WO2007082424A1

WO2007082424A1 - A method for identifying multiple emulation traffic flow paths

Info

Publication number: WO2007082424A1
Application number: PCT/CN2006/002168
Authority: WO
Inventors: Huachen Zhang; Huaming Lu; Jian Qiao
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-01-23
Filing date: 2006-08-24
Publication date: 2007-07-26
Also published as: CN1878136A; CN100433722C

Abstract

A method for identifying multiple emulation traffic flow paths includes: in the mode of N to 1 that multiple emulation traffic flows are carried by one traffic flow path, the attachment circuit identifier identifying the sub-attachment circuit is set; one end of the pseudo wire sends the message which carries the attachment circuit identifier identifying the first sub-attachment circuit, and the other end of the pseudo wire searches the second sub-attachment circuit which has the same attachment circuit identifier according to the received attachment circuit identifier; if the second sub-attachment circuit and the pseudo wire work normally, the hardware forwarding table is sent down and the service message is forwarded. In the present invention, the identifier (AC-id) is used to identify the AC service, the different AC services are identified, the information of the emulation service is obtained veraciously, and the PW condition and the actual forwarding condition are consistent strictly. Therefore, the waste of the process resource and the network bandwidth resource of the nodes on the way is avoided when the traffic transmission could not be intercommunicated, meanwhile, the forwarding rate is increased.

Description

Method for identifying multiple simulation service flow paths

The present invention relates to the field of communications technologies, and in particular, to an end-to-end pseudowire simulation.

(PWE3, Pseudo-Wire Emulation Edge-to-Edge) A method of identifying multiple simulated traffic flow paths. Background of the invention

At present, when operators provide multiple services, they basically adopt a parallel or "overlap" approach, that is, by setting up and maintaining multiple networks, and using different access devices for each different service at the presentation point. In this way, in addition to making network planning more complex, it also increases construction costs and operating costs.

In order to provide a unified multi-service network platform, the IETF began the standardization of transmitting any service (X over PSN) on the packet switched network (PSN), and named the work as end-to-end pseudo-line emulation, ie PWE3, the service. An auxiliary circuit (AC, Attachment Circuit) is established between the customer edge device (CE) and the Provider Equipment (PE) through the pseudowire (PW) to connect the CE and the PE. One is that one emulation service flow path carries only one emulation service flow, that is, 1 TO 1 mode. At this time, one AC monopolizes an internal label; the other is that one emulation service flow path carries multiple emulation service flows, that is, N T0 1 way, at this point all ACs share an internal tag. An emulated traffic flow path The benefit of carrying multiple emulated traffic flows is that PW headers can be used more efficiently.

The establishment of the PW is the result of mutual negotiation between the two Provider Equipments (PEs). Therefore, the PEs at both ends must exchange the local PW forwarding status. The forwarding state of the local F depends on the state of the AC service that needs to be simulated, and the label distribution protocol session of the remote PE. The status of the (LDP session) and the state of the outer tunnel carrying the pseudowire service.

In the N TO 1 mode, the state of the AC service depends on the sum of the N sub-AC states corresponding to the PW. In the existing protocol network model, multiple permanent virtual connections (PVCs) of the same PW are simultaneously bound in the N TO 1 mode. Permanent Virtual Connect is collectively referred to as an AC. This document complies with the terminology in the existing protocol network model. However, for the convenience of description, a PVC in the AC in the N T0 1 mode is called a sub-AC of the AC. The status of the service is determined as follows: If the sub-AC corresponding to the normal state (UP) fails in the multiple sub-ACs corresponding to W, and changes to the abnormal working state (DOWN), it is generally said. If the DOWN is off, the status of the AC is DOWN. If the status of the first sub-AC in all sub-ACs corresponding to the PW is UP, the status of the AC is UP. There are two ways for PEs to advertise AC status to each other: Notice of announcement and extension of Martini mode

( otification ) notification of the method.

1. Announcement of Martini mode:

Figure 1 is a schematic diagram of the Martini advertisement. As shown in Figure 1, PE1 is the local PE and PE2 is the remote PE. The state of the AC1 between PE1 and CE1, the LDP session state of the remote PE, and the state of the tunnel provided by the outer tunnel, that is, the corresponding simulated service flow path are both UP, the forwarding state of the local PW is forwardable, and PE1 sends the status to PE2. The mapping of the mapping of the inner label to the label of the inner label. In this case, if one of the status of the AC1, the LDP session status of the remote PE, and the status of the outer tunnel is DOWN, the forwarding status of the local PW is unavailable. After forwarding, PE1 sends an Withdraw message to PE2 and reclaims the inner label. For example, if the status of the local PW is Up, as long as the AC DOWN is lost, the forwarding status of the local PW is not forwarded, the Withdraw packet is sent, and the protocol is removed. It should be noted that the device P shown in FIG. 1 does not process the PWE3 related messages that are exchanged between PE1 and PE2, but only transparently transmits, and PE1 and PE2 can also be directly connected.

2. Notification of notification method: Figure 2 is a schematic diagram of the Notification notification. Assume that PE1 is the local PE and PE2 is the remote PE. AC1 is established between PE1 and CE1. AC2 is established between PE2 and CE2. After the internal label is exchanged between PE1 and PE2, the protocol is not deleted. The local PW status of the two parties is exchanged by sending a Notification packet. For example, if the status of the local PW is Up, the forwarding state of the local PW is not forwardable as long as the AC1 DOWN is lost. However, PE1 does not send the Withdraw packet teardown protocol, but sends a Notification packet to notify PE2. The forwarding state of the PW is not forwardable. For example, the local PW is saved by advertising the status code of the local PW. As shown in Figure 2, the notification packet contains the status code of the local PW.

In the Martini mode, whether the packet is sent depends on the status of the AC, the status of the LDP session of the peer PE, and the status of the outer tunnel. If the status of the three is DOWN, the device sends the Withdraw packet. The internal label is reclaimed. In the notification mode, if the status of the LDP session of the peer PE is Up, the mapping packet is sent regardless of whether the status of the AC or the outer tunnel is Up. After the state or the state of the outer tunnel is DOWN, the local PW status code is updated, and the local PW status code is notified to the peer PE through the Notification message.

The difference between the notification mode and the Martini mode is as follows: As long as the configuration is not deleted, the protocol is not removed, the inner label is reclaimed, and only the notification is sent to notify the local PW status that the status is not forwardable. Thus, when the status or outer layer of the AC is When the status of the tunnel is re-up, you do not need to re-allocate the label. You only need to send a Notification packet to advertise the local PW forwarding status to forwardable. It can be seen that the prior art notification mode reduces the interaction of message messages between PEs compared with the Martini mode.

However, a common disadvantage of the Notification method and the Martini method is that it cannot advertise the information of a specific AC service pair. 3 is a schematic diagram of a PW network in the prior art N TO 1 mode, as shown in FIG. 3, where sub-AC1-sub AC3 (subACl-subAC3) and The subAC2-subAC ⁴ is two service flows, which form two sub-AC service pairs, and multiplex the pseudo-line 1 by using N TO 1. SubACl and subAC2 are respectively connected to different ports of PE1, and the two states are combined to form an AC state at PE1; subAC3 and subAC4 are respectively connected to different ports of PE2, and the states of the two are combined to form an AC state at PE2.

If the status of the LDP session of the PE1 and the remote PE is UP, the AC status of the PE1 is Up and the local PW forwarding status is OK. The forwarding state is either the sending of the MAPP message or the notification of the local PW status. At PE2, when the LDP session status of the PE2 and the peer PE and the status of the outer tunnel are both UP, if the subAC4 status changes from DOWN to UP, the AC status at PE2 is UP, and the forwarding status of PE2 is also It is a forwardable state. The local and remote PW forwarding states are both forwardable. Therefore, the PW is in the Up state and the forwarding entry is sent.

The actual situation is that subACl and subAC3 are a service pair. Therefore, after subACl service information reaches PE2 through PW1, if subAC3 status is DOWN, subACl service packets are discarded by PE2. Therefore, in this situation, neither the Martini nor the Notification can advertise the correct service pair information of the AC. As a result, the service information of the subACl cannot be finally forwarded to the destination after being sent to the PE2 through the PW1, but is discarded. It has increased the processing burden of nodes along the way, and more importantly, wasted network bandwidth resources.

The following describes the specific packet encapsulation format of the PW service in the N TO 1 mode. The encapsulation of other services is similar. Table 1 is a schematic diagram of a format of a packet encapsulation of an NTO 1 ATM PW packet in the prior art. Table 2 is a schematic diagram of a specific encapsulation format of an ATM service Payload in an N TO 1 ATM PW packet frame in the prior art, such as The encapsulation format shown in Tables 1 and 2 distinguishes the specific AC by the virtual channel identifier/virtual path identifier (VPI/VCI) carried in the packet. Regulation: To ensure that the VPI/VCI values of PVCs from different ports are different, but it is difficult to guarantee in practical applications. Therefore, you need to use the output configured by user commands.

The VPI/Output VCI (outvpi/outvci) performs a conversion on the VPI/VCI value of the PVCs from each port, so that it is globally unique, so that when the N TO 1 ATM PW message frame is received, the outvpi/outvci is used to find the specific PVC, processed separately for different businesses. For a detailed description of the fields in Table 1 and Table 2, refer to the related protocol, which is not described here.

Packet switched transport header (if required) (PSN Transport Header)

Pseudo Wire Header

Flag (Flag) Reserved (Res) Length (Length) Serial Number

( Sequence Number ) Asynchronous Transfer Mode Service Payload ( ATM Service Payload )

Table 1

Control word (optional) ( Control Word )

Virtual Channel Identification (VPI) Virtual Path Identification (VCI) Payload Type Identifier (PTI) Loss Priority (C) Asynchronous Transfer Mode Payload (ATM Payload) Virtual Channel Identifier (VPI) Virtual Path Identifier (VCI) Payload Type Identifier (PTI) Loss Priority (C) Asynchronous Transfer Mode Payload (ATM Payload)

The limitations of the specific packet encapsulation format of the PW service in the existing N TO 1 mode shown in Table 1 and Table 2 are as follows:

1) ^"The value of the outvpi/outvci in the outbound direction of the PW and the inputvpi/inputvci in the inbound direction are not necessarily the same. Therefore, the binding commands of the PW and the PVC need to be configured in both the inbound and outbound directions, such as: a. PVC + PW + Outvpi/outvci

b. inputvpi/inputvci + PW + PVC

This increases the complexity of user configuration. 2) 'Hardware implementation is more complicated, and the search efficiency is lower. For the inbound direction, the corresponding PVC needs to be obtained according to the inputvpi/inputvci in the packet. The range of vpi/vci is 12 bits/16 bits respectively, but the number of PVCs supported by the general device is much smaller than the 28th power of 2, so HASH is required to complete the mapping on the hardware.

In summary, the PW state is determined by the PW state when the AC status of the non-service pair is Up, and the PW state is not forwarded. This is inconsistent with the actual forwarding state. In this case, even if the AC information of one end reaches the PE of the other end through the PW pseudowire, it cannot be forwarded, but is discarded by the PE, thus wasting the processing resources and network bandwidth of the nodes along the path. Defects in resources. Summary of the invention

In view of this, the main purpose of the present invention is to provide a method for identifying a plurality of simulated service flow paths, which can accurately learn the information of the simulated service, make the PW state and the actual forwarding state consistent, and reduce the processing load of the nodes along the path, saving Network bandwidth resources.

In order to achieve the above object, the technical solution of the present invention is specifically implemented as follows:

A method for identifying a plurality of simulated service flow paths, wherein an emulation service flow path carries a plurality of emulation service flows N TO 1 mode, and an auxiliary circuit identifier for identifying a sub-attachment circuit service pair is set; the method further includes:

A. The first end of the pseudowire sends an advertisement message carrying the identifier of the auxiliary circuit identifying the service pair of the sub-attachment circuit to which the first sub-attachment circuit belongs, and the second end of the pseudo-line finds the same auxiliary circuit identifier according to the received accessory circuit identifier. Second sub-attachment circuit;

B. If the second sub-auxiliary circuit and the pseudowire are in a normal working state, the hardware sends a publication item and forwards the service packet.

The advertisement message includes: a normal advertisement message that informs that the first sub-affiliated circuit is in a normal state, or informs that the first sub-affiliated circuit is an abnormal abnormal advertisement message. The advertisement message is a normal advertisement; the step Β specifically includes:

If the state of the second sub-auxiliary circuit is a normal working state, further determining whether the pseudowire state is normal,

If the pseudowire is in a normal working state, the state of the first terminal accessory circuit of the sub-auxiliary circuit service pair in the second service provider device at the second end of the pseudowire is set to a normal working state, and is sent The hardware forwards the entry and forwards the service packet.

If the pseudowire is in an abnormal working state, the state of the first terminal accessory circuit of the sub-auxiliary circuit service pair in the second service provider device at the second end of the pseudowire is set to a normal working state.

The method further includes:

If the state of the second sub-auxiliary circuit is an abnormal working state, the state of the first sub-auxiliary circuit in the second service-side device located at the second end of the pseudowire is set to a normal working state.

The notification message is an abnormal advertisement message. The step Β specifically includes: if the state of the second sub-auxiliary circuit is a normal working state, further determining whether the pseudowire state is normal,

If the pseudowire is in a normal working state, setting a state of the first terminal accessory circuit of the sub-auxiliary circuit service pair in the second service provider device at the second end of the pseudowire to an abnormal working state, and Delete the hardware forwarding entry.

And if the pseudowire is in an abnormal working state, setting a state of the first terminal auxiliary circuit of the sub-auxiliary circuit service pair in the second service provider located at the second end of the pseudowire to a non-normal working state.

The accessory circuit identifier is carried in an attached circuit identifier forwarding index set in the advertisement message.

The method for determining whether the pseudowire state is normal is: If the inner layer labels at both ends of the pseudowire are allocated, the pseudowire state is a normal working state; otherwise, the pseudowire state is an abnormal working state.

As can be seen from the foregoing technical solutions, the beneficial effects of the present invention are: by using the AC identifier (AC-id) that identifies the AC service pair, identifying different AC service pairs, accurately obtaining the simulated service pair information, and making the PW state and the actual forwarding. The state is strictly consistent, and the processing resources and the network bandwidth resources of the nodes along the path are avoided in the service transmission that cannot be finally intercommunicated; and in the N TO 1 mode, the present invention adopts a simple AC and PW binding service configuration command, and the configuration amount is only At the same time, the AC-id forwarding index field is used instead of the VPI/VCI field to specifically identify a PVC for forwarding, and the hardware implementation is implemented. The information of the specific PVC is determined by looking up the forwarding index corresponding to the AC-id. Forwarding speed. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of the network announced by the Martini mode;

2 is a schematic diagram of a network notified by a notification method;

3 is a schematic diagram of a PW network in the prior art N TO 1 mode;

4 is a schematic diagram of a PW network in the N T0 1 mode of the present invention. Mode for carrying out the invention

The core idea of the present invention is: In the N TO 1 mode, an auxiliary circuit identifier for identifying a sub-subsidiary circuit service pair is set; and a pseudowire end transmits an advertisement message carrying an auxiliary circuit identifier identifying the first sub-auxiliary circuit, and is pseudo- The other end of the line finds the second sub-attachment circuit having the same auxiliary circuit identifier according to the received accessory circuit identifier; if the second sub-affiliated circuit and the pseudowire are in a normal working state, the hardware forwarding entry and the forwarding service are delivered. Message.

The present invention will be further described in detail below with reference to the drawings and preferred embodiments. The method for identifying a plurality of simulated service flow paths based on the PWE3 includes the following process: When configuring the AC N TO 1 mode PW binding command, setting an AC-id forwarding index configuration item for identifying an AC service pair; The AC-id forwarding index field is added to the notification packet. When the peer receives the notification packet, it searches for the matching (corresponding) sub-AC according to the AC-id forwarding index. Only the status of the two ends of the AC pair in the simulated service flow path. When the status is UP and the status of the PW is also Up, the hardware forwarding entry is sent and the service packet is forwarded. Otherwise, the service is not forwarded. The specific method is as follows:

1. Configure the configuration item of the AC-id forwarding index to identify the AC service pair when you configure the NTO 1 PW binding command.

4 is a schematic diagram of a PW network in the N TO 1 mode of the present invention. As shown in FIG. 4, for example, the AC-id of the subACl-subAC3 service pair is set to 1 and the AC-id of the subAC2-subAC4 service pair is set to 2.

2. Add the AC-id forwarding index field to the sent notification packet, and advertise the status of the sub-AC corresponding to the AC-id on the peer PE.

As shown in Figure 4, it is assumed that the first sub-AC of all the sub-ACs of the PW, such as PE1, is sub-ACI. When the status of the sub-ACl is changed from the DOW to the UP, the PE1 sends a Notification packet to the peer, such as the PE2. The Notification packet carries the notification packet. The AC-id of the subACl, advertises that the current status of subACl is UP;

After receiving the Notification packet, PE2 searches for the sub-AC service that matches the AC-id carried in the Notification packet, which is assumed to be subAC3. If the subAC3 service status of PE2 is DOWN, PE2 will be the peer end of its own data structure. The status of the subACl of the PE1 is set to UP. If the subAC3 service status of the PE2 is also Up, and the status of the PW is Up, the PE2 sets the status of the subACl of the PE1 in the data structure to UP and sends the hardware forwarding entry. The service packet is forwarded. However, if the state of the PW is DOWN, PE2 only sets the state of subACl of PE1 in its own data structure to UP. In addition, it is assumed that the last sub-AC of all sub-ACs of the PW, such as PE1, is sub-ACI. When the status of sub-ACl changes from UP to DOW, PE1 sends a Notification packet to the peer, such as PE2. The Notification message carries the AC of subACl. -id, advertises the current status of subACl as DOWN;

After receiving the Notification packet, PE2 searches for the sub-AC service that matches the AC-id carried in the Notification packet, which is assumed to be subAC3. If the subAC3 service status of PE2 is Up and the PW status is Up, PE2 will In the self-data structure, the peer, that is, the state of subACl of PE1 is set to DOWN, and the hardware forwarding entry is deleted. Otherwise, only the state of subACl of PE1 in its own data structure is set to DOWN. In this way, the PE can clearly know the PW status, the AC status of the terminal in a service flow path, and the AC status of the terminal.

The present invention strictly distinguishes the state of the PW from the state of the sub-AC service, and stipulates that if the PW tags of both ends of the PE are already allocated, that is, both the tagging message is sent to the peer end, and the tagging message from the peer end is also received. Then, the state of receiving and transmitting the PW in both directions is UP, otherwise the state of the PW is DOWN. In doing so, the state of the PW is independent of the AC state, the state is more clearly differentiated, the understanding of the protocol and the implementation are more clear, and it is more in line with the agreement "dmft-ietf-pwe3-control-protocol-14.txt" The PW is understood in the PWE3 Reference Model specified in the specification, that is, the state of the PW should be independent of the AC state.

3. Adjust the FW message frame encapsulation format of the N TO 1 mode.

Table 3 is a schematic diagram of a specific encapsulation format of the asynchronous transport mode service payload in the N TO 1 ATM PW packet frame of the present invention. As shown in Table 3, the adjustment of the PW packet frame encapsulation format of the ATM N TO 1 mode is taken as an example. The method for adjusting the format of the NTO 1 PW encapsulation packet is described. The VPI and VCI fields in the existing N TO 1 ATM PW packet frame encapsulation format are replaced by the AC-id forwarding index field, and the index words are forwarded according to different AC-ids. Segments specifically index different PVCs.

Control word (optional) ( Control Word )

AC-id forwarding index payload type identifier (PTI) loss priority (C)

Asynchronous Transfer Mode Payload ( ATM Payload )

AC-id forwarding index payload type identifier (PTI) loss priority (C)

Asynchronous Transfer Mode Payload ( ATM Payload )

table 3

For the adjustment of the N TO 1 encapsulation format of other pseudowire services, such as the emulation service of Frame Relay (FR), the AC-id forwarding index is also used to index a specific FR service flow.

As can be seen from the above, the present invention introduces a sub-service identification mechanism, so that the PE device can distinguish a specific AC service pair, and avoids the PW state UP caused by the AC UP of the non-service pair, but cannot be actually forwarded. The status of the text. Moreover, through the mechanism of the present invention, it is also possible to avoid the problem that the corresponding PVC is inefficiently searched by the inputvpi/inputvci hardware.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modifications, equivalents, improvements, etc., which are made within the spirit and principles of the present invention, should be included. It is within the scope of the invention.

Claims

Claim

A method for identifying a plurality of simulated service flow paths, wherein an emulation service flow path carries a plurality of emulation service flows N TO 1 mode, wherein the auxiliary circuit identifiers for identifying sub-affiliated circuit service pairs are set; The method also includes:

The method according to claim 1, wherein the advertisement message comprises: a normal advertisement message that informs that the first sub-affiliated circuit is in a normal state, or informs that the first sub-affiliated circuit is non- A normal abnormal notification message.

The method according to claim 1, wherein the advertisement message is a normal advertisement message; the step B specifically includes:

4. The method of claim 3, wherein the method further comprises: if the state of the second sub-auxiliary circuit is an abnormal operating state, then the pseudo-location is located The state of the first sub-auxiliary circuit in the second service-on device at the second end of the line is set to a normal operating state.

The method according to claim 1, wherein the advertisement message is an abnormal advertisement message; the step B specifically includes:

The method according to claim 1, wherein the auxiliary circuit identifier is carried in an auxiliary circuit identifier forwarding index set in the advertisement message.

The method according to claim 3 or 5, wherein: the method for determining whether the pseudowire state is normal is:

If the inner layer labels at both ends of the pseudowire are allocated, the pseudowire state is a normal working state; otherwise, the pseudowire state is an abnormal working state.