CN101047617B

CN101047617B - Method and device of mobile multicast switchover

Info

Publication number: CN101047617B
Application number: CN2006100667218A
Authority: CN
Inventors: 张宏科; 张晖; 邵书超
Original assignee: Huawei Technologies Co Ltd; Beijing Jiaotong University
Current assignee: Huawei Technologies Co Ltd; Beijing Jiaotong University
Priority date: 2006-04-05
Filing date: 2006-04-05
Publication date: 2011-12-07
Anticipated expiration: 2026-04-05
Also published as: CN101047617A

Abstract

A method for switching over mobile multicast includes setting access router message listing in each branch countermark exchange router and mobile anchor point and seeking cross countermark exchange router according to message listing of access router then buffer-storing multicast data in cross countermark exchange router till smooth switchover is finalized by mobile node. The device used for realizing said method is also disclosed.

Description

Method and device that a kind of mobile multicast switches

Technical field

The present invention relates to the communications field, particularly based on the inquiry of multiprotocol label switching (MPLS-Multi-Protocol Label Switching) network intersect LSR method and utilize described intersection LSR querying method to carry out the method that mobile multicast switches.

Background technology

Along with network-multimedia application such as Web TV and video conference are increasingly extensive, utilizing multicasting technology to come support point is the effective means that reduces bandwidth consumption, improves service quality to multi-point to multiple spot, multiple spot.Mobile multicast is as focus that the new technology that application prospect arranged is very much studied especially in the mobile Internet.

The continuation of under mobile environment, communicating by letter in recent years for multicast, some solutions have been proposed, one class is based on the local signature, as mobile IP bidirectional tunnel (MIP-BT:MobileInternet Protocol-bidirectional tunnel), mobile multicast protocol (MoM-Mobile Multicast Protocol) and based on mobile multicast (RBMoM-Range based MoM) of scope etc., their common feature is all to need the next responsible adding multicast tree of a home agent (HA-Home Agent) and packet is transmitted to mobile node (MN-Mobility Node), its multicast tree need not be because of the change reconstruct of MN position, but long tunnel has caused big transmission delay, bearing very heavy home agent (HA) often becomes the bottleneck of communication, thereby exists the triangle route, the problem of tunnel aggregates; Another kind of solution is based on long-range signature, as long-range signature of mobile IP (MIP-RS Mobile Internetprotocol-remote subscription) and multicast agent (MA) agreement etc., they all are to be responsible for adding multicast tree by Foreign Agent (FA-Foreign Agent), its multicast path is optimized, but the mobile meeting of MN brings the frequent reconstruct of multicast tree, can bring the frequent reconstruct of multicast tree, handover delay is long, the problem that packet loss is many; Also having a class solution in addition is above both mixing, and promptly home agent and Foreign Agent all are responsible for adding multicast tree, and its major defect is a complexity too.More than several mechanism have separately problem respectively, can't satisfy the performance requirement that real-time multimedia is used.

Multiprotocol label switching (MPLS-Multi Protocol Label Switch) multicast can be so that multicast packet transmits quickly and efficiently by the multicast tree of a network layer being mapped to the label switched path (LSP-Label Switch Path) that a little arrives multiple spot (P2MP-Point to MultiPoint).Present MPLS multicast mechanism all is to propose under the constant prerequisite of hypothesis multicast recipient and sender's fixed-site, does not also propose the solution of maturation at problem that can also receiving multicast data after changing when the receiving node occurrence positions.Wherein have two as follows with the more approaching scheme of the present invention:

Technical scheme 1: the mechanism of in the MPLS network, setting up multicast tree for mobile node

In this scheme, the management of multicast tree is based on the MPLS label.Mobile node detects the back and can add a specific multicast tree by outlet tag edge router (Egress LER-Egress Label EdgeRouter) moving, and outlet LER is responsible for adding multicast tree and multicast data transmission to MN as long-range signature.After MN added multicast tree, data forwarding was based on MPLS.

Referring to Fig. 1, suppose to enter the mouth LER (Ingress LER) and all LSRs (LSR-Label Switched Router) can be handled the Join message from MN, and LER exercises the function of home agent or Foreign Agent.Inlet LER be multicast tree root or with the tie point of other multicast networks, the multicast tree in its supervising the network.

After MN added multicast tree, data were through inlet LER and LSR, and LER sends MN to from outlet.Data are according to the MPLS tag transmits between inlet LER and outlet LER.Between LER and outside, use the IP transmission.Outlet LER exercises the function of Foreign Agent or nonlocal router, and inlet LER exercises the function of home agent.MN need preserve the information of multicast tree address and multicast source, is used for the reconstruction of multicast tree.

When a mobile node moved to a new field network, it must add multicast tree again, because its access point has changed, Care-of Address has also changed.MN is divided into two states and adds multicast tree.First kind is the initial-join state, and this state is that MN also adds the multicast tree situation less than information and needs about multicast tree.Second kind is the handoff-join state, and this state is to receive the situation that multicast packets moves to new field network as MN, and this moment, MN had multicast tree information, postpones so can reduce to add.

Technical scheme 1 has following shortcoming:

(1) only supports the macro-mobility of MN, do not support hierarchical mobile management.Each switching all needs to re-register to home agent.Do not support quick switching (FHMIP).

In the network in future, in order to hold more mobile node, the honeycomb radius can be more and more littler, and the number of times of switching can be more and more frequent, and grand moving under this environment can be caused sizable handover delay and packet loss.

(2) switching of MN belongs to " direct-cut operation ", can cause bigger packet loss.

Technical scheme 2: the scheme of in based on the network of MPLS, supporting seamless switching

This programme has designed a kind of seamless switching scheme integrated in the mobile IP v 6 network of multiprotocol label switching, and it realizes switching to the two multicast datas of main frame by the reconstruction scope of restriction label switched path (LSP) with when switching.And proposed a kind of main frame of searching and send grouping before and after switching and go through the algorithm of the nearest common point (intersection LSR) in path and rebuild scope to reduce LSP.

In having the mobile anchor point of hierarchical structure (MAP-Mobility Anchor Point) zone, the path that arrives MAP by each node has only one, then each node in the zone is numbered.Wherein root node (being MAP) be numbered 0, the numbering of all the other nodes is made up of two parts, first half is the numbering of father node, latter half is the numbering of the child node under same father node.The numbering of intersection LSR (CR-Cross Router) equals that the numbering of primary access router and new couple in router is mated resulting maximum coupling and goes here and there.In order to find CR, require each node should preserve the numbering of oneself.

After finding CR according to the longest coupling of router, set up the reconstruction that from CR to the new couple in router LSP (nAR-New Access Router) has promptly finished whole LSP.At the CR place NAR and existing couple in router (oAR-01d Access Router) are carried out two broadcasting to realize seamless switching then.

Technical scheme 2 has following shortcoming:

(1) when network size increases, router-number can become increasingly complex, and has reduced the treatment effeciency of router.

(2) do not support multicast, thereby can not utilize bandwidth resources better.

In addition, in the prior art, before carrying out three layers of switching, FMI Pv6 agreement can reduce switching delay and packet loss effectively by set up bidirectional tunnel between oAR and nAR.In the MPLS network, utilize that explicit LSP is easier to set up needed tunnel.But FMIPv6 protocol requirement packet be redirected must with the actual mobile strict synchronism of MN, otherwise may packet loss in the process of switching.Such as, if be redirected too early, when packet arrived new link, MN did not switch in the past as yet; If be redirected too late, MN has switched to new link, but packet still is sent on the old link.

Summary of the invention

In order to solve in the mobile multicast handoff procedure that exists in the prior art problems such as the frequent reconstruct of multicast tree, packet loss and handover delay be bigger, the object of the present invention is to provide a kind of changing method of mobile multicast, in network based on MPLS, under little mobile situation, provide multicast services for mobile node, by rationally setting up the scope of multicast tree and control multicast tree, to reduce handover delay and packet loss, improve service quality and the level of resources utilization.Technical scheme of the present invention is as follows:

The present invention has at first proposed a kind of method of inquiring about the intersection LSR, network node in each zone all is connected to backbone network by a mobile anchor point, and the path of each node arrival mobile anchor point is unique, in each branch label switch router and mobile anchor point, the couple in router messaging list is set, the address information of described each branch label switch router or all couple in routers of mobile anchor point downstream is preserved in described tabulation, and described querying method may further comprise the steps:

Steps A: mobile node obtains the address information of new couple in router;

Step B: the upstream branch label switch router of described mobile node sends intersection LSR query requests, comprises the address information of new couple in router and existing couple in router in the described query requests;

Step C: described branch label switch router is searched described intersection LSR according to described couple in router messaging list after receiving described intersection LSR query requests;

Wherein, described step C specifically comprises:

Described branch label switch router after receiving described intersection LSR query requests is compared the couple in router address information in the couple in router messaging list of described new couple in router and the address information that shows couple in router and this locality;

If comprised the information of new couple in router and existing couple in router in the couple in router messaging list of described this locality, then this branch label switch router is for intersecting LSR, otherwise continuing upstream, the branch label switch router sends intersection LSR query messages, and repeated execution of steps C, until reaching mobile anchor point.

Described query requests is sent by the beginning buffered message.

The present invention is based on above-mentioned intersection LSR querying method, a kind of method that mobile multicast switches of carrying out also be provided, said method comprising the steps of:

Steps A: mobile node obtains the address information of new couple in router;

Step C: described branch label switch router is searched described intersection LSR according to described couple in router messaging list after receiving described intersection LSR query requests.

Step D: described mobile node is to intersecting LSR transmission beginning buffered message, and described intersection LSR carries out buffer memory with the multicast traffic stream that receives after receiving described beginning buffered message;

Step e: described mobile node leaves old couple in router, sends to new couple in router to join request;

Step F: described new couple in router joins new couple in router with described mobile node after receiving joining request of mobile node;

Step G: described intersection LSR is transmitted to mobile node with multicast packet in the buffer memory and the multicast packet that receives by new couple in router.

Further comprise after new couple in router is received joining request of mobile node described in the described step F: described new couple in router judges whether that other main frame is using identical multicast service, if, described mobile node is directly joined described new couple in router, otherwise described new couple in router sends to described intersection LSR and adds message, sets up new label switched path.

Further comprise after the described step F:

Described mobile node sends leave group message to old couple in router, after described old couple in router is received described leave group message, if judge this multicast member that does not have other in the local subnet, then described old couple in router of beta pruning and the label between the LSR of intersecting.

Further comprise before the described step G:

Described intersection LSR carries out two broadcasting to old couple in router and new couple in router.

The present invention also provides a kind of device of inquiring about the intersection LSR, network node in each zone all is connected to backbone network by a mobile anchor point, and the path of each node arrival mobile anchor point is unique, in each branch label switch router and mobile anchor point, the couple in router messaging list is set, the address information of described each branch label switch router or all couple in routers of mobile anchor point downstream is preserved in described tabulation, and described inquiry unit comprises the query requests module and searches module;

Described query requests module is used for the upstream branch label switch router of mobile node and sends intersection LSR query requests, comprises the address information of new couple in router and existing couple in router in the described query requests;

The described module of searching is used for searching described intersection LSR according to described couple in router messaging list after described branch label switch router is received described intersection LSR query requests;

Wherein, the described module of searching specifically comprises comparing module and judge module;

Described comparing module is used for after described branch label switch router is received described intersection LSR query requests the address information of described new couple in router and existing couple in router being compared with the couple in router address information of the couple in router messaging list of this locality;

Described judge module is used for judging if the couple in router messaging list of described this locality has comprised the information of new couple in router and existing couple in router, then this branch label switch router is for intersecting LSR, and the branch label switch router sends intersection LSR query messages otherwise continue upstream.

The beneficial effect that technical solution of the present invention is brought is as follows:

(1) introducing by the hierarchical network structure and search CLSR is compared with mixed mechanism with the local signature, and this method has reduced to add the delay of message and the new LSP of reconstruction greatly.

(2) home agent does not use non-polymeric tunnel to give each MN with transmitting multicast data, does not just have the tunnel aggregates problem of MIP-BT agreement yet, can reduce the burden of home agent and network greatly.

(3) compare with long-range signature, it does not need the frequent reconstruct of multicast tree, and also have relatively the multicast path optimized by.

(4) introducing of dynamic buffering mechanism has reduced packet loss.

(5) router in the core net only need be preserved the information of MAP, need not preserve any information about other LSR in MN and the MAP, has reduced the burden of core router.

(6) algorithm is simple, and is very little to existing MIPv6 agreement change, is easy to realize.

(7) in network,, thereby Internet resources such as bandwidth have been effectively utilized effectively for mobile node provides multicast services based on MPLS.

Brief Description Of Drawings

Fig. 1 is a network structure of the prior art;

Fig. 2 is for based on the network structure that mobile multicast service is provided in the MPLS network;

Fig. 3 takes over seamlessly flow chart in the mobile multicast territory;

Fig. 4 is a CLSR decision flowchart of the present invention;

Fig. 5 is a structure chart of searching the device of CLSR of the present invention.

Below in conjunction with drawings and Examples the present invention is further specified, but do not represent limitation of the invention.

In order to deepen that the understanding of the technical program handover delay based on the MPLS network is analyzed as follows:

With after mobile IP v 6 combines, the handover delay of mobile node can be expressed as with MPLS:

D _handoff＝D _connect+D _rd+D _dad+D _reg+D _lsp (1)

When mobile node switches to field network 2 by field network 1, at first will carry out link layer and switch, this switching delay promptly is expressed as D _ConnectMobile node carries out the router search according to mobile detection algorithm subsequently, makes the decision of three layers of switching of beginning, and this delay is expressed as D _RdIn case mobile node begins to switch, and then begins to dispose new Care-of Address, new Care-of Address is carried out the time D of duplicate address detection _DadThen mobile node sends Binding Update to local agent and the new Care-of Address of Correspondent Node registration, and this postpones to be D _RegAnd D _LspIt is the time delay that the MPLS network is set up new LSP path.

In general, link layer handover delay D _ConnectMuch smaller than other time delay, can ignore.D _RegAnd D _LspBe directly proportional with the time delay of network entity processing signaling and the distance of the required transmission of signaling.Formula (1) can further be expressed as:

D _handoff＝D _rd+D _dad+αL _reg+βL _lsp (2)

L wherein _RegIt is the signaling transmission range of the new Care-of Address of registration; L _LspIt is the signaling transmission range of setting up new LSP; α and β are proportionality coefficients.As can be seen from the above equation, switch fast, should reduce every value as much as possible in order farthest to realize.Such as in the scheme of existing local signature, after switching, must register mobile node to HA, be responsible for adding multicast tree by HA, between FA and HA, rebulid LSP then, at this moment L _RegAnd L _LspAll be between FA and the HA apart from length.

The present invention makes existing couple in router (oAR) obtain its subnet information by two layers of Signalling exchange with new couple in router (nAR) in conjunction with the FMIPv6 technology, and mobile node is constructed new local Care-of Address in advance, can eliminate router search delay D fully like this _RdReach and reduce duplicate address detection delay D greatly _DadUtilize the HMIPv6 technology, make L _RegAnd L _LspShorten to FA to the distance between the regional gateway, on this basis, define the public LSR that arrives on mobile anchor point (MAP) path before and after the mobile node switching and be intersection LSR (CLSR), make the reconstruction of LSP only be limited in the part of real change, the delay that has further reduced registration and rebuild LSP, and the method that has proposed to search CLSR.

Embodiment 1:

The present invention proposes a kind of mobile multicast switching method based on the MPLS network, binding hierarchy mobile IP v 6 technology (HMIPv6) and quick handoff technique (FMIPv6), by inquiry intersection LSR, and the method for dynamic buffering is set up in utilization on intersection LSR (CROSS LSR), realized that the quick and smooth of multicast under mobile condition switches, and low handover delay and packet loss are arranged, have important and practical meanings.Referring to Fig. 3, the step of mobile multicast switching method of the present invention is as follows:

Step 101: before MN disconnected connection from link-local, oAR sent L2Trigger to MN, was used to notify MN to prepare to switch.

Step 102:MN receives after the L2Trigger of oAR transmission, based on the FMIPv6 agreement, sends router solicitation proxy message (RtSolPr) message to oAR, and notice oAR will switch, and needed information is switched in request.

Step 103:oAR sends it back the PrRtAdv message of answering to MN after receiving the RtSolPr message of MN transmission, is used to provide subnet prefix and the address information of nAR.

Step 104:MN helps move detection according to the PrRtAdv message of receiving after receiving the PrRtAdv message of oAR transmission, and MN uses the Care-of Address that the automatic arrangement in stateless address makes new advances subsequently.

Step 105:MN sends the CLSR query messages to the MAP direction, obtains the CLSR on this path, switching front and back, and sends Query Result to MN.The specific implementation method of this step sees embodiment 2 for details.

Step 106:MN begins carry out buffer memory with notice CLSR with the multicast traffic stream that receives to CLSR transmission beginning buffer memory (StartBuffer) message after receiving Query Result.In order to reduce the signaling load in the network, CLSR query messages and StartBuffer message can be merged into the upwards transmission of a signaling, in case search out real CLSR, it begins the buffer memory multicast packet immediately.

Step 107:MN disconnects and being connected with this locality of oAR, enters the link of nAR.MN simultaneously initiatively sends leave group message to oAR, after oAR receives the leave group message of MN, if in the local subnet of oAR, there is not other this multicast tree member, the oAR that receives leave group message should begin and CLSR between label cancel and dispose procedure.The method of being specially is that cross exchange router hop-by-hop sends label release message to old couple in router, and latter's hop-by-hop returns label and withdraws message, thereby the label switched path beta pruning that this is old is fallen.Also can adopt the LSP method for dismounting of implicit expression, because the lifetime of the tag forwarding information base of each FEC correspondence (LFIB) list item must depend on the renewal in signaling cycle, if overtime renewal, then this list item is with deleted, and corresponding LSP also is removed.

After step 108:nAR detects new MN access, send multicast member inquiry (Membership Query) message to MN, whether inquiry MN needs to add multicast tree, and the multicast services content that can provide has been provided in query messages.

After step 109:MN receives Membership Query message, the multicast services of describing in query messages according to the multicast services and the nAR of own needs compares the back decision and whether will add multicast tree, add if desired, then send multicast member report (Membership Report) message and give nAR, comprising joining request.

After the message that joins request of step 110:nAR in receiving the multicast member report, whether check has other main frame using identical multicast service, if exist, then MN only need join nAR and gets final product, do not need to rebulid new LSP, and execution in step 113, use the multicast listener discovery protocol (MLDv2) of IPv6 to manage the MN adding or leave multicast tree.If there is no, execution in step 111.

Step 111:nAR sends to CLSR and adds (Join) message.

Step 112: the multicast congruent point is after CLSR receives the adding message of nAR transmission, uses MPLS tag distribution protocol (Label Request, Label Mapping) to set up new LSP, and multicast tree is expanded to nAR.

Step 113:CLSR is transmitted to MN together with the multicast packet that receives by nAR with the multicast packet in the own buffer memory.

Embodiment 2:

In order to shorten the distance that needs the LSP that rebulids after mobile node switches to greatest extent, reduce to move the delay of switching, the present invention proposes method, the reconstruction of LSP only is limited between nAR and the CLSR, thereby makes D by the intersection point-intersection LSR (CLSR) of common path before and after judge switching _LspValue minimizes.

Referring to Fig. 2, the network of MPLS described in the figure can be divided into different zones, network node in each zone all passes through a mobile anchor point (MAP) and is connected to backbone network, MAP is in charge of moving of the interior main frame in zone, and unique by the pre-configured path that makes each node arrive MAP to routing table.In order to inquire about CLSR, at first each LSR of branch in the zone comprises that MAP has an ARInfo tabulation, the AR information that this in store downstream of tabulating is all.For example, the information that AR1, AR2, AR3 and AR4 are preserved in the ARInfo of LSR2 tabulation among Fig. 2, and the information of AR2 and AR3 is arranged in the ARInfo of the LSR3 tabulation.

Referring to Fig. 4, the finding step of CLSR is as follows:

Step 201: to 104, MN obtains subnet information and the address information of new Care-of Address and nAR according to step 101;

Step 202:MN upstream sends the CLSR query messages along the MAP direction by old link, comprises the address of couple in router of haveing been friends in the past (oAR) and new couple in router (nAR) in the message;

Step 203: the LSR of branch receives the CLSR query messages;

Step 204: the LSR of branch compares AR information in the ARInfo tabulation of the CLSR query messages that receives and its preservation, if having the information of oAR and nAR in the ARInfo tabulation simultaneously, then the LSR of this branch is the CLSR on the toggle path.Otherwise LSR continues upwards to transmit the CLSR query messages, and repeating step 203, until arriving mobile anchor point (MAP) or finding CLSR.

Further be example, describe and search the CLSR detailed process with Fig. 2:

1, the access point of MN switches to AR1 by AR2, when MN still is connected on the oAR, has obtained subnet information and the address information of new Care-of Address and nAR according to the step 101 among the embodiment 1 to step 104;

2, MN upstream is that LSR3 sends the CLSR query messages by the link at AR2 place, comprises the address of AR2 and AR1 in the message;

3, after branch office router LSR3 received this message, the ARInfo that searches for its preservation tabulates, and (AR2 AR3), compared with the information of access route that carries in the CLSR query messages, finds only to contain AR2 in the ARInfo tabulation, and does not have the information of AR1.LSR2 transmits the CLSR query messages so LSR3 continues upstream;

4, upstream branch router LSR2 receives this query messages, with itself and the ARInfo tabulation (AR1 that preserves, AR2, AR3, AR4) compare, the ARInfo tabulation of finding oneself had both comprised the information that the router-A R2 that is inserted before MN switches also comprises after the switching AR1 that will insert, and oneself was intersection LSR CLSR on this toggle path of MN so LSR2 just can know.

Because the introducing of CLSR, multicast tree only need be rebuild the part from CLSR to nAR, and does not need from MAP to begin to rebuild, and has reduced the reconstruction scope, has reduced network switching delay and signaling load.

More than be to taking over seamlessly the description of scheme in the mobile multicast territory, the situation that regards to cross-domain switching is down simply described, and switch instances is similar substantially in its principle and the territory.MN disconnect with being connected of link-local before, by two layers of mechanism obtain Zone switched MAP (nMAP) information, between existing regional MAP (oMAP) and nMAP, set up the tunnel subsequently, the multicast packet that receives is sent to nMAP, carry out buffer memory by it.MN switches and finishes, and sets up the new LSP that plays nMAP, and nMAP is transmitted to MN with the multicast packet of data cached and new reception via new LSP again.If the AR for the MN service in the nMAP territory has the main frame that uses the same multicast service, then do not need to rebulid LSP.MN is from the nMAP receiving multicast data afterwards, and being connected of disconnection and oMAP.

Referring to Fig. 5, the present invention also provides the present invention also a kind of device of inquiring about the intersection LSR, network node in each zone all is connected to backbone network by a mobile anchor point, and the path of each node arrival mobile anchor point is unique, in each branch label switch router and mobile anchor point, the couple in router messaging list is set, the address information of described each branch label switch router or all couple in routers of mobile anchor point downstream is preserved in described tabulation, and described inquiry unit comprises the query requests module and searches module;

The described module of searching is used for searching described intersection LSR according to described couple in router messaging list after described branch label switch router is received described intersection LSR query requests.

The described module of searching specifically comprises comparing module and judge module;

More than mode by example the preferred embodiment of invention is described in detail, but those of ordinary skill in the art should be realized that and do not deviating under the spirit and scope of the present invention, can make various modifications to the present invention.

Claims

1. inquire about and intersect the method for LSR for one kind, network node in each zone all is connected to backbone network by a mobile anchor point, and the path of each node arrival mobile anchor point is unique, it is characterized in that, in each branch label switch router and mobile anchor point, the couple in router messaging list is set, the address information of described each branch label switch router or all couple in routers of mobile anchor point downstream is preserved in described tabulation, and described querying method may further comprise the steps:

Steps A: mobile node obtains the address information of new couple in router;

Wherein, described step C specifically comprises:

2. the method for an inquiry intersection LSR as claimed in claim 1 is characterized in that, described query requests is sent by the beginning buffered message.

3. one kind is utilized the described intersection LSR of claim 1 querying method to carry out the method that mobile multicast switches, and it is characterized in that, said method comprising the steps of:

Steps A: mobile node obtains the address information of new couple in router;

4. the method that mobile multicast as claimed in claim 3 switches, it is characterized in that, further comprise after new couple in router is received joining request of mobile node described in the described step F: described new couple in router judges whether that other main frame is using identical multicast service, if, described mobile node is directly joined described new couple in router, otherwise described new couple in router sends to described intersection LSR and adds message, sets up new label switched path.

5. the method that mobile multicast as claimed in claim 3 switches is characterized in that, further comprises after the described step F:

6. the method that mobile multicast as claimed in claim 3 switches is characterized in that, further comprises before the described step G:

7. inquire about and intersect the device of LSR for one kind, network node in each zone all is connected to backbone network by a mobile anchor point, and the path of each node arrival mobile anchor point is unique, it is characterized in that, in each branch label switch router and mobile anchor point, the couple in router messaging list is set, the address information of described each branch label switch router or all couple in routers of mobile anchor point downstream is preserved in described tabulation, and described inquiry unit comprises the query requests module and searches module;