CN107888493B

CN107888493B - Method and device for establishing label switching path

Info

Publication number: CN107888493B
Application number: CN201711237925.8A
Authority: CN
Inventors: 李�诚
Original assignee: Maipu Communication Technology Co Ltd
Current assignee: Maipu Communication Technology Co Ltd
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2020-04-21
Anticipated expiration: 2037-11-30
Also published as: CN107888493A

Abstract

The application provides a method and a device for establishing a label switched path, relates to the field of communication, and can protect a public network tunnel and avoid bandwidth waste. The method comprises the following steps: the first node selects a main upstream node and a backup upstream node according to the saved routing table; sending a first label mapping message comprising the FEC and a main label distributed by the first node to the main upstream node, and sending a second label mapping message comprising the FEC, a backup label distributed by the first node and an IP address of the first node to the backup upstream node; and the first node generates and stores the first forwarding table. The method and the device are used for establishing the label switching path.

Description

Method and device for establishing label switching path

Technical Field

The present application relates to the field of communications, and in particular, to a method and an apparatus for establishing a label switched path.

Background

The multicast VPN (chinese: virtual private network) may open a multicast service on an existing BGP (border gateway protocol)/MPLS (multi-protocol label switching, chinese: internet protocol) IP (internet protocol, chinese: VPN) VPN, and transmit a private multicast data traffic (i.e., a data packet) to a remote site of the VPN through a public network.

The multicast VPN may use MPLS technology to establish a public network tunnel, which includes establishing mLDP (chinese: the multipoint extension for label distribution protocol) P2MP (english: point-to-multipoint) LSP (english: label switch path). As shown in fig. 1, a tree-shaped mLDP P2MP LSP from an ingress node (PE 1 in the figure) to a plurality of destination nodes (PE3, PE4, PE5) is established, and multicast traffic (i.e., data packets) is introduced into a tunnel at the ingress node for forwarding. During actual forwarding, only one message is sent on the inlet node, and the message is copied on the branch node (P4), so that the bandwidth is not repeatedly occupied. Specifically, the mLDPP2MP LSP may be established by allocating a label downstream, and the leaf nodes (e.g., nodes PE3, PE4, and PE5 in fig. 1) and the intermediate nodes (e.g., nodes P1, P3, P4, and PE2 in fig. 1) all need to send a label mapping message to their respective upstream nodes, select a next hop of a preferred route to the root node (e.g., PE1 in fig. 1) as their own upstream node, and generate a corresponding ILM (incoming label lmap, chinese: incoming label mapping), specifically, the leaf nodes may send the label mapping message directly upstream and generate a corresponding forwarding table entry; after receiving the label mapping message from the downstream, the intermediate node inquires whether the label mapping message is sent to the upstream, and if the label is not sent to the upstream, the intermediate node inquires a routing table, determines the upstream and sends the label mapping message. If it has already been sent, it does not need to be sent again. Finally, generating a corresponding ILM; after receiving the label mapping message sent downstream, the root node generates a corresponding FTN (english: Forwarding Equivalence Class to Next Hop label Forwarding Entry, chinese: Forwarding Equivalence Class to Next Hop label Forwarding Entry). To this end, an mLDP P2MP LSP was established.

In the label switching path established above, if a node or link in the public network fails, the multicast service may be interrupted for a long time, so as to protect the public network tunnel. The prior art provides a method for establishing a label switched path as shown in the following 2: namely, two root nodes, namely PE1 and PE2 in fig. 2, are deployed in the same MVPN, and two mLDP P2MP LSPs with PE1 and PE2 as root nodes are created, wherein the mLDP 2MP LSP with PE1 as root node may be the primary path. The mLDP P2MP LSP with PE2 as the root node is the backup path, and PE3 is the leaf node of these two paths. Generally, when multicast data traffic is sent to PE1 and PE2 by a multicast source device through CE1 and CE2, respectively, PE1 may import the multicast data traffic into a main path and send the multicast data traffic to PE3 through the main path, then PE3 may export the multicast data traffic flowing in from the main path to CE3, and finally CE3 forwards the multicast data traffic to a user; PE2 may direct multicast data traffic into the backup tunnel and send it along the backup tunnel to PE3, while PE3 discards multicast data traffic from the backup path. When the PE3 detects a failure of the primary path through BFD (Bidirectional Forwarding Detection, chinese), it selects the multicast data traffic sent from the backup path.

Although the above scheme may protect the public network tunnel, because two mLDP 2MP LSPs are created in the above scheme, which take PE1 and PE2 as root nodes, when the primary path is not failed, data traffic is not only forwarded on the primary path but also forwarded on the backup path in the process of transmitting data, so that there is redundant multicast data traffic, which causes bandwidth waste.

Disclosure of Invention

The embodiment of the invention provides a method and a device for establishing a label switching path. The method can protect the public network tunnel and avoid causing bandwidth waste.

In a first aspect, a method for establishing a label switched path is provided, where the method includes:

the first node selects a main upstream node and a backup upstream node according to the saved routing table;

a first node sends a first label mapping message to a main upstream node, wherein the first label mapping message sent by the first node comprises FEC and a main label distributed by the first node;

the first node sends a second label mapping message to the backup upstream node, wherein the second label mapping message sent by the first node comprises FEC, a backup label distributed by the first node and an IP address of the first node;

the first node generates and saves a first forwarding table, the first forwarding table comprising: the mapping relation between the primary label and the FEC distributed by the first node, and the mapping relation between the backup label distributed by the first node and the FEC.

Optionally, before the first node selects the main upstream node and the backup upstream node according to the stored routing table, the method further includes:

a first node receives a first label mapping message sent by a downstream node; the first label mapping message sent by the downstream node comprises FEC and a main label distributed by the downstream node;

the first transfer table specifically includes: the mapping relation between the main label distributed by the downstream node, the main label distributed by the first node and the FEC, and the mapping relation between the main label distributed by the downstream node, the backup label distributed by the first node and the FEC.

According to the establishment method of the label switching path, the first node can select the main upstream node and the backup upstream node according to the stored routing table; sending a first label mapping message comprising the FEC and a main label distributed by the first node to the main upstream node, and sending a second label mapping message comprising the FEC, a backup label distributed by the first node and an IP address of the first node to the backup upstream node; and the first node generates and stores the first forwarding table. Thus, two label switching paths with the same routing device as a root node can be established, wherein one path is used as a main path and the other path is used as a backup path. Therefore, under the condition that the main path has no fault, the data flow can be forwarded only on the main path, and the bandwidth waste can be avoided while the public network tunnel is protected.

In a second aspect, a method for establishing a multicast label switched path is provided, the method comprising:

the second node receives a second label mapping message sent by the downstream node; the second label mapping message sent by the downstream node comprises FEC, backup labels distributed by the downstream node and the IP address of the first node;

in case the second node has received at least one first label mapping message carrying the same FEC as that carried in the second label mapping message,

the second node inquires a stored routing table according to the IP address of the first node so as to determine the IP address of the next hop from the second node to the first node;

determining a first label mapping message corresponding to a first LDP session of an IP address of which the next hop is received; the first label mapping message comprises FEC and a main label distributed by a next hop;

generating and storing a second forwarding table according to the second label mapping message and the first label mapping message, wherein the second forwarding table comprises: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises the mapping relation between the main label and the FEC distributed by the next hop; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between a backup label distributed by the downstream node and the FEC.

Optionally, the method further comprises:

the second node sends a first label mapping message to the upstream node, wherein the first label mapping message sent by the second node comprises FEC and a main label distributed by the second node;

the main forwarding table entry specifically includes a mapping relationship between a main label allocated by the second node, a main label allocated by the next hop, and the FEC; the backup forwarding table entry of the main forwarding table entry specifically includes a mapping relationship between a main label allocated by the second node, a backup label allocated by the downstream node, and the FEC.

Optionally, the method further comprises:

the second node periodically detects a main path corresponding to a main forwarding table entry in a second forwarding table;

if the main path has no fault, the main forwarding table entry is identified as effective;

if the main path fails, the main forwarding table entry is identified as invalid.

Optionally, the method further comprises:

the second node checks the state of the main forwarding table entry in the second forwarding table;

if the forwarding table entry is valid, forwarding the data message according to the main forwarding table entry in the second forwarding table;

and if the data message is invalid, forwarding the data message according to the backup forwarding table entry of the main forwarding table entry in the second forwarding table entry.

In the method for establishing a label switched path, a second node may receive a second label mapping message that includes an FEC, a backup label allocated by a downstream node, and an IP address of a first node and is sent by the downstream node, and in a case where the second node receives at least one first label mapping message that carries the FEC that is the same as the FEC carried in the second label mapping message, the second node queries a stored routing table according to the IP address of the first node to determine an IP address of a next hop between the second node and the first node, and determines a first label mapping message corresponding to a first LDP session that receives the IP address of the next hop; and generating and storing a second forwarding table according to the second label mapping message and the first label mapping message. Thus, two label switching paths with the same routing device as a root node can be established, wherein one path is used as a main path and the other path is used as a backup path. Therefore, under the condition that the main path has no fault, the data flow can be forwarded only on the main path, and the bandwidth waste can be avoided while the public network tunnel is protected.

In a third aspect, a first node is provided, the first node comprising: the device comprises a storage module, a processing module and a sending module;

the storage module is used for storing the routing table and the first forwarding table;

the processing module is used for selecting a main upstream node and a backup upstream node according to the routing table stored by the storage module; and generating a first forwarding table; the first transfer table includes: the mapping relation between the main label distributed by the first node and the FEC, and the mapping relation between the backup label distributed by the first node and the FEC;

the sending module is used for sending a first label mapping message to the main upstream node and sending a second label mapping message to the backup upstream node; a first label mapping message sent by a first node comprises FEC and a main label distributed by the first node; the second label mapping message sent by the first node includes FEC, a backup label allocated by the first node, and an IP address of the first node.

Optionally, the first node further includes a receiving module;

the receiving module is used for receiving a first label mapping message sent by a downstream node; the first label mapping message sent by the downstream node comprises FEC and a main label distributed by the downstream node;

For the description of the technical effect of the third aspect or the alternative implementation manner thereof, reference may be made to the above description of the technical effect of the first aspect or the alternative implementation manner thereof, and details are not described herein again.

In a fourth aspect, a second node is provided, the second node comprising: the device comprises a storage module, a receiving module and a processing module;

the storage module is used for storing the routing table and the second forwarding table;

the receiving module is used for receiving a second label mapping message sent by a downstream node; the second label mapping message sent by the downstream node comprises FEC, backup labels distributed by the downstream node and the IP address of the first node;

the processing module is used for inquiring the stored routing table according to the IP address of the first node under the condition that the second node receives at least one first label mapping message which carries the FEC and is the same as the FEC carried in the second label mapping message so as to determine the IP address of the next hop from the second node to the first node; determining a first label mapping message corresponding to a first LDP session of an IP address of which the next hop is received; generating a second forwarding table according to the second label mapping message and the first label mapping message; the first label mapping message comprises FEC and a main label distributed by a next hop; the second forwarding table includes: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises the mapping relation between the main label and the FEC distributed by the next hop; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between a backup label distributed by the downstream node and the FEC.

Optionally, the second node further includes a sending module;

a sending module, configured to send a first label mapping message to an upstream node, where the first label mapping message sent by a second node includes an FEC and a main label allocated by the second node;

Optionally, the processing module is further configured to periodically detect a main path corresponding to a main forwarding table entry in the second forwarding table;

Optionally, the processing module is further configured to check a state of a main forwarding table entry in the second forwarding table;

For a description of the technical effect of the fourth aspect or the alternative implementation manner thereof, reference may be made to the above description of the technical effect of the second aspect or the alternative implementation manner thereof, and details are not described herein again.

Drawings

Fig. 1 is a first schematic view of a scenario for establishing a label switched path in the prior art;

fig. 2 is a schematic diagram of a scenario of establishing a label switched path in the prior art;

fig. 3 is a schematic diagram of scenario 1 for establishing a label switched path according to an embodiment of the present invention;

fig. 4 is a schematic diagram of scenario 2 for establishing a label switched path according to an embodiment of the present invention;

fig. 5 is a first schematic diagram illustrating a method for establishing a label switched path according to an embodiment of the present invention;

fig. 6 is a schematic diagram illustrating a method for establishing a label switched path according to an embodiment of the present invention;

fig. 7 is a first schematic structural diagram of a first node according to an embodiment of the present invention;

fig. 8 is a second schematic structural diagram of a first node according to an embodiment of the present invention;

fig. 9 is a first schematic structural diagram of a second node according to an embodiment of the present invention;

fig. 10 is a second schematic structural diagram of a second node according to an embodiment of the present invention.

Detailed Description

The following describes a method and an apparatus for establishing a label switched path according to an embodiment of the present invention in detail with reference to the accompanying drawings.

In the embodiments of the present invention, words such as "exemplary" or "for example" are used to mean serving as examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "e.g.," an embodiment of the present invention is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. The symbol "/" herein denotes a relationship in which the associated object is or, for example, a/B denotes a or B.

In the conventional method for establishing a label switched path, as shown in fig. 2, two mLDP 2MP LSPs using PE1 and PE2 as root nodes are created, so that when a primary path (mLDP 2MP LSP using PE1 as root node) fails, data traffic is forwarded on the primary path and also on a backup path in the process of transmitting data, and thus redundant multicast data traffic exists, which causes bandwidth waste.

The method for establishing the label switching path provided by the embodiment of the invention can establish two label switching paths which take the same routing device as a root node, wherein one of the two label switching paths is used as a main path and the other is used as a backup path, so that under the condition that the main path has no fault, data flow is only forwarded on the main path, and the public network tunnel can be protected while bandwidth waste is avoided.

The method for establishing the label switching path provided by the embodiment of the invention is executed by the device for establishing the label switching path. The label switching path establishing device is a node in the public network.

For example, the node in the public network may specifically be a routing device in the public network.

The method for establishing a label switched path according to the embodiment of the present invention may be applied to the following public network scenario one for establishing a label switched path as shown in fig. 3, or the public network scenario two for establishing a label switched path as shown in fig. 4. In both scenario 1 and scenario 2, a primary path, shown by the implementation arrow, and a backup path, shown by the dashed arrow, may be established. It should be noted that, in the scenario one shown in fig. 3, a plurality of nodes may be included in both the main path direction and the backup path direction between the first node and the second node, and fig. 3 exemplifies that one node a is included in the main path direction and one node b is included in the backup path; similarly, in a second scenario shown in fig. 4, a plurality of nodes may be included in both the main path direction and the backup path direction between the first node and the second node, and fig. 4 illustrates an example in which one node a is included in the main path direction and one node b is included in the backup path.

For more clearly describing the establishment method of the label switched path provided by the embodiment of the present invention, an exemplary description will be made with reference to scenario 1 shown in fig. 3 and scenario 2 shown in fig. 4.

Scene 1

As shown in fig. 5, an embodiment of the present invention provides a method for establishing a label switched path, where the method includes:

s101, the first node selects the node a as a main upstream node and selects the node b as a backup upstream node according to the routing table.

In the embodiment of the invention, the first node selects the main upstream node and the backup upstream node according to the saved routing table. Since the IP route from the first node to the root node address is included in the stored routing table, the first node can select the primary upstream node and the backup upstream node according to the IP route from the first node to the root node address stored in the routing table.

In the embodiment of the invention, the second node is a root node, and the first node is a sink node.

According to mLDP, a routing device in a public network usually selects a next hop of an IP route as an upstream node according to the IP route to a root node address, whereas in the embodiment of the present invention, a first node selects a backup upstream node at another next hop (i.e. another next hop than the next hop selected as the primary upstream node) in addition to selecting a next hop of the IP route as a primary upstream node according to the IP route to the root node address.

Among them, the next hop generally includes two types, one is: load next hop, another class is: the next hop is backed up and may also be referred to as FRR (fast-route, chinese) next hop. All the next-hop of the load can work simultaneously, the backup next-hop is backup equipment of a certain next-hop, and the backup next-hop works only when the certain next-hop fails.

In the embodiment of the present invention, the first node may select node a as a primary upstream node and select node b as a backup upstream node.

Illustratively, the first node may select its own primary upstream node based on a preferred one of the IP routes to the root node address.

Optionally, in the embodiment of the present invention, when a node in a public network selects an upstream node, if an IP route to a root node address has only one next hop, the node may select an upstream node, as in the prior art; if there are multiple next hops to the IP route to the root node address, then a primary upstream node and a backup upstream node may be selected using the method of embodiments of the present invention.

Optionally, when a node (which may be the first node) in the public network selects a backup upstream node from next hops, it may determine whether an LDP session exists between the next hop and the node, and select the backup upstream node from the next hop with which the LDP session exists.

S102, the first node allocates a main label and a backup label, and generates and stores a first forwarding table.

Wherein the first transfer table comprises: the mapping relation between the primary label and the FEC distributed by the first node, and the mapping relation between the backup label distributed by the first node and the FEC.

The first forwarding table may be ILM (incorporated Label Map, chinese: Label mapping), in which a mapping relationship between the Label and the FEC is stored. Unlike the prior art, there are 2 incoming labels corresponding to 1 FEC in the first forwarding table (i.e. the primary label assigned by the first node and the backup label assigned by the first node).

Illustratively, as shown in table 1 below, the first forwarding table may be stored in a form in which a label 11 in table 1 represents a primary label assigned by the first node, a label 21 represents a backup label assigned by the first node, and FEC1 represents the above FEC. Note that, the label 11 and the label 21 in the following table 1 may be different or the same, and this is not limited in the embodiment of the present invention.

TABLE 1

S103, the first node sends a first label mapping message to the node a, and the corresponding node a receives the first label mapping message.

Wherein, the first label mapping message sent by the first node includes FEC and a main label allocated by the first node. The primary label assigned by the first node is the incoming label of the first node.

The first label mapping message sent by the first node is similar to the label mapping message in the prior art.

S104, the first node sends a second label mapping message to the node b, and the corresponding node b receives the second label mapping message.

Wherein, the second label mapping message sent by the first node includes the FEC, the backup label allocated by the first node, and the IP address of the first node.

Optionally, the backup tag allocated by the first node may also be an incoming tag of the first node, but the tag is different from the primary tag allocated by the first node in that the tag is identified as the backup tag in the second tag mapping message sent by the first node.

In the embodiment of the invention, the existing label mapping message is expanded, the incoming label of the first node in the second label mapping message sent by the first node is identified as the backup label, and the address of the first node (namely the aggregation node) is carried in the second label mapping message.

Illustratively, the IP address of the first node may be a LDP transport address of the first node, and may also be an LDP router identification of the first node.

In the embodiment of the present invention, the FEC carried in the first label mapping message and the FEC carried in the second label mapping message are both the same, so as to identify the same virtual private network.

In the embodiment of the present invention, the execution sequence of the sending S103 and S104 is not limited, that is, S103 may be executed first, and then S104 may be executed; or executing S104 first and then executing S103; s103 and S104 may also be performed simultaneously.

S105, the node a distributes the main label and generates and stores a third forwarding table.

In the embodiment of the present invention, after the node a receives the first label mapping message, the primary label may be allocated, and the third forwarding table may be saved.

The third forwarding table includes a corresponding relationship between the primary label allocated by the node a, the primary label allocated by the first node, and the FEC. The primary label and FEC assigned by the first node may both be obtained from the first label mapping message received by the first node.

For node a, the primary label assigned by the first node is an outgoing label of node a, and the primary label assigned by node a is an incoming label of node a.

Optionally, the third forwarding table may also be an ILM, in which a mapping relationship between an ingress label, an egress label, and an FEC is stored.

Illustratively, as shown in table 2, the third forwarding table may be stored in a form that a label 11 represents a primary label assigned by the first node, a label 12 represents a primary label assigned by node a, and FEC1 represents the above FEC.

TABLE 2

Go into label	Go out label	FEC
			Label 12	Label 11	FEC1

S106, the node a sends a first label mapping message to the second node, and the corresponding second node receives the first label mapping message.

Wherein, the first label mapping message sent by the node a carries the FEC and the primary label allocated by the node a.

S107, the node b allocates the backup label and generates and stores a fourth forwarding table.

In the embodiment of the present invention, after the node b receives the second label mapping message sent by the first node, a backup label may be allocated, and a fourth forwarding table may be stored.

The fourth forwarding table includes a corresponding relationship between the backup label allocated by the node b, the backup label allocated by the first node, and the FEC. The backup label and FEC allocated by the first node may both be obtained from the second label mapping message received by the first node.

For node b, the backup label allocated by the first node is an outgoing label of node b, and the backup label allocated by node b is an incoming label of node b.

Optionally, the fourth forwarding table may also be an ILM, in which a mapping relationship between an ingress label, an egress label, and an FEC is stored.

Illustratively, as shown in table 3, the fourth forwarding table may be stored in a form that label 21 represents the backup label allocated by the first node, label 22 represents the backup label allocated by node b, and FEC1 represents the above FEC in table 3.

TABLE 3

Go into label	Go out label	FEC
			Label 22	Label 21	FEC1

Optionally, in this embodiment of the present invention, after receiving the second label mapping message sent by the first node, the node b may determine whether the node b is a PLR (point of local repair, chinese). Specifically, the node b may determine whether it has received at least one first label mapping message that carries the same FEC as that carried in the second label mapping message, and if it has received at least one first label mapping message, it indicates that the node b is a PLR, and if it has not received at least one first label mapping message, it indicates that the node b is not a PLR. In the scenario shown in fig. 3, node b is not the PLR, and then node b performs the following S108.

S108, the node b sends a second label mapping message to the second node, and the corresponding second node receives the second label mapping message.

And the second label mapping message sent by the node b carries the FEC, the backup label allocated by the node b and the IP address of the first node.

Optionally, in the embodiment of the present invention, after the second node receives the second label mapping message sent by the node b, the second node may determine whether the second node is a PLR (point of local repair node, chinese). Specifically, the second node may determine whether it has received at least one first label mapping message that carries the same FEC as that carried in the second label mapping message, and if it has received at least one first label mapping message, it indicates that the second node is a PLR, and if it has not received at least one first label mapping message, it indicates that the second node is not a PLR. In scenario one shown in fig. 3, the second node is a PLR, and the second node performs the following S109.

In this embodiment of the present invention, the first label mapping message includes the FEC and a primary label allocated by node a.

S109, the second node generates and stores a second forwarding table according to the second label mapping message and the first label mapping message.

In this embodiment of the present invention, the second forwarding table includes: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises a mapping relation between a main label and an FEC distributed by the node a; the backup forwarding table entry of the main forwarding table entry includes a mapping relationship between the backup label and the FEC allocated by the node b.

For the second node, the primary label allocated by the node a is the outgoing label of the second node, and the backup label allocated by the node b may also be the outgoing label of the second node.

Optionally, the second forwarding table may be an FTN, where a mapping relationship between the outgoing label and the FEC is stored.

Illustratively, as shown in table 4, the second forwarding table may be stored in a form that a label 12 represents a primary label assigned by node a, a label 22 represents a backup label assigned by node b, and FEC1 represents the above FEC.

TABLE 4

In this embodiment of the present invention, after determining that the second node receives at least one first label mapping message that carries the FEC that is the same as the FEC carried in the second label mapping message received by the second node, before the second node stores the second entry, the method may include the following steps:

A. and inquiring the stored routing table according to the IP address of the first node so as to determine the IP address of the next hop from the second node to the first node.

For example, taking fig. 3 as an example, in the embodiment of the present invention, the IP address of the next hop from the second node to the first node, which is determined by querying the saved routing table according to the IP address of the first node, may include the IP address of node a and the IP address of node b in fig. 3.

B. The second node determines that a first label mapping message corresponding to a first LDP session of the IP address of the next hop is received.

Wherein, the first label mapping message includes FEC and a main label allocated by a next hop.

After the steps a and B are performed, the second node may generate and store a second forwarding table according to the received second label mapping message and the first label mapping message corresponding to the first LDP session. Wherein the second forwarding table comprises: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry includes a mapping relationship between a main label and an FEC allocated by a next hop (i.e., node a); the backup forwarding table entry of the main forwarding table entry includes a mapping relationship between the backup label and the FEC allocated by the downstream node (i.e., node b).

For example, in this embodiment of the present invention, the second node may determine the LDP session (may be referred to as session 1 in this embodiment of the present invention) that has received the IP address of node a and the LDP session (may be referred to as session 2 in this embodiment of the present invention) that has received the IP address of node b, and then determine that the session that has sent the first label mapping message that carries the same FEC as the FEC carried in the second label mapping message that it receives in sessions 1 and 2 is session 1. So that the first label mapping message used for establishing the second forwarding table can be determined to be the first label mapping message sent by the node a.

Scene two

As shown in fig. 6, an embodiment of the present invention provides a method for establishing a label switched path, where the method includes:

s201, the node c allocates the main label, and generates and stores a fifth forwarding table.

Wherein the fifth forwarding table comprises: and the mapping relation between the primary label distributed by the node c and the FEC.

The fifth forwarding table may be an ILM, in which a mapping relationship between ingress labels and FECs is stored.

Illustratively, as shown in table 5 below, this fifth forwarding table may be stored in a form in which the label 10 in table 5 represents the primary label assigned by node c, and the FEC1 represents the above FEC.

TABLE 5

Go into label	FEC
		Label 10	FEC1

S202, the node c sends a first label mapping message to the first node, and the corresponding first node receives the first label mapping message.

In the embodiment of the invention, a first node can receive a first label mapping message sent by a downstream node; the first label mapping message sent by the downstream node includes FEC and a main label allocated by the downstream node.

Illustratively, in this embodiment of the present invention, the node c is a downstream node of the first node, and the first label mapping message sent by the node c includes the FEC and the primary label allocated by the node c.

For node c, the primary label assigned by node c may be an incoming label of node c.

S203, the first node selects the node a as a main upstream node and selects the node b as a backup upstream node according to the routing table.

For the description of S203, reference may be made to the above description of S101, and details are not repeated here.

S204, the first node allocates a main label and a backup label, and generates and stores a first forwarding table.

In this embodiment of the present invention, the node c is a downstream node of the first node, and therefore the first forwarding table in this embodiment of the present invention specifically includes: the mapping relationship between the primary label distributed by the node c, the primary label distributed by the first node and the FEC, and the mapping relationship between the primary label distributed by the node c, the backup label distributed by the first node and the FEC.

For the first node, the main label allocated by the node c is the outgoing label of the first node, and the main label and the backup label allocated by the first node are both the incoming label of the first node.

Optionally, the first forwarding table may be an ILM, where a mapping relationship between an outgoing label, an incoming label, and an FEC is stored. Unlike the prior art, there are 2 incoming labels corresponding to 1 FEC in the first forwarding table (i.e. the primary label assigned by the first node and the backup label assigned by the first node).

Illustratively, as shown in table 6 below, the first forwarding table may be stored in a form in which, in table 6, a label 10 represents a primary label assigned by the node c, a label 11 represents a primary label assigned by the first node, a label 21 represents a backup label assigned by the first node, and FEC1 represents the above FEC. Similarly, the label 11 and the label 21 in the following table 6 may be different or the same, and this is not limited in the embodiment of the present invention.

TABLE 6

S205, the first node sends a first label mapping message to the node a, and the corresponding node a receives the first label mapping message.

S206, the first node sends a second label mapping message to the node b, and the corresponding node b receives the second label mapping message.

S207, the node a distributes the main label and generates and stores a third forwarding table.

S208, the node a sends a first label mapping message to the second node, and the corresponding second node receives the first label mapping message.

S209, the node b allocates a backup label and generates and stores a fourth forwarding table.

S210, the node b sends a second label mapping message to the second node, and the corresponding second node receives the second label mapping message.

For the descriptions of S205-S210, reference may be made to the above description of S103-S208, which is not repeated herein.

S211, the second node distributes the main label, and generates and stores a second forwarding table according to the second label mapping message and the first label mapping message.

In this embodiment of the present invention, the second forwarding table includes: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry specifically includes: the mapping relation of the main label distributed by the second node, the main label distributed by the node a and the FEC; the backup forwarding table entry of the main forwarding table entry specifically includes a mapping relationship between the main label allocated by the second node, the backup label allocated by the node b, and the FEC.

For the second node, the primary label allocated by the node a may be an outgoing label of the second node, the backup label allocated by the node b may be an outgoing label of the second node, and the primary label allocated by the second node may be an incoming label of the second node.

Optionally, the second forwarding table may be an ILM, where a mapping relationship between an outgoing label, an incoming label, and an FEC is stored.

Illustratively, as shown in table 7, the second forwarding table may be stored in a form that label 13 represents the primary label assigned by the second node, label 12 represents the primary label assigned by node a, label 22 represents the backup label assigned by node b, and FEC1 represents the above FEC.

TABLE 7

S212, the second node sends a first label mapping message to the node d, and the corresponding node d receives the first label mapping message.

Wherein, the first label mapping message sent by the second node includes the FEC and the main label allocated by the second node.

S213, the node d generates and stores a sixth forwarding table.

For node d, the primary label assigned by the second node is the outgoing label of node d.

Optionally, the sixth forwarding table may be an FTN, where a mapping relationship between the outgoing label and the FEC is stored.

Illustratively, as shown in table 8, the sixth forwarding table may be stored in a form that the label 13 in table 8 represents the primary label assigned by the second node, and the FEC1 represents the FEC.

TABLE 8

Go out label	FEC
		Label 13	FEC1

According to the above methods for establishing the label switched paths shown in fig. 5 and fig. 6, two label switched paths can be established with the same routing device as a root node, wherein one of the two label switched paths serves as a primary path and the other serves as a backup path. Illustratively, the established primary path is shown by a solid arrow in fig. 3 or fig. 4, and the established backup path is shown by a dashed arrow in fig. 3 or fig. 4.

In this embodiment of the present invention, after two label switched paths using the same routing device as a root node are established, the method for establishing a label switched path provided in this embodiment of the present invention further includes:

a. and the second node periodically detects the main path corresponding to the main forwarding table entry in the second forwarding table.

b. And if the main path has no fault, identifying the main forwarding table entry as effective.

c. And if the main path has a fault, marking the main forwarding table entry as invalid.

In the embodiment of the present invention, the second node may periodically detect the primary path corresponding to the primary forwarding table entry in the second forwarding table in at least one of the following three manners.

The first method is as follows: and detecting a path corresponding to the label in the main forwarding table entry through single-hop BFD.

This approach may implement detecting whether there is a failure in the primary path between the second node to node a in fig. 3 or fig. 4.

The second method comprises the following steps: the IP path from PLR to MP is detected by multi-hop BFD.

This approach may implement detecting whether there is a failure in the primary path between the second node to the first node in fig. 3 or fig. 4.

The third method comprises the following steps: the LSP path from PLR to MP is detected through MPLS BFD.

This approach may also be implemented to detect whether there is a failure in the primary path between the second node and the first node in fig. 3 or fig. 4.

Optionally, when forwarding data traffic, the method for establishing a label switched path provided in the embodiment of the present invention further includes:

d. the second node checks the state of the main forwarding table entry in the second forwarding table;

e. if the forwarding table entry is valid, forwarding the data message according to the main forwarding table entry in the second forwarding table;

f. and if the data message is invalid, forwarding the data message according to the backup forwarding table entry of the main forwarding table entry in the second forwarding table entry.

In the embodiment of the invention, when the flow is forwarded, the state of the main forwarding table entry is checked, if the state is valid, the main path is free from fault, the flow is only forwarded on the main path, and if the state is invalid, the main path is faulty, the standby forwarding table entry is used for forwarding, so that the data flow is switched to the backup path.

As shown in fig. 7, there is provided a first node comprising: a saving module 31, a processing module 32 and a sending module 33;

a saving module 31, configured to save the routing table and the first forwarding table;

a processing module 32, configured to select a main upstream node and a backup upstream node according to the routing table stored in the storage module 31; and generating a first forwarding table; the first transfer table includes: the mapping relation between the primary label and the FEC distributed by the first node, and the mapping relation between the backup label distributed by the first node and the FEC.

The sending module 33 is configured to send a first label mapping message to the main upstream node, and send a second label mapping message to the backup upstream node; a first label mapping message sent by a first node comprises FEC and a main label distributed by the first node; the second label mapping message sent by the first node comprises FEC, a backup label distributed by the first node and an IP address of the first node;

optionally, as shown in fig. 8, the first node further includes a receiving module 34;

a receiving module 34, configured to receive a first label mapping message sent by a downstream node; the first label mapping message sent by the downstream node comprises FEC and a main label distributed by the downstream node;

As shown in fig. 9, an embodiment of the present invention provides a second node, where the second node includes: a saving module 41, a receiving module 42 and a processing module 43;

a saving module 41, configured to save the routing table and the second forwarding table;

a receiving module 42, configured to receive a second label mapping message sent by a downstream node; the second label mapping message sent by the downstream node comprises FEC, backup labels distributed by the downstream node and the IP address of the first node;

a processing module 43, configured to, when the second node receives at least one first label mapping message that carries the FEC that is the same as the FEC carried in the second label mapping message, query the stored routing table according to the IP address of the first node, so as to determine an IP address of a next hop from the second node to the first node; determining a first label mapping message corresponding to a first LDP session of an IP address of which the next hop is received; generating a second forwarding table according to the second label mapping message and the first label mapping message; the first label mapping message comprises FEC and a main label distributed by a next hop; the second forwarding table includes: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises the mapping relation between the main label and the FEC distributed by the next hop; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between a backup label distributed by the downstream node and the FEC.

Optionally, as shown in fig. 10, the second node further includes a sending module 44;

a sending module 44, configured to send a first label mapping message to an upstream node, where the first label mapping message sent by the second node includes an FEC and a main label allocated by the second node;

Optionally, the processing module 43 is further configured to periodically detect a main path corresponding to a main forwarding table entry in the second forwarding table;

Optionally, the processing module 43 is further configured to check a state of a main forwarding table entry in the second forwarding table;

The technical solutions provided in the embodiments of the present invention are essentially or partially contributed to by the prior art, or all or part of the technical solutions may be implemented by software programs, hardware, firmware, or any combination thereof. When implemented using a software program, the computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the flow or functions according to embodiments of the invention, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device including one or more available media integrated servers, data centers, and the like. The usable medium may be a magnetic medium (e.g., floppy disk, magnetic tape), an optical medium (e.g., Digital Video Disk (DVD)), or a semiconductor medium (e.g., Solid State Drive (SSD)), among others.

Through the above description of the embodiments, it is clear to those skilled in the art that, for convenience and simplicity of description, only the division of the functional modules is illustrated, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device may be divided into different functional modules to complete all or part of the above described functions. For the specific working processes of the system, the apparatus and the unit described above, reference may be made to the corresponding processes in the foregoing method embodiments, and details are not described here again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, a module or a unit may be divided into only one logical function, and may be implemented in other ways, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for establishing a label switched path, comprising:

the first node sends a first label mapping message to the main upstream node, wherein the first label mapping message sent by the first node comprises FEC and a main label distributed by the first node;

the first node sends a second label mapping message to the backup upstream node, wherein the second label mapping message sent by the first node comprises the FEC, a backup label distributed by the first node and an IP address of the first node;

the first node generates and maintains a first forwarding table, the first forwarding table comprising: the mapping relation between the primary label allocated by the first node and the FEC, and the mapping relation between the backup label allocated by the first node and the FEC;

causing the backup upstream node to send a second label mapping message to a second node upstream thereof; the second label mapping message sent by the backup upstream node comprises FEC, a backup label distributed by the backup upstream node and the IP address of the first node;

causing the primary upstream node to send a first label mapping message to the second node upstream thereof, the first label mapping message sent by the primary upstream node comprising a FEC, a primary label assigned by the primary upstream node;

enabling the second node to generate and store a second forwarding table according to the received second label mapping message and the received first label mapping message, wherein the second forwarding table comprises: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises a mapping relation between a main label distributed by the main upstream node and the FEC; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between a backup label distributed by the backup upstream node and the FEC;

enabling the second node to periodically detect a main path corresponding to the main forwarding table entry in a second forwarding table; if the main path has no fault, the main forwarding table entry is identified as effective, and the data message is forwarded according to the main forwarding table entry; if the main path has a fault, the main forwarding table entry is marked as invalid, and the data message is forwarded according to the backup forwarding table entry.

2. The method of claim 1, wherein before the first node selects the primary upstream node and the backup upstream node based on the saved routing table, the method further comprises:

the first node receives a first label mapping message sent by a downstream node; a first label mapping message sent by the downstream node comprises the FEC and a main label distributed by the downstream node;

the first transfer table specifically includes: the mapping relationship between the main label allocated by the downstream node, the main label allocated by the first node and the FEC, and the mapping relationship between the main label allocated by the downstream node, the backup label allocated by the first node and the FEC.

3. A method for establishing a multicast label switched path, comprising:

in case the second node has received at least one first label mapping message carrying a FEC that is the same as the FEC carried in a second label mapping message,

the second node inquires a saved routing table according to the IP address of the first node so as to determine the IP address of the next hop from the second node to the first node;

determining a first label mapping message corresponding to a first LDP session of the IP address of the next hop; the first label mapping message comprises the FEC and a main label distributed by the next hop;

generating and storing a second forwarding table according to the second label mapping message and the first label mapping message, wherein the second forwarding table comprises: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises a mapping relation between the main label allocated by the next hop and the FEC; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between the backup label distributed by the downstream node and the FEC;

the second node periodically detects a main path corresponding to the main forwarding table entry in a second forwarding table;

if the main path has no fault, the main forwarding table entry is identified as effective, and the data message is forwarded according to the main forwarding table entry in a second forwarding table;

if the main path fails, the main forwarding table entry is identified as invalid, and the data message is forwarded according to a backup forwarding table entry of the main forwarding table entry in a second forwarding table entry.

4. The method of claim 3, further comprising:

the second node sends a first label mapping message to an upstream node, wherein the first label mapping message sent by the second node comprises the FEC and a main label distributed by the second node;

the main forwarding table entry specifically includes a mapping relationship between a main label allocated by the second node, a main label allocated by the next hop, and the FEC; the backup forwarding table entry of the main forwarding table entry specifically includes a mapping relationship between the main label allocated by the second node, the backup label allocated by the downstream node, and the FEC.

5. A first node, comprising: the device comprises a storage module, a processing module and a sending module;

the processing module is used for selecting a main upstream node and a backup upstream node according to the routing table stored by the storage module; and generating the first forwarding table; the first transfer table includes: the mapping relation between the main label distributed by the first node and the FEC, and the mapping relation between the backup label distributed by the first node and the FEC;

the sending module is used for sending a first label mapping message to the main upstream node and sending a second label mapping message to the backup upstream node; a first label mapping message sent by the first node comprises FEC and a main label distributed by the first node; the second label mapping message sent by the first node comprises the FEC, a backup label distributed by the first node and the IP address of the first node;

the processing module is further configured to cause the backup upstream node to send a second label mapping message to a second node located upstream of the backup upstream node; the second label mapping message sent by the backup upstream node comprises FEC, a backup label distributed by the backup upstream node and the IP address of the first node;

6. The first node of claim 5, wherein the first node further comprises a receiving module;

the receiving module is used for receiving a first label mapping message sent by a downstream node; a first label mapping message sent by the downstream node comprises the FEC and a main label distributed by the downstream node;

7. A second node, comprising: the device comprises a storage module, a receiving module and a processing module;

the storage module is used for storing a routing table and a second forwarding table;

the processing module is configured to, when the second node receives at least one first label mapping message that carries an FEC that is the same as the FEC carried in a second label mapping message, query a stored routing table according to an IP address of the first node to determine an IP address of a next hop from the second node to the first node; determining a first label mapping message corresponding to a first LDP session of the IP address of the next hop; generating a second forwarding table according to the second label mapping message and the first label mapping message; the first label mapping message comprises the FEC and a main label distributed by the next hop; the second forwarding table comprises: a main forwarding table entry and a backup forwarding table entry of the main forwarding table entry; the main forwarding table entry comprises a mapping relation between the main label allocated by the next hop and the FEC; the backup forwarding table entry of the main forwarding table entry comprises a mapping relation between the backup label distributed by the downstream node and the FEC;

the processing module is further configured to periodically detect a main path corresponding to the main forwarding table entry in the second forwarding table;

8. The second node of claim 7, wherein the second node further comprises a sending module;

the sending module is configured to send a first label mapping message to an upstream node, where the first label mapping message sent by the second node includes the FEC and a main label allocated by the second node;