WO2012000234A1 - 链路间快速切换的方法、装置和系统 - Google Patents

链路间快速切换的方法、装置和系统 Download PDF

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Publication number
WO2012000234A1
WO2012000234A1 PCT/CN2010/076907 CN2010076907W WO2012000234A1 WO 2012000234 A1 WO2012000234 A1 WO 2012000234A1 CN 2010076907 W CN2010076907 W CN 2010076907W WO 2012000234 A1 WO2012000234 A1 WO 2012000234A1
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WIPO (PCT)
Prior art keywords
link
detection
sub
primary
route
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PCT/CN2010/076907
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English (en)
French (fr)
Inventor
马岚
张利锋
李石法
钱炜
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中兴通讯股份有限公司
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Publication of WO2012000234A1 publication Critical patent/WO2012000234A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L49/00—Packet switching elements
    • H04L49/10—Packet switching elements characterised by the switching fabric construction
    • 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
    • H04L41/04—Network management architectures or arrangements
    • 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
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/34—Signalling channels for network management communication
    • H04L41/344—Out-of-band transfers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0805—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters by checking availability
    • H04L43/0811—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters by checking availability by checking connectivity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/10—Active monitoring, e.g. heartbeat, ping or trace-route
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/40—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection

Definitions

  • the present invention relates to the field of data communications, and in particular, to a method, apparatus and system for fast handover between links.
  • IP networks have become an indispensable communication tool in people's daily work and life.
  • the reliability requirements of IP applications for IP networks are increasing, especially for end users, and it is very important to be able to maintain reliable connections with other parts of the network in real time. Therefore, some link detection and link protection mechanisms have emerged.
  • VRRP Virtual Router Redundancy Protocol
  • the VRRP protocol virtualizes a group of routers into a virtual router, and selects the active state device (hereinafter referred to as the master device, which is different from the master device below) in the group of routers through specific rules.
  • the active device performs the action of the gateway, and is responsible for the response of the virtual address ARP (Address Resolution Protocol) and the IP address forwarding.
  • the other router acts as the standby state device (hereinafter referred to as the standby device, and the standby device below). The difference is in standby.
  • the active device periodically sends VRRP advertisements to advertise the working status and priority of the device.
  • the standby device periodically monitors the advertisement packets of the active device.
  • the standby device fails to receive the VRRP advertisement packet within three consecutive advertising intervals, or receives the advertisement packet with the priority 0, the standby router can automatically switch to the active state. The entire switching process does not require modification of the configuration, so it is completely transparent to the end user.
  • Figure 1 shows the topology of a service access network using VRRP technology.
  • the master device and the backup device can simultaneously advertise the network segment routing information of the user side to the backbone network.
  • the uplink device can form an ECMP (Equal-Cost MultiPath) for the terminal user. Some of the traffic will also be taken to make the most of the resources.
  • the VRRP group forms a downlink backup to switch traffic to the standby link when the downlink primary link is abnormal, and to switch back traffic when the primary link returns to normal.
  • ECMP Equal-Cost MultiPath
  • the VRRP advertisement packet can be used to detect the available status of the master device and the standby device to implement the node protection. However, when the downlink link is abnormal, the VRRP cannot detect which side of the link is abnormal. Switching will cause traffic interruption. In order to improve the switching speed of the master device and the standby device in the event of a link failure, a redundant protection scheme combining link detection technology and VRRP is proposed.
  • the link fault detection technology is used to detect the state of the back-to-back link between the VRRP master device and the standby device.
  • VRRP controls the switchover between the master device and the standby device according to the link detection state. This can be completed in less than 1 second interval. Quickly switch.
  • the link detection is generally based on the addresses at both ends of the link. That is, the addresses at the other end of the link are used as the destination address for reachability detection.
  • Figure 1 is used as an example.
  • the main link is abnormal, the main link is deployed.
  • the device detects that the link is unavailable and notifies the routing module to invalidate the network segment of the link.
  • the detection packet of the ping detection depends on the network segment route of the link.
  • the traffic cannot be sent back. Therefore, even if the link is restored, the ping detection cannot be detected. Therefore, the link recovery information cannot be notified to the routing module to refresh the route of the link network segment.
  • the traffic cannot be switched back.
  • the invention provides a method, device and system for fast switching between links, which solves the problem of fast switching after a link failure.
  • a method for fast switching between links where the method is applied to a situation in which a primary link includes a detection sub-link and a service sub-link, and the method includes:
  • the master device sends a detection packet through the detection sub-link.
  • the detection result is fed back to the service sub-link to perform link switching.
  • the method may further include: configuring a parallel sub-interface on the downlink direct connection port of the primary device, and directing the detection address to the interface address of the opposite end of the detection sub-link before the step of the primary device transmitting the detection packet by detecting the sub-link .
  • the detection result can be the primary link abnormality or fault recovery.
  • the step of performing the link switching may include: when the detection result is abnormal on the primary link, the primary device performs route reselection, determines a new optimal route, and issues the new to the neighbor. The optimal route is switched from the primary link to the backup link.
  • the master device performs route reselection, determines a new optimal route, and advertises the new optimal route to the neighbor. Switch traffic from the standby link to the primary link.
  • the present invention also provides an apparatus for fast switching between links, where the apparatus is applied to a situation in which a primary link includes a detection sub-link and a service sub-link, and the apparatus includes:
  • a detecting module configured to send a detection message by using the detecting sublink
  • the switching execution module is configured to feed back the detection result to the service sub-link and perform link switching when the link status changes.
  • the detection module can also be configured to: configure a parallel sub-interface on the downlink direct connection port of the master device, and point the detection address to the interface address of the opposite end of the detection sub-link.
  • the detection result can be the primary link abnormality or fault recovery.
  • the switch execution module can be configured to perform link switchover as follows: When the detection result is abnormal on the primary link, perform route reselection, determine a new optimal route, and release a new optimal route to the neighbor and traffic from the main The link is switched to the standby link. When the detection result is fault recovery, route reselection is performed to determine a new optimal route, and a new optimal route is advertised to the neighbor and the service traffic is switched from the standby link to the primary link.
  • the present invention further provides a system for fast switching between links, including a first device and a second device, wherein the first device and the second device are mutually redundant groups, and the first device is a current primary device.
  • the first device is connected to a primary link, where the primary link includes a detection sub-link and a service sub-link;
  • the first device is configured to send a detection packet by using the detection sublink, when the link status is sent When the change occurs, the detection result is fed back to the service sub-link, and link switching is performed.
  • the first device may be further configured to configure a parallel sub-interface on its downlink direct connection port and point the detection address to the interface address of the opposite end of the detection sub-link.
  • the detection result can be the primary link abnormality or fault recovery.
  • the first device may be configured to perform link switching in the following manner: when the detection result is abnormal on the primary link, perform route reselection, determine a new optimal route, and release a new optimal route to the neighbor and traffic from the main The link is switched to the standby link.
  • route reselection is performed to determine a new optimal route, and a new optimal route is advertised to the neighbor and the service traffic is switched from the standby link to the primary link.
  • the system provided by the invention for fast switching between links realizes detecting the link at the third layer of the communication network, and solves the problem of fast switching after the link failure.
  • Figure 1 is a topology diagram of a service access network using VRRP technology
  • FIG. 2 is a schematic structural diagram of an apparatus for fast switching between links according to an embodiment of the present invention
  • FIG. 3 is a flowchart of a method for fast switching between links according to Embodiment 1 of the present invention
  • FIG. 4 is a specific flowchart of step 302 in FIG.
  • Figure 5 is a specific flow chart of step 303 in Figure 3;
  • Figure 6 is a specific flow chart of step 309 in Figure 3;
  • FIG. 7 is a flowchart of a method for fast handover between links according to Embodiment 2 of the present invention
  • FIG. 8 is a schematic diagram of a traffic path when an abnormality occurs in each downlink link of a transmission network.
  • the link detection based on the user equipment is limited by the detection function supported by the user equipment.
  • the link detection function of the Layer 2 detects that the packet does not depend on the route. Therefore, there is no contradiction between the detection and the route switch, but the function is on the device. The requirements are higher (common in medium and high-end transmission equipment), and common user equipment is usually not supported. Therefore, when the optional link detection technology sends and receives packets, it needs to rely on Layer 3 routing. There is a contradiction between detecting packet transmission and reception and routing switching. If an abnormality occurs on the primary link, if the route is switched from the primary link to the backup link based on the detection result, the detection packet is affected by the route switch, and the primary link cannot be detected. The failback of traffic cannot be achieved.
  • the network side's perception of the access side handover is ignored.
  • the uplink traffic of the user (the traffic sent by the user to the network side) passes.
  • VRRP is switched to the standby device, but the downstream traffic on the network side (the traffic sent from the network to the user side) still goes to the primary device, causing traffic loss.
  • an embodiment of the present invention provides a method for fast switching between links, adding a fast switching device to each device of the redundancy group, and determining the primary device (for example, only two devices constitute redundant After the remaining group is the master device, the device for fast switching on the master device is activated.
  • the structure of the above fast switching device is as shown in FIG. 2, including:
  • the detection module 201 includes a detection application management unit 2011 and a detection control unit 2012.
  • the detection application management unit 2011 is mainly configured to manage the detection information of the upper application registration, and notify the registered upper application after the detection status is determined, and belong to the detected external interface module.
  • the detection control unit 2012 is configured to receive the notification of the detection application management unit 2011, control the detection of the designated link, maintain the detection state, and transmit the detection result back to the detection application management module; the core implementation module belonging to the detection.
  • the routing module 202 includes a routing management unit 2021 and a routing control unit 2022.
  • the routing management unit 2021 is configured to maintain the detection object information of the routing application configuration, transfer the detection object of the routing application to the detection application management unit 2012, and process the detection result returned by the detection application management unit 2012, and notify the routing control unit 2022 after the analysis. .
  • the routing control unit 2022 is configured to receive the available or unavailable path information provided by the routing management unit 2021, and is responsible for selecting the optimal route, and providing the Layer 3 forwarding control module 206 with the three-layer routing forwarding information to guide the forwarding.
  • the VRRP module 203 includes a VRRP control unit 2031 and a VRRP management unit 2032.
  • the VRRP management unit 2032 is configured to maintain the VRRP virtual router configuration information, and is responsible for transmitting the detection object of the VRRP application to the detection application management unit 2011, and processing the detection result returned by the detection application management unit 2011, and then notifying the VRRP control unit 2031 after parsing;
  • the VRRP control unit 2031 is configured to maintain the priority information of the VRRP virtual router, and is mainly responsible for responding to the detection result notified by the VRRP management unit 2032, updating the priority, recalculating the priority order between the master device and the standby device, and maintaining the use of the master device and the standby device. Status and release of VRRP advertisement messages.
  • the routing protocol module 204 is mainly responsible for sending routes to neighbors and receiving routing information advertised by neighbors.
  • the Layer 2 forwarding module 205 is responsible for organizing the Layer 2 forwarding information on the basis of the Layer 3 IP forwarding information, and completing the encapsulation of the Ethernet packet, which is a driver implementation of the product hardware.
  • the Layer 3 forwarding module 206 is responsible for parsing and encapsulating the Layer 3 forwarding information according to the routing information provided by the routing control unit 2022, and transmitting the Layer 3 information to the Layer 2 forwarding module 205 for further processing.
  • Hardware driver implementation is responsible for parsing and encapsulating the Layer 3 forwarding information according to the routing information provided by the routing control unit 2022, and transmitting the Layer 3 information to the Layer 2 forwarding module 205 for further processing.
  • the first embodiment of the present invention provides a method for fast switching between links.
  • the method detects the link at the third layer, and solves the problem that the service traffic is interrupted for a long time after the link failure.
  • the process of managing the status of the active and standby devices in the redundancy group and updating the routing information by using the fast switching method provided by the embodiment of the present invention, and the fast switching device shown in FIG. 2, as shown in FIG. 3, includes:
  • Step 301 Set two access devices in parallel, and configure a direct link address between the two devices, and between the upper backbone network and the user equipment.
  • Step 302 Perform VRRP group configuration.
  • Step 3021 Configure the same VRRP group on the downlink of the two devices. Same priority
  • Step 3022 Set a VRRP virtual address on the two devices.
  • Step 3023 Specify the corresponding outbound port of the heartbeat line on the two devices.
  • the VRRP performs state negotiation between the two devices to determine the master device and the standby device.
  • the master device uses the virtual address to advertise the gratuitous ARP packets.
  • Step 303 Configure a detection function on the primary device.
  • Step 3031 Point the destination detection address to an address of the downlink user equipment.
  • Step 3032 Configure the detected interval of sending packets and timeout parameters.
  • Step 3033 Configure a parallel sub-interface on the downlink direct interface of the master device, and point the detection address to the interface address of the detection sub-link.
  • the downlink of the master device is the primary link.
  • the detection function based on the Layer 3 route forwarding
  • the sub-link is used as a detection link, and the detection address is directed to the interface address of the corresponding detection sub-link on the user equipment.
  • Step 304 Configure a dynamic routing protocol between the backbone network and the direct route re-distribution on the two devices.
  • the routing protocol module advertises the downlink network segment directly connected to the user to the backbone network.
  • step 304 the route to the user equipment is cleared.
  • the master device and the backup device can form ECMP to the user on the backbone network to share the downlink traffic.
  • Step 305 Configure a detection function on a downlink of the primary device.
  • the detection sub-link of the same link is bound to the service sub-link, that is, the on/off of the service sub-link is detected by detecting the sub-link, and the detection result of the detection sub-link directly reflects the service. On the sub-link.
  • the master device can detect the service sub-link by detecting the sub-link.
  • the master device sends a detection packet through the detection sub-link.
  • the device detects.
  • the result is fed back to the service sub-link, and link switching is performed.
  • the detection result is abnormal on the main link.
  • the master device performs route reselection, determines a new optimal route, and advertises the new optimal route to the neighbor and switches the service traffic from the primary link to the standby link. Specifically, as shown in steps 306 to 310.
  • Step 306 The master device in the redundancy group sends a detection packet by detecting the sub-link, and detects a service sub-link corresponding to the detection sub-link.
  • the detection control unit After the configuration of the step 305 is complete, the detection control unit starts to send a packet detection packet at the detection sub-link timing. When it is detected that the detection sub-link status changes, the service sub-link is considered to be abnormal, and step 307 is performed.
  • the detection packet is sent through the detection sub-link, so that after the link is restored, the on-off status of the service sub-link can be immediately known. Update routing information.
  • Step 307 The detecting module notifies the VRRP module of the downlink link abnormality information.
  • the main link is considered to be faulty and cannot work normally.
  • the link abnormality information is generated, and the link abnormality information is notified to the VRRP management unit and the route management unit to indicate the service sub- The link performs link switching.
  • Step 308 The VRRP module re-negotiates the status of the master device and the standby device according to the received link abnormality information.
  • the VRRP control unit detects the link abnormality information sent by the module according to step 307, and re-negotiates the master device and the standby device in the redundancy group.
  • the new master device advertises VRRP control information, including the active state information and the free ARP of the virtual address. Message.
  • Step 309 Determine a new optimal route according to the detection result.
  • the routing module recalculates the optimal forwarding route according to the received link abnormality information, and the faulty link is removed from the forwarding entry.
  • the specific steps are as shown in FIG. 6, including:
  • Step 3011 When the downlink optimal route changes, the routing control unit synchronizes the information of the optimal route to the Layer 3 forwarding module, and notifies the Layer 3 forwarding module to delete the fault when there is no optimal route.
  • Step 3092 When the downlink optimal route changes, the routing control unit notifies the routing protocol module of the optimal routing information, and when there is no optimal route, notifies the routing protocol module that the optimal route is invalid, and deletes the forwarding corresponding to the faulty link. entry.
  • the routing control unit also generates new optimal routing information when the failed link is recovered.
  • the detecting module can quickly detect the link change in step 305, and notify the VRRP management unit and the route management unit of the link recovery information to perform the failback.
  • Step 310 When the routing protocol module receives the local routing change information notified by the routing module, the new optimal route is advertised to the neighbor;
  • the routing protocol module updates the routing information to the neighbor, which specifically includes the following two situations:
  • the routing protocol module When the local route change information received by the routing protocol module indicates that the optimal route becomes invalid, the revoke message of the route is advertised to the neighbor, and the neighbor is notified to delete the forwarding entry corresponding to the faulty link.
  • routing protocol module When the routing protocol module receives the local route again, it advertises the route to the neighbor and notifies the neighbor to add the forwarding entry.
  • the master device may continue to detect the service sub-link through the detection sub-link of the link when the link is faulty, and the master device sends the detection packet through the detection sub-link, when the link status changes. And feeding back the detection result to the service sub-link, and performing link switching.
  • the detection result is fault recovery, the primary device performs route reselection, determines a new optimal route, and advertises the new optimal route to the neighbor and switches the service traffic from the standby link to the primary link.
  • the embodiment of the present invention provides a method for fast switching between links, in which a primary device in a redundancy group sends a detection packet by detecting a sub-link, and the service sub-link corresponding to the detection sub-link is associated with the detection result, and According to the detection result, the optimal routing of the new service data is determined, and the link is detected at the IP layer of the communication network, and the link routing is switched based on the detection, and the optimal routing information is immediately released, thereby greatly shortening the link.
  • the interruption time of traffic after a fault reduces the impact of link failure on the service.
  • route-based link detection technology and route switching it is proposed to use the detection sub-link for link detection and guide the update of routing information.
  • the control method of the link linkage switching solves the problem of traffic loss caused by the downlink separate handover through the release of the routing information.
  • the method for fast handover provided by the embodiment of the present invention is completely based on the existing hardware implementation of the device, and is easy to implement.
  • the embodiment of the invention provides a method for fast switching between links, establishing a VRRP virtual router group between two access devices, and establishing an end-to-end link detection between the primary device and the user equipment across the transmission network.
  • Some detection technologies sense the link status to assist VRRP in determining the selection of the primary device and the backup device.
  • the detection packet and the service packet are multiplexed with the same physical link, but the management detects the separation of the sub-link and the service sub-link.
  • the master device and the standby device simultaneously advertise the same network segment routing information directly connected to the user equipment to the backbone network.
  • the two devices share the downlink traffic.
  • the dynamic routing protocol on the active device revokes the advertisement of the directly connected network segment, and simultaneously switches the upstream and downstream traffic to the backup link to resolve the downlink. Downstream traffic loss caused by handover but no uplink handover.
  • Step 701 Set two access devices in parallel to perform basic link configuration.
  • the primary device and the standby device are determined according to factors such as device performance and reliability, and then the primary device and the standby device are connected to the backbone network and the user device, and the address configuration of the link between the primary device and the standby device is respectively configured.
  • the link between the device and the user device is configured as the same network segment.
  • An additional sub-interface is configured on the link between the master device and the user device.
  • Step 702 Configure a dynamic routing protocol with the backbone network on the two devices, and configure direct route redistribution in the dynamic protocol.
  • the routing protocol module advertises the downlink network segment route to the backbone network to form an uplink. The road is in line with the burden.
  • Step 703 Perform setting of a VRRP backup group.
  • Step 704 The VRRP negotiation determines the master device and the standby device.
  • both devices are in the initial state of VRRP, and each device sends a broadcast advertisement packet, which carries the priority of the device.
  • the priority of the device that receives the advertisement packet is compared with its own priority. If the priority of the device is lower than the priority of the packet, the state of the device in the VRRP backup group will be switched to the standby state. Otherwise, the device will switch to the active state.
  • Step 705 After the active device determines, the free ARP corresponding to the virtual address is advertised, and the transmission network is notified to update the ARP entry.
  • the transmission network refers to the network from the primary and backup devices to the user equipment.
  • Step 706 Perform configuration of a detection function on the primary device.
  • the link detection is performed by using Ping as an example.
  • the destination address must be configured as the interface address of the detection sub-link on the user equipment in parallel with the service sub-link. .
  • Step 707 Bind the VRRP, routing, and detection functions on the master device.
  • the association detection group is configured on the downlink service link, and the detection function is enabled to establish binding of VRRP, routing, and detection functions.
  • the downlink service sub-link has two detection states: normal and abnormal. When the downlink service sub-link detection status is abnormal, the downlink service sub-link is considered to be faulty, and the active/standby switchover and update routing information need to be triggered.
  • the downlink sub-link of the master device is the main link.
  • Step 708 The detecting module periodically sends a detection packet (ie, a ping packet) to the detection destination address (ie, the user equipment) by detecting the sub-link, and simultaneously monitors the response of the destination address.
  • a detection packet ie, a ping packet
  • Step 709 Compare the change of the state before and after the detection module is detected, and change the state before and after the detection state, and continue to perform step 708 periodically, otherwise step 710 is performed.
  • Step 710 When the detection status is normal, but the response message of the destination address is not received within the set detection function waiting interval, step 711 is performed; when the detection status is abnormal, but the response is received from the destination address thereafter. ⁇ , then step 714 is performed.
  • the detection result is specific to the main link abnormality or fault recovery.
  • Step 711 The detection status is updated to be abnormal, the detection module notifies the registered application, and the VRRP and the routing module respond to the status transition event of the detection group, and then proceeds to step 712 to implement application protection for the abnormal link.
  • Step 712 The VRRP master device lowers the priority and sends an advertisement packet to the standby device through the heartbeat line. After receiving the advertisement packet, the standby device switches from the standby state to the active state according to the priority comparison, and releases the virtual address for free.
  • the ARP packet informs the transport network device to update the ARP table corresponding to the gateway address. At the same time, the master device switches from the active state to the standby state.
  • Step 713 The routing module finds the port associated with the detection group (that is, the primary service outgoing port), and invalidates the route that the outbound interface points to the port, notifies the Layer 3 forwarding module to delete the forwarding entry, and notifies the routing protocol module to cancel the primary The network segment route of the service link.
  • Step 714 The detection status is updated to normal, the detection module notifies the registered application, the VRRP and the routing module process the state transition event of the detection group, and proceeds to step 715 to implement application protection for the abnormal link.
  • Step 715 The VRRP master device restores the priority and sends an advertisement packet to the standby device through the heartbeat line. After receiving the advertisement packet, the standby device switches from the active state to the standby state according to the priority comparison. Return to the active state and advertise the gratuitous ARP packet of the virtual address to notify the transport network device to update the ARP table corresponding to the gateway address.
  • Step 716 The routing module finds the port associated with the detection group (that is, the primary service outgoing port), and effectively processes the route that the outbound interface points to the port, notifies the Layer 3 forwarding module to add a forwarding entry, and notifies the routing protocol module to issue the primary The network segment route of the service link.
  • Figure 8 shows the path through which upstream traffic and downstream traffic pass when the downlink links of the transmission network are abnormal. It can be seen from Figure 8 (b) that when link 7 or link 11 is abnormal, the VRRP virtual router group and the uplink do not switch, and the link protection can be performed through the ring network; When the link 4 is abnormal, the VRRP virtual router group will switch after receiving the link detection notification. The master device switches from the active state to the standby state, and the standby device is reversed, so that the upstream traffic is switched by the primary link. To the backup link. At this time, the backbone network synchronously cancels the route of the network segment that the master device advertises to the user, so the downlink traffic is also switched from the primary link to the standby link.
  • the target path of the detection of the packet is not changed during the entire handover process. Therefore, when the link 4 is restored, the link detection can be quickly detected, and the upper-layer application is notified to perform link switchback processing, thereby restoring the available state of the downlink primary link and Uplink Road ECMP 0
  • the master device in the redundancy group sends a detection packet by detecting the sub-link, and detects a service sub-link corresponding to the detection sub-link, and according to the detection result, Determining the new optimal route, realizing the detection of the link in the third layer of the communication network, realizing the detection of the link at the IP layer of the communication network, and timely transmitting the optimal route through the linkage switching of the detection based link.
  • the information greatly shortens the interruption time of the traffic after the link failure, reduces the impact of the link failure on the service, and solves the problem of low routing efficiency. It can provide reliable backup and system control methods for service access networks using different topologies and different transmission modes, and improve the reliability of the access network for service support.
  • the embodiment of the present invention further provides a system for rapidly switching between links, including a first device and a second device, where the first device and the second device are mutually redundant groups, and the first device is The current primary device, the first device is connected to a link, and the link includes a detection sub-link and a service sub-link;
  • the first device is configured to send a detection packet by using the detection sub-link.
  • the detection result is fed back to the service sub-link, and the link switching is performed.
  • the first device is further configured to configure a parallel sub-interface on its downlink direct connection port, and point the detection address to the interface address of the opposite end of the detection sub-link. Further, the detection result is a primary link abnormality or a fault recovery.
  • the fast switching system provided by the embodiment of the present invention may be combined with a fast switching method provided by an embodiment of the present invention, where a primary device in a redundancy group sends a detection packet by detecting a sub-link, Detecting the service sub-link corresponding to the sub-link to detect, and determining a new optimal route according to the detection result, realizing the detection of the link at the third layer of the communication network, and solving the long-term service traffic after the link failure The problem of interruption.
  • all or part of the steps of the above embodiments may also be implemented using an integrated circuit.
  • the steps may be separately fabricated into individual integrated circuit modules, or multiple of the modules or steps may be implemented as a single integrated circuit module.
  • the invention is not limited to any specific combination of hardware and software.
  • the devices, functional modules or functional units in the above embodiments may be implemented by a general-purpose computing device, which may be centralized on a single computing device or distributed over a network of multiple computing devices.
  • the devices, functional modules or functional units in the above embodiments are implemented in the form of software functional modules and sold or used as separate products, they may be stored in a computer readable storage medium.
  • the above mentioned computer readable storage medium may be a read only memory, a magnetic disk or an optical disk or the like.
  • the invention realizes the detection of the link at the third layer of the communication network, and solves the problem of fast switching after the link failure.

Abstract

本发明提供一种链路间快速切换的方法、装置和系统，所述方法应用于主链路中包含检测子链路和业务子链路的情形，包括：主设备通过所述检测子链路发送检测报文，当链路状态发生变化时，将检测结果反馈给所述业务子链路，执行链路切换。本发明实现了在通信网的第三层对链路进行检测，解决了链路故障后快速切换的问题。

Description

链路间快速切换的方法、 装置和系统
技术领域
本发明涉及数据通信领域， 尤其涉及一种链路间快速切换的方法、 装置 和系统。
背景技术
随着因特网的迅猛发展， IP网络逐渐成为人们日常工作和生活中必不可 少的通信工具。 网络应用对 IP网络的可靠性要求与日倶增， 特别是对于终端 用户来说， 能够实时与网络中的其他部分保持可靠连接是非常重要的。 因此， 一些链路检测、 链路保护机制应运而生。
VRRP ( Virtual Router Redundancy Protocol, 虚拟路由冗余协议）就是一 种较为常用的链路保护技术， 其实质是利用默认网关的冗余设置进行备份保 护。 VRRP协议将一组路由器虚构成一台虚拟路由器， 并通过特定的规则在 这组路由器中竟选出主用状态设备（以下简称主用设备， 和下文中的主设备 相区别） 。 主用设备执行网关的动作， 负责虚地址 ARP ( Address Resolution Protocol, 地址解析协议） 的响应和 IP ^艮文转发； 另一路由器则作为备用状 态设备（以下简称备用设备， 和下文中的备设备相区别）处于待命状态。 主 用设备定期发送 VRRP通告报文，发布自身的工作状态和优先级等协商信息； 备用设备定时监测主用设备的通告报文。 当备用设备在连续三个通告间隔内 收不到 VRRP通告报文， 或者收到优先级为 0的通告报文后， 备用路由器能 自动切换到主用状态。 整个切换过程无需修改配置， 故对于终端用户完全透 明。
图 1给出了使用 VRRP技术的业务接入网的拓朴图， 以两台设备构成冗 余组为例， 一台为主设备， 另一台即为备设备。 主设备和备设备可同时将用 户侧的网段路由信息向骨干网发布， 在上行链路可以形成到达终端用户的 ECMP ( Equal-Cost MultiPath, 负荷分担） ， 这样备设备在主设备正常工作时 也会承担一部分流量， 以充分利用资源。 此外， 主设备和备设备之间建立 VRRP组， 形成下行链路的备份， 以便在下行主链路异常时能将流量切换到 备链路， 并当主链路恢复正常时将流量回切。
虽然可以通过 VRRP通告报文对主设备、 备设备的可用状态进行检测， 以实现结点保护， 但当下行链路出现异常时， 由于 VRRP无法感知是哪一侧 链路出现异常， 因此无法实施切换， 会造成流量中断。 为了提高链路故障发 生时主设备和备设备感知异常的切换速度， 链路检测技术和 VRRP相结合的 冗余保护方案被提出。
釆用链路故障检测技术检测 VRRP主设备和备设备间背靠背链路的状 态， VRRP根据链路检测状态控制主设备和备设备间使用状态的切换， 这样 可以在小于 1秒的时间间隔内完成快速切换。
釆用上述技术方案， 存在以下缺点：
1、 当用户端设备不支持二层检测功能， 需要部署基于三层报文的检测功 能， 如 Ping检测， 在检测报文发送和路由切换两者之间就存在矛盾：
链路检测的部署一般都基于链路两端的地址， 即在两端设备上各将链路 另一端的地址作为可达性检测的目标地址； 以图 1为例， 当主链路异常时， 主设备上 Ping检测发现链路不可用并通知路由模块将该链路的网段路由置无 效， 但由于 Ping检测的检测报文依赖于该链路的网段路由 , 在路由无效后检 测报文将无法继续发送， 这样即使链路恢复， Ping检测也无法感知， 因而不 能将链路恢复信息告知路由模块刷新该链路网段路由为可用状态， 流量始终 无法回切。
2、 下行链路异常切换后， 上行链路如不同步切换， 下行去往用户侧的流 量在主设备上依然会丟失。
发明内容
本发明提供了一种链路间快速切换的方法、 装置和系统， 解决了链路故 障后快速切换的问题。
一种链路间快速切换的方法， 所述方法应用于主链路中包含检测子链路 和业务子链路的情形， 所述方法包括： 主设备通过所述检测子链路发送检测报文， 当链路状态发生变化时， 将 检测结果反馈给所述业务子链路， 执行链路切换。
该方法在主设备通过检测子链路发送检测报文的步骤之前还可包括： 在 主设备的下行链路直连接口上配置一个并行子接口， 并将检测地址指向检测 子链路对端的接口地址。
检测结果可以为主链路异常或故障恢复。将检测结果反馈给业务子链路， 执行链路切换的步骤可以包括： 当检测结果为主链路异常时， 主设备进行路 由重选， 确定新的最优路由， 向邻居发布所述新的最优路由并将业务流量从 主链路切换到备链路； 当检测结果为故障恢复时， 主设备进行路由重选， 确 定新的最优路由， 向邻居发布所述新的最优路由并将业务流量从备链路切换 到主链路。
本发明还提供一种链路间快速切换的装置， 所述装置应用于主链路包含 中检测子链路和业务子链路的情形， 该装置包括：
检测模块， 其设置成通过所述检测子链路发送检测报文；
切换执行模块， 其设置成当链路状态发生变化时， 将检测结果反馈给所 述业务子链路， 执行链路切换。
检测模块还可设置成： 在主设备的下行链路直连接口上配置一个并行子 接口， 并将检测地址指向检测子链路对端的接口地址。 检测结果可以为主链路异常或故障恢复。 切换执行模块可以设置成通过 如下方式执行链路切换： 在检测结果为主链路异常时， 进行路由重选， 确定 新的最优路由， 向邻居发布新的最优路由并将业务流量从主链路切换到备链 路； 当检测结果为故障恢复时， 进行路由重选， 确定新的最优路由， 向邻居 发布新的最优路由并将业务流量从备链路切换到主链路。
本发明还提供一种链路间快速切换的系统， 包括第一设备和第二设备， 所述第一设备和所述第二设备互为冗余组， 所述第一设备为当前的主设备， 所述第一设备连接有主链路， 该主链路中包含检测子链路和业务子链路； 其 中，
所述第一设备设置成通过所述检测子链路发送检测报文， 当链路状态发 生变化时， 将检测结果反馈给所述业务子链路， 执行链路切换。
第一设备还可设置成在其下行链路直连接口上配置一个并行子接口， 并 将检测地址指向所述检测子链路对端的接口地址。
检测结果可以为主链路异常或故障恢复。 第一设备可以设置成通过如下 方式执行链路切换： 在检测结果为主链路异常时， 进行路由重选， 确定新的 最优路由， 向邻居发布新的最优路由并将业务流量从主链路切换到备链路； 当检测结果为故障恢复时， 进行路由重选， 确定新的最优路由， 向邻居发布 新的最优路由并将业务流量从备链路切换到主链路。
本发明提供的一种链路间快速切换的系统， 实现了在通信网的第三层对 链路进行检测， 解决了链路故障后快速切换的问题。
附图概述
图 1为使用 VRRP技术的业务接入网的拓朴图；
图 2 为本发明的实施例提供的一种链路间快速切换的装置的结构示意 图；
图 3为本发明的实施例一提供的一种链路间快速切换的方法的流程图； 图 4为图 3中步骤 302的具体流程图；
图 5为图 3中步骤 303的具体流程图；
图 6为图 3中步骤 309的具体流程图；
图 7为本发明的实施例二提供的一种链路间快速切换的方法的流程图； 图 8为传输网下行各段链路出现异常时流量路径示意图。
本发明的较佳实施方式
基于用户设备的链路检测将受限于用户设备所支持检测功能的约束， 二 层的链路检测功能检测报文不依赖路由， 因此不存在检测和路由切换间的矛 盾， 但该功能对设备的要求较高 （常见于中、 高端传输设备） ， 普通用户设 备通常不支持。 因此， 当可选的链路检测技术其报文收发需要依赖三层路由 时， 在检测报文收发和路由切换两者之间就存在矛盾。 以主链路发生异常为 例， 如果根据检测结果将路由从主链路切换到备链路， 检测报文受路由切换 影响， 将不能继续对主链路进行检测， 这样即使主链路恢复也不能实现流量 的回切。
此外， 在主备切换的过程中， 忽略了网络侧对接入侧切换的感知， 在实 际应用时一旦主设备下行链路通讯异常， 虽然用户上行流量（用户侧发向网 络侧的流量）通过 VRRP切换到备设备， 但网络侧下行流量（网络侧发向用 户侧的流量）仍走主设备， 从而造成流量丟失。
为了解决上述问题，本发明的实施例提供了一种链路间快速切换的方法， 在冗余组的各设备上添加一快速切换的装置， 在确定主用设备（如只有两台 设备构成冗余组， 则为主设备）后， 激活该主设备上的快速切换的装置。 上 述快速切换的装置的结构如图 2所示， 包括：
检测模块 201、 路由模块 202、 VRRP模块 203和路由协议模块 204。 进一步地， 该装置还包括二层转发模块 205和三层转发模块 206。
检测模块 201包括检测应用管理单元 2011和检测控制单元 2012。
其中， 检测应用管理单元 2011 主要设置成管理上层应用注册的检测信 息， 并在检测状态确定后通知已注册的上层应用， 层次上属于检测的外部接 口模块。
检测控制单元 2012设置成接收检测应用管理单元 2011的通知， 控制对 指定链路的检测， 维护检测状态， 并将检测结果传递回检测应用管理模块； 层次上属于检测的核心实现模块。
路由模块 202包括路由管理单元 2021和路由控制单元 2022。
路由管理单元 2021设置成维护路由应用配置的检测对象信息，将路由应 用的检测对象传递到检测应用管理单元 2012,并处理检测应用管理单元 2012 回传的检测结果， 解析后通知到路由控制单元 2022。
路由控制单元 2022设置成接收路由管理单元 2021提供的可用或不可用 路径信息， 负责最优路由的选取， 并向三层转发控制模块 206提供三层路由 转发信息以指导^^文转发。 VRRP模块 203包括 VRRP控制单元 2031和 VRRP管理单元 2032。
VRRP管理单元 2032设置成维护 VRRP虚拟路由器配置信息， 负责将 VRRP应用的检测对象传递到检测应用管理单元 2011 , 并处理检测应用管理 单元 2011回传的检测结果， 解析后通知到 VRRP控制单元 2031 ;
VRRP控制单元 2031设置成维护 VRRP虚拟路由器的优先级信息，主要 负责响应 VRRP管理单元 2032通知的检测结果，更新优先级并重新计算主设 备和备设备间的优先顺序， 维护主设备、 备设备使用状态的和 VRRP通告报 文的发布。
路由协议模块 204主要负责向邻居发送路由， 以及接收邻居发布的路由 信息。
二层转发模块 205负责在三层 IP转发信息的基础上， 继续组织二层转发 信息， 完成以太报文的封装， 层次上属于产品硬件的驱动实现。
三层转发模块 206 负责根据路由控制单元 2022提供的路由信息， 对 IP "^文进行三层转发信息的解析和封装，并将三层信息传递到二层转发模块 205 继续处理， 层次上属于产品硬件的驱动实现。
下面结合附图， 对本发明的实施例进行详细说明。
首先， 对本发明的实施例一进行说明。
本发明的实施例一提供了一种链路间快速切换的方法， 通过该方法在三 层对链路进行检测， 解决了链路故障后业务流量长时间中断的问题。
使用本发明实施例提供的快速切换的方法， 结合图 2所示的快速切换的 装置， 对冗余组中的主备设备状态进行管理， 并更新路由信息的过程如图 3 所示， 包括：
步骤 301、 并行设置两台接入设备， 配置两台设备间、 和上层骨干网、 用户设备间直连链路地址；
步骤 302、 进行 VRRP组的配置；
本步骤具体如图 4所示， 包括：
步骤 3021、 在两台设备的下行链路， 分别配置相同的 VRRP组， 设置不 同的优先级；
步骤 3022、 在两台设备上分别设置 VRRP虚地址；
步骤 3023、 在两台设备上分别指定心跳线对应出端口。
步骤 302完成后， VRRP会在两台设备间进行状态协商， 确定主设备和 备设备， 同时主设备使用虚地址向外发布免费 ARP报文。
步骤 303、 主设备上配置检测功能；
本步骤具体如图 5所示， 包括：
步骤 3031、 将目的检测地址指向下行链路用户设备的地址；
步骤 3032、 配置检测的发包间隔和超时参数；
步骤 3033、 在所述主设备的下行链路直接接口上配置一个并行子接口， 并将检测地址指向检测子链路的接口地址；
本发明实施例中， 主设备的下行链路即为主链路。 当配置基于三层路由 转发的检测功能时， 需要先在主设备下行链路直连接口上配置一个并行子接 口， 将一条链路分为检测子链路和业务子链路两部分， 将该检测子链路作为 检测用链路， 将检测地址指向用户设备上对应的检测子链路的接口地址。
步骤 304、 在两台设备上分别配置与骨干网间的动态路由协议， 并配置 直连路由重分发， 路由协议模块将下行链路与用户直连的网段路由向骨干网 发布；
通过步骤 304 , 打通骨干网到用户设备的路由， 当主设备的检测子链路 检测状态正常时， 主设备和备设备在骨干网就可以形成到达用户的 ECMP, 分担下行流量。
步骤 305、 在主设备的下行链路上配置检测功能；
本步骤中， 将同一链路的检测子链路和业务子链路绑定， 即业务子链路 的通断是通过检测子链路进行检测的， 检测子链路的检测结果直接反应到业 务子链路上。
在配置完成后，主设备就可以通过检测子链路对业务子链路进行检测了， 主设备通过所述检测子链路发送检测报文， 当链路状态发生变化时， 将检测 结果反馈给所述业务子链路， 执行链路切换。 本发明实施例中， 检测结果具 体为主链路异常。 主设备进行路由重选， 确定新的最优路由， 向邻居发布所 述新的最优路由并将业务流量从主链路切换到备链路。具体如步骤 306至 310 所示。
步骤 306、 冗余组中的主设备通过检测子链路发送检测报文， 对所述检 测子链路对应的业务子链路进行检测；
步骤 305配置完成后， 检测控制单元开始在检测子链路定时发包检测报 文， 当检测到检测子链路状态发生变化时， 认为业务子链路出现异常， 执行 步骤 307。
需要说明的是， 即使检测结果为业务子链路异常， 仍继续通过检测子链 路发送检测报文， 这样， 在链路恢复后， 也可立即获知业务子链路的通断状 况， 能够及时更新路由信息。
步骤 307、 检测模块将下行的链路异常信息通知 VRRP模块；
本步骤中， 当检测到检测子链路异常时， 认为主链路故障， 不能正常工 作， 生成链路异常信息， 并将链路异常信息通知给 VRRP管理单元和路由管 理单元， 以指示业务子链路进行链路切换。
步骤 308、 VRRP模块根据收到的链路异常信息重新进行主设备和备设备 的状态协商；
本步骤中， VRRP控制单元根据步骤 307检测模块发送的链路异常信息， 重新进行冗余组中主设备和备设备的协商。
当主设备状态发生变化时（即原主设备在协商后成为备设备， 原备设备 在协商后变为主设备） ， 新的主用设备发布 VRRP控制信息， 包括主用状态 信息和虚地址的免费 ARP报文。
步骤 309、 根据检测结果， 确定新的最优路由；
本步骤中，路由模块根据收到的链路异常信息， 重新计算最优转发路由， 即将故障的链路由转发条目中剔除， 具体步骤如图 6所示， 包括：
步骤 3091、 当下行链路最优路由发生变化时， 路由控制单元将最优路由 的信息同步给三层转发模块， 当无最优路由时通知三层转发模块删除该故障 链路对应的转发条目；
步骤 3092、 当下行链路最优路由发生变化时， 路由控制单元将最优路由 信息通知路由协议模块， 当无最优路由时通知路由协议模块最优路由无效， 删除该故障链路对应的转发条目。
此外， 在检测到故障的链路已恢复时， 路由控制单元也会生成新的最优 路由信息。 当主链路恢复后， 检测模块通过步骤 305能快速感知链路变化， 将链路恢复信息通知给 VRRP管理单元和路由管理单元， 以进行回切。
步骤 310、 当路由协议模块收到路由模块通知的本地路由变化信息时， 向邻居发布所述新的最优路由；
本步骤中， 当路由协议模块收到路由模块通知的本地路由变化信息后， 路由协议模块向邻居更新路由信息， 具体包括如下两种情况：
1、 当路由协议模块收到的本地路由变化信息指示最优路由变无效时， 向 邻居发布该路由的撤销消息， 通知邻居删除该故障链路对应的转发条目；
2、 当路由协议模块收到本地路由重新生效时， 向邻居发布该路由， 通知 邻居添加此转发条目。
此外， 主设备还可以在链路故障时继续通过该链路的检测子链路对业务 子链路进行检测， 主设备通过所述检测子链路发送检测报文， 当链路状态发 生变化时， 将检测结果反馈给所述业务子链路， 执行链路切换。 所述检测结 果为故障恢复， 所述主设备进行路由重选， 确定新的最优路由， 向邻居发布 所述新的最优路由并将业务流量从备链路切换到主链路。 具体实施流程与步 骤 306至 310无差异， 不再重复说明。
本发明实施例提供了一种链路间快速切换的方法， 冗余组中的主设备通 过检测子链路发送检测报文， 所述检测子链路对应的业务子链路关联检测结 果， 并根据检测结果， 决定新的业务数据的转发最优路由， 实现了在通信网 的 IP层对链路进行检测， 通过基于检测的链路联动切换， 即时发布最优路由 信息， 大大缩短了链路故障后流量的中断时间， 减少链路故障对业务的影响。 充分考虑了基于路由的链路检测技术和路由切换之间的矛盾， 提出利用检测 子链路进行链路检测， 指导路由信息的更新； 同时， 还提供了下行链路和上 行链路联动切换的控制方法， 通过路由信息的发布， 解决了下行单独切换造 成的流量丟失问题。 本发明实施例提供的快速切换的方法完全基于设备现有 的硬件实现， 易于实施。
下面结合附图及对本发明的实施例二进行详细说明。
本发明实施例提供了一种链路间快速切换的方法， 在两台接入设备间建 立一个 VRRP虚拟路由器组， 跨越传输网在主设备和用户设备间建立端到端 的链路检测， 利用现有的检测技术感知链路状态， 以协助 VRRP决策主用设 备和备用设备的选择； 检测报文和业务报文复用同一物理链路， 但管理上将 检测子链路和业务子链路分离到两个并行子链路上， 以解决链路异常恢复时 依赖路由的检测状态无法回切的问题； 主设备和备设备同时向骨干网发布与 用户设备直连的同网段路由信息， 正常情况两台设备一起分担下行流量； 当 检测到主链路异常时， 主用设备上动态路由协议撤销该直连网段的发布， 将 上下行的流量同时切换到备份链路， 解决下行链路切换但上行链路未切换造 成的下行流量丟失问题。
使用本发明实施例提供的快速切换的方法， 结合图 2所示快速切换的装 置， 对冗余组中的主备设备状态进行管理， 并更新路由信息的过程如图 7所 示， 包括：
步骤 701、 并行设置两台接入设备， 进行基本链路配置；
本步骤中， 首先根据设备性能和可靠性等因素决定主设备、 备设备， 然 后分别进行主设备、 备设备到骨干网和用户设备， 以及主设备和备设备间链 路的地址配置， 其中主设备、 备设备与用户设备间的链路配置为同一网段； 在主设备与用户设备间的链路上额外配置一子接口。
步骤 702、 在两台设备上分别配置与骨干网间的动态路由协议， 并在动 态协议中配置直连路由重分发， 路由协议模块将下行链路的网段路由向骨干 网发布， 形成上行链路的符合分担。
步骤 703、 进行 VRRP备份组的设置；
本步骤中，在主设备和备设备上配置相同的 VRRP组号和相同的虚地址， 指定心跳线对应的出端口，同时在主设备上设置高于备设备的 VRRP优先级。 步骤 704、 VRRP协商决定主设备和备设备；
首先， 两台设备均处于 VRRP初始状态， 分别发送广播通告报文， 该报 文中携带该设备的优先级； 收到通告报文的设备提取优先级与自身优先级相 比， 如果本设备优先级低于报文携带的优先级， 则本设备的在 VRRP备份组 中的状态会切换到备用状态， 反之， 则切换到主用状态。
步骤 705、 主用设备确定后， 发布虚地址对应的免费 ARP "^艮文， 通知传 输网更新 ARP表项；
传输网指的是主、 备设备到用户设备的网络。
步骤 706、 主设备上进行检测功能的配置；
本发明实施例以釆用 Ping进行链路检测为例。
本步骤中， 在主设备上配置 Ping检则组， 设置检测报文的发送频率， 指 定检测的目的地址， 目的地址需配置为用户设备上与业务子链路并行的检测 子链路的接口地址。
步骤 707、 主设备上设置 VRRP、 路由与检测功能的绑定；
本步骤中，在下行业务链路配置关联检测组，开启检测功能，建立 VRRP、 路由和检测功能的绑定。 下行业务子链路有两种检测状态： 正常和异常。 当 下行业务子链路检测状态为异常时， 即认为下行业务子链路故障， 需要触发 主备切换及更新路由信息。 本发明实施例中， 主设备的下行子链路即为主链 路。
步骤 708、 检测模块定时通过检测子链路向检测目的地址 (即用户设备 ) 发送检测报文（即 Ping报文 ) , 同时监测目的地址的回应情况。
步骤 709、 比较检测模块定时检测前后状态的变化， 检测状态前后无变 化， 继续定时执行步骤 708, 否则执行步骤 710。
步骤 710、 当检测状态正常， 但其后在设定的检测功能等待间隔内未收 到目的地址的回应报文， 则执行步骤 711 ; 当检测状态异常， 但其后收到来 自目的地址的回应 ^艮文， 则执行步骤 714。
本发明实施例中， 检测结果具体为主链路异常或故障恢复。 步骤 711、 检测状态更新为异常， 检测模块通知已注册的应用， VRRP 和路由模块响应该检测组的状态跃迁事件， 继续执行步骤 712以实现对异常 链路的应用保护。
步骤 712、 VRRP主设备降低优先级，经过心跳线向备设备发布通告报文， 备设备收到通告报文后， 根据优先级比较从备用状态切换到主用状态， 向外 发布虚地址的免费 ARP报文， 通知传输网设备更新网关地址对应的 ARP表； 同时主设备从主用状态切换到备用状态。
步骤 713、 路由模块找到与该检测组关联的端口 （即主业务出端口） ， 将出接口指向该端口的路由做无效处理， 通知三层转发模块删除转发表项， 同时通知路由协议模块撤销主业务链路的网段路由。
步骤 714、 检测状态更新为正常， 检测模块通知已注册的应用， VRRP 和路由模块处理该检测组的状态跃迁事件， 继续执行步骤 715实现对异常链 路的应用保护；
步骤 715、 VRRP主设备恢复优先级，经过心跳线向备设备发布通告报文， 备设备收到通告报文后， 根据优先级比较从主用状态切换到备用状态； 同时 主设备从备用状态切换回主用状态， 向外发布虚地址的免费 ARP报文， 通知 传输网设备更新网关地址对应的 ARP表。
步骤 716、 路由模块找到与该检测组关联的端口 （即主业务出端口） ， 将出接口指向该端口的路由做有效处理， 通知三层转发模块添加转发表项， 同时通知路由协议模块发布主业务链路的网段路由。
图 8给出了传输网下行各段链路出现异常时， 上行流量和下行流量经过 的路径。 由图 8 ( b )可以看出， 当链路 7或链路 11出现异常时， VRRP虚拟 路由器组和上行链路并不发生切换， 可以通过环网进行链路保护； 而在图 8 ( a ) 中， 当链路 4出现异常时， VRRP虚拟路由器组收到链路检测通知后会 进行切换， 主设备由主用状态切换到备用状态， 备设备相反， 这样上行流量 就由主链路切换到备链路。 此时骨干网同步撤销了主设备发布的到达用户的 网段路由， 故下行流量也从主链路切换到备链路。 整个切换过程检测报文检 测的目标路径并没有发生变化， 故当链路 4恢复时， 链路检测能快速感知， 通知上层应用进行链路回切处理， 从而恢复下行主链路的可用状态和上行链 路的 ECMP0
本发明的实施例提供的快速切换的方法， 冗余组中的主设备通过检测子 链路发送检测报文， 对所述检测子链路对应的业务子链路进行检测， 并根据 检测结果， 确定新的最优路由， 实现了在通信网的第三层对链路进行检测， 实现了在通信网的 IP层对链路进行检测， 通过基于检测的链路联动切换， 即 时发布最优路由信息， 大大缩短了链路故障后流量的中断时间， 减少链路故 障对业务的影响， 解决了路由效率低的问题。 可以为使用不同拓朴、 不同传 输模式的业务接入网提供可靠的备份和系统的控制方法， 提高接入网对业务 支持的可靠性。
本发明的实施例还提供了一种链路间快速切换的系统， 包括第一设备和 第二设备， 所述第一设备和所述第二设备互为冗余组， 所述第一设备为当前 的主设备， 所述第一设备连接有一链路， 该链路包含一检测子链路和一业务 子链路；
所述第一设备设置成通过所述检测子链路发送检测报文， 当链路状态发 生变化时， 将检测结果反馈给所述业务子链路， 执行链路切换。
进一步地， 所述第一设备还设置成在其下行链路直连接口上配置一个并 行子接口， 并将检测地址指向所述检测子链路对端的接口地址。 进一步地， 所述检测结果为主链路异常或故障恢复。
本发明的实施例提供的快速切换的系统， 可以与本发明的实施例提供的 一种快速切换的方法相结合， 冗余组中的主设备通过检测子链路发送检测报 文， 对所述检测子链路对应的业务子链路进行检测， 并根据检测结果， 确定 新的最优路由， 实现了在通信网的第三层对链路进行检测， 解决了链路故障 后业务流量长时间中断的问题。
本领域普通技术人员可以理解上述实施例的全部或部分步骤可以使用计 算机程序流程来实现，所述计算机程序可以存储于一计算机可读存储介质中 , 所述计算机程序在相应的硬件平台上（如系统、 设备、 装置、 器件等）执行， 在执行时， 包括方法实施例的步骤之一或其组合。
可选地， 上述实施例的全部或部分步骤也可以使用集成电路来实现， 这 些步骤可以被分别制作成一个个集成电路模块， 或者将它们中的多个模块或 步骤制作成单个集成电路模块来实现。 这样， 本发明不限制于任何特定的硬 件和软件结合。
上述实施例中的各装置、 功能模块或功能单元可以釆用通用的计算装置 来实现， 它们可以集中在单个的计算装置上， 也可以分布在多个计算装置所 组成的网络上。
上述实施例中的各装置、 功能模块或功能单元以软件功能模块的形式实 现并作为独立的产品销售或使用时， 可以存储在一个计算机可读取存储介质 中。 上述提到的计算机可读取存储介质可以是只读存储器， 磁盘或光盘等。
工业实用性
与现有技术相比， 本发明实现了在通信网的第三层对链路进行检测， 解 决了链路故障后快速切换的问题。

Claims

权 利 要 求 书
1、 一种链路间快速切换的方法， 其特征在于， 所述方法应用于主链路中 包含检测子链路和业务子链路的情形， 所述方法包括：
主设备通过所述检测子链路发送检测报文， 当链路状态发生变化时， 将 检测结果反馈给所述业务子链路， 执行链路切换。
2、根据权利要求 1所述的方法， 其在主设备通过所述检测子链路发送检 测报文的步骤之前还包括：
在所述主设备的下行链路直连接口上配置一个并行子接口， 并将检测地 址指向所述检测子链路对端的接口地址。
3、 根据权利要求 1所述的方法， 其中， 所述检测结果为主链路异常或故 障恢复。
4、 根据权利要求 3所述的方法， 其中， 将检测结果反馈给所述业务子链 路， 执行链路切换的步骤包括：
所述检测结果为主链路异常时， 所述主设备进行路由重选， 确定新的最 优路由，向邻居发布所述新的最优路由并将业务流量从主链路切换到备链路； 所述检测结果为故障恢复时， 所述主设备进行路由重选， 确定新的最优路 由， 向邻居发布所述新的最优路由并将业务流量从备链路切换到主链路。
5、 一种链路间快速切换的装置， 其特征在于， 所述装置应用于主链路包 含中检测子链路和业务子链路的情形， 该装置包括：
检测模块， 其设置成通过所述检测子链路发送检测报文；
切换执行模块， 其设置成当链路状态发生变化时， 将检测结果反馈给所 述业务子链路， 执行链路切换。
6、 根据权利要求 5所述的装置， 其中，
所述检测模块还设置成： 在所述主设备的下行链路直连接口上配置一个 并行子接口， 并将检测地址指向所述检测子链路对端的接口地址。
7、 根据权利要求 5所述的装置， 其中， 所述检测结果为主链路异常或故 障恢复。
8、 如权利要求 7所述的装置， 其中， 所述切换执行模块设置成通过如下 方式执行链路切换：
在所述检测结果为主链路异常时， 进行路由重选， 确定新的最优路由， 向邻居发布所述新的最优路由并将业务流量从主链路切换到备链路；
当所述检测结果为故障恢复时， 进行路由重选， 确定新的最优路由， 向 邻居发布所述新的最优路由并将业务流量从备链路切换到主链路。
9、 一种链路间快速切换的系统， 包括第一设备和第二设备， 所述第一设 备和所述第二设备互为冗余组， 所述第一设备为当前的主设备， 所述第一设 备连接有主链路， 该主链路中包含检测子链路和业务子链路； 其中，
所述第一设备设置成通过所述检测子链路发送检测报文， 当链路状态发 生变化时， 将检测结果反馈给所述业务子链路， 执行链路切换。
10、 根据权利要求 9所述的系统， 其中，
所述第一设备还设置成在其下行链路直连接口上配置一个并行子接口， 并将检测地址指向所述检测子链路对端的接口地址。
11、 根据权利要求 9所述的系统， 其中， 所述检测结果为主链路异常或 故障恢复。
12、 如权利要求 11所述的系统， 其中， 所述第一设备设置成通过如下方 式执行链路切换：
在所述检测结果为主链路异常时， 进行路由重选， 确定新的最优路由， 向邻居发布所述新的最优路由并将业务流量从主链路切换到备链路；
当所述检测结果为故障恢复时， 进行路由重选， 确定新的最优路由， 向 邻居发布所述新的最优路由并将业务流量从备链路切换到主链路。
PCT/CN2010/076907 2010-06-28 2010-09-14 链路间快速切换的方法、装置和系统 WO2012000234A1 (zh)

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