypass PW fault refer to the following examples.
  • the second PE device switches the priority forwarding state of the second PE device to the bypass PW from the Balance state to the Bypass state, and sends a termination packet to the first PE device, where the termination packet is used. Instructing to terminate the Balance state of the Bypass PW.
  • the second PE device After the second PE device fails to receive the fault detection message from the third PE device within a predetermined period, the second PE device forwards the second PE device preferentially with respect to the bypass PW.
  • the state is switched from the Balance state to the Bypass state, and the termination message is sent to the first PE device via the primary PW.
  • the termination packet For the implementation of the termination packet, refer to the corresponding description in the foregoing S208, and details are not described herein.
  • the second PE device sends a termination message to the third PE device via the Bypass PW.
  • the termination message cannot be received by the third PE device due to the failure of the third PE device.
  • the sending, by the second PE device, the termination message is to reduce the complexity of performing the operation of the second PE device.
  • the first PE device determines, according to the termination packet, that the Bypass PW is switched from a Balance state to a Bypass state.
  • the subsequent data traffic is forwarded, which may reduce the possibility of packet loss.
  • the forwarding mode of the VPWS PW redundant network is switched from the traffic balancing mode to the redundant protection mode.
  • the data traffic forwarding path is: the first CE device - the first PE device - the primary PW - the second PE device - the primary link - the second CE device.
  • the VPWS PW redundant network may enter the traffic balancing mode again according to the implementation shown in FIG. 3.
  • FIG. 10 is a flowchart showing a method of processing the fault 6 in FIG. 4, and the method shown in FIG. 10 is a fault processing after the fault 6 occurs in the case where the traffic balancing manner shown in FIG. 2 has been implemented. Method to realize.
  • the fault 6 indicates that the Bypass PW between the second PE device and the third PE device is faulty.
  • the method includes:
  • the second PE device determines that the fault detection packet from the third PE device cannot be received within a predetermined period.
  • the second PE device switches the priority forwarding state of the second PE device to the bypass PW from the Balance state to the Bypass state, and sends a termination packet to the first PE device, where the termination packet is used. Instructing to terminate the Balance state of the Bypass PW.
  • the third PE device determines that the fault detection report from the second PE device cannot be received within a predetermined period. Text.
  • the third PE device switches the priority forwarding state of the third PE device with respect to the Bypass PW from the Balance state to the Bypass state, and sends a termination packet to the first PE device, where the termination packet is used to indicate Terminate the Balance state of the Bypass PW.
  • the first PE device receives a termination packet from the second PE device and the third PE device.
  • the first PE device may determine that the Bypass PW is faulty according to the situation that the termination packet from the second PE device and the termination packet from the third PE device are received, and triggers S706. And step S707.
  • the first device switches the priority forwarding state of the first PE device relative to the primary PW from the Balance state to the Active state, and sends a third packet to the second PE device, where the third packet is used.
  • the request is to switch the primary PW from the Balance state to the Active state.
  • the first device switches the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to a Standby state, and sends a fourth packet to the third PE device, where the fourth packet is sent.
  • the message is used to request that the backup PW be switched from the Balance state to the Standby state.
  • the second PE device receives the third packet.
  • the second PE device switches the priority forwarding state of the second PE device relative to the primary PW from a Balance state to an Active state according to the third packet.
  • the second PE device receives, by using the primary PW, a PW status notification message carrying an Active status code, and the second PE device is compared to the primary according to the PW status notification message.
  • the priority forwarding state of the PW is switched from the Balance state to the Active state.
  • the third PE device receives the fourth packet.
  • the third PE device switches the priority forwarding state of the third PE device relative to the backup PW from a Balance state to a Standby state according to the fourth packet.
  • the third PE device receives, by using the backup PW, a PW status notification message carrying a Standby status code, and the first PE device is compared to the backup according to the PW status notification message.
  • the priority forwarding state of the PW is switched from the Balance state to the Standby state.
  • the forwarding mode of the VPWS PW redundant network is switched from the traffic balancing mode to the redundant protection mode. And because the Bypass PW is faulty, the data traffic forwarding path is: the first CE device - the first PE device - the primary PW - the second PE device - the primary link - the second CE device. After the fault 6 is excluded, the VPWS PW redundant network may enter the traffic again according to the implementation manner shown in FIG. Equilibrium mode.
  • FIG. 11 to FIG. 16 are schematic diagrams of respective PE structures and hardware of the VPWS PW redundant network in the present application, where the VPWS PW redundant network includes a first PE device, a second PE device, and a third PE device, the first A primary PW is established between the PE device and the second PE device, and a backup PW is established between the first PE device and the third PE device, and the second PE device and the third PE device are configured.
  • a bypass pseudowire, Bypass PW is established.
  • FIG. 11 is a schematic structural diagram of a first PE device 1000 according to an embodiment of the present application.
  • the first PE device shown in FIG. 11 can perform the corresponding steps performed by the first PE device in the method of the above embodiment.
  • the first PE device 1000 includes a receiving unit 1002, a processing unit 1004, and a sending unit 1006, where:
  • the sending unit 1006 is configured to send, by using the primary PW, a first packet to the second PE device, where the first packet is used to request that the primary PW be switched from an active active state of forwarding traffic to forwarding.
  • Balanced balance state of the traffic the Balance state is used to indicate that the traffic is forwarded in a traffic balanced manner;
  • the sending unit 1006 is further configured to send, by using the backup PW, a second packet to the third PE device, where the second packet is used to request that the backup PW be switched from a standby Standby state that does not forward traffic to Equilibrium Balance state of forwarding traffic;
  • the receiving unit 1002 is configured to receive, by the primary PW, a response packet from the second PE device, where the response packet is sent by the second PE device according to the first packet and the first And the second packet is obtained by the second PE device being forwarded by the second PE device by using the Bypass PW, and the response packet is used to indicate that the message is agreed to. a switching request of a message and the second message;
  • the processing unit 1004 is configured to switch, according to the response packet, a priority forwarding state of the first PE device with respect to the primary PW from an Active state of forwarding traffic to a Balance state of forwarding traffic, and the first The priority forwarding state of the PE device with respect to the backup PW is switched from a Standby state that does not forward traffic to a Balance state that forwards traffic.
  • the receiving unit 1002 is further configured to receive traffic from the CE device, where the sending unit is further configured to use the primary PW and the backup PW of the Balance state to the second PE according to a traffic balancing manner.
  • the device and the third PE device forward traffic from the CE device.
  • the processing unit 1004 is further configured to: before the sending unit 1006 sends the first packet to the second PE device by using the primary PW, determining, by the sending unit 1006, the second PE device The bandwidth usage of the sent traffic exceeds a predetermined threshold.
  • the processing unit 1004 is further configured to determine that the fault detection packet from the second PE device cannot be received within a predetermined period, and the priority forwarding state of the first PE device relative to the primary PW is determined by The balance state is switched to the standby state.
  • the sending unit 1006 is further configured to send a third packet to the second PE device, where the third packet is used to request that the primary PW be switched from the Balance state to the Standby state.
  • the processing unit 1004 is further configured to switch the priority forwarding state of the first PE device with respect to the backup PW from a Balance state to an Active state.
  • the sending unit 1006 is further configured to send the third PE device to the third PE device.
  • the fourth message is used to request that the backup PW be switched from the Balance state to the Active state.
  • the processing unit 1004 is further configured to determine that the fault detection packet from the third PE device cannot be received within a predetermined period, and the priority forwarding state of the first PE device relative to the primary PW is determined by The balancing state is switched to the active state, and the sending unit 1006 is further configured to send the third packet to the second PE device.
  • the third packet is used to request that the primary PW be switched from the Balance state to the Active state.
  • the processing unit 1004 is further configured to: use the priority forwarding state of the first PE device with respect to the backup PW by the Balance state. Switching to the Standby state; the sending unit 1006 is further configured to send a fourth packet to the third PE device, where the fourth packet request is to indicate that the backup PW is switched from the Balance state to the Standby state.
  • the receiving unit 1002 is further configured to receive a termination message from the second PE device and the third PE device, where the termination message is used to indicate that the Balance state of the Bypass PW is terminated;
  • the unit 1004 is further configured to switch the priority forwarding state of the first PE device with respect to the primary PW from a Balance state to an Active state.
  • the sending unit 1006 is further configured to send a third packet to the second PE device. The third packet is used to request that the primary PW be switched from the Balance state to the Active state.
  • the processing unit 1004 is further configured to use the Balance forwarding state of the first PE device relative to the backup PW by Balance. The state is switched to the Standby state.
  • the sending unit 1006 is further configured to send a fourth packet to the third PE device, where the fourth packet is used to request to switch the backup PW from the Balance state to the Standby state.
  • the first PE device shown in FIG. 11 can perform the corresponding steps performed by the first PE device in the method of the above embodiment.
  • the traffic balancing between the primary PW and the backup PW is implemented, which helps to improve the bandwidth utilization of the VPWS PW.
  • FIG. 12 is a schematic structural diagram of hardware of a first PE device 1100 according to an embodiment of the present application.
  • the first PE device shown in FIG. 12 can perform the corresponding steps performed by the first PE device in the method of the above embodiment.
  • the first PE device 1100 includes a processor 1101, a memory 1102, an interface 1103, and a bus 1104.
  • the interface 1103 can be implemented in a wireless or wired manner, and specifically, may be, for example, a network card or the like.
  • the processor 1101, the memory 1102, and the interface 1103 are connected by a bus 1104.
  • the interface 1103 may specifically include a transmitter and a receiver, configured to send and receive information between the first PE device and the second PE device and the third PE device in the foregoing embodiment, or to use the first PE device and the first A first CE device connected to a PE device sends and receives information.
  • the interface 1103 is used to support the processes S101, S102, S109, S202, S203, S302, S303, S502, S503, S602, S603, S705, S706 and S707 in FIG. 3, FIG. 5-10.
  • the processor 1101 is configured to perform processing performed by the first PE device in the above embodiment.
  • the processor 1101 is configured to switch the priority forwarding state of the first PE device with respect to the primary PW and the backup PW, and is further configured to generate a PW status notification message and/or a failure detection message, and send the interface to the second PE through the interface 1103.
  • the device and the third PE device send a PW status notification message and/or a failure detection message; and are also configured to process PW status notification messages and/or termination messages from the second PE device and the third PE device; and/or Other processes for the techniques described herein.
  • the processor 1101 is configured to support processes S110, S201, S202, S203, S301, S302, S303, S401, S402, S501, S502, S503, S508, S601 in FIG.
  • the memory 1102 includes an operating system 11021 and an application 11022 for storing programs, codes, or instructions.
  • FIG. 3 may be completed.
  • FIG. 5-10 relates to the first PE device. Process.
  • Figure 12 only shows a simplified design of the first PE device.
  • the first PE device may include any number of interfaces, processors, memories, etc., and all of the first PE devices that can implement the present application are within the scope of the present application.
  • the embodiment of the present application provides a computer storage medium for storing computer software instructions used by the first PE device, which is configured to perform the foregoing embodiment shown in FIG. 3 and FIG. 5 to FIG. Cheng sequence.
  • FIG. 13 is a schematic structural diagram of a second PE device 1200 according to an embodiment of the present application.
  • the second PE device shown in FIG. 13 can perform the corresponding steps performed by the second PE device in the method of the above embodiment.
  • the second PE device 1200 includes a receiving unit 1202, a processing unit 1204, and a sending unit 1206, where:
  • the receiving unit 1202 is configured to receive, by using the primary PW, a first packet from the first PE device, where the first packet is used to request that the active PW is switched from an active Active state of forwarding traffic to Forwarding the balance of the traffic, the Balance state is used to indicate that the traffic is forwarded in a traffic-balanced manner;
  • the receiving unit 1202 is further configured to receive, by using the Bypass PW, a second packet forwarded by the third PE device, where the second packet is used to request that the backup PW be switched by a standby Standby state that does not forward traffic. Balanced Balance state for forwarding traffic;
  • the processing unit 1204 is configured to generate, according to the first packet and the second packet, a response packet, and the priority forwarding state of the second PE device relative to the primary PW is determined by an Active state of forwarding traffic. Switching to the Balance state of the forwarding traffic, and switching the priority forwarding state of the second PE device relative to the Bypass PW from the Bypass state to the Balance state;
  • the sending unit 1206 is configured to send the response packet to the first PE device by using the primary PW, and send the response packet to the third PE device by using the Bypass PW, the response packet
  • the text is used to indicate that the handover request of the first packet and the second packet is agreed.
  • the CE device is dual-homed to the second PE device and the third PE device in the VPWS PW redundant network by using an MC-Trunk link, and the CE device and the second PE device
  • the link between the CE device and the third PE device is a backup link
  • the receiving unit 1202 is further configured to receive the source through the primary link.
  • the sending unit 1206 is further configured to forward, by the primary PW and the bypass PW in the Balance state, the CE device from the CE device to the first PE device and the third PE device according to a traffic balancing manner. Traffic.
  • the processing unit 1204 is further configured to: generate a response packet according to the first packet and the second packet, and forward a preferential forwarding state of the second PE device relative to the primary PW by Determining, by the second PE device, that the active state of the forwarding traffic is switched to the Balance state of the forwarding traffic, and before the priority forwarding state of the second PE device is changed from the Bypass state to the Balance state with respect to the preferential forwarding state of the Bypass PW
  • the bandwidth occupation rate of the outbound interface that the third PE device sends traffic is less than a predetermined threshold.
  • the processing unit 1204 is further configured to determine that the fault detection packet from the first PE device cannot be received within a predetermined period, and the priority forwarding state of the second PE device relative to the primary PW is determined by The balance state is switched to the standby state.
  • the sending unit 1206 is further configured to send a fault notification message to the first PE device, where the fault notification message is used to notify the first PE device of the second PE device.
  • the processing unit 1204 is further configured to switch the priority forwarding state of the second PE device relative to the Bypass PW from a Balance state to a Bypass state; the sending unit 1206 is further configured to perform the third The PE device sends a termination message, where the termination message is used to indicate that the Balance state of the Bypass PW is terminated.
  • the processing unit 1204 is further configured to: determine that the fault detection packet from the CE device cannot be received within a predetermined period, and determine that the priority forwarding state of the second PE device relative to the primary PW is a Balance state. Maintaining a Balance state with respect to the primary PW, and not controlling the sending unit 1206 to send a message for switching the Balance state of the primary PW to the first PE device.
  • the processing unit 1204 is further configured to determine that the fault detection packet from the third PE device cannot be received within a predetermined period, and the priority forwarding state of the second PE device relative to the Bypass PW is determined by The balance unit is switched to the Bypass state.
  • the sending unit 1206 is further configured to send a termination packet to the first PE device, where the termination packet is used to indicate that the Balance state of the Bypass PW is terminated; and the receiving unit 1202 is further used to: Receiving a third packet from the first PE device, where the third packet is used to request to switch the primary PW from a Balance state to an Active state; the processing unit 1204 is further configured to perform, according to the foregoing The third packet is switched from the Balance state to the Active state by the priority forwarding state of the second PE device with respect to the primary PW.
  • the second PE device shown in FIG. 13 can perform the corresponding steps performed by the second PE device in the method of the above embodiment.
  • the traffic balancing between the primary PW and the backup PW is implemented, which helps to improve the bandwidth utilization of the VPWS PW.
  • FIG. 14 is a schematic structural diagram of hardware of a second PE device 1300 according to an embodiment of the present application.
  • the second PE device shown in FIG. 14 can perform the corresponding steps performed by the second PE device in the method of the above embodiment.
  • the second PE device 1300 includes a processor 1301, a memory 1302, an interface 1303, and a bus 1304.
  • the interface 1303 can be implemented by using a wireless or wired manner, and specifically, for example, a network card or the like.
  • the processor 1301, the memory 1302, and the interface 1303 are connected by a bus 1304.
  • the interface 1303 may specifically include a transmitter and a receiver, configured to send and receive information between the second PE device and the first PE device and the third PE device in the foregoing embodiment, or to use the second PE device and the first
  • the second CE device connected to the PE device sends and receives information.
  • the interface 1303 is used to support the processes S103, S106, S108, S207, S208, S304, S309, S604, S607, S702 and S708 in FIG. 3, FIG. 5-10.
  • the processor 1301 is configured to perform processing performed by the second PE device in the above embodiment.
  • the processor 1301 is configured to switch the priority forwarding state of the second PE device with respect to the primary PW and the bypass PW; and is further configured to generate a PW status notification message, a fault detection message, and/or a termination message, through the interface 1303. And sending the PW status notification message, the fault detection message, and/or the termination message to the first PE device and the third PE device, and is further configured to process the PW status notification message from the first PE device and the third PE device, and/or Or terminate the message; and/or other processes for the techniques described herein.
  • the processor 1301 is configured to support processes S107, S206, S207, S208, S305, S310, S605, S606, S607, S701, S702, and S709 in FIG. 3, FIG. 5-10.
  • the memory 1302 includes an operating system 13021 and an application 13022 for storing programs, codes or instructions, which can be completed when the processor or the hardware device executes the programs, codes or instructions, and the second PE device is involved in FIGS. 5-10. Process.
  • Figure 14 only shows a simplified design of the second PE device.
  • the second PE device may include any number of interfaces, processors, memories, etc., and all second PE devices that can implement the present application are within the scope of the present application.
  • the embodiment of the present application provides a computer storage medium for storing computer software instructions used by the second PE device, which is configured to perform the foregoing embodiment shown in FIG. 3 and FIG. 5 to FIG. program.
  • FIG. 15 is a schematic structural diagram of a third PE device 1400 according to an embodiment of the present application.
  • the third PE device shown in FIG. 15 can perform the corresponding steps performed by the third PE device in the method of the above embodiment.
  • the third PE device 1400 includes a receiving unit 1402, a processing unit 1404, and a transmitting unit 1406, where:
  • the receiving unit 1402 is configured to receive, by using the backup PW, a first packet from the first PE device, where the first packet is used to request that the backup PW be switched by a standby Standby state that does not forward traffic. Balanced Balance state for forwarding traffic;
  • the sending unit 1406 is configured to forward the first packet to the second PE device by using the Bypass PW;
  • the receiving unit 1402 is further configured to receive, by using the Bypass PW, a response packet from the second PE device, where the response packet is used to indicate that the handover request of the first packet is agreed.
  • the processing unit 1404 is configured to switch, according to the response packet, a priority forwarding state of the third PE device with respect to the backup PW by a Standby state that does not forward traffic to a Balance state that forwards traffic, and The priority forwarding state of the third PE device with respect to the Bypass PW is switched from the Bypass state to the Balance state.
  • the processing unit 1404 is further configured to: before the sending unit 1406 forwards the first packet to the second PE device by using the Bypass PW, determining, by the third PE device, the first The bandwidth usage of the outbound interface of the two PEs that send traffic is less than a predetermined threshold.
  • the processing unit 1404 is further configured to determine that the fault detection packet from the first PE device cannot be received within a predetermined period, and the priority forwarding state of the third PE device relative to the backup PW is determined by The balance state is switched to the standby state.
  • the sending unit 1406 is further configured to send a fault notification message to the first PE device, where the fault notification message is used to notify the first PE device of the third PE device.
  • the processing unit 1404 is further configured to switch the priority forwarding state of the third PE device relative to the Bypass PW from a Balance state to a Bypass state; the sending unit 1406 is further configured to send the second The PE device sends a termination message, where the termination message is used to indicate that the Balance state of the Bypass PW is terminated.
  • the processing unit 1404 is further configured to determine that the fault detection packet from the second PE device cannot be received within a predetermined period, and the priority forwarding state of the third PE device relative to the Bypass PW is determined by The balance unit is switched to the Bypass state.
  • the sending unit 1406 is further configured to send a termination packet to the first PE device, where the termination packet is used to indicate that the Balance state of the Bypass PW is terminated; and the receiving unit 1402 is further used to: Receiving a second packet from the first PE device, where the second packet is used to request to switch the backup PW from a Balance state to an Active state or a Standby state; the processing unit 1404 is further configured to The second packet switches the priority forwarding state of the third PE device relative to the backup PW from a Balance state to an Active state or a Standby state.
  • the third PE device shown in FIG. 15 can perform the corresponding steps performed by the third PE device in the method of the above embodiment.
  • the traffic balancing between the primary PW and the backup PW is implemented, which helps to improve the bandwidth utilization of the VPWS PW.
  • FIG. 16 is a schematic structural diagram of hardware of a third PE device 1500 according to an embodiment of the present application.
  • the third PE device shown in FIG. 16 can perform the corresponding steps performed by the third PE device in the method of the above embodiment.
  • the third PE device 1500 includes a processor 1501, a memory 1502, an interface 1503, and a bus 1504.
  • the interface 1503 can be implemented by using a wireless or wired manner, and specifically, for example, a network card or the like.
  • the processor 1501, the memory 1502, and the interface 1503 are connected by a bus 1504.
  • the interface 1503 may specifically include a transmitter and a receiver, configured to send and receive information between the third PE device and the first PE device and the second PE device in the foregoing embodiment, or to use the third PE device and the first Three PE
  • the second CE device connected to the device sends and receives information.
  • the interface 1503 is used to support the processes S104, S105, S111, S204, S209, S307, S308, S504, S507, S704 and S710 in FIG. 3, FIG. 5-10.
  • the processor 1501 is configured to perform processing performed by the third PE device in the above embodiment.
  • the processor 1501 is configured to switch the priority forwarding state of the third PE device with respect to the backup PW and the bypass PW, and is further configured to generate a PW status notification message, a fault detection message, and/or a termination message, through the interface 1503. And sending a PW status notification message, a fault detection message, and/or a termination message to the first PE device and the second PE device, and configured to process the PW status notification message from the first PE device and the second PE device, and/or Or terminate the message; and/or other processes for the techniques described herein.
  • the processor 1501 is configured to support processes S112, S205, S210, S306, S307, S308, S505, S506, S507, S703, S704 and S711 in FIG. 3, FIG. 5-10.
  • the memory 1502 includes an operating system 15021 and an application program 15022 for storing programs, codes or instructions.
  • FIG. 5 to FIG. 10 relate to the third PE device. Process.
  • Figure 16 only shows a simplified design of the third PE device.
  • the third PE device may include any number of interfaces, processors, memories, etc., and all third PE devices that can implement the present application are within the scope of the present application.
  • the embodiment of the present application provides a computer storage medium for storing computer software instructions used by the third PE device, which is configured to perform the foregoing embodiment shown in FIG. 3 and FIG. 5 to FIG. program.
  • the first packet and the second packet carry a PW status code, where the PW status code is used to indicate that the state of the PW is a Balance state.
  • FIG. 2 is a schematic structural diagram of a VPWS PW redundant network according to an embodiment of the present invention.
  • the system includes the aforementioned first PE device of FIG. 11 or FIG. 12, the aforementioned second PE device of FIG. 13 or FIG. 14 and the aforementioned third PE device of FIG. 15 or FIG.
  • the steps of a method or algorithm described in connection with the present disclosure may be implemented in a hardware or may be implemented by a processor executing software instructions.
  • the software instructions may be comprised of corresponding software modules that may be stored in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable hard disk, CD-ROM, or any other form of storage well known in the art.
  • An exemplary storage medium is coupled to the processor to enable the processor to read information from, and write information to, the storage medium.
  • the storage medium can also be an integral part of the processor.
  • the processor and the storage medium can be located in an ASIC. Additionally, the ASIC can be located in the user equipment.
  • the processor and the storage medium may also reside as discrete components in the user equipment.
  • the functions described herein can be implemented in hardware, software, firmware, or any combination thereof.
  • the functions may be stored in a computer readable medium or transmitted as one or more instructions or code on a computer readable medium.
  • Computer readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one location to another.
  • a storage medium may be any available media that can be accessed by a general purpose or special purpose computer.

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Abstract

一种用于转发报文的方法、设备及系统。通过第一PE设备分别向第二PE设备和第三PE设备发送请求报文。第二PE设备经由主PW和经由备份PW、第三PE设备和Bypass PW接收两个请求报文，并且将相对于主PW和Bypass PW的优先转发状态切换为Balance状态，然后通过回应报文通知第一PE设备和第三PE设备。第一PE设备根据回应报文将相对于主PW和备份PW的优先转发状态切换为Balance状态。第三PE设备根据所述回应报文将相对于Bypass PW的优先转发状态切换为Balance状态。从而，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。

Description

一种转发报文的方法、设备及系统
本申请要求于2016年12月20日提交中国专利局、申请号为201611187143.3、申请名称为“一种转发报文的方法、设备及系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种转发报文的方法、设备及系统。更具体的，本申请涉及PW冗余(Pseudo Wire Redundancy)技术。
背景技术
PW冗余技术基于边缘到边缘伪线仿真(Pseudo Wire Emulation Edge-to-Edge，PWE3)系统，提供一种用户边缘(Customer Edge，CE)设备双归属场景下的运营商边缘(Provider Edge，PE)设备或接入链路(Attachment Circuit，AC)的保护机制。通过配置主(Primary)伪线(Pseudo Wire，PW)和备份(Secondary)PW，构成一个PW冗余组。PW冗余组中的PW都可以进行数据流量转发，但任何时候只有一条PW用来转发数据流量，正常情况下，主PW转发数据流量。当主PW失效时，将数据流量快速切换到备份PW上进行转发。当主PW恢复有效时，数据流量将被回切到主PW上进行转发。
虚拟专用线路业务伪线(Virtual Private Wire Service Pseudo Wire，VPWS PW)是PW冗余技术的一种具体实现方式。其中，虚拟专用线路业务(Virtual Private Wire Service，VPWS)也可称为虚拟租用线(Virtual Leased Line，VLL)。VPWS是指在分组交换网络(Packet Switched Network，PSN)中尽可能真实的模仿异步传输模式(Asynchronous Transfer Mode，ATM)、帧中继(Frame Relay，FR)、以太网(Ethernet)、低速时分复用(Time Division Multiplexing，TDM)电路和同步光纤网(Synchronous Optical Network，SONET)/同步数字体系(Synchronous Digital Hierarchy，SDH)等业务的基本行为和特征的一种二层业务承载技术。
在实际的应用场景中，VPWS PW中的主PW和备份PW实现了冗余保护功能。但是，由于在任何时候只有一条PW用来转发数据流量，造成PW冗余组的带宽资源无法被充分利用。例如，当主PW被用来转发数据流量时，备份PW将处于备用(Standby)状态，备份PW不转发数据流量。即使主PW的带宽资源出现不足时，备份PW的带宽资源也无法被利用。
发明内容
有鉴于此，本申请实施例提供了一种转发报文的方法、设备及系统，从而在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，有助于提高实现VPWS PW的带宽利用率。
本申请实施例提供的技术方案如下。
第一方面，提供了一种转发报文的方法，所述方法应用于VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备。其中，所 述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW。所述方法包括，所述第一PE设备经由所述主PW向所述第二PE设备发送第一报文(第一报文例如是PW状态通知报文，具体的可以是标签分发协议(Label Distribution Protocol，LDP)报文)，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量。所述第一PE设备还经由所述备份PW向所述第三PE设备发送第二报文(第二报文例如是PW状态通知报文，具体的可以是LDP报文)，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态。然后，所述第一PE设备经由所述主PW接收来自所述第二PE设备的回应报文，所述回应报文是由所述第二PE设备根据所述第一报文和所述第二报文确定得到的。其中，所述第二报文是所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发得到的，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求。并且，所述第一PE设备根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态。
基于实施例提供的方案，在VPWS PW网络运行过程中，第一PE设备可以通过与第二PE设备和第三PE设备协商的方式，将主PW和备份PW确定为Balance状态，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
在第一方面的一种可能的实现方式中，所述方法还包括，所述第一PE设备接收来自第一CE设备的流量。并且，所述第一PE设备按照流量均衡的方式经由Balance状态的所述主PW和所述备份PW向所述第二PE设备和第三PE设备转发来自所述第一CE设备的流量。
在第一方面的再一种可能的实现方式中，在所述第一PE设备经由所述主PW向所述第二PE设备发送第一报文之前，所述方法还包括，所述第一PE设备确定所述第一PE设备向所述第二PE设备发送流量的带宽占用率超过预定阈值。
通过上述实施方式，所述VPWS PW可以根据转发流量的带宽情况，自动的选择冗余模式转发数据流量和流量均衡模式转发数据流量。其中，对于阈值的选择不进行限定，例如使用PW的额定带宽作为阈值或者由操作人员进行配置。
在第一方面的又一种可能的实现方式中，在所述第一PE设备经由所述主PW向所述第二PE设备发送第一报文之前，所述方法还包括，所述第一PE设备确定所述第一PE设备向所述第二PE设备发送流量的时刻起，经历预定的时间周期。
基于上述实现方式，有利于在冗余模式转发数据流量稳定后，切换为流量均衡模式转发数据流量。
在第一方面的又一种可能的实现方式中，所述方法还包括，所述第一PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文。然后，所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由 Balance状态切换为Standby状态。并且，所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Active状态。
基于上述实现方式，第一PE设备在确定主PW或第二PE设备故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
在第一方面的又一种可能的实现方式中，所述方法还包括，所述第一PE设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文。然后，所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。并且，所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文请求将指示所述备份PW由Balance状态切换为Standby状态。
基于上述实现方式，第一PE设备在确定备份PW或第三PE设备故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
在第一方面的又一种可能的实现方式中，所述方法还包括，所述第一PE设备接收来自所述第二PE设备和所述第三PE设备的终止报文，所述终止报文用于指示终止Bypass PW的Balance状态。然后，所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。并且，所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
基于上述实现方式，第一PE设备在确定Bypass PW故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
第二方面，提供了一种转发报文的方法，所述方法应用于VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备。其中，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW。所述方法包括，所述第二PE设备经由所述主PW接收来自所述第一PE设备的第一报文(第一报文例如是PW状态通知报文，具体的可以是LDP报文)，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量。而且，所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发的第二报文(第二报文例如是PW状态通知报文，具体的可以是LDP报文)，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态。然后，所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的 Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。另外，所述第二PE设备经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求。
基于实施例提供的方案，在VPWS PW网络运行过程中，第二PE设备可以通过与第一PE设备和第三PE设备协商的方式，将主PW和Bypass PW确定为Balance状态，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
在第二方面的一种可能的实现方式中，第二CE设备通过MC-Trunk链路双归属连接到所述VPWS PW冗余网络中的所述第二PE设备和所述第三PE设备。其中，所述CE设备与所述第二PE设备之间的链路为主用链路，所述CE设备与所述第三PE设备之间的链路为备用链路。所述方法还包括，所述第二PE设备经由所述主用链路接收来自所述CE设备的流量。然后，所述第二PE设备按照流量均衡的方式经由Balance状态的所述主PW和所述Bypass PW向所述第一PE设备和第三PE设备转发来自所述CE设备的流量。
在第二方面的再一种可能的实现方式中，在所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态之前，所述方法还包括，所述第二PE设备确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率小于预定阈值。
在第二方面的又一种可能的实现方式中，在所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态之前，所述方法还包括，所述第二PE设备确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率大于或等于预定阈值，所述第二PE设备生成拒绝报文，并经由所述主PW向所述第一PE设备和经由所述Bypass PW向所述第三PE设备发送所述拒绝报文，所述拒绝报文用于指示不同意所述第一报文和所述第二报文的切换请求。
基于上述实现方式，有助于减少流量均衡模式协商不成功的情况，并且有助于减少切换为流量均衡模式后链路拥塞的情况。
在第二方面的又一种可能的实现方式中，所述方法还包括，所述第二PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文。然后，所述第二PE设备将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第二PE设备发现的故障。而且，所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第三PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
基于上述实现方式，第二PE设备在确定主PW故障后，进行PW转发状态的切换， 确保业务流量顺利转发，避免产生业务中断。
在第二方面的又一种可能的实现方式中，所述方法还包括，所述第二PE设备确定预定周期内无法收到来自所述CE设备的故障检测报文。然后，所述第二PE设备确定所述第二PE设备相对于所述主PW的优先转发状态为Balance状态，保持相对于所述主PW的Balance状态，并且不向所述第一PE设备发送用于切换所述主PW的Balance状态的报文。
基于上述实现方式，第二PE设备在确定远端AC侧网络的主用链路故障后，并且确定PW侧网络的PW转发状态为Balance状态时，保持Balance状态，确保业务流量顺利转发，避免产生业务中断。
在第二方面的又一种可能的实现方式中，所述方法还包括，所述第二PE设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文。然后，所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态。所述第二PE设备接收来自所述所述第一PE设备的第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。并且，所述第二PE设备根据所述第三报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
基于上述实现方式，第二PE设备在确定Bypass PW或第三PE设备故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
第三方面，提供了一种转发报文的方法，所述方法应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备。其中，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW。所述方法包括，所述第三PE设备经由所述备份PW接收来自所述第一PE设备的第一报文(第一报文例如是PW状态通知报文，具体的可以是LDP报文)，所述第一报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态。然后，所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第一报文。而且，所述第三PE设备经由所述Bypass PW接收来自所述第二PE设备的回应报文，所述回应报文用于指示同意所述第一报文的切换请求。另外，所述第三PE设备根据所述回应报文，将所述第三PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
基于实施例提供的方案，在VPWS PW网络运行过程中，第三PE设备可以通过与第一PE设备和第二PE设备协商的方式，将备份PW和Bypass PW确定为Balance状态，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
在第三方面的一种可能的实现方式中，在所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第一报文之前，所述方法还包括，所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值。
在第三方面的再一种可能的实现方式中，在所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第一报文之前，所述方法还包括，所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率大于或等于预定阈值，所述第三PE设备生成拒绝报文，并经由所述备份PW向所述第一PE设备发送所述拒绝报文，所述拒绝报文用于指示不同意所述第二报文的切换请求。
基于上述实现方式，有助于减少流量均衡模式协商不成功的情况，并且有助于减少切换为流量均衡模式后链路拥塞的情况。
在第三方面的又一种可能的实现方式中，所述方法还包括：所述第三PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文。然后，所述第三PE设备将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第三PE设备发现的故障。并且，所述第三PE设备将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第二PE设备发送终止报文，所述终止报文用于指示终止所述BypassPW的Balance状态。
基于上述实现方式，第三PE设备在确定备份PW故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
在第三方面的又一种可能的实现方式中，所述方法还包括：所述第三PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文。然后，所述第三PE设备将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态。所述第三PE设备接收来自所述所述第一PE设备的第二报文，所述第二报文用于请求将所述备份PW由Balance状态切换为Active状态或Standby状态。然后，所述第三PE设备根据所述第二报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态或Standby状态。
基于上述实现方式，第三PE设备在确定Bypass PW或第二PE设备故障后，进行PW转发状态的切换，确保业务流量顺利转发，避免产生业务中断。
第四方面，提供了第一PE设备，所述第一PE设备具有实现上述方法中第一PE设备行为的功能。所述功能可以基于硬件实现，也可以基于硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
在一个可能的设计中，第一PE设备的结构中包括处理器和接口，所述处理器被配置为支持第一PE设备执行上述方法中相应的功能。所述接口用于支持第一PE设备与第二PE设备和第三PE设备之间的通信，向第二PE设备和第三PE设备发送上述方法中所涉及的信息或者指令，或者从第二PE设备和第三PE设备接收上述方法中所涉及的信息或者指令。所述第一PE设备还可以包括存储器，所述存储器用于与处理器耦合，其保存第一PE设备必要的程序指令和数据。
第五方面，提供了第二PE设备，所述第二PE设备具有实现上述方法中第二PE设备行为的功能。所述功能可以基于硬件实现，也可以基于硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
在一个可能的设计中，第二PE设备的结构中包括处理器和接口，所述处理器被配置为支持第二PE设备执行上述方法中相应的功能。所述接口用于支持第二PE设备与第一PE设备和第三PE设备之间的通信，向第一PE设备和第三PE设备发送上述方法中所涉及的信息或者指令，或者从第一PE设备和第三PE设备接收上述方法中所涉及的信息或者指令。所述第二PE设备还可以包括存储器，所述存储器用于与处理器耦合，其保存第二PE设备必要的程序指令和数据。
第六方面，提供了第三PE设备，所述第三PE设备具有实现上述方法中第三PE设备行为的功能。所述功能可以基于硬件实现，也可以基于硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块。
在一个可能的设计中，第三PE设备的结构中包括处理器和接口，所述处理器被配置为支持第三PE设备执行上述方法中相应的功能。所述接口用于支持第三PE设备与第一PE设备和第二PE设备之间的通信，向第一PE设备和第二PE设备发送上述方法中所涉及的信息或者指令，或者从第一PE设备和第二PE设备接收上述方法中所涉及的信息或者指令。所述第三PE设备还可以包括存储器，所述存储器用于与处理器耦合，其保存第三PE设备必要的程序指令和数据。
在上述第一方面，第二方面，第三方面，第四方面，第五方面和第六方面中，可选的，所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
第七方面，提供了一种VPWS PW冗余网络系统，所述系统包括第四方面所述的第一PE设备，第五方面所述的第二PE设备和第六方面所述的第三PE设备。
第八方面，提供了一种计算机存储介质，用于储存为上述第一PE设备所用的程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成上述方面中第一PE设备的功能或步骤。
第九方面，提供了一种计算机存储介质，用于储存为上述第二PE设备所用的程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成上述方面中第二PE设备的功能或步骤。
第十方面，提供了一种计算机存储介质，用于储存为上述第三PE设备所用的程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成上述方面中第三PE设备的功能或步骤。
通过上述方案，本申请实施例提供的用于转发报文的方法、设备及系统，通过第一PE设备分别经由主PW和备份PW向第二PE设备和第三PE设备发送请求切换为Balance状态的请求报文；所述第二PE设备经由所述主PW和经由所述备份PW、所述第三PE设备和Bypass PW接收两个请求报文；所述第二PE设备将所述第二PE设备相对于所述主PW和所述Bypass PW的优先转发状态切换为Balance状态，并通过回应报文通知所述第一PE设备和所述第三PE设备；所述第一PE设备根据所述回应报文将所述第一PE设备相对于所述主PW和所述备份PW的优先转发状态切换为Balance状态，所述第三PE设备根据所述回应报文将所述第三PE设备相对于所述Bypass PW的优先转发状态切换为Balance状态。从而，在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现主PW和备份PW的流量均衡，有助于提高 VPWS PW的带宽利用率。
附图说明
图1为本申请实施例的一种VPWS PW冗余网络结构示意图；
图2为本申请实施例的另一种VPWS PW冗余网络结构示意图；
图3为本申请实施例的一种转发报文的方法流程图；
图4为本申请实施例的又一种VPWS PW冗余网络结构示意图；
图5为本申请实施例的一种处理故障的方法流程图；
图6为本申请实施例的另一种处理故障的方法流程图；
图7为本申请实施例的又一种处理故障的方法流程图；
图8为本申请实施例的又一种处理故障的方法流程图；
图9为本申请实施例的又一种处理故障的方法流程图；
图10为本申请实施例的又一种处理故障的方法流程图；
图11为本申请实施例的第一PE设备的结构示意图；
图12为本申请实施例的第一PE设备的硬件结构示意图；
图13为本申请实施例的第二PE设备的结构示意图；
图14为本申请实施例的第二PE设备的硬件结构示意图；
图15为本申请实施例的第三PE设备的结构示意图；
图16为本申请实施例的第三PE设备的硬件结构示意图。
具体实施方式
本申请实施例提供了一种转发报文的方法、设备及系统，从而在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，有助于提高实现VPWS PW的带宽利用率。
下面通过具体实施例，分别进行详细的说明。
为使得本申请的发明目的、特征、优点能更加的明显和易懂，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚地描述。显然下面所描述的实施例仅仅是本申请一部分实施例，而非全部的实施例。基于本申请中的实施例，本领域普通技术人员可以获得其他实施例。
本申请的说明书和权利要求书及附图中的术语“第一”、“第二”、“第三”和“第四”等是用于区别不同对象，而不是用于描述特定顺序。此外，术语“包括”和“具有”不是排他的。例如包括了一系列步骤或单元的过程、方法、系统、产品或设备没有限定于已列出的步骤或单元，还可以包括没有列出的步骤或单元。
图1为本申请实施例的一种VPWS PW冗余网络结构示意图。该VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备。所述第一PE设备分别通过通信链路与所述第二PE设备和所述第三PE设备进行通信。所述第一PE设备与所述第二PE设备和所述第三PE设备之间建立PW冗余组，所述PW冗余组包括主PW和备份PW。其中，所述第一PE设备与所述第二PE设备之间建立所述主PW，所述第一PE设备与所述第三PE设备之间建立所述备份PW。所述主PW和所述备份PW的建立过程可以依据因特网工程任务组(Internet Engineering Task Force，IETF)制定的相应标准实现，例如征求意见稿(Requirement For Comments，RFC)6718，本申请不进 行赘述。另外，所述第二PE设备与所述第三PE设备之间建立了旁路伪线(Bypass PW)。其中，所述Bypass PW可以采用框间备份伪线(Inter-Chassis Backup Pseudo Wire，ICB PW)或双节点互联伪线(Dual Node Interconnection Pseudo Wire，DNI PW)。如此这样，在VPWS PW冗余网络中，所述第一PE设备、第二PE设备和第三PE设备组成的网络可以称为PW侧网络。
所述第一PE设备通过通信链路与第一CE设备进行通信。所述第一CE设备可以经由所述第一PE设备向所述PW冗余组发送数据流量，也可以经由所述第一PE设备接收来自所述PW冗余组的数据流量。其中，所述第一CE设备与所述第一PE设备之间的通信链路可以是一条物理链路，也可以是由多条物理链路组成的聚合链路以太Trunk(Eth-Trunk)链路。如此这样，在VPWS PW冗余网络中，所述第一PE设备和所述第一CE设备组成的网络可以称为本地AC侧网络。
第二CE设备通过聚合链路多框Trunk(Multi-Chassis Trunk，MC-Trunk)链路双归属连接到所述VPWS PW冗余网络中的所述第二PE设备和所述第三PE设备。其中，MC-Trunk链路也可以称为增强Trunk(Enhanced Trunk，E-trunk)。具体的，所述MC-Trunk链路包括两条成员Eth-Trunk链路。其中，一条Eth-Trunk链路被设置于所述第二CE设备与所述第二PE设备之间，另一条Eth-Trunk链路被设置于所述第二CE设备与所述第三PE设备之间。在所述MC-Trunk链路中，需要配置两条成员Eth-Trunk链路的主备状态。如图1所示，将所述第二CE设备与所述第二PE设备之间的Eth-Trunk链路确定为主用链路，或者称为主用Eth-Trunk链路；将所述第二CE设备与所述第三PE设备之间的Eth-Trunk链路确定为备用链路，或者称为备用Eth-Trunk链路。如此这样，在VPWS PW冗余网络中，所述第二PE设备、第三PE设备和所述第二CE设备组成的网络可以称为远端AC侧网络。
在图1所示的VPWS PW冗余网络中，CE设备可以是交换机或路由器，PE设备可以是路由器或三层交换机。图1所示的VPWS PW冗余网络可以应用于多种场景中。例如，所述VPWS PW冗余网络应用于移动承载网(Mobile Bearer Network)，典型的移动承载网是互联网协议化无线接入网(Internet Protocol Radio Access Network，IP RAN)。在移动承载网中，所述第一CE设备可以是基站(Base Transceiver Station，BTS)，所述第二CE设备可以是基站控制器(Base Station Controller，BSC)或无线网络控制器(Radio Network Controller，RNC)，所述第一PE设备可以是基站侧网关(Cell Site Gateway，CSG)，所述第二PE设备和所述第三PE设备可以是基站控制器侧网关(Radio Network Controller Site Gateway，RSG)。又例如，所述VPWS PW冗余网络应用于固网(Fixed Network)。在固网中，所述第一CE设备和所述第二CE设备可以是用户侧的站点(Site)，所述站点可以位于虚拟专用网(Virtual Private Network，VPN)中，所述第一PE设备可以是数字用户线接入复接器(Digital Subscriber Line Access Multiplexer，DSLAM)，所述第二PE设备和所述第三PE设备可以是宽带接入服务器(Broadband Access Server，BAS)。
在图1中，VPWS PW冗余保护机制可以采用两种工作模式：主/从模式(Master/Slave Mode)和独立模式(Independent Mode)。接下来，分别对两种工作模式进行介绍。
对于主从模式，在PW侧网络中，第一PE设备将所述第一PE设备相对于主PW的优先转发状态(preferential forwarding status)确定为激活(Active)状态，并且向第二PE设备发送携带Active状态码的PW状态通知报文。其中，所述优先转发状态用于指示PE设备所确定的PW的转发状态。所述Active状态码用于指示PW为转发流量的Active状态，例如，根据IETF制定的RFC4447或RFC6870，所述Active状态码的值设置为0x00(0x表示16进制)。所述第二PE设备接收到携带Active状态码的PW状态通知报文后，将所述第二PE设备相对于所述主PW的优先转发状态确定为Active状态，并且向所述第一PE设备返回携带Active状态码的PW状态通知报文。如此这样，所述第一PE设备和所述第二PE设备都将自身相对于所述主PW的优先转发状态确定为Active状态，所述主PW两端的优先转发状态相同，从而所述主PW被确定为Active状态。而且，所述第一PE设备将所述第一PE设备相对于备份PW的优先转发状态确定为备用(Standby)状态，并且向第三PE设备发送携带Standby状态码的PW状态通知报文。所述Standby状态码用于指示PW为不转发流量的Standby状态，例如，根据IETF制定的RFC4447或RFC6870，所述Standby状态码的值设置为0x20。所述第三PE设备接收到携带Standby状态码的PW状态通知报文后，将所述第三PE设备相对于所述备份PW的优先转发状态确定为Standby状态，并且向所述第一PE设备返回携带Standby状态码的PW状态通知报文。如此这样，所述第一PE设备和所述第三PE设备都将自身相对于所述备份PW的优先转发状态确定为Standby状态，所述备份PW两端的优先转发状态相同，从而所述备份PW被确定为Standby状态。其中，所述PW状态通知报文可以是标签分发协议(Label Distribution Protocol，LDP)报文。在远端AC侧网络中，第二CE设备与所述第二PE设备通过链路聚合控制协议(Link Aggregation Control Protocol，LACP)报文，将所述第二CE设备与所述第二PE设备之间的Eth-Trunk链路协商为主用链路。第二CE设备与所述第三PE设备通过LACP报文，将所述第二CE设备与所述第三PE设备之间的Eth-Trunk链路协商为备用链路。在主从模式中，所述PW侧网络和所述远端AC侧网络的协商过程是相互隔离的。通过上述的协商过程，所述第一CE设备和所述第二CE设备可以通过所述主PW和所述主用链路相互转发数据流量，数据流量的转发路径是：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。
对于独立模式，PW侧网络中的PW状态由远端AC侧网络中的Eth-Trunk链路状态和PW侧网络中交互的PW状态通知报文共同确定。具体的，第二CE设备与第二PE设备之间的Eth-Trunk链路被协商为主用链路，所述第二CE设备第三PE设备之间的Eth-Trunk链路被协商为备用链路。第一PE设备确定本地优先转发状态为Active状态，并分别向所述第二PE设备和所述第三PE设备发送携带Active状态码的PW状态通知报文。因为所述第二CE设备与第二PE设备之间的Eth-Trunk链路被协商为主用链路，所述第二PE设备确定出的本地优先转发状态为Active状态。所述第二PE设备比较所述PW状态通知报文的Active状态码与所述本地优先转发状态相匹配，均为Active状态，因此，所述第二PE设备将所述第二PE设备相对于主PW的优先转发状态确定为Active状态，并向所述第一PE设备发送携带Active状态码的PW状态通知报文。并且，因为所述第二CE设备与第三PE设备之间的Eth-Trunk链路被协商为备 用链路，所述第三PE设备确定出的本地优先转发状态为Standby状态。所述第三PE设备比较所述PW状态通知报文的Active状态码与所述本地优先转发状态不匹配，因此，所述第三PE设备将所述第二PE设备相对于备份PW的优先转发状态确定为Standby状态，并向所述第一PE设备发送携带Standby状态码的PW状态通知报文。所述第一PE设备根据接收到的所述携带Active状态码的PW状态通知报文，并且比较所述PW状态通知报文的Active状态码与所述本地优先转发状态相匹配，均为Active状态，因此，所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态确定为Active状态。从而，所述主PW被确定为Active状态。相应的，所述第一PE设备根据接收到的所述携带Standby状态码的PW状态通知报文，并且比较所述PW状态通知报文的Active状态码与所述本地优先转发状态不匹配，因此，所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态确定为Standby状态。从而，所述备份PW被确定为Standby状态。通过上述的协商过程，所述第一CE设备和所述第二CE设备可以通过所述主PW和所述主用链路相互转发数据流量，数据流量的转发路径是：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。其中，所述PW状态通知报文可以是LDP报文。
在上述两种工作模式中，任何时候只有一条PW用来转发数据流量。在实际的应用场景中，还可以设置多条PW或者在一条PW中承载多条隧道。例如，所述第一PE设备与所述第二PE设备之间设置两条PW，一条为主PW，另一条为备份PW；相应的，所述第一PE设备与所述第三PE设备之间设置两条PW，一条为主PW，另一条为备份PW。这样的设置可以实现所述第一PE设备基于不同的PW冗余组同时向所述第二PE设备和第三PE设备传送数据流量。又例如，所述第一PE设备与所述第二PE设备之间设置一条PW，所述PW包括多条隧道；相应的，所述第一PE设备与所述第三PE设备之间设置一条PW，所述PW包括多条隧道。这样的设置可以实现所述第一PE设备基于不同的隧道冗余组同时向所述第二PE设备和第三PE设备传送数据流量。然而，对于上述实现方式，每个PW冗余组中的两条PW或每个隧道冗余组中的两条隧道均要保持一主一备，只有一条PW或一条隧道用来转发数据流量，无法实现真正的流量均衡。
本申请实施例提供了一种转发报文的方法，以便在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现流量均衡的功能，提高VPWS PW的带宽利用率。在本申请中，流量均衡也可以称为负载分担(load sharing)，在不增加特殊说明的情况下，流量均衡等同于负载分担。
图3示出了本申请实施例的一种转发报文的方法流程图。图3所示的方法可以应用于图1和图2所示的VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了Bypass PW。具体的，在图1所示的VPWS PW冗余网络的转发状态下，应用图3所示的方法，将所述VPWS PW冗余网络的转发状态切换为图2所示的转发状态。该方法包括：
S101、所述第一PE设备向所述第二PE设备发送第一报文，所述第一报文用于请 求将所述主PW由Active状态切换为均衡(Balance)状态。
S102、所述第一PE设备向所述第三PE设备发送第二报文，所述第二报文用于请求将所述备份PW由Standby状态切换为Balance状态。
根据前述实施例针对图1所示场景的描述，通过协商过程，第一CE设备和第二CE设备可以通过所述主PW和所述主用链路相互转发数据流量，数据流量的转发路径是：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。也就是说，所述主PW的状态为转发数据流量的Active状态，所述备份PW的状态为不转发数据流量的Standby状态。
所述第一PE设备经由所述主PW向所述第二PE设备发送所述第一报文，所述第一报文用于请求将所述主PW由Active状态切换为Balance状态，所述Balance状态用于指示以流量均衡的方式转发数据流量。可选的，所述第一报文是携带着Balance状态码的PW状态通知报文。所述Balance状态码用于指示PW为转发流量的Balance状态。由于所述主PW的当前状态为Active状态，因此，所述Balance状态码可以被看作指示所述主PW由Active状态切换为Balance状态。其中，所述PW状态通知报文可以是LDP报文。所述Balance状态码的值例如可以设置为0x30。
基于上述相同的方式，所述第一PE设备还经由所述备份PW向所述第三PE设备发送所述第二报文，所述第二报文用于请求将所述备份PW由Standby状态切换为Balance状态，所述Balance状态用于指示以流量均衡的方式转发数据流量。可选的，所述第二报文是携带着Balance状态码的PW状态通知报文。所述Balance状态码用于指示PW为转发流量的Balance状态。由于所述备份PW的当前状态为Standby状态，因此，Balance状态码可以被看作指示所述备份PW由Standby状态切换为Balance状态。其中，所述PW状态通知报文可以是LDP报文。所述Balance状态码的值例如可以设置为0x30。
其中，本实施例并不限定S101和S102执行的先后顺序，应当理解，S101可以先于S102执行；S101也可以在S102之后执行；S101还可以与S102同时执行。
S103、所述第二PE设备接收所述第一报文。
S104、所述第三PE设备接收所述第二报文。
举例说明，所述第二PE设备经由所述主PW接收来自所述第一PE设备的携带着Balance状态码的PW状态通知报文。所述第三PE设备经由所述备份PW接收来自所述第一PE设备的携带着Balance状态码的PW状态通知报文。
S105、所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第二报文。
S106、所述第二PE设备接收所述第二报文。
举例说明，所述第三PE设备在接收到来自所述第一PE设备的携带着Balance状态码的PW状态通知报文后，经由所述第二PE设备和所述第三PE设备之间的BypassPW，向所述第二PE设备转发该PW状态通知报文。相应的，所述第二PE设备经由所述Bypass PW接收该PW状态通知报文。
S107、所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由Active状态切换为Balance状态， 并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
举例说明，所述第二PE设备在接收到两个携带着Balance状态码的PW状态通知报文后，确定两个PW状态通知报文均携带着Balance状态码，生成回应报文，所述回应报文表示同意所述两个PW状态通知报文的切换请求。其中，所述两个PW状态通知报文中，一个PW状态通知报文是所述第一PE设备经由所述主PW发送的，另一个PW状态通知报文是所述第一PE设备经由所述备份PW，所述第二PE设备和所述Bypass PW发送的。所述第二PE设备还将所述第二PE设备相对于所述主PW的优先转发状态由Active状态切换为Balance状态和将所述第二PE设备相对于所述BypassPW的优先转发状态由Bypass状态切换为Balance状态。其中，所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态切换为Balance状态的有益效果是，所述第二CE设备向所述第一CE设备发送的数据流量经由远端AC侧网络的主用链路到达所述第二PE设备后，可以由所述第二PE设备将所述数据流量均衡到所述主PW和所述Bypass PW进行传输。
S108、所述第二PE设备经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文，所述回应报文用于指示同意第一报文和第二报文的切换请求。
举例说明，所述回应报文可以是携带着Balance状态码的PW状态通知报文，所述PW状态通知报文可以是LDP报文。所述第二PE设备可以将所述回应报文复制成两个，或者直接生成两个所述回应报文，即得到两个携带着Balance状态码的PW状态通知报文。从而，所述第二PE设备经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文。
S109、所述第一PE设备接收所述回应报文。
S110、所述第一PE设备根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由Active状态切换为Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由Standby状态切换为Balance状态。
具体的，当所述第一PE设备接收到所述回应报文，所述第一PE设备能够确认所述第二PE设备接收了所述第一PE设备经由所述主PW发送的第一报文和所述第一PE设备经由所述备份PW和所述Bypass PW发送的第二报文，并且第二PE设备已经将所述第二PE设备相对于所述主PW的优先转发状态和所述Bypass PW的优先转发状态切换为Balance状态。因此，所述第一PE设备可以根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由Active状态切换为Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由Standby状态切换为Balance状态。结合S107的描述，所述第二PE设备已经将所述第二PE设备相对于所述主PW的优先转发状态由Active状态切换为Balance状态。由于所述主PW两端的设备均将自身相对于所述主PW的优先转发状态切换为Balance状态，从而，所述主PW被确定为Balance状态，完成相应的切换。
S111、所述第三PE设备接收所述回应报文。
S112、所述第三PE设备根据所述回应报文，将所述第三PE设备相对于所述备份 PW的优先转发状态由Standby状态切换为Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
具体的，当所述第三PE设备接收到所述回应报文，所述第三PE设备能够确认所述第二PE设备接收了所述第一PE设备经由所述主PW发送的第一报文和所述第一PE设备经由所述备份PW和所述Bypass PW发送的第二报文，并且第二PE设备已经将所述第二PE设备相对于所述主PW的优先转发状态和所述Bypass PW的优先转发状态切换为Balance状态。因此，所述第三PE设备可以根据所述回应报文将所述第三PE设备相对于所述备份PW的优先转发状态由Standby状态切换为Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。结合S107和S110的描述，所述第二PE设备已经将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态和所述第一PE设备已经将所述第一PE设备相对于所述备份PW的优先转发状态由Standby状态切换为Balance状态。由此，所述备份PW和所述Bypass PW被确定为Balance状态，完成相应的切换。
完成上述S101-S112的协商过程后，所述VPWS PW冗余网络的转发状态如图2所示。如此这样，所述第一PE设备可以基于哈希(Hash)算法，对来自所述第一CE设备的数据流量进行流量均衡计算。所述第一PE设备将所述数据流量的一部分流量将由所述主PW发送到所述第二PE设备，并经由主用链路到达所述第二CE设备；所述第一PE设备还将所述数据流量的另一部分流量将由所述备份PW发送到所述第三PE设备，并经由所述Bypass PW、所述第二PE设备和主用链路到达所述第二CE设备。同样的道理，所述第二CE设备发出的数据流量经由所述主用链路到达所述第二PE后，所述第二PE设备可以基于Hash算法对所述数据流量进行流量均衡计算，一部分流量经由所述主PW到达所述第一PE设备，另一部分流量经由所述Bypass PW、所述第三PE设备和所述备份PW到达所述第一PE设备。其中，本申请对流量均衡计算时的计算原则不进行限定，例如，可以平均分配流量，或者根据两条PW的带宽分配流量，或者根据流量的业务类型分配流量。
通过上述实施方式，第一PE设备分别经由主PW和备份PW向第二PE设备和第三PE设备发送请求切换为Balance状态的请求报文；所述第二PE设备经由所述主PW和经由所述备份PW、所述第三PE设备和Bypass PW接收两个请求报文；所述第二PE设备将所述第二PE设备相对于所述主PW和所述Bypass PW的优先转发状态切换为Balance状态，并通过回应报文通知所述第一PE设备和所述第三PE设备；所述第一PE设备根据所述回应报文将所述第一PE设备相对于所述主PW和所述备份PW的优先转发状态切换为Balance状态，所述第三PE设备根据所述回应报文将所述第三PE设备相对于所述Bypass PW的优先转发状态切换为Balance状态。从而，在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
可选的，所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
举例说明，所述第一报文和所述第二报文可以采用LDP报文，在所述LDP报文 中携带有PW状态码，所述PW状态码可以是Balance状态码，所述Balance状态码的值例如可以设置为0x30。
可选的，在S101之前，所述方法还包括：所述第一PE设备确定所述第一PE设备向所述第二PE设备发送流量的带宽占用率超过预定阈值。
举例说明，在执行上述S101之前，所述VPWS PW的PW转发方式已经被协商为图1所示的场景，并且，数据流量经由Active的主PW转发，备份PW处于Standby状态。所述第一PE设备可以周期的检测所述所述第一PE设备的出接口的带宽占用率，所述出接口用于连接所述主PW，即，所述第一PE设备周期的检测发到Active状态的主PW上的流量。当带宽占用率超过预定阈值时，说明主PW可能处于超负荷运转或发生拥塞。基于所述带宽占用率超过预定阈值的情况，所述第一PE设备触发S101的执行，即触发图3所示的流程。基于上述实现方式，所述VPWS PW可以根据转发流量的带宽情况，自动的选择冗余模式转发数据流量和流量均衡模式转发数据流量。其中，对于阈值的选择不进行限定，例如使用PW的额定带宽作为阈值或者由操作人员进行配置。
可选的，在S101之前，所述方法还包括：所述第一PE设备确定所述第一PE设备向所述第二PE设备发送流量的时刻起，经历预定的时间周期。
举例说明，在执行上述S101之前，所述VPWS PW的PW转发方式已经被协商为图1所示的场景，并且，数据流量经由Active的主PW转发，备份PW处于Standby状态。所述第一PE设备在向所述第二PE设备发送流量时起，经历预定的时间周期后，所述第一PE设备触发S101的执行，即触发图3所示的流程。基于上述实现方式，有利于在冗余模式转发数据流量稳定后，切换为流量均衡模式转发数据流量。
可选的，在S107之前，所述方法还包括：所述第二PE设备确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率小于预定阈值。
具体的，PW链路承载于物理链路上，因此，所述物理链路可能还传输有非PW流量。所述非PW流量是指不经由PW链路传输，而经由承载所述PW链路的物理链路传输的流量。物理链路的总带宽是固定的，如果所述物理链路上的非PW流量占用带宽过高，将会导致所述物理链路承载的PW链路的带宽降低。因此，即使PW链路上不存在流量的情况下，也可能出现因物理链路的非PW流量过载，造成PW链路的拥塞或通信质量不佳。所述第二PE设备在根据所述第一报文和所述第二报文生成回应报文之前，对所述第二PE设备发送到所述第二PE设备和所述第三PE设备之间的物理链路上的流量进行检测，即所述第二PE设备对所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率进行检测。当所述出接口的带宽占用率小于预定阈值时，说明所述第二PE设备和所述第三PE设备之间的物理链路上承载的Bypass PW有剩余带宽承载PW流量。基于上述实现方式，有助于减少流量均衡模式协商不成功的情况，并且有助于减少切换为流量均衡模式后链路拥塞的情况。
可选的，在S107之前，所述方法还包括：所述第二PE设备确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率大于或等于预定阈值，所述第二PE设备生成拒绝报文，并经由所述主PW向所述第一PE设备和经由所述Bypass PW向所述第三PE设备发送所述拒绝报文，所述拒绝报文用于指示不同意所述第一报文 和所述第二报文的切换请求。
结合上述的描述，当所述第二PE设备的所述出接口的带宽占用率大于或等于预定阈值时，生成所述拒绝报文，并且向所述第一PE设备和所述第三PE设备通告所述拒绝报文。所述第一PE设备和所述第三PE设备在接收到所述拒绝报文后，终止切换为流量均衡模式的协商过程。可选的，所述拒绝报文是携带着拒绝状态码的PW状态通知报文，所述PW状态通知报文可以是LDP报文。所述拒绝状态码的值例如可以设置为0x31。
相应的，当该步骤被触发后，图3所示的方法将不再执行S107-S112的相应步骤。
可选的，在S105之前，所述方法还包括：所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值。
可选的，在S105之前，所述方法还包括：所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率大于或等于预定阈值，所述第三PE设备生成拒绝报文，并经由所述备份PW向所述第一PE设备发送所述拒绝报文，所述拒绝报文用于指示不同意所述第二报文的切换请求。
基于上述的描述，基于与所述第二PE设备检测出接口的带宽占用率的实现方式同样道理，所述第三PE设备在接收到所述第一PE设备经由所述备份PW发送的所述第二报文后，检测所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率是否小于预定阈值。如果所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值，将执行S105步骤。所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率大于或等于预定阈值，所述第三PE设备生成拒绝报文，并经由所述备份PW向所述第一PE设备发送所述拒绝报文，相应的，图3所示的方法将不再执行S105-S112的相应步骤。
图4示出本申请实施例的又一种VPWS PW冗余网络结构示意图。图4是基于图2所示的流量均衡的转发方式下，发生故障的场景图。在图4中显示了故障1、故障2、故障3、故障4、故障5和故障6。应当理解，在图4所呈现的场景并不代表上述6种故障同时发生，而是表示上述6种故障出现的位置。本申请接下来的实施例，将会讨论每个故障的处理方法。而且，以下实施例只讨论同时刻出现一种故障的情况，不讨论同时刻出现两种或两种以上故障的情况。
图5示出了处理图4中故障1的方法流程图，并且，图5所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障1后的故障处理实现方式。其中，故障1是指第一PE设备和第二PE设备之间的主PW存在故障。该方法包括：
S201、所述第一PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文。
基于前述实施例，从第一CE设备发送到第二CE设备的数据流量，以及从第二CE设备发送到第一CE设备的数据流量，均以流量均衡的方式被分担到主PW和备份PW进行转发。在转发数据流量的过程中，所述第一PE设备可以经由所述主PW向所述第二PE设备发送故障检测报文，相应的，所述第二PE设备可以经由所述主PW向所述第一PE设备发送故障检测报文，即所述第一PE设备和所述第二PE设备之间双向发送所述故障检测报文。所述故障检测报文用于指示PW链路或PE设备的故障。 可选的，所述故障检测报文可以按照预定的时间间隔周期发送，所述故障检测报文可以是双向转发检测(Bidirectional Forwarding Detection，BFD)报文。如果在预定的周期内，所述第一PE设备没有接收到所述第二PE设备发送的故障检测报文，所述第一设备可以确定所述主PW或所述第二PE设备出现了故障(本实施例以主PW出现故障为例，第二PE设备故障可参见后续实施例)。
S202、所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Standby状态。
S203、所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Active状态。
所述第一PE设备在确定预定周期内无法收到来自所述第二PE设备的故障检测报文后，将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且经由所述主PW向所述第二PE设备发送第三报文。其中，所述第三报文可以是携带着Standby状态码的PW状态通知报文，所述PW状态通知报文可以是LDP报文，所述Standby状态码例如为0x20。同样道理，所述第一PE设备还将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态，并且经由所述备份PW向所述第三PE设备发送第四报文。其中，所述第四报文可以是携带着Active状态码的PW状态通知报文，所述PW状态通知报文可以是LDP报文，所述Active状态码例如为0x00。
所述第一PE设备在执行S202和S203时，不限定执行顺序，可以先执行S202后执行S203，也可以先执行S203后执行S202，还可以同时执行。另外，由于主PW故障，所述第三报文可能无法被所述第二PE设备接收。在这种情况下，所述第一PE设备依然发送所述第三报文是为了减少所述第一PE设备的执行操作的复杂性。
在一种可能的实现方式中，所述第三报文中还可以携带故障码，这种情况下，所述第三报文可以被看做是切换报文和故障通告报文的组合报文。在另一种可能的实现方式中，例如在独立模式下，所述第三报文可以不采用携带着Standby状态码的PW状态通知报文，而是采用携带故障状态码的LDP报文。
S204、所述第三PE设备接收所述第四报文。
S205、所述第三PE设备根据所述第四报文将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态。
举例说明，所述第三PE设备经由备份PW接收携带着Active状态码的PW状态通知报文，根据所述PW状态通知报文将所述备份PW由Balance状态切换为Active状态。
S206、所述第二PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文。
S206与S201并不限定执行顺序，均是依据故障检测报文进行触发的。所述主PW故障后，如果故障检测报文是双向发送的，所述第二PE设备也将在预定周期内无法收到来自所述第一PE设备的故障检测报文。所述故障检测报文的实现方式参见上述 S201的相应描述，此处不进行赘述。
另外，PW链路属于双向链路，即使PW链路发生单方向故障，也会导致双方PE设备均无法收到对方的故障检测报文。例如，所述第一PE设备和所述第二PE设备相互发送BFD报文，假设所述第一PE设备到所述第二PE设备的方向上出现故障，而所述第而PE设备到所述第一PE设备的方向上正常通信。所述第二PE设备将无法接受到来自所述第一PE设备的BFD报文，所述第二PE设备将端口置为DOWN，从而导致所述第二PE设备不再向所述第一PE设备发送BFD报文。因此，导致所述第一PE设备也无法接受到来自所述第二PE设备的BFD报文。
S207、所述第二PE设备将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第二PE设备发现的故障。
S208、所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第三PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
所述第二PE设备在确定预定周期内无法收到来自所述第一PE设备的故障检测报文后，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且经由所述主PW向所述第一PE设备发送故障通告报文。其中，所述故障通告报文可以是LDP报文。同样道理，所述第二PE设备还将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且经由所述Bypass PW向所述第三PE设备发送终止报文。其中，所述终止报文是携带着终止状态码的PW状态通知报文，所述PW状态通知报文可以是LDP报文，所述终止状态码例如为0x32。另外，由于主PW故障，所述故障通告报文可能无法被所述第一PE设备接收。
S209、所述第三PE设备接收所述终止报文。
S210、所述第三PE设备根据终止报文所述将所述第三PE设备相对于Bypass PW的优先转发状态由Balance状态切换为Bypass状态。
举例说明，所述第三PE设备经由Bypass PW接收携带着终止状态码的PW状态通知报文，根据所述PW状态通知报文将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态。
通过上述S201-S210的故障处理过程，所述VPWS PW冗余网络的转发模式由流量均衡模式切换为冗余保护模式。并且由于主PW故障，数据流量转发路径为：第一CE设备-第一PE设备-备份PW-第三PE设备-Bypass PW-第二PE设备-主用链路-第二CE设备。当所述故障1被排除后，所述VPWS PW冗余网络可以按照图3所示的实现方式，再次进入流量均衡模式。
图6示出了处理图4中故障2的方法流程图，并且，图6所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障2后的故障处理实现方式。其中，故障2是指第一PE设备和第三PE设备之间的备份PW存在故障。该方法包括：
S301、所述第一设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文。
S302、所述第一设备将所述第一PE设备相对于主PW的优先转发状态由Balance状态切换为Active状态，并且向第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。
S303、所述第一设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
基于上述实施例，对于S301-S303的实现过程和故障检测报文、第三报文和第四报文的实现方式，可以参见前述实施例中S201-S203的相应描述，此处不进行赘述。
所述第一PE设备在执行S302和S303时，不限定执行顺序，可以先执行S302后执行S303，也可以先执行S303后执行S302，还可以同时执行。另外，由于备份PW故障，所述第四报文可能无法被所述第三PE设备接收。在这种情况下，所述第一PE设备依然发送所述第四报文是为了减少所述第一PE设备的执行操作的复杂性。
在一种可能的实现方式中，所述第四报文中还可以携带故障码，这种情况下，所述第四报文可以被看做是切换报文和故障通告报文的组合报文。在另一种可能的实现方式中，例如在独立模式下，所述第四报文可以不采用携带着Standby状态码的PW状态通知报文，而是采用携带故障状态码的LDP报文。
S304、所述第二PE设备接收所述第三报文。
S305、所述第二PE设备根据所述第三报文将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
举例说明，所述第二PE设备经由主PW接收携带着Active状态码的PW状态通知报文，根据所述PW状态通知报文将所述主PW由Balance状态切换为Active状态。
S306、所述第三PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文。
S307、所述第三PE设备将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第三PE设备发现的故障。
S308、所述第三PE设备将所述第三PE设备相对于Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第二PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
基于上述实施例，对于S306-S308的实现过程和故障检测报文、故障通告报文和终止报文的实现方式，可以参见前述实施例中S206-S208的相应描述，此处不进行赘述。
S309、所述第二PE设备接收所述终止报文。
S310、所述第二PE设备根据所述终止报文将所述Bypass PW由Balance状态切换为Bypass状态。
举例说明，所述第二PE设备经由Bypass PW接收携带着终止状态码的PW状态通知报文，根据所述PW状态通知报文将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态。
通过上述S301-S310的故障处理过程，所述VPWS PW冗余网络的转发模式由流 量均衡模式切换为冗余保护模式。并且由于备份PW故障，数据流量转发路径为：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。当所述故障2被排除后，所述VPWS PW冗余网络可以按照图3所示的实现方式，再次进入流量均衡模式。
图7示出了处理图4中故障3的方法流程图，并且，图7所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障3后的故障处理实现方式。其中，故障3是指第二PE设备和第二CE设备之间的主用链路存在故障。该方法包括：
S401、所述第二PE设备确定预定周期内无法收到来自所述第二CE设备的故障检测报文。
根据前述实施例，所述第二CE设备通过MC-Trunk链路双归属连接到所述VPWSPW冗余网络中的所述第二PE设备和所述第三PE设备。并且，在主/从模式和独立模式中，将所述第二CE设备与所述第二PE设备之间的Eth-Trunk链路协商为主用链路和将所述第二CE设备与所述第三PE设备之间的Eth-Trunk链路协商为备用链路。在图2所示的场景中，从所述第一CE设备发出的数据流量，经过“第一PE设备-主PW-第二PE设备-主用链路”和“第一PE设备-备份PW-第三PE设备-Bypass PW-第二PE设备-主用链路”两条路径转发到所述第二CE设备；从所述第二CE设备发出的数据流量，经过“主用链路-第二PE设备-主PW-第一PE设备”和“主用链路-第二PE设备-Bypass PW-第三PE设备-备份PW-第一PE设备”两条路径转发到所述第一CE设备。
所述第二PE设备和所述第二CE设备相互向对方发送故障检测报文，当第二PE设备确定预定周期内无法收到来自所述第二CE设备的故障检测报文时，所述第二设备可以确定所述主用链路发生故障。所述第二PE设备和所述第二CE设备交互故障检测报文和所述故障检测报文的描述，可以参见前述实施例的描述，此处不进行赘述。
S402、所述第二PE设备确定所述第二PE设备相对于主PW的优先转发状态为Balance状态，保持相对于所述主PW的Balance状态，并且不向第一PE设备发送用于切换所述主PW的Balance状态的报文。
当所述第二PE设备确定预定周期内无法收到来自所述第二CE设备的故障检测报文时，相应的，所述第二CE设备确定预定周期内也无法收到来自所述第二PE设备的故障检测报文。如此这样，所述第二CE设备将触发远端AC侧网络的主用链路和备用链路的主备倒换，从而将数据流量切换到所述备用链路。
在图1所示的场景中，对于主/从模式，在所述第二CE设备触发远端AC侧网络的主用链路和备用链路的主备倒换后，PW侧网络将保持不变。也就是说，所述主PW保持Active状态，所述备份PW保持Standby状态。例如，从所述第一CE设备发出的数据流量，经过“第一PE设备-主PW-第二PE设备-Bypass PW-第三PE设备-备用链路”发到所述第二CE设备。在图1所示的场景中，对于独立模式，在所述第二CE设备触发远端AC侧网络的主用链路和备用链路的主备倒换后，PW侧网络将跟随远端AC侧网络的主备关系进行切换。也就是说，所述主PW保持Standby状态，所述备份PW保持Active状态。例如，从所述第一CE设备发出的数据流量，经过“第一PE设备-备份PW-第三PE设备-备用链路”发到所述第二CE设备。
在图2所示的场景中，所述主PW和所述备份PW均为Balance状态。因此，在主/从模式和独立模式中，所述第二PE设备确定主PW的状态为Balance状态，保持所述主PW的Balance状态，并且不向第一PE设备发送用于切换所述主PW的Balance状态的报文。这样，所述第二PE设备不对所述第二PE设备相对于所述主PW的Balance优先转发状态进行切换，也不向所述第一PE设备发送任何触发报文。从而导致所述第一PE设备保持所述第一PE设备相对于所述主PW的Balance优先转发状态和所述备份PW的Balance优先转发状态，进一步导致所述第三PE设备保持所述第三PE设备相对于所述备份PW的Balance优先转发状态。PW侧网络依然保持流量均衡模式。例如，从所述第一CE设备发出的数据流量，经过“第一PE设备-主PW-第二PE设备-Bypass PW-第三PE设备-备用链路”和“第一PE设备-备份PW-第三PE设备-备用链路”两条路径转发到所述第二CE设备。
图8示出了处理图4中故障4的方法流程图，并且，图8所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障4后的故障处理实现方式。其中，故障4是指第二PE设备存在故障。该方法包括：
S501、第一PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文。
S502、所述第一PE设备将所述第一PE设备相对于主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Standby状态。
S503、所述第一PE设备将所述第一PE设备相对于备份PW的优先转发状态由Balance状态切换为Active状态，并且向第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Active状态。
S504、所述第三PE设备接收所述第四报文。
S505、所述第三PE设备根据所述第四报文将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态。
上述S501-S505的实现过程可以参见前述实施例中的S201-S205的相应描述，此处不进行赘述。其中在S502中，所述第二PE设备由于故障将无法接受所述第三报文，但为了减少所述第一PE设备的执行操作的复杂性，所述第一PE设备依然向所述第二PE设备发送所述第三报文。
S506、所述第三PE设备确定预定周期内无法收到来自第二PE设备的故障检测报文。
在图2所示的正常的流量转发场景中，所述第二PE设备和所述第三PE设备经由Bypass PW相互向对方发送故障检测报文，即所述第二PE设备周期的向所述第三PE设备发送故障检测报文，同时所述第三PE设备周期的向所述第二PE设备发送故障检测报文。根据前述实施例，所述故障检测报文可以是BFD报文。如果在预定的周期内，所述第三PE设备没有接收到所述第二PE设备经由所述Bypass PW发送的故障检测报文，所述第三设备可以确定所述Bypass PW或所述第二PE设备出现了故障(本实施例以第二PE设备出现故障为例，Bypass PW故障可参见后续实施例)。
S507、所述第三PE设备将所述第三PE设备相对于Bypass PW的优先转发状态由 Balance状态切换为Bypass状态，并且向第一PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
所述第三PE设备在确定预定周期内无法收到来自所述第二PE设备的故障检测报文后，所述第三PE设备将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且经由所述备份PW向所述第一PE设备发送终止报文。其中，所述终止报文的实现可以参见前述S208的相应描述，此处不进行赘述。
另外，可选的，所述第三PE设备经由所述Bypass PW向所述第二PE设备发送终止报文。由于所述第二PE设备故障，所述终止报文无法被所述第二PE设备接收。所述第三PE设备发送所述终止报文是为了减少所述第三PE设备的执行操作的复杂性。
S508、所述第一PE设备根据所述终止报文，确定所述Bypass PW由Balance状态切换为Bypass状态。
具体的，所述第一PE设备在根据所述终止报文确定所述Bypass PW由Balance状态切换为Bypass状态后，再进行后续数据流量的转发，可以减少丢包的可能。
相应的，由于所述第二PE设备故障，导致第二CE设备触发远端AC侧网络的主用链路和备用链路的主备倒换，从而将数据流量切换到所述备用链路。
通过上述S501-S507的故障处理过程，所述VPWS PW冗余网络的转发模式由流量均衡模式切换为冗余保护模式。并且由于第二PE设备故障，数据流量转发路径为：第一CE设备-第一PE设备-备份PW-第三PE设备-备用链路-第二CE设备。当所述故障4被排除后，所述VPWS PW冗余网络可以按照图3所示的实现方式，再次进入流量均衡模式。
图9示出了处理图4中故障5的方法流程图，并且，图9所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障5后的故障处理实现方式。其中，故障5是指第三PE设备存在故障。该方法包括：
S601、所述第一设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文。
S602、所述第一设备将所述第一PE设备相对于主PW的优先转发状态由Balance状态切换为Active状态，并且向第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。
S603、所述第一设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
S604、所述第二PE设备接收所述第三报文。
S605、所述第二PE设备根据所述第三报文将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
上述S601-S605的实现过程可以参见前述实施例中的S301-S305的相应描述，此处不进行赘述。其中在S603中，所述第三PE设备由于故障将无法接受所述第四报文，但为了减少所述第一PE设备的执行操作的复杂性，所述第一PE设备依然向所述第三PE设备发送所述第四报文。
S606、所述第二PE设备确定预定周期内无法收到来自所述第三PE设备的故障检 测报文。
在图2所示的正常的流量转发场景中，所述第二PE设备和所述第三PE设备经由Bypass PW相互向对方发送故障检测报文，即所述第二PE设备周期的向所述第三PE设备发送故障检测报文，同时所述第三PE设备周期的向所述第二PE设备发送故障检测报文。根据前述实施例，所述故障检测报文可以是BFD报文。如果在预定的周期内，所述第二PE设备没有接收到所述第三PE设备经由所述Bypass PW发送的故障检测报文，所述第二设备可以确定所述Bypass PW或所述第三PE设备出现了故障(本实施例以第三PE设备出现故障为例，Bypass PW故障可参见后续实施例)。
S607、所述第二PE设备将所述第二PE设备相对于Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
所述第二PE设备在确定预定周期内无法收到来自所述第三PE设备的故障检测报文后，所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且经由所述主PW向所述第一PE设备发送终止报文。其中，所述终止报文的实现可以参见前述S208的相应描述，此处不进行赘述。
另外，可选的，所述第二PE设备经由所述Bypass PW向所述第三PE设备发送终止报文。由于所述第三PE设备故障，所述终止报文无法被所述第三PE设备接收。所述第二PE设备发送所述终止报文是为了减少所述第二PE设备的执行操作的复杂性。
S608、所述第一PE设备根据所述终止报文，确定所述Bypass PW由Balance状态切换为Bypass状态。
具体的，所述第一PE设备在根据所述终止报文确定所述Bypass PW由Balance状态切换为Bypass状态后，再进行后续数据流量的转发，可以减少丢包的可能。
通过上述S601-S608的故障处理过程，所述VPWS PW冗余网络的转发模式由流量均衡模式切换为冗余保护模式。并且由于第三PE设备故障，数据流量转发路径为：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。当所述故障5被排除后，所述VPWS PW冗余网络可以按照图3所示的实现方式，再次进入流量均衡模式。
图10示出了处理图4中故障6的方法流程图，并且，图10所示的方法是在已经实现图2所示的流量均衡的转发方式的情况下，发生了故障6后的故障处理实现方式。其中，故障6是指第二PE设备与第三PE设备之间的Bypass PW存在故障。该方法包括：
S701、所述第二PE设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文。
S702、所述第二PE设备将所述第二PE设备相对于Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
上述S701-S702的实现过程可以参见前述实施例中的S606-S607的相应描述，此处不进行赘述。
S703、所述第三PE设备确定预定周期内无法收到来自第二PE设备的故障检测报 文。
S704、所述第三PE设备将所述第三PE设备相对于Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向第一PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
上述S703-S704的实现过程可以参见前述实施例中的S506-S507的相应描述，此处不进行赘述。
S705、所述第一PE设备接收来自所述第二PE设备和所述第三PE设备的终止报文。
上述S705的实现过程可以参见前述实施例中的S508和S608的相应描述。根据上述S508和S608的相应描述，如果所述第一PE设备只接收到来自所述第二PE设备的终止报文或者只接收到来自所述第三PE设备的终止报文，所述第一PE设备将无法确定所述Bypass PW存在故障。这是由于所述第二PE设备或所述第三PE设备故障可能导致终止报文无法发出。因此，所述第一PE设备根据能够收到来自所述第二PE设备的终止报文和来自所述第三PE设备的终止报文的情况，可以确定所述Bypass PW存在故障，并触发S706和S707步骤。
S706、所述第一设备将所述第一PE设备相对于主PW的优先转发状态由Balance状态切换为Active状态，并且向第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态。
S707、所述第一设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
上述S706-S707的实现过程可以参见前述实施例中的S302-S303的相应描述，此处不进行赘述。
S708、所述第二PE设备接收所述第三报文。
S709、所述第二PE设备根据所述第三报文将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
结合前述实施例，举例说明，所述第二PE设备经由主PW接收携带着Active状态码的PW状态通知报文，根据所述PW状态通知报文将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
S710、所述第三PE设备接收所述第四报文。
S711、所述第三PE设备根据所述第四报文将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态。
结合前述实施例，举例说明，所述第三PE设备经由备份PW接收携带着Standby状态码的PW状态通知报文，根据所述PW状态通知报文将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态。
通过上述S701-S711的故障处理过程，所述VPWS PW冗余网络的转发模式由流量均衡模式切换为冗余保护模式。并且由于Bypass PW故障，数据流量转发路径为：第一CE设备-第一PE设备-主PW-第二PE设备-主用链路-第二CE设备。当所述故障6被排除后，所述VPWS PW冗余网络可以按照图3所示的实现方式，再次进入流量 均衡模式。
图11-图16是本申请中的VPWS PW冗余网络的各个PE结构和硬件示意图，所述VPWS PW冗余网络包括第一PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW。
图11为本申请实施例的第一PE设备1000的结构示意图。图11所示的第一PE设备可以执行上述实施例的方法中第一PE设备执行的相应步骤。如图11所示，所述第一PE设备1000包括接收单元1002，处理单元1004和发送单元1006，其中：
所述发送单元1006，用于经由所述主PW向所述第二PE设备发送第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
所述发送单元1006还用于经由所述备份PW向所述第三PE设备发送第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
所述接收单元1002，用于经由所述主PW接收来自所述第二PE设备的回应报文，所述回应报文是由所述第二PE设备根据所述第一报文和所述第二报文确定得到的，其中，所述第二报文是所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发得到的，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求；
所述处理单元1004，用于根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态。
可选的，所述接收单元1002还用于接收来自CE设备的流量；所述发送单元还用于按照流量均衡的方式经由Balance状态的所述主PW和所述备份PW向所述第二PE设备和第三PE设备转发来自所述CE设备的流量。
可选的，所述处理单元1004还用于在所述发送单元1006经由所述主PW向所述第二PE设备发送第一报文之前，确定所述发送单元1006向所述第二PE设备发送流量的带宽占用率超过预定阈值。
可选的，所述处理单元1004还用于确定预定周期内无法收到来自所述第二PE设备的故障检测报文，将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态；所述发送单元1006还用于向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Standby状态；所述处理单元1004还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态；所述发送单元1006还用于向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Active状态。
可选的，所述处理单元1004还用于确定预定周期内无法收到来自所述第三PE设备的故障检测报文，将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态；所述发送单元1006还用于向所述第二PE设备发送第三报文， 所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；所述处理单元1004还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；所述发送单元1006还用于向所述第三PE设备发送第四报文，所述第四报文请求将指示所述备份PW由Balance状态切换为Standby状态。
可选的，所述接收单元1002还用于接收来自所述第二PE设备和所述第三PE设备的终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；所述处理单元1004还用于将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态；所述发送单元1006还用于向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；所述处理单元1004还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；所述发送单元1006还用于向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
图11所示的第一PE设备可以执行上述实施例的方法中第一PE设备执行的相应步骤。以确保在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
图12为本申请实施例的第一PE设备1100的硬件结构示意图。图12所示的第一PE设备可以执行上述实施例的方法中第一PE设备执行的相应步骤。
如图12所示，所述第一PE设备1100包括处理器1101、存储器1102、接口1103和总线1104，其中接口1103可以通过无线或有线的方式实现，具体来讲可以是例如网卡等元件，上述处理器1101、存储器1102和接口1103通过总线1104连接。
所述接口1103具体可以包括发送器和接收器，用于第一PE设备与上述实施例中的第二PE设备和第三PE设备之间收发信息；或者用于第一PE设备与所述第一PE设备连接的第一CE设备之间收发信息。作为举例，所述接口1103用于支持图3，图5-图10中的过程S101，S102，S109，S202，S203，S302，S303，S502，S503，S602，S603，S705，S706和S707。所述处理器1101用于执行上述实施例中由第一PE设备进行的处理。例如，处理器1101用于切换所述第一PE设备相对于主PW和备份PW的优先转发状态；还用于生成PW状态通知报文和/或故障检测报文，通过接口1103向第二PE设备和第三PE设备发送PW状态通知报文和/或故障检测报文；还用于处理来自第二PE设备和第三PE设备的PW状态通知报文和/或终止报文；和/或用于本文所描述的技术的其他过程。作为举例，所述处理器1101用于支持图3，图5-图10中的过程S110，S201，S202，S203，S301，S302，S303，S401，S402，S501，S502，S503，S508，S601，S602，S603，S608，S706和S707。存储器1102包括操作系统11021和应用程序11022，用于存储程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成图3，图5-图10中涉及第一PE设备的处理过程。
可以理解的是，图12仅仅示出了第一PE设备的简化设计。在实际应用中，第一PE设备可以包含任意数量的接口，处理器，存储器等，而所有可以实现本申请的第一PE设备都在本申请的保护范围之内。
另外，本申请实施例提供了一种计算机存储介质，用于储存为上述第一PE设备所用的计算机软件指令，其包含用于执行上述图3，图5-图10所示实施例所设计的程 序。
图13为本申请实施例的第二PE设备1200的结构示意图。图13所示的第二PE设备可以执行上述实施例的方法中第二PE设备执行的相应步骤。如图13所示，所述第二PE设备1200包括接收单元1202，处理单元1204和发送单元1206，其中：
所述接收单元1202，用于经由所述主PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
所述接收单元1202还用于经由所述Bypass PW接收所述第三PE设备转发的第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
所述处理单元1204，用于根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态；
所述发送单元1206，用于经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求。
可选的，CE设备通过MC-Trunk链路双归属连接到所述VPWS PW冗余网络中的所述第二PE设备和所述第三PE设备，所述CE设备与所述第二PE设备之间的链路为主用链路，所述CE设备与所述第三PE设备之间的链路为备用链路，所述接收单元1202还用于经由所述主用链路接收来自所述CE设备的流量；所述发送单元1206还用于按照流量均衡的方式经由Balance状态的所述主PW和所述Bypass PW向所述第一PE设备和第三PE设备转发来自所述CE设备的流量。
可选的，所述处理单元1204还用于在根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态之前，确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率小于预定阈值。
可选的，所述处理单元1204还用于确定预定周期内无法收到来自所述第一PE设备的故障检测报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态；所述发送单元1206还用于向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第二PE设备发现的故障；所述处理单元1204还用于将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；所述发送单元1206还用于向所述第三PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
可选的，所述处理单元1204还用于确定预定周期内无法收到来自所述CE设备的故障检测报文，确定所述第二PE设备相对于所述主PW的优先转发状态为Balance状态，保持相对于所述主PW的Balance状态，并且不控制所述发送单元1206向所述第一PE设备发送用于切换所述主PW的Balance状态的报文。
可选的，所述处理单元1204还用于确定预定周期内无法收到来自所述第三PE设备的故障检测报文，将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；所述发送单元1206还用于向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；所述接收单元1202还用于接收来自所述所述第一PE设备的第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；所述处理单元1204还用于根据所述第三报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
图13所示的第二PE设备可以执行上述实施例的方法中第二PE设备执行的相应步骤。以确保在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
图14为本申请实施例的第二PE设备1300的硬件结构示意图。图14所示的第二PE设备可以执行上述实施例的方法中第二PE设备执行的相应步骤。
如图14所示，所述第二PE设备1300包括处理器1301、存储器1302、接口1303和总线1304，其中接口1303可以通过无线或有线的方式实现，具体来讲可以是例如网卡等元件，上述处理器1301、存储器1302和接口1303通过总线1304连接。
所述接口1303具体可以包括发送器和接收器，用于第二PE设备与上述实施例中的第一PE设备和第三PE设备之间收发信息；或者用于第二PE设备与所述第二PE设备连接的第二CE设备之间收发信息。作为举例，所述接口1303用于支持图3，图5-图10中的过程S103，S106，S108，S207，S208，S304，S309，S604，S607，S702和S708。所述处理器1301用于执行上述实施例中由第二PE设备进行的处理。例如，处理器1301用于切换所述第二PE设备相对于主PW和Bypass PW的优先转发状态；还用于生成PW状态通知报文、故障检测报文和/或终止报文，通过接口1303向第一PE设备和第三PE设备发送PW状态通知报文、故障检测报文和/或终止报文；还用于处理来自第一PE设备和第三PE设备的PW状态通知报文和/或终止报文；和/或用于本文所描述的技术的其他过程。作为举例，所述处理器1301用于支持图3，图5-图10中的过程S107，S206，S207，S208，S305，S310，S605，S606，S607，S701，S702和S709。存储器1302包括操作系统13021和应用程序13022，用于存储程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成图3，图5-图10中涉及第二PE设备的处理过程。
可以理解的是，图14仅仅示出了第二PE设备的简化设计。在实际应用中，第二PE设备可以包含任意数量的接口，处理器，存储器等，而所有可以实现本申请的第二PE设备都在本申请的保护范围之内。
另外，本申请实施例提供了一种计算机存储介质，用于储存为上述第二PE设备所用的计算机软件指令，其包含用于执行上述图3，图5-图10所示实施例所设计的程序。
图15为本申请实施例的第三PE设备1400的结构示意图。图15所示的第三PE设备可以执行上述实施例的方法中第三PE设备执行的相应步骤。如图15所示，所述第三PE设备1400包括接收单元1402，处理单元1404和发送单元1406，其中：
所述接收单元1402，用于经由所述备份PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
所述发送单元1406，用于经由所述Bypass PW向所述第二PE设备转发所述第一报文；
所述接收单元1402还用于经由所述Bypass PW接收来自所述第二PE设备的回应报文，所述回应报文用于指示同意所述第一报文的切换请求；
所述处理单元1404，用于根据所述回应报文，将所述第三PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
可选的，所述处理单元1404还用于在所述发送单元1406经由所述Bypass PW向所述第二PE设备转发所述第一报文之前，确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值。
可选的，所述处理单元1404还用于确定预定周期内无法收到来自所述第一PE设备的故障检测报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；所述发送单元1406还用于向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第三PE设备发现的故障；所述处理单元1404还用于将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；所述发送单元1406还用于向所述第二PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
可选的，所述处理单元1404还用于确定预定周期内无法收到来自所述第二PE设备的故障检测报文，将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；所述发送单元1406还用于向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；所述接收单元1402还用于接收来自所述所述第一PE设备的第二报文，所述第二报文用于请求将所述备份PW由Balance状态切换为Active状态或Standby状态；所述处理单元1404还用于根据所述第二报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态或Standby状态。
图15所示的第三PE设备可以执行上述实施例的方法中第三PE设备执行的相应步骤。以确保在保留VPWS PW中主PW和备份PW的冗余保护功能的基础上，实现主PW和备份PW的流量均衡，有助于提高VPWS PW的带宽利用率。
图16为本申请实施例的第三PE设备1500的硬件结构示意图。图16所示的第三PE设备可以执行上述实施例的方法中第三PE设备执行的相应步骤。
如图16所示，所述第三PE设备1500包括处理器1501、存储器1502、接口1503和总线1504，其中接口1503可以通过无线或有线的方式实现，具体来讲可以是例如网卡等元件，上述处理器1501、存储器1502和接口1503通过总线1504连接。
所述接口1503具体可以包括发送器和接收器，用于第三PE设备与上述实施例中的第一PE设备和第二PE设备之间收发信息；或者用于第三PE设备与所述第三PE 设备连接的第二CE设备之间收发信息。作为举例，所述接口1503用于支持图3，图5-图10中的过程S104，S105，S111，S204，S209，S307，S308，S504，S507，S704和S710。所述处理器1501用于执行上述实施例中由第三PE设备进行的处理。例如，处理器1501用于切换所述第三PE设备相对于备份PW和Bypass PW的优先转发状态；还用于生成PW状态通知报文、故障检测报文和/或终止报文，通过接口1503向第一PE设备和第二PE设备发送PW状态通知报文、故障检测报文和/或终止报文；还用于处理来自第一PE设备和第二PE设备的PW状态通知报文和/或终止报文；和/或用于本文所描述的技术的其他过程。作为举例，所述处理器1501用于支持图3，图5-图10中的过程S112，S205，S210，S306，S307，S308，S505，S506，S507，S703，S704和S711。存储器1502包括操作系统15021和应用程序15022，用于存储程序、代码或指令，当处理器或硬件设备执行这些程序、代码或指令时可以完成图3，图5-图10中涉及第三PE设备的处理过程。
可以理解的是，图16仅仅示出了第三PE设备的简化设计。在实际应用中，第三PE设备可以包含任意数量的接口，处理器，存储器等，而所有可以实现本申请的第三PE设备都在本申请的保护范围之内。
另外，本申请实施例提供了一种计算机存储介质，用于储存为上述第三PE设备所用的计算机软件指令，其包含用于执行上述图3，图5-图10所示实施例所设计的程序。
根据图11-图16所示的实施例，可选的，所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
图2为本发明实施例的VPWS PW冗余网络结构示意图。所述系统包括前述图11或图12中的第一PE设备，前述图13或图14中的第二PE设备和前述图15或图16中的第三PE设备。
结合本申请公开内容所描述的方法或者算法的步骤可以硬件的方式来实现，也可以是由处理器执行软件指令的方式来实现。软件指令可以由相应的软件模块组成，软件模块可以被存放于RAM存储器、闪存、ROM存储器、EPROM存储器、EEPROM存储器、寄存器、硬盘、移动硬盘、CD-ROM或者本领域熟知的任何其它形式的存储介质中。一种示例性的存储介质耦合至处理器，从而使处理器能够从该存储介质读取信息，且可向该存储介质写入信息。当然，存储介质也可以是处理器的组成部分。处理器和存储介质可以位于ASIC中。另外，该ASIC可以位于用户设备中。当然，处理器和存储介质也可以作为分立组件存在于用户设备中。
本领域技术人员应该可以意识到，在上述一个或多个示例中，本申请所描述的功能可以用硬件、软件、固件或它们的任意组合来实现。当使用软件实现时，可以将这些功能存储在计算机可读介质中或者作为计算机可读介质上的一个或多个指令或代码进行传输。计算机可读介质包括计算机存储介质和通信介质，其中通信介质包括便于从一个地方向另一个地方传送计算机程序的任何介质。存储介质可以是通用或专用计算机能够存取的任何可用介质。
以上所述的具体实施方式，对本申请的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本申请的具体实施方式而已，并不用于限定本申请的保护范围，凡在本申请的技术方案的基础之上，所做的任何修改、等同替换、改进等，均应包括在本申请的保护范围之内。

Claims (39)

  1. 一种转发报文的方法，所述方法应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一运营商边缘PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述方法包括：
    所述第一PE设备经由所述主PW向所述第二PE设备发送第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
    所述第一PE设备经由所述备份PW向所述第三PE设备发送第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    所述第一PE设备经由所述主PW接收来自所述第二PE设备的回应报文，所述回应报文是由所述第二PE设备根据所述第一报文和所述第二报文确定得到的，其中，所述第二报文是所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发得到的，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求；
    所述第一PE设备根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态。
  2. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    所述第一PE设备接收来自用户边缘CE设备的流量；
    所述第一PE设备按照流量均衡的方式经由Balance状态的所述主PW和所述备份PW向所述第二PE设备和第三PE设备转发来自所述CE设备的流量。
  3. 根据权利要求1或2所述的方法，其特征在于，
    所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  4. 根据权利要求1-3中任一项所述的方法，其特征在于，在所述第一PE设备经由所述主PW向所述第二PE设备发送第一报文之前，所述方法还包括：
    所述第一PE设备确定所述第一PE设备向所述第二PE设备发送流量的带宽占用率超过预定阈值。
  5. 根据权利要求1-4中任一项所述的方法，其特征在于，所述方法还包括：
    所述第一PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文；
    所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Standby状态；
    所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态，并且向所述第三PE设备发送第四报文，所述第四报 文用于请求将所述备份PW由Balance状态切换为Active状态。
  6. 根据权利要求1-4中任一项所述的方法，其特征在于，所述方法还包括：
    所述第一PE设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文；
    所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文请求将指示所述备份PW由Balance状态切换为Standby状态。
  7. 根据权利要求1-4中任一项所述的方法，其特征在于，所述方法还包括：
    所述第一PE设备接收来自所述第二PE设备和所述第三PE设备的终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述第一PE设备将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态，并且向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述第一PE设备将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
  8. 一种转发报文的方法，所述方法应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一运营商边缘PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述方法包括：
    所述第二PE设备经由所述主PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
    所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发的第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态；
    所述第二PE设备经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求。
  9. 根据权利要求8所述的方法，用户边缘CE设备通过多框Trunk MC-Trunk链路双归属连接到所述VPWS PW冗余网络中的所述第二PE设备和所述第三PE设备，所述CE设备与所述第二PE设备之间的链路为主用链路，所述CE设备与所述第三PE 设备之间的链路为备用链路，其特征在于，所述方法还包括：
    所述第二PE设备经由所述主用链路接收来自所述CE设备的流量；
    所述第二PE设备按照流量均衡的方式经由Balance状态的所述主PW和所述Bypass PW向所述第一PE设备和第三PE设备转发来自所述CE设备的流量。
  10. 根据权利要求8或9所述的方法，其特征在于，
    所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  11. 根据权利要求8-10中任一项所述的方法，其特征在于，在所述第二PE设备根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态之前，所述方法还包括：
    所述第二PE设备确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率小于预定阈值。
  12. 根据权利要求8-11中任一项所述的方法，其特征在于，所述方法还包括：
    所述第二PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文；
    所述第二PE设备将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第二PE设备发现的故障；
    所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第三PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
  13. 根据权利要求9-11中任一项所述的方法，其特征在于，所述方法还包括：
    所述第二PE设备确定预定周期内无法收到来自所述CE设备的故障检测报文；
    所述第二PE设备确定所述第二PE设备相对于所述主PW的优先转发状态为Balance状态，保持相对于所述主PW的Balance状态，并且不向所述第一PE设备发送用于切换所述主PW的Balance状态的报文。
  14. 根据权利要求8-11中任一项所述的方法，其特征在于，所述方法还包括：
    所述第二PE设备确定预定周期内无法收到来自所述第三PE设备的故障检测报文；
    所述第二PE设备将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述第二PE设备接收来自所述所述第一PE设备的第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述第二PE设备根据所述第三报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
  15. 一种转发报文的方法，所述方法应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一运营商边缘PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设 备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述方法包括：
    所述第三PE设备经由所述备份PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第一报文；
    所述第三PE设备经由所述Bypass PW接收来自所述第二PE设备的回应报文，所述回应报文用于指示同意所述第一报文的切换请求；
    所述第三PE设备根据所述回应报文，将所述第三PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
  16. 根据权利要求15所述的方法，其特征在于，
    所述第一报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  17. 根据权利要求15或16所述的方法，其特征在于，在所述第三PE设备经由所述Bypass PW向所述第二PE设备转发所述第一报文之前，所述方法还包括：
    所述第三PE设备确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值。
  18. 根据权利要求15-17中任一项所述的方法，其特征在于，所述方法还包括：
    所述第三PE设备确定预定周期内无法收到来自所述第一PE设备的故障检测报文；
    所述第三PE设备将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态，并且向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第三PE设备发现的故障；
    所述第三PE设备将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第二PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
  19. 根据权利要求15-17中任一项所述的方法，其特征在于，所述方法还包括：
    所述第三PE设备确定预定周期内无法收到来自所述第二PE设备的故障检测报文；
    所述第三PE设备将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态，并且向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述第三PE设备接收来自所述所述第一PE设备的第二报文，所述第二报文用于请求将所述备份PW由Balance状态切换为Active状态或Standby状态；
    所述第三PE设备根据所述第二报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态或Standby状态。
  20. 一种第一运营商边缘PE设备，所述第一PE设备应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络还包括第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所 述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述第一PE设备包括：
    发送单元，用于经由所述主PW向所述第二PE设备发送第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
    所述发送单元还用于经由所述备份PW向所述第三PE设备发送第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    接收单元，用于经由所述主PW接收来自所述第二PE设备的回应报文，所述回应报文是由所述第二PE设备根据所述第一报文和所述第二报文确定得到的，其中，所述第二报文是所述第二PE设备经由所述Bypass PW接收所述第三PE设备转发得到的，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求；
    处理单元，用于根据所述回应报文将所述第一PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态和将所述第一PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态。
  21. 根据权利要求20所述的第一PE设备，其特征在于，
    所述接收单元还用于接收来自用户边缘CE设备的流量；
    所述发送单元还用于按照流量均衡的方式经由Balance状态的所述主PW和所述备份PW向所述第二PE设备和第三PE设备转发来自所述CE设备的流量。
  22. 根据权利要求20或21所述的第一PE设备，其特征在于，
    所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  23. 根据权利要求20-22中任一项所述的第一PE设备，其特征在于，所述处理单元还用于在所述发送单元经由所述主PW向所述第二PE设备发送第一报文之前，确定所述发送单元向所述第二PE设备发送流量的带宽占用率超过预定阈值。
  24. 根据权利要求20-23中任一项所述的第一PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第二PE设备的故障检测报文，将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态；
    所述发送单元还用于向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Standby状态；
    所述处理单元还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态；
    所述发送单元还用于向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Active状态。
  25. 根据权利要求20-23中任一项所述的第一PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第三PE设备的故障检测报文，将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为 Active状态；
    所述发送单元还用于向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述处理单元还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；
    所述发送单元还用于向所述第三PE设备发送第四报文，所述第四报文请求将指示所述备份PW由Balance状态切换为Standby状态。
  26. 根据权利要求20-23中任一项所述的第一PE设备，其特征在于，
    所述接收单元还用于接收来自所述第二PE设备和所述第三PE设备的终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述处理单元还用于将所述第一PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态；
    所述发送单元还用于向所述第二PE设备发送第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述处理单元还用于将所述第一PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；
    所述发送单元还用于向所述第三PE设备发送第四报文，所述第四报文用于请求将所述备份PW由Balance状态切换为Standby状态。
  27. 一种第二运营商边缘PE设备，所述第二PE设备应用于虚拟专用线路业务伪线VPWS PW冗余网络中，所述VPWS PW冗余网络还包括第一PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述第二PE设备包括：
    接收单元，用于经由所述主PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述主PW由转发流量的激活Active状态切换为转发流量的均衡Balance状态，所述Balance状态用于指示以流量均衡的方式转发流量；
    所述接收单元还用于经由所述Bypass PW接收所述第三PE设备转发的第二报文，所述第二报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    处理单元，用于根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态；
    发送单元，用于经由所述主PW向所述第一PE设备发送所述回应报文和经由所述Bypass PW向所述第三PE设备发送所述回应报文，所述回应报文用于指示同意所述第一报文和所述第二报文的切换请求。
  28. 根据权利要求27所述的第二PE设备，用户边缘CE设备通过多框Trunk MC-Trunk链路双归属连接到所述VPWS PW冗余网络中的所述第二PE设备和所述第三PE设备，所述CE设备与所述第二PE设备之间的链路为主用链路，所述CE设备 与所述第三PE设备之间的链路为备用链路，其特征在于，
    所述接收单元还用于经由所述主用链路接收来自所述CE设备的流量；
    所述发送单元还用于按照流量均衡的方式经由Balance状态的所述主PW和所述Bypass PW向所述第一PE设备和第三PE设备转发来自所述CE设备的流量。
  29. 根据权利要求27或28所述的第二PE设备，其特征在于，
    所述第一报文和所述第二报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  30. 根据权利要求27-29中任一项所述的第二PE设备，其特征在于，
    所述处理单元还用于在根据所述第一报文和所述第二报文生成回应报文，将所述第二PE设备相对于所述主PW的优先转发状态由转发流量的Active状态切换为转发流量的Balance状态，并且将所述第二PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态之前，确定所述第二PE设备向所述第三PE设备发送流量的出接口的带宽占用率小于预定阈值。
  31. 根据权利要求27-30中任一项所述的第二PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第一PE设备的故障检测报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Standby状态；
    所述发送单元还用于向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第二PE设备发现的故障；
    所述处理单元还用于将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；
    所述发送单元还用于向所述第三PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
  32. 根据权利要求28-30中任一项所述的第二PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述CE设备的故障检测报文，确定所述第二PE设备相对于所述主PW的优先转发状态为Balance状态，保持相对于所述主PW的Balance状态，并且不控制所述发送单元向所述第一PE设备发送用于切换所述主PW的Balance状态的报文。
  33. 根据权利要求27-30中任一项所述的第二PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第三PE设备的故障检测报文，将所述第二PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；
    所述发送单元还用于向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述接收单元还用于接收来自所述所述第一PE设备的第三报文，所述第三报文用于请求将所述主PW由Balance状态切换为Active状态；
    所述处理单元还用于根据所述第三报文，将所述第二PE设备相对于所述主PW的优先转发状态由Balance状态切换为Active状态。
  34. 一种第三运营商边缘PE设备，所述第三PE设备应用于虚拟专用线路业务伪 线VPWS PW冗余网络中，所述VPWS PW冗余网络包括第一PE设备和第二PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述第三PE设备包括：
    接收单元，用于经由所述备份PW接收来自所述第一PE设备的第一报文，所述第一报文用于请求将所述备份PW由不转发流量的备用Standby状态切换为转发流量的均衡Balance状态；
    发送单元，用于经由所述Bypass PW向所述第二PE设备转发所述第一报文；
    所述接收单元还用于经由所述Bypass PW接收来自所述第二PE设备的回应报文，所述回应报文用于指示同意所述第一报文的切换请求；
    处理单元，用于根据所述回应报文，将所述第三PE设备相对于所述备份PW的优先转发状态由不转发流量的Standby状态切换为转发流量的Balance状态，并且将所述第三PE设备相对于所述Bypass PW的优先转发状态由Bypass状态切换为Balance状态。
  35. 根据权利要求34所述的第三PE设备，其特征在于，
    所述第一报文携带有PW状态码，所述PW状态码用于指示PW的状态为Balance状态。
  36. 根据权利要求34或35所述的第三PE设备，其特征在于，
    所述处理单元还用于在所述发送单元经由所述Bypass PW向所述第二PE设备转发所述第一报文之前，确定所述第三PE设备向所述第二PE设备发送流量的出接口的带宽占用率小于预定阈值。
  37. 根据权利要求34-36中任一项所述的第三PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第一PE设备的故障检测报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Standby状态；
    所述发送单元还用于向所述第一PE设备发送故障通告报文，所述故障通告报文用于向所述第一PE设备通告所述第三PE设备发现的故障；
    所述处理单元还用于将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；
    所述发送单元还用于向所述第二PE设备发送终止报文，所述终止报文用于指示终止所述Bypass PW的Balance状态。
  38. 根据权利要求34-36中任一项所述的第三PE设备，其特征在于，
    所述处理单元还用于确定预定周期内无法收到来自所述第二PE设备的故障检测报文，将所述第三PE设备相对于所述Bypass PW的优先转发状态由Balance状态切换为Bypass状态；
    所述发送单元还用于向所述第一PE设备发送终止报文，所述终止报文用于指示终止Bypass PW的Balance状态；
    所述接收单元还用于接收来自所述所述第一PE设备的第二报文，所述第二报文用于请求将所述备份PW由Balance状态切换为Active状态或Standby状态；
    所述处理单元还用于根据所述第二报文，将所述第三PE设备相对于所述备份PW的优先转发状态由Balance状态切换为Active状态或Standby状态。
  39. 一种虚拟专用线路业务伪线VPWS PW冗余网络系统，所述VPWS PW冗余网络包括第一运营商边缘PE设备、第二PE设备和第三PE设备，所述第一PE设备与所述第二PE设备之间建立了主PW，所述第一PE设备与所述第三PE设备之间建立了备份PW，所述第二PE设备与所述第三PE设备之间建立了旁路伪线Bypass PW，其特征在于，所述第一PE设备为权利要求20至26中任一所述的第一PE设备，所述第二PE设备为权利要求27至33中任一所述的第二PE设备，所述第三PE设备为权利要求34至38中任一所述的第三PE设备。
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