CN102624610A

CN102624610A - Device and method capable of achieving label distribution

Info

Publication number: CN102624610A
Application number: CN2012100489396A
Authority: CN
Inventors: 李�诚; 郭晓丹
Original assignee: Maipu Communication Technology Co Ltd
Current assignee: Maipu Communication Technology Co Ltd
Priority date: 2012-02-29
Filing date: 2012-02-29
Publication date: 2012-08-01
Anticipated expiration: 2032-02-29
Also published as: CN102624610B

Abstract

The invention relates to the field of computer communication and discloses a device capable of achieving label distribution, and solves the problem of a low forwarding efficiency caused by the fact that two label distribution protocols of label distribution protocol (LDP) and resource reservation protocol-traffic engineering (RSVP-TE) which exist in a traditional multiple protocol label switching (MPLS) network can not serve as a complete multiple protocol label switching label switched path (MPLS LSP) to forward data traffic. The technical scheme includes a prefix comparison unit, a label distribution unit and a label installation unit, wherein the prefix comparison unit is used for comparing whether a destination address of a newly increased routing with a tunnel serving as an exit matches with the existing forwarding equivalence class (FEC), or the prefix comparison unit is used for comparing whether a newly increased FEC matches with a destination address of an existing routing with the tunnel serving as the exit; the label distribution unit is used for distributing a label for an upstream label switching router (LSR) and is used for redistributing a label distribution protocol (LDP) for FEC matched by the prefix comparison unit; and the label installation unit is used for sending information of incoming label and outgoing label from a protocol control layer to a forwarding layer to guide data forwarding. Besides, a method capable of achieving the label distribution is provided, and the device and the method capable of achieving the label distribution is suitable for a high speed forwarding for data of the communication device.

Description

Equipment and method for realizing label distribution

Technical Field

The invention relates to the field of computer communication, in particular to Label Distribution equipment and a method for realizing the splicing of a Label Switched Path (LSP) of a Label Distribution Protocol (LDP) and an LSP of a Resource ReSerVation Protocol (RSVP-TE) of flow engineering extension in an MPLS (multiprotocol Label switching) network.

Background

In the MPLS network, a Label Switching Router is a node of the MPLS network, a Label distribution protocol is run on the Label Switching Router (LSR), the Label distribution protocol is specially designed to distribute labels, different FECs (Forwarding equality classes) are divided according to elements of a data packet, then different labels are distributed for the different FECs and advertised to a neighbor LSR, and data of the same FEC is processed in the same manner by the LSR in a Forwarding process. The IP routing table comprises basic elements such as routing prefix, next hop, outgoing interface and the like, the label distribution protocol divides FEC according to the routing prefix is a common method, and the FEC elements generally comprise information such as routing prefix, host address, next hop and the like; when using the FEC element, FEC may be divided using a combination of one or more of information; currently, the prior art is generally divided according to routing prefixes, that is, the label distribution protocol distributes different labels to different routing prefixes to establish different LSPs. When an IP packet enters the MPLS network, the ingress LSR may determine a corresponding FEC and a corresponding label according to a certain rule, and then add the corresponding label to the packet and send the packet out from a certain interface. The subsequent LSR only needs to forward the message along the path determined by the label switching, when the message reaches the export LSR, the export LSR will strip the label, and then process the message according to the IP forwarding rule. The data transmission path formed by the set of LSRs through which a packet passes from an ingress LSR to an egress LSR is an LSP.

RSVP is a resource reservation protocol, and its main application is to implement MPLS traffic engineering, i.e., MPLS TE; the most important goal of MPLS TE is to limit routing or control traffic based on resource conditions. The requirement of MPLS traffic engineering can be met by carrying out certain expansion on the RSVP protocol. The extended protocol of RSVP, called RSVP-TE, which enables label distribution independently, establishing independent LSPs, and working independently of label distribution protocol LDP, enables it to carry MPLS label information and other TE specific parameters. Traffic engineering is deployed in MPLS networks at a relatively high probability, and as a basic label distribution protocol, in a non-traffic engineering area, basically, an LSP of MPLS is established through a label distribution protocol LDP, so that the LDP LSP and the RSVP-TE LSP are spliced relatively frequently.

Referring to fig. 1, a diagram of a hybrid application of an LDP LSP and an RSVP-TE LSP in an MPLS network in the prior art is shown. In fig. 1, LSPs are established between routers R1, R2, R3, R4 according to LDP protocol, LSPs are established between routers R4, R5 and R6 according to RSVP-TE protocol, and R4 is used as an intermediate device between LDP LSP and RSVP-TE LSP; and a tunnel from R4 to R6 is established between R4 and R6. The current processing mode generally works independently for two protocols, and at the position of the spliced LSR R4, there are different LSPs upstream and downstream, so that R4 can only serve as two LSPs, but cannot serve as a complete MPLS LSP to forward data traffic.

In the prior art, the label distribution protocol LDP generally determines whether a current LSR is an egress LSR of an LSP according to two conditions, the first condition is: at an LSR device, if a FEC is generated locally, the LSR device is an egress for the FEC; the second condition is: if a session is not established with the next hop of the FEC on a certain LSR device, or if a session is established but no label is received from the session, the LSR device is determined to be the egress of the FEC.

According to a second condition, if no session is established with the FEC next hop, the label switching router is considered as the FEC egress in the MPLS domain and will distribute empty labels upstream, whereas in fact router R4 at the splice as in fig. 1 is the start of the LSP for RSVP-TE and remains labeled. Therefore, when data arrives at the place, R4 needs to query the IP routing table first and then query the MPLS label information table, which inevitably results in low forwarding efficiency.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: a device and a method for realizing label distribution are provided, which solve the problem that the forwarding efficiency is low because the data flow can not be forwarded as a complete MPLS LSP when two label distribution protocols of LDP and RSVP-TE appear in the MPLS network of the traditional technology.

The scheme adopted by the invention for solving the technical problems is as follows: an apparatus for enabling distribution of labels, comprising:

a prefix comparing unit, configured to compare whether a destination address of the newly added route with the Tunnel as an exit is matched with an existing FEC; or, the method is used for comparing whether the destination address of the newly added FEC is matched with the destination address of the existing route with the Tunnel exit;

the label distribution unit is used for distributing labels to the upstream LSR and redistributing the LDP labels for the FEC matched by the prefix comparison unit;

and the label installation unit is used for sending the information of the incoming label and the outgoing label from the protocol control layer to the forwarding layer and guiding data forwarding.

Further, the label installation unit is responsible for combining an incoming label distributed by LDP and an outgoing label distributed by RSVP-TE, and installing the ILM entry to the forwarding layer.

Specifically, the operation code of the ILM entry is a user-defined operation code indicating that the label distributed by RSVP-TE for the current tunnel replaces the LDP label of the message header.

Specifically, the prefix comparing unit compares whether the destination address of the newly added route with the Tunnel exit is matched with the existing FEC, that is, whether the prefix or the destination host address of the destination address of the newly added route with the Tunnel exit is matched with the existing FEC.

A method of enabling label distribution, comprising: when an LDP of an LSR on a label switching router receives a new route with an exit being a Tunnel, checking whether a corresponding FEC is matched with a destination address of the new route; if yes, and the LSR is the outlet of the FEC, the following steps are executed:

a label distribution processing step of distributing a non-null label to the upstream of the FEC as an incoming label of the FEC on the label switching router;

and a label installation processing step, namely obtaining the label value distributed for the Tunnel from RSVP-TE, using the label value as an outgoing label, notifying the outgoing label to a forwarding layer, and installing an ILM table item to the forwarding layer.

The invention has the beneficial effects that: the LSP created by different label distribution protocols can be spliced in the MPLS domain, and the table look-up times when the MPLS data flow on the router at the splicing position is forwarded are reduced, so that the forwarding efficiency is improved.

Drawings

FIG. 1 is a diagram illustrating a mixed application of LDP LSP and RSVP-TE LSP in MPLS network in the prior art;

FIG. 2 is a block diagram of the structure of the device for implementing label distribution of LDP LSP and RSVP-TE LSP splicing of the present invention;

FIG. 3 is a label distribution process flow diagram;

FIG. 4 is a flow chart of a tag installation process;

FIG. 5 is a diagram of the LDP LSP and RSVP-TE LSP spliced by the method of the present invention.

Detailed Description

The invention provides a device and a method for realizing label distribution according to the characteristics of LDP (label distribution protocol) distribution labels, so as to reduce the number of table lookup times when forwarding MPLS (multi-protocol label switching) data streams on LSRs (Label switching elements) at the joint of an LDP LSP and an RSVP-TE LSP, thereby improving the forwarding efficiency. As shown in fig. 2, the apparatus includes: the device comprises a prefix comparison unit, a label distribution unit and a label installation unit; wherein,

a prefix comparing unit, configured to compare whether a destination address of a newly added route with a Tunnel (Tunnel) as an exit is matched with an existing FEC; the method is also used for comparing whether the destination address of the newly added FEC is matched with the destination address of the existing route with the Tunnel exit;

the label distributing unit is used for distributing labels to the upstream LSR and redistributing the labels for the FEC matched by the prefix comparing unit;

the label installation unit is used for sending information of an incoming label and an outgoing label from the protocol control layer to the forwarding layer and guiding data forwarding; and the label installation unit is used for combining the label input distributed by the LDP and the label output distributed by the RSVP-TE and installing the ILM table item to the forwarding layer.

The method of the invention comprises the following steps: when LDP receives a new route with an exit being a Tunnel, checking whether a corresponding FEC is consistent with a destination address prefix of the new route; if yes, and the LSR is an outlet of the FEC, distributing a non-empty label to an upstream of the FEC to serve as an incoming label of the FEC on the LSR; and then obtaining the label value distributed for the Tunnel from RSVP-TE as an outgoing label, notifying the outgoing label to a forwarding layer, and installing an ILM table item to the forwarding layer.

The implementation method can be divided into a label distribution processing step and a label installation processing step:

referring to fig. 3, the corresponding LDP label processing flow includes:

step 201: the LDP receives the corresponding information of the route;

step 202: judging whether the route output interface is a tunnel port or not by analyzing the route information; if yes, go to step 203, otherwise, go to step 204;

step 203: judging whether the LDP has the FEC matched with the destination address prefix of the Tunnel, if not, turning to step 211; if so, go to step 205;

step 204: creating a new FEC according to the routing information, the new FEC being divided according to the prefix of the route, go to step 208;

step 205: if the LSR is the egress of the FEC, go to step 206 if yes, otherwise go to step 211;

step 206: revoking empty tags previously distributed to upstream;

step 207: the recurrence distributes a non-null label to all upstream;

step 208: checking whether the destination address of the tunnel in the routing table is the same as the prefix depended by the newly created FEC, if so, entering the step 209, otherwise, going to the step 210;

step 209: if the LSR is the egress of the new FEC, go to step 207 if yes, go to step 210 if no;

step 210: distributing labels according to a normal flow;

step 211: and ending the flow.

Referring to fig. 4, the corresponding tag installation process flow includes:

step 301: receiving label information of a certain FEC from LDP, and storing the label information at a certain position;

step 302: judging whether the outgoing label of the FEC is received from RSVP-TE or not;

step 303: if the outgoing label distributed by RSVP-TE is received, then ILM table items are installed TO the forwarding, the operation code is SWAP _ TO _ TUNNEL, and the step 305 is carried out;

step 304: installing a normal flow distribution label;

step 305: and ending the flow.

Example (b):

referring to fig. 5, where the intermediate of R1, R2, R3 and R4 establishes LSP according to LDP protocol, and a tunnel from R4 to R6 is established between R4 and R6, R4 is used as an intermediate device between LDP LSP and RSVP-TE LSP, there is a special processing flow, which includes the following steps:

step 401: r4 receives a piece of routing information, the routing prefix is 240.0.0.0/24, a FEC A is created, the next hop device of the routing is R5, but an LDP session is not established between R4 and R5, so that LDP judges that R4 is the exit of FECA in the MPLS domain;

step 402: but at the same time, it is checked that there is a tunnel X with the destination address prefix of 240.0.0.0/24, which is the same as the prefix of FEC a;

step 403: LDP will distribute non-empty labels upstream and advertise this incoming label to the label installation module;

step 404: RSVP-TE receives the label distributed by R6 for the tunnel, and also informs the label installation module;

step 405: the label installation module checks that the incoming label is LDP distribution and the outgoing label is RSVP-TE distribution, and then an ILM is installed, wherein the operation code is SWAP _ TO _ TUNNEL;

when the MPLS data stream with the destination of 240.0.0.0/24 reaches R4, R4 will continue to forward MPLS data according to ILM in the label forwarding information table, without popping up labels, looking up the routing table, and then looking up the actions of the MPLS label forwarding information table.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. An apparatus for enabling distribution of labels, comprising:

a prefix comparing unit, configured to compare whether a destination address of the newly added route with the Tunnel as an exit is matched with an existing FEC; the method is also used for comparing whether the destination address of the newly added FEC is matched with the destination address of the existing route with the Tunnel exit;

the label distribution unit is used for distributing labels to the upstream LSR and redistributing Label Distribution Protocol (LDP) labels for the FEC matched by the prefix comparison unit;

2. The apparatus for implementing label distribution as claimed in claim 1, wherein said label installing unit is further responsible for combining incoming label distributed by LDP and outgoing label distributed by RSVP-TE to install ILM entry to forwarding layer.

3. The apparatus for implementing label distribution according to claim 2, wherein the opcode of the ILM entry is a user-defined opcode indicating that the label distributed by the RSVP-TE current tunnel is to replace the LDP label of the message header.

4. The apparatus for implementing label distribution according to any one of claims 1 to 3, wherein the prefix comparison unit compares whether the destination address of the newly added route exported as Tunnel matches with the existing FEC, that is, whether the prefix of the destination address of the newly added route exported as Tunnel or the destination host address matches with the existing FEC.

5. A method for enabling label distribution, comprising: when a label distribution protocol LDP (label distribution protocol) running on a Label Switching Router (LSR) receives a new route with an exit being a Tunnel Tunnel, checking whether a corresponding FEC (forward error correction) is matched with a destination address of the new route; if yes, and the LSR is the egress of the FEC, the following steps are performed:

a label distribution processing step of distributing a non-empty label to an upstream LSR of the FEC as an ingress label of the FEC on the LSR;

6. The method for implementing label distribution according to claim 5, further comprising the steps of: when a label distribution protocol LDP running on a label switching router LSR receives a newly added FEC, judging whether the FEC is matched with a destination address of an existing route with a Tunnel outlet; if yes, and the LSR is the egress of the FEC, the following steps are performed:

7. The method for implementing label distribution according to claim 5, wherein the label distribution processing step specifically includes:

a1. when receiving the routing information, the LDP of the LSR analyzes the routing information and judges whether an outgoing interface of the route is a Tunnel port; if yes, go to step a2, otherwise, go to step a 3;

a2. judging whether the LDP has the FEC matched with the Tunnel destination address prefix or the destination host address, if so, entering a step a4, otherwise, ending the flow;

a3. creating a new FEC according to the routing information, and turning to step a 6;

a4. judging whether the LSR is an outlet of the FEC matched with the destination address prefix of the Tunnel, if so, entering a step a5, otherwise, ending the flow;

a5. canceling the empty label distributed to the upstream LSR before and redistributing the non-empty label to all the upstream LSRs;

a6. judging whether a Tunnel destination address prefix matched with the new FEC exists in the routing table, if so, entering a step a7, otherwise, entering a step a 8;

a7. judging whether the LSR is an outlet of the new FEC, if so, redistributing non-empty labels to all upstream LSRs; if not, go to step a 8;

a8. and if the LSR is the outlet LSR of the FEC, distributing the empty label to an upstream LSR, and if the LSR is not the outlet LSR of the FEC, distributing the non-empty label to the upstream LSR.

8. The method for realizing label distribution according to claim 5 or 7, wherein the label installation processing step comprises:

b1. when label information of a certain FEC is received from the LDP, the label information is stored;

b2. judging whether the outbound label of the FEC is received from RSVP-TE, if so, entering the step b3, otherwise, entering the step b 4;

b3. installing ILM table items to a forwarding layer;

b4. and distributing the labels according to a normal flow.

9. The method for realizing label distribution according to claim 5 or 6, wherein the operation code of the ILM table entry is a user-defined operation code indicating that RSVP-TE is used for the label distributed by the current tunnel to replace the LDP label of the message header.