WO2008043230A1

WO2008043230A1 - Method, device and system for establishing a bi-directional label switched path

Info

Publication number: WO2008043230A1
Application number: PCT/CN2007/001698
Authority: WO
Inventors: Hongguang Guan
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-09-30
Filing date: 2007-05-25
Publication date: 2008-04-17
Also published as: CN101155178A; CN101155178B

Abstract

A method, device and system for establishing a bi-directional label switched path are provided. The method inculdes: if the source node hasn't available forward LSP, the source node establishes directly the forward LSP; if the source node hasn't available backward LSP, the source node informs the sink node by peer to peer to establish the backward LSP; the sink node establishes the backward LSP. According to the said method,device and system, existent forward LSP and/or backward LSP can be utilized to provide bi-directional services, so as to improve the utility of network resources; the transmission of control message by peer to peer mitigates the processing burden of the middle nodes; and the flexibility of providing bi-directional services is improved because of the independence of forward LSP and backward LSP.

Description

Method, device and system for establishing a two-way label switching path. This application claims to be a method, device and system for establishing a bidirectional LSP in a multi-protocol label switching, submitted to the Chinese Patent Office on September 30, 2006, application number 200610062993.0, and entitled "Multi-Protocol Label Switching" The priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference. Technical field

The present invention relates to the field of network communication technologies, and in particular, to a method, device and system for establishing a bidirectional label switching path.

Background technique

In the multi-protocol label switching (MPLS), the Label Switched Path (LSP) is established by exchanging signaling information by hop-by-hop routing, that is, label request and label mapping. The established LSP is a one-way LSP from the local Label Switched Router (LSR) node to the sink node.

With the widespread use of MPLS, some services such as voice and video TV require the use of two-way LSPs to transmit service data. From the perspective of effective data transmission, it is necessary to bind the LSPs in the opposite direction between the two end nodes, that is, the LSPs from the source node to the sink node and the sink node to the source node, as a directional LSP.

In order to support the establishment and maintenance management of bidirectional LSPs, a new mechanism is necessary. For the sake of clarity, the convention will trigger the direction in which the source node establishing the bidirectional LSP towards the sink node is called foward, and the direction in which the corresponding sink node is toward the source node is called backward. It should be noted that for a two-way LSP, the two unidirectional LSPs are forward and reverse LSPs.

Referring to the prior art shown in FIG. 1, a schematic diagram of establishing a bidirectional LSP. The source node R0 of the forward LSP initiates the establishment of a forward LSP to the neighboring node R5 through the intermediate nodes R1 and R2. The upstream node issues a label request message to the downstream node and assigns a label corresponding to the reverse LSP to the downstream node. [(1), (2), (3)] in the figure is a tag request message, and [(4), (5), (6] are tag mapping messages.

Another schematic diagram of establishing a bidirectional LSP is shown in the prior art shown in FIG. 2. The routing node follows the traditional label issuing signaling processing mechanism for label allocation. The label request message [(1), (2), (3)] sent by the source node R0 of the forward LSP to the sink node R5 through the intermediate nodes R1, R2 includes an indication that the reverse LSP and the corresponding parameter are established. Information (such as FEC, QoS parameters, traffic engineering parameters, etc.), which is inserted into the label request message [(1)] by the source node R0 of the forward LSP. For intermediate node R1 In contrast to R2, the intermediate node is responsible for copying and forwarding this information to the sink node.

After receiving the forward LSP setup message [(3)] from its upstream node R2, the sink node R5 of the forward LSP follows the traditional label issuing signaling processing mechanism to assign a label to its upstream node R2 for the FEC specified in the message. The assigned label is advertised to its upstream node R2 by the label mapping message [(4)]; likewise, the nodes R2, R1 advertise the label assigned to its upstream node by the label mapping message [(7)], [(9)] respectively. . At this point, the forward LSP (R0->R1->R2->R5) is successfully established.

In addition, the sink node R5 of the forward LSP receives the forward LSP establishment message [(3)] from its upstream node R2 and finds the information inserted by the source node to establish the reverse LSP, and then extracts the corresponding information. The parameter information is initiated to establish a reverse LSP. Assuming that the reverse LSP adopts the same path as the forward LSP, the sink node R5 of the forward LSP sends a label request message [(5)] for the reverse LSP designation EBC to the downstream node R2 of its reverse LSP. Similarly, the node R2 and R1 respectively send label request messages [(6)], [(8)] for the reverse LSP designated FEC to their downstream nodes.

After receiving the message [(8)], the sink node R0 of the reverse LSP follows the traditional label issuing signaling processing mechanism to assign a label to the reverse LSP upstream node R1 for the FEC specified in the message, and the assigned label is labeled by the label. The mapping message [(10)] is advertised to its upstream node R1; likewise, the nodes R1, R2 advertise the label assigned to its upstream node by the label mapping message [(11)], [(12)], respectively. At this point, the reverse LSP (R5->R2->R1 ->R0) is successfully established.

After both the forward LSP and the reverse LSP are established, they are bound to a bidirectional LSP on edge nodes R0 and R5.

In the process of implementing the present invention, the inventors have found that at least the following problems exist in the prior art:

1. In the prior art, each time a two-way LSP is established, two new one-way LSPs with opposite directions are established and bound. If there is already an LSP for the same Forwarding Equivalence Class (FEC) in the direction of the edge node of the bidirectional LSP, the LSP must be removed before the bidirectional LSP can be established. This will greatly waste network resources and also cause damage to normal business delivery.

2. In the prior art, the message indicating that the reverse LSP is established is inserted into the label request message at the ingress edge node of the forward LSP. There is no independent control channel, and the label is inconvenient for management and maintenance, and the processing load of the intermediate node is also increased. Because these indication messages are meaningless to the intermediate nodes. In another aspect, the indication information for establishing the reverse LSP is inserted into the label request message such that the forward LSP and The reverse LSP cannot be established in an orderly manner. That is, the LSP in one direction is successfully established and the LSP in the other direction fails to be established. At this time, the LSP that has been established in one direction has to be cleared to re-attempt to establish the LSP in both directions. This greatly increases the processing overhead.

Summary of the invention

The embodiments of the present invention provide a method, a device, and a system for establishing a bidirectional label switching path, so as to improve network resource utilization, ensure orderly establishment and management of forward LSPs and reverse LSPs, and reduce processing overhead.

An embodiment of the present invention provides a method for establishing a bidirectional LSP, where the method includes: if there is no forward LSP available for service between the source and the sink node, the source node directly establishes the forward LSP;

If there is no reverse LSP available for service between the source and the sink node, the source node notifies the sink node to establish the reverse LSP in a point-to-point manner;

The sink node establishes the reverse LSP.

An embodiment of the present invention provides a network device, including:

a detecting unit, configured to check whether the local end has a forward LSP and a reverse LSP available for service;

And a sending notification unit, configured to: when the detecting unit detects that the local end does not have a forward LSP or a reverse LSP, where the service is available, the notification message includes: Notifying the LSP and the lack of the reverse LSP notification message;

a forwarding unit, configured to receive the notification message of the sending notification unit, and forward the notification message of the reverse notification LSP of the sending notification unit to other network devices in a peer-to-peer manner, and receive the reverse LSP from other network devices Notification message

The LSP executing unit is configured to establish a forward LSP after receiving the notification of the short forward LSP forwarded by the forwarding unit.

The embodiment of the present invention further provides a label switching routing system, including at least two label switching routers, and the source label switching router notifies the sink label switching router establishment point-to-point manner when there is no reverse LSP available at the local end. a reverse LSP; a sink label switching router establishes the reverse LSP; the source label switching router includes:

Sending a notification unit, configured to detect, in the detecting unit, that the local end does not have a service available The LSP or the reverse LSP is configured to include a notification message indicating that the LSP corresponding to the service is established, where the notification message includes a lack of a forward LSP notification message and a lack of a reverse LSP notification message;

a forwarding unit, configured to receive the notification message of the sending notification unit, and forward the notification message of the reverse notification LSP of the sending notification unit to other network devices in a point-to-point manner, and receive the reverse LSP from other network devices Notification message

Since the embodiment of the present invention provides a bidirectional LSP service based on an independent unidirectional LSP, it means that each unidirectional LSP can independently implement traffic engineering, and can also utilize an existing one-way LSP, which is compared with the prior art. It greatly provides the utilization of network resources, ensures the orderly establishment and management of forward LSPs and reverse LSPs, and reduces processing overhead.

DRAWINGS

FIG. 1 is a schematic diagram of a network for establishing a bidirectional LSP in the prior art;

2 is a schematic diagram of another network for establishing a bidirectional LSP in the prior art;

3-1 is a flowchart of a method for establishing a bidirectional LSP according to an embodiment of the present invention; FIG. 3-2 is another flowchart of a method for establishing a bidirectional LSP according to an embodiment of the present invention; A flowchart of managing a bidirectional LSP according to an embodiment of the invention;

5-1 is a schematic diagram of a network for establishing a bidirectional LSP according to the first embodiment of the present invention;

5-2 is a timing chart showing the establishment of a bidirectional LSP according to the first embodiment of the present invention;

6-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a second embodiment of the present invention;

6-2 is a timing chart of establishing a bidirectional LSP according to a second embodiment of the present invention;

7-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a third embodiment of the present invention;

7-2 is a timing chart showing the establishment of a bidirectional LSP according to a third embodiment of the present invention;

8-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a fourth embodiment of the present invention;

8-2 is a timing chart of establishing a bidirectional LSP according to a fourth embodiment of the present invention;

9-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a fifth embodiment of the present invention;

9-2 is a timing chart showing the establishment of a bidirectional LSP according to a fifth embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a network device according to an embodiment of the present invention; FIG.

11 is a schematic block diagram of a label switching routing system in accordance with an embodiment of the present invention. detailed description

In the embodiment of the present invention, before the bidirectional LSP is established, the source node detects the forward LSP and the reverse LSP that are available to the local end. If the forward LSP is not available, the local end directly initiates the establishment of the forward LSP. If the local end does not have the reverse LSP, the local end notifies the sink node to establish the reverse LSP in a point-to-point manner; the sink node establishes the reverse LSP.

The source node and the sink node may be Label Switched Routers (LSRs), and the notification message sent by the source node to the sink node may specify the FE corresponding to the reverse LSP (:, traffic engineering parameter, QoS parameter, bandwidth) Parameters and other LSP-related control parameters. The point-to-point notification message is forwarded to the destination edge node via the intermediate node route, and the notification message is transparent to the intermediate node, and the intermediate node only forwards the notification message without the IP address in the notification message. The content of the load on the layer is processed.

After successfully establishing an LSP, any party will send a setup success message to the peer to notify the peer. Once the LSR node detects that the local forward LSP and the reverse LSP are available, the two unidirectional LSPs are bound to become a bidirectional LSP. The binding success message is sent to the destination node. If the LSR node fails to establish an LSP at any end, it will send a setup failure message to the sink node, or it will be automatically perceived by the local end in other ways, such as using a handshake mechanism. If the label switching routing node fails to establish a forward LSP or fails to establish a reverse LSP, the labeling routing node performs fault and exception handling.

After the bidirectional LSP is established, the point-to-point control message is transmitted between the source node of the forward LSP (ie, the sink node of the reverse LSP) and the sink node of the forward LSP (ie, the source node of the reverse LSP), such as establishment, Bind, update, and maintain, remove bidirectional LSPs, and more. For example, in the Resource Reservation Protocol- Traffic Engineering (RSVP-TE) signaling, the Notify message is used as a point-to-point control message between the bidirectional LSP edge nodes to directly manage the bidirectional LSP.

It should be noted here that the forward LSP and the reverse LSP are for the originator of the service. For the sake of clearer description, the direction that the agreement will trigger the establishment of the source node of the Han-direction service towards the sink node is called forward ( The direction in which the corresponding sink node is toward the source node is referred to as "backward" - an embodiment of the present invention will be further described below with reference to the accompanying drawings.

Referring to FIG. 3-1, a flow chart of a method for establishing a bidirectional LSP according to an embodiment of the present invention is shown. The process of establishing a bidirectional LSP includes the following steps: 301: The source node determines whether there is a forward LSP available at the local end, and if there is a forward LSP, enters 304, otherwise enters 302;

302: A forward LSP is initiated by the source node.

303: The source node determines whether the local end successfully establishes a forward LSP, if yes, enters 304, otherwise enters 309;

304: The source node determines whether there is an available reverse LSP, if yes, enters 307, otherwise enters

305;

305: The source node directly notifies the neighboring node to initiate establishment of a reverse LSP.

306: The source node determines whether the opposite sink node successfully establishes a reverse LSP, if yes, enters 307, otherwise enters 309;

307: The local binding forward LSP and the reverse LSP are bidirectional LSPs;

308: Directly notify the peer end to bind the forward LSP and the reverse LSP into a bidirectional LSP, and enter 310 after completion; 309: perform fault and exception processing;

310: End the process.

In step 302, after the source node initiates the establishment of the forward LSP, the forward direction initiated by the source node of the forward LSP

The LSP setup message can be processed according to the traditional LSP label request message processing mechanism. Similarly, after receiving the forward LSP setup message from its upstream node, the sink node follows the traditional label issuing signaling processing mechanism for the FEC direction specified in the message. The upstream node allocates a label, and the assigned label is advertised to its upstream node by the label mapping message, and the process is repeated until the source node, thereby successfully establishing a forward LSP.

In step 305, the process in which the source node directly informs the sink node to initiate the establishment of the reverse LSP is specifically: sending the information indicating the establishment of the reverse LSP and the corresponding parameter directly from the source node to the sink node; after receiving the notification, the sink node initiates establishment. The reverse LSP, which establishes a reverse LSP, has the same mechanism as the source node establishes a forward LSP, and follows the traditional standard LSP establishment processing mechanism. The corresponding parameter information includes: FEC, QoS parameters, traffic engineering parameters, bandwidth parameters, and other LSP related control parameters corresponding to the reverse LSP.

In step 306, if the sink node successfully establishes a reverse LSP, and sends a reverse LSP establishment confirmation message to the source node, the source node determines that the reverse LSP is successfully established after receiving the reverse setup acknowledgement message.

3-2 is another flow chart of a method for establishing a bidirectional LSP according to an embodiment of the present invention. The process of establishing a bidirectional LSP includes the following steps: 401: The source node determines whether there is an available reverse LSP at the local end, if there is a reverse LSP, enter 404, otherwise enter 402;

402: The source node notifies the neighboring node to initiate establishment of a reverse LSP.

403: The source node determines whether the opposite sink node successfully establishes a reverse LSP, if yes, enters 404, otherwise enters 409;

404: The source node determines whether there is a forward LSP available, and if yes, enters 407, otherwise enters

405;

405: The source node locally initiates establishment of a forward LSP.

406: The source node determines whether the local forward LSP is successfully established, if yes, enters 407, otherwise enters 409;

407: The local binding forward LSP and the reverse LSP are bidirectional LSPs;

408: Directly notify the peer to bind the forward LSP and the reverse LSP into a bidirectional LSP, and enter 410 after completion; 409: Perform fault and exception handling;

410: End the process.

It can be seen from the above process that the difference between the forward LSP and the reverse LSP of the corresponding FEC included in the local end is different from that of the embodiment shown in FIG. 3. In FIG. 4, it is first determined whether there is a reverse LSP and then judged whether Has a forward LSP. According to the embodiment of the present invention, the order of changing the judgment, or periodically checking the forward LSP and the reverse LSP of the local end, and the like do not exceed the scope of the present invention.

4 is a flowchart of managing a bidirectional LSP according to an embodiment of the present invention, including the following steps:

411: The source node determines whether it is necessary to control the reverse LSP, if yes, enter 412, otherwise enter 415; 412: The source node sends a point-to-point control message to the opposite-end sink node, informing the sink node to control the reverse LSP according to the requirement;

413: The source node determines whether the peer end acknowledges receipt of the control message, and if yes, enters 415, otherwise proceeds to 414;

414: The source node retransmits the control message to the peer sink node, and then enters 415 after completing;

415: End this management process.

The above process is described from the perspective of the ingress node (ie, the source node) of the forward LSP, because the two unidirectional LSPs in the bidirectional LSP are in opposite directions and have the same edge node, that is, the two unidirectional The LSPs are forward and reverse mutually. Therefore, the process of managing the forward LSP from the ingress node (ie, the sink node) of the reverse LSP is similar to the above.

Figure 5-1 is a schematic diagram of a network for establishing a bidirectional LSP according to an embodiment of the present invention, and Figure 5-2 is a timing chart for establishing a bidirectional LSP.

Referring to FIG. 5-1 and FIG. 5-2, in the first embodiment of the present invention, the LSR node R0 is used as the source node of the forward LSP, and no forward LSP and reverse are available on the source node of the forward LSP. To the LSP. The process of establishing a bidirectional LSP is as follows:

501: First, the source node R0 informs the downstream node R1 of the forward LSP to establish a forward LSP through the LSP establishment message [(1)], and after receiving the message [(1)], R1 sends a corresponding forward LSP to its downstream node R2. The request message [(2)] is established, and after receiving the message [(2)], R2 sends a corresponding forward LSP establishment request message [(3)] to its downstream node R5, that is, the sink node of the forward LSP.

502: The sink node R5 of the forward LSP sends a label mapping message [(4)] to the upstream node R2 according to the traditional LSP establishment processing mechanism after receiving the forward LSP establishment request message [(3)], and receives the message [ (4) After R2 issues a setup confirmation message [(5)] to its upstream node R1, after receiving the message [(5)], R1 issues a setup confirmation message to its upstream node R0, that is, the source node of the forward LSP [(6) )], the forward LSP is successfully established.

503: After the forward LSP is successfully established, the source node R0 of the forward LSP directly informs the sink node R5 of the forward LSP to establish a reverse LSP by using a point-to-point message [(7)].

504: The sink node R5 initiates establishment of the reverse LSP after receiving the notification message [(7)]. The sink node R5 initiates the establishment of the reverse LSP by using the information contained in the notification message [(7)] (such as FEC, QoS parameters, process engineering parameters, etc.). R5 sends a reverse LSP setup request message [(8)] for the specified FEC to the node R2 of its reverse LSP, and after receiving the message, R2 sends a reverse LSP setup request for the specified FEC to the node R1 of its reverse LSP. Message [(9)], after receiving the message, R1 sends a reverse LSP establishment request message [(10)] for the specified FEC to its neighbor node R0.

505: The source node R0 of the forward LSP issues a setup confirmation message [(11)] to the upstream node R1 of its reverse LSP following the receipt of the reverse LSP establishment request message [(10)], following the conventional LSP establishment processing mechanism, After receiving the message [(11)], R1 issues a setup confirmation message [(12)] to its upstream node R2, and after receiving the message [(12)], R2 issues a setup confirmation message [(13)] to its upstream node R5. At this point, the reverse LSP is successfully established.

506: The sink node R5 sends a reverse LSP establishment acknowledgement message to the source node R0 in a point-to-point manner, and the source node R0 receives the message binding forward and reverse LSPs as a bidirectional LSP; 507: The source node R0 informs the sink node R5 to establish a bidirectional LSP in a point-to-point manner, and the sink node R5 receives the message binding forward LSP and the reverse LSP as a silent LSP.

After the forward LSP and the reverse LSP are successfully established, the source node of the forward LSP (ie, the sink node of the reverse LSP) R0 notifies the sink node of the forward LSP by the point-to-point message [(7)] (ie, the reverse Source node of the LSP) R5 binds the forward and reverse LSPs into a bidirectional LSP.

In this embodiment, the path of the reverse LSP established by the sink node R5 in step 504 is the same as the forward LSP path established by R0. The LSP establishment request message is generally a label request message, such as a Resource Reservation Protocol (Traffic Engineering, RSVP-TE) Path message, and the LSP establishment confirmation message is generally a label mapping message such as RSVP-TE RESV. Message.

Figure 6-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a second embodiment of the present invention, and Figure 6-2 is a timing chart for establishing a bidirectional LSP. The second embodiment is basically the same as the process of establishing a bidirectional LSP in the first embodiment. The difference is that the reverse LSP uses a different path from the forward LSP in the second embodiment, and the reverse LSP and the positive in the first embodiment. Use the same path to the LSP. The process of establishing a two-way LSP is as follows:

601 to 603: The same as steps 501 to 503 shown in Fig. 5-2.

604: The sink node R5 initiates establishment of the reverse LSP after receiving the notification message [(7)]. The sink node R5 initiates the establishment of the reverse LSP by using the information contained in the notification message [(7)] (such as FEC, QoS parameters, process engineering parameters, etc.). R5 sends a reverse LSP setup request message [(8)] for the specified FEC to the downstream node R4 of its reverse LSP, and after receiving the message, R4 sends a reverse LSP for the designated FEC to the downstream node R3 of its reverse LSP. A request message [(9)] is established, and after receiving the message, R3 sends a reverse LSP establishment request message [(10)] for the specified FEC to its neighbor node R0.

605: The source node R0 of the forward LSP issues a setup confirmation message [(11)] to the upstream node R3 of its reverse LSP following the receipt of the reverse LSP establishment request message [(10)], following the conventional LSP establishment processing mechanism, After receiving the message [(11)], R3 issues a setup confirmation message [(12)] to its upstream node R4, and after receiving the message [(12)], R4 issues a setup confirmation message [(13)] to its upstream node R5, At this point, the reverse LSP is successfully established.

606: The sink node R5 sends a reverse LSP establishment acknowledgement message to the source node R0 in a point-to-point manner, and the source node R0 receives the message binding forward and reverse LSPs as a bidirectional LSP;

607: The source node R0 informs the sink node R5 to establish a bidirectional LSP in a point-to-point manner, and the sink node R5 receives the message binding forward LSP and the reverse LSP as a bidirectional LSP.

After the forward LSP and the reverse LSP are successfully established, the source node of the forward LSP (that is, the sink of the reverse LSP) Node) R0 informs the sink node of the forward LSP (ie, the source node of the reverse LSP) through the point-to-point message [(7)]. R5 Binds the forward and reverse LSPs into a bidirectional LSP.

Figure 7-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a third embodiment of the present invention, and Figure 7-2 is a timing chart for establishing a bidirectional LSP. Referring to FIG. 7-1 and FIG. 7-2, in the third embodiment of the present invention, the LSR node R0 is used as the source node of the forward LSP, and the reverse LSP available on the source node of the forward LSP is available. To establish a bidirectional LSP, only the forward LSP needs to be established and bound on the edge node. In this embodiment, after the forward LSP is established, a binding success message is sent to the correspondent node in a point-to-point manner to notify the peer to bind the forward and reverse LSPs to establish a bidirectional LSP. The process of establishing a two-way LSP is as follows:

701: First, the source node R0 informs the downstream node R1 of the forward LSP to establish a forward LSP through the LSP establishment message [(1)], and after receiving the message [(1)], R1 sends a corresponding forward LSP to its downstream node R2. The request message [(2)] is established, and after receiving the message [(2)], R2 sends a corresponding forward LSP establishment request message [(3)] to its downstream node R5, that is, the sink node of the forward LSP.

702: The sink node R5 of the forward LSP sends a label mapping message [(4)] to the upstream node R2 according to the traditional LSP establishment processing mechanism after receiving the forward LSP establishment request message [(3)], and receives the message [ (4) After R2 issues a setup confirmation message [(5)] to its upstream node R1, after receiving the message [(5)], R1 issues a setup confirmation message to its upstream node: R0, that is, the source node of the forward LSP [( 6)], the forward LSP is successfully established.

Since the reverse LSP is available on the source node R0, after the forward LSP is successfully established, you only need to bind it on the edge node.

703: The source node R0 informs the sink node R5 to establish a bidirectional LSP in a point-to-point manner, and the sink node R5 receives the message binding forward LSP and the reverse LSP as a bidirectional LSP.

After the forward LSP and the reverse LSP are successfully established, the source node of the forward LSP (ie, the sink node of the reverse LSP) R0 notifies the sink node of the forward LSP by the point-to-point message [(7)] (ie, the reverse The source node of the LSP) R5 binds the forward and reverse LSPs to a joyful LSP.

8-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a fourth embodiment of the present invention, and FIG. 8-2 is a sequence flowchart for establishing a bidirectional LSP. Referring to FIG. 8-1 and FIG. 8-2, in the fourth embodiment of the present invention, the LSR node R0 is used as the source node of the forward LSP, which is different from the third embodiment in that the source of the forward LSP is at this time. A forward LSP is available on the node. To establish a bidirectional LSP, you only need to establish a reverse LSP and bind it to the edge node. In this embodiment, the peer is directly notified by a point-to-point message. Node R5 initiates the establishment of a reverse LSP. After the reverse LSP is established, the local LSP is bound to the forward and reverse LSPs to establish a bidirectional LSP, and the peer-to-peer message is used to notify the opposite end R5 to bind the forward and reverse LSPs to establish a bidirectional LSP. The process of establishing a bidirectional LSP is as follows:

801: First, the source node R0 directly informs the sink node R5 of the forward LSP through the point-to-point message [(1)] to initiate the establishment of the reverse LSP.

802: The sink node R5 initiates the establishment of the reverse LSP after receiving the notification message [(1)]. The sink node R5 initiates the establishment of the reverse LSP by using the information contained in the notification message [(1)] (such as FEC, QoS parameters, process engineering parameters, etc.). R5 sends a reverse LSP setup request message [(2)] for the specified FEC to the node R2 of its reverse LSP, and after receiving the message, R2 sends a reverse LSP setup request for the specified FEC to the node R1 of its reverse LSP. Message [(3)], after receiving the message, R1 sends a reverse LSP establishment request message [(4)] for the specified FEC to its neighbor node R0.

803: The source node R0 of the forward LSP issues a setup confirmation message [(5)] to the upstream node R1 of the reverse LSP according to the traditional LSP establishment processing mechanism after receiving the reverse LSP establishment request message [(4)]. After receiving the message [(5)], R1 issues a setup confirmation message [(6)] to its upstream node R2, and after receiving the message [(6)], R2 issues a setup confirmation message [(7)] to its upstream node R5. At this point, the reverse LSP is successfully established.

804: The sink node R5 sends a reverse LSP establishment acknowledgement message to the source node R0 in a point-to-point manner, and the source node R0 receives the message binding forward and reverse LSPs as a bidirectional LSP;

805: The source node R0 informs the sink node R5 to establish a bidirectional LSP in a point-to-point manner, and the sink node R5 receives the message binding forward LSP and the reverse LSP as a bidirectional LSP.

9-1 is a schematic diagram of a network for establishing a bidirectional LSP according to a fifth embodiment of the present invention, and FIG. 9-2 is a sequence flowchart for establishing a bidirectional LSP. Referring to FIG. 9-1 and FIG. 9-2, in the fifth embodiment of the present invention, the LSR node R0 is used as the source node of the forward LSP, and is available on the source node of the forward LSP as in the fourth embodiment. The forward LSP only needs to establish a reverse LSP and bind on the edge node to establish a bidirectional LSP. Directly through the point-to-point message, the neighboring sink node R5 initiates the establishment of the reverse LSP. After the reverse LSP is established, the local end R0 is bound to the forward and reverse LSPs to establish a bidirectional LSP, and the peer-to-peer message is used to notify the opposite end R5 to bind the forward and reverse LSPs to establish a bidirectional LSP. The difference between this embodiment and the fourth embodiment is that the reverse LSP is established and the forward LSP adopts a different path. The process of establishing a bidirectional LSP is as follows:

901: First, the source node R0 directly informs the sink node R5 of the forward LSP through the point-to-point message [(1)]. Initiate the establishment of a reverse LSP.

902: The sink node R5 initiates establishment of the reverse LSP after receiving the notification message [(1)]. The sink node R5 initiates the establishment of the reverse LSP by using the information contained in the notification message [(1)] (such as FEC, QoS parameters, process engineering parameters, etc.). R5 sends a reverse LSP setup request message [(2)] for the specified FEC to the node R4 of its reverse LSP, and after receiving the message, R4 sends a reverse LSP setup request for the specified FEC to the node R3 of its reverse LSP. Message [(3)], after receiving the message, R3 sends a reverse LSP establishment request message [(4)] for the specified FEC to its neighbor node R0.

903: The source node R0 of the forward LSP issues a setup confirmation message [(5)] to the upstream node R3 of its reverse LSP following the receipt of the reverse LSP establishment request message [(4)], following the conventional LSP establishment processing mechanism, After receiving the message [(5)], R3 issues a setup confirmation message [(6)] to its upstream node R4, and after receiving the message [(6)], R2 issues a setup confirmation message [(7)] to its upstream node R5. At this point, the reverse LSP is successfully established.

904: The sink node R5 sends a reverse LSP establishment acknowledgement message to the source node R0 in a point-to-point manner, and the source node R0 receives the message binding forward and reverse LSPs as a bidirectional LSP;

905: The source node R0 informs the sink node R5 to establish a bidirectional LSP in a point-to-point manner, and the sink node R5 receives the message binding forward LSP and the reverse LSP as a bidirectional LSP.

It should be noted that, in the embodiments of the present invention, any LSR node can bind the forward LSP and the reverse LSP as long as it detects that the local end includes the forward LSP and the reverse LSP of the corresponding FEC, and whether the opposite end is bound to the opposite end. Binding is independent of each other.

It can be seen from the foregoing embodiments that the embodiment of the present invention provides a bidirectional LSP service based on an independent unidirectional LSP, which means that each unidirectional LSP can independently implement traffic engineering, and can also utilize an existing one-way LSP. This will greatly provide network resource utilization compared to the prior art. In addition, since the embodiment of the present invention uses a point-to-point control message to manage the bidirectional LSP, this will significantly reduce the processing load of the intermediate node compared to the prior art. Moreover, since the independent control channel of the embodiment of the present invention ensures the orderly establishment and management of the forward and reverse LSPs, the risk of high processing overhead can be avoided compared to the prior art.

FIG. 10 is a schematic structural diagram of a network device according to an embodiment of the present invention, and also shows signaling flow between units of the network device. The network device includes a detecting unit 101, a sending notification unit 102, a forwarding unit 103, and an LSP executing unit 104. The network device may further include a binding unit 105, a fault and exception processing unit 106, and an LSP management unit 107. The detecting unit 101 is configured to detect that the local node includes the forward LSP and the reverse LSP corresponding to the FEC, and if there is no forward LSP or reverse LSP, notify the sending notification unit 102 if there is both a forward LSP and a reverse LSP. , the binding unit is notified to perform binding 105.

The sending notification unit 102 is configured to create a notification message indicating that the LSP of the corresponding FEC is established according to the detection result of the detecting unit 101, and send a notification message indicating that the forward LSP is established to the forwarding unit 103 if the notification of the lack of the forward direction is received. If a notification of lack of reversal is received, a notification message indicating that the reverse LSP is established is sent to the forwarding unit 103.

The forwarding unit 103 is configured to receive a control message from another unit or the peer network device at the local end, and forward the received control message to the corresponding unit, for example, after receiving the notification message of the forward LSP by the sending notification unit 102, The LSP execution unit 104 is instructed to establish a forward LSP. After receiving the notification message of the reverse LSP that is sent by the notification unit 102, the message is forwarded to the peer network device.

The LSP executing unit 104 receives the function of establishing a forward notification, performing LSP establishment, forwarding, and the like, and can work according to a traditional label forwarding mechanism. The forwarding of the LSP and the forwarding of the control message are independent of each other, and different control channels can be used.

The binding unit 105 receives the notification binding message of the detecting unit 101, that is, when the detecting unit 101 detects that the local end has a forward LSP and a reverse LSP, the binding unit 105 binds the forward LSP and the reverse LSP.

The fault and abnormality processing unit 106 performs corresponding fault and abnormality processing when the forward LSP establishment fails or the reverse LSP establishment fails or other fault abnormalities occur.

The LSP management unit 107 manages and maintains the bidirectional LSP, and the management message is forwarded by the forwarding unit 103, which is independent of the channel used by the traditional mechanism label forwarding. Management messages include establishing messages, binding messages, updating messages, maintaining messages, tearing down messages, and the like.

With the network device shown in FIG. 10, the label switching routing system provided by the embodiment of the present invention is as shown in FIG. 11:

In the system, including: at least two label switching routers, as shown in the figure, the source label switching router 110 and the sink label switching router 120. Of course, there may be one in the source label switching router 110 and the sink label switching router 120. Or multiple intermediate routers, such as the intermediate router 130 shown in the figure. The source label switching router 110 notifies the sink label switching router to establish the reverse LSP in a point-to-point manner when the local end has no reverse LSP available for the service; the notification message is transparent to the intermediate router 130, and the intermediate router 130 only routes and forwards the notification message. Without carrying the IP layer on the notification message The content is processed. The sink label switching router establishes the reverse LSP according to the notification. The structure of the source label switching router 110 and the sink label switching router 120 is the same as that of the network device shown in FIG. 10, and details are not described herein again. The source label switching router 110 and the sink label switching router 120 send a notification message through the intermediate node 130. The process of establishing a reverse LSP has been described in detail above, and will not be described here.

With the system of the embodiment of the present invention, a bidirectional LSP can be established, and a bidirectional LSP service is provided based on an independent unidirectional LSP, so that each unidirectional LSP can independently implement traffic engineering; and LSP management in the label switching router is utilized. The unit can manage the bidirectional LSP through the point-to-point control message, thereby reducing the processing load of the intermediate router and reducing the processing overhead.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Rights request

A method for establishing a bidirectional label switching path, the method comprising: if a source or a sink node has no forward LSP available for service, the source node directly establishes the forward LSP;

The sink node establishes the reverse LSP.

2. The method according to claim 1, wherein the method further comprises:

After the sink node successfully establishes the reverse LSP, the source node is notified in a point-to-point manner to successfully establish the reverse LSP.

The method according to claim 1, wherein the method further comprises:

After the source and the sink nodes have a forward LSP and a reverse LSP available for the service, the source node binds the forward LSP and the reverse LSP; or

The sink node binds the forward LSP and the reverse LSP when the forward LSP and the reverse LSP corresponding to the FEC.

The method according to claim 1, wherein the step of the source node notifying the sink node to establish the reverse LSP by means of a point-to-point method comprises:

The source node sends a point-to-point notification message to the sink node, where the notification message includes: a reverse LSP indicating establishment of a service, and an FEC, a QoS parameter, a traffic engineering parameter, and a bandwidth parameter related to the reverse LSP.

The method according to claim 1, wherein the sink node initiates establishment of the reverse LSP by using a path that is the same as or different from the forward LSP.

The method according to claim 3, wherein the method further comprises: sending or receiving a label control management message in a point-to-point manner between the source node and the sink node, managing the forward LSP and The reverse LSP.

7. A network device, comprising:

a sending notification unit, configured to: when the detecting unit detects that the local end does not have a forward--LSP or a reverse LSP available for the service, creating a notification message that includes the LSP indicating that the service is established, where The notification message includes a lack of a forward LSP notification message and a lack of a reverse LSP notification message;

The network device according to claim 7, wherein the network device further includes: a binding unit, configured to: when the detecting unit detects that the local end has a forward LSP or a reverse LSP available for service Binding the forward LSP and the reverse LSP.

The network device according to claim 7 or 8, wherein the network device further comprises:

And an LSP management unit, configured to manage the forward LSP and the reverse LSP; and send, by using the forwarding unit, a management message including the control of the reverse LSP, in a point-to-point manner.

The fault and exception handling unit is configured to perform fault and exception handling when the local forward LSP establishment fails or the reverse LSP establishment fails or other fault abnormalities occur.

A label switching routing system, comprising at least two label switching routers, wherein the source label switching router notifies the sink label switching router to establish the inverse in a peer-to-peer manner when there is no reverse LSP available at the local end. Establishing the reverse LSP to an LSP; a sink label switching router; the source label switching router includes:

An LSP executing unit, configured to receive, by the forwarding unit, the notification that the forward LSP is forwarded After that, a forward LSP is established.

The label switching routing system according to claim 11, wherein the source label switching router and the sink label switching router each comprise:

The binding unit is configured to bind the forward LSP and the reverse LSP when the local end has a forward LSP and a reverse LSP available for the service.

The label switching routing system according to claim 12, wherein the source label switching router and the sink label switching router each comprise:

The LSP management unit is configured to transmit a management control message of the bidirectional LSP in a point-to-point manner between the source label switching router and the sink label switching router to implement control and management of the bidirectional LSP.