WO2013004138A1 - Mobility realization method based on location/identifier separation protocol (lisp) and tunnel router - Google Patents

Abstract

Disclosed are a mobility realization method based on Location/Identifier Separation Protocol (LISP) and a tunnel router. To solve aforementioned technical problem, the method comprises: after obtaining the routing locator (ORLOC) of an old egress tunnel router(OETR) which a mobile node (MN) attached to before switching, a new egress tunnel router (NETR) establishes a forwarding tunnel with the OETR; the OETR forwards the messages, whose destination end identifier (EID) points to the MN, to the NETR through the forwarding tunnel. The aforementioned method and tunnel router enable the OELR to forward messages accurately even after the MN has switched to the NETR.

Description

 LISP-based mobility implementation method and tunnel router

Technical field

 The present invention relates to the field of network technologies, and in particular, to a mobility implementation method based on LISP (Location/ID Separation Protocol) and a tunnel router.

Background technique

 The size of the DFZ (Default Free Zone) routing table increases at an increasing rate, which compromises the scalability of the route and the execution of route aggregation. Routing scalability issues have generated great interest in industry and academia.

 Members of the IAB (Internet Architecture Board) discussed that the underlying reason for the increase in the DFZ routing table is the dual semantics of IP addresses, where IP addresses are both identifiers and locations.

 The IRTF RRG (Internet Research Task Force Routing Research Grou) is currently working on new routing and address architectures to support multi-hole, traffic engineering and mobility.

 LISP is a new routing framework based on the RRG (Routing Research Group) requirements for routing and address research, led by Cisco, by separating the current IP address into terminal identifiers (EIDs, End-identifiers) and Routing locations (RLOCs, Routing Locators) to reduce the size of the DFZ (default-free zone) routing table, increase the number of extensions and reduce the number of globally visible, routing prefixes.

The network structure of LISP is shown in Figure 1. The basic idea of LISP is to encapsulate an IP packet header outside the IP layer to reduce the impact of routes generated by the increase of edge network users on the routing table of the backbone network and maintain the stability of the backbone network routing table (BGP routing table). . LISP divides the existing IP address system into terminal identification (EID) and routing location (RLOC), and introduces the concept of tunnel routers ("Tunnel Routers"). The tunnel routers are divided into ITRs (Ingress Tunnel Routers). And ETR (Egress Tunnel Router). Both ITR and ETR need to register the binding of EID and RLOC in the mapping server MS (Map-Server). For ETR For the host on the side, the ETR is responsible for registering the EID of this host and binding to the RLOC. The ITR is responsible for buffering the EID/RLOC binding of the ETR-side host. Similarly for the ITR side host, the ITR registers the binding of the host's EID with the RLOC. In addition, the IRP in LISP is responsible for the data encapsulation and mapping search, and finds the corresponding RLOC information according to the destination EID information, and encapsulates a layer of LISP header and IP packet header outside the original host "3⁄4 text." EISP is responsible for datagrams in LISP. Decapsulation of the text.

 The host (including the mobile node (MN)) in LISP does not make any changes. The IP address of the data sent by the host is represented by EID. The transmission of data packets in the network depends on the routing location (RLOC) information, according to the lookup RLOC routing table. Forwarding of the message.

 The encapsulation of the LISP data packet is performed on the ingress tunnel router ITR, and is encapsulated in a 'ΊΡ-ΙΝ-ΙΡ' manner, and an IP packet header is encapsulated outside the ordinary IP packet. The source IP address and the destination IP address field of the packet header are respectively represented by the source EID and the destination EID, and the source IP address and the destination IP address of the outer IP header are represented by the source RLOC and the destination RLOC, respectively. During the transmission of the network, only the destination RLOC of the outer IP packet header needs to be routed and forwarded. The inner IP packet header remains unchanged during the transmission process. The solution of the identity identifier and the location separated data packet The encapsulation is completed on the egress router ETR. The data forwarding process of the LISP protocol is as shown in Figure 2.

 The original intention of the LISP protocol is to solve the scale of the routing table, and can not solve the mobility of the network. With the development of the network, the mobility of the network is necessary, and the LISP design needs the LISP to solve the mobility and multi-hole. .

 Huawei proposed LISP-PMIP to solve the mobility of LISP. The idea of this solution is to PMIP.

(Proxy Mobile IP, Proxy Mobile IP) Introducing LISP, LISP-PMIP-based mobile management network structure is shown in Figure 3. The ETR in the LISP system is used as the LMA (Local Mobility Anchor) in the PMIP. The MS maintains the MN's EID (the EID is equivalent to the HoA in the PMIP) and the RLOC mapping of the ETR. The MAG is introduced between the ETR and the MN. Mobile Access Gateway (Mobile Access Gateway), a PMIP tunnel is established between the MAG and the ETR, and the ETR maintains a mapping between the HoA of the MN and the proxy CoA of the MAG.

PMIP is a solution for network-based local mobility management. Its goal is to define a simple extension of ΜΙΡνό, support IPv6-based mobility management, and reuse ΜΙΡν6 signaling and features. PMIP can implement IP mobility of the host without requiring the host to participate in any mobile phase Off signaling. In the PMIP protocol, the network replaces the host to manage the mobility of the IP. The mobile entity in the network tracks the movement of the host and initiates the necessary mobile signaling. The mobile management network structure diagram of PMIP is shown in Figure 4. PMIP can only solve the handover between different MAGs under the same LMA. In FIG. 4, since MAG1 and MAG2 belong to one LMA, the mobile node can switch from the area of MAG1 to the area of MAG2. PMIP cannot solve the handover between different MAGs under different LMAs, that is, PMIP cannot implement the handover of mobile nodes from MAG2 to MAG3 in Figure 4.

 In the PMIP, the LMA is responsible for processing the routing information of the mobile node, and the routing information is forwarded by the mobile access gateway (MAG) to which the mobile node belongs, and the packet sent to the mobile node and the mobile node passes through the anchor point. When a mobile node moves from one mobile access gateway to another, the mobile access gateway generates a routing update to the LMA. The PMIP-based switching process is shown in Figure 5:

 RtrSol (Router Solicitation Messages): The mobile node sends a route request signal to the new mobile access gateway (NMAG). The IPv6 source address header of the signal may be the link-local address of the mobile node. May be a non-specific address (RFC4861).

 RtrAdv (Router Advertisement Messages): After receiving the route request signal, the NMAG will generate a route broadcast signal containing the mobile node's home network prefix, which will be used as the connection prefix. So far, the connection link between the mobile node and the new mobile access gateway is established.

 Step 501: Link layer (layer 2) handover: When the mobile node arrives within the range of the NMAG (new mobile access gateway), it receives a wireless signal sent from the NMAG, and the signal contains route broadcast information, thereby moving The node can obtain the prefix information of the NMAG.

 Step 502: Proxy Binding Update (PBU): The OMAG (Old Mobile Access Gateway) sends a proxy binding update signal to the LMA, notifying the LMA mobile node that a handover is to be initiated, requesting to release the pre-mobile access gateway (MAG). Binding of the Proxy-CoA to the MN-HoA (home address) of the mobile node.

Step 503: Proxy Binding Acknowledgement (PBA): The LMA sends a PBA signal to the OMAG, indicating that the proxy binding update signal has been received. Step 504: Proxy Binding Update (PBU): The new mobile access gateway (NMAG, New Mobile Access Gateway) sends a binding registration request signal to the LMA, requesting to establish the MN-HoA of the mobile node and the Proxy of the NMAG. Binding of CoA (Proxy-CoA, proxy care-of address).

 Step 505: Proxy Binding Acknowledgement (PBA): The LMA sends a registration response signal to the NMAG, indicating that the proxy binding update signal has been received.

 Step 506: A bidirectional tunnel between the NMAG and the LMA is established. The two-way tunnel hides the network topology. The mobile node can easily access the mobile access gateway using any network link by using the address of its home network prefix. The two-way tunnel is encapsulated in the "IP-in-IP" manner. (See RFC2473 for details).

 The PMIP protocol only gives the handover management of the mobile terminal under the same LMA.

The existing PMIP protocol of the LMA management scope cannot be solved.

 Such constant anchor points can cause a series of problems. For example, it leads to a widely recognized routing problem in the industry: The location of the terminal can change during the connection and use of the service. When the terminal is currently located away from its anchor point, the data stream that the terminal interacts with the outside world is also forwarded through its anchor point. Especially when the current location of the terminal is closer to the service source it accesses, the routing roundabout problem will be more obvious. On the one hand, routing detours will waste the carrier's transmission bearer resources, which is not conducive to cost savings. On the other hand, it increases the delay between the terminal and the communication peer to send and receive IP data packets, which is not conducive to improving the user's service experience. When the IP packet of the terminal is transmitted on the network, it encounters the possibility of network congestion, which causes the terminal service to be blocked or even impossible to implement (for example, real-time services such as voice and video).

In LISP-PMIP, a mobility scenario in which an anchor point changes is proposed. In LISP-PMIP, hierarchical IPIP is used to achieve mobility across anchors, that is, when terminal moves from one anchor (old ETR, OETR) to another (new ETR, NETR) The mobile terminal is attached to the new ETR (NETR). At this time, the mobile terminal communicates using the new IP address, that is, the NLROC where the NETR is located, but the EID of the mobile terminal does not change. The MS (Map-Server) in LISP updates the mapping of its stored EID to the RLOC where the ETR attached to the mobile terminal is located. The ETR attached to the mobile terminal updates the binding between the stored EID and the CoA (care-of address) of the MAG and the EID. The NETR updates the binding between the CoA and the EID where the NMAG is located. NETR registers the mapping update of NLROC and EID to the MS. The update of the MS in LISP guarantees the MN's The packet is sent to the CN via the new ETR.

 The above description of LISP-PMIP is only a brief mobility change scenario of anchor point change. When the terminal moves from the OETR to the NETR when the terminal moves, the data packet is switched to the NETR forwarding through OETR forwarding. There is no specific program introduction. Summary of the invention

 The technical problem to be solved by the present invention is to provide a LISP mobility implementation method and a tunnel router to solve the technical problem that the OELR cannot correctly forward packets when the anchor point changes.

 To solve the above technical problem, the present invention provides a mobility implementation method for a Address Separation Protocol (LISP), the method comprising:

 The new egress tunnel router (NETR) obtains a routing tunnel (ORLOC) attached to the old egress tunnel router (OETR) attached before the handover of the mobile node (MN), and establishes a forwarding tunnel with the OETR;

 The OETR forwards the packet with the destination terminal identifier (EID) to the MN to the NETR through the forwarding tunnel.

 Preferably, the NETR queries the mapping server (MS) according to the EID of the MN to obtain the ORLOC.

 Preferably, the NETR queries the mapping server (MS) to obtain the ORLOC according to the EID of the MN, and registers with the MS to update the binding relationship between the EID of the MN and the routing location (NRLOC) of the NETR. .

 Preferably, the step of establishing, by the NETR, a forwarding tunnel between the ORLOC and the OETR includes:

 The NETR sends a forwarding tunnel establishment request to the OETR according to the ORLOC, where the routing location (NRLOC) of the NETR and the EID of the MN are carried;

 And the OETR returns a tunneling response to the NETR, and saves a binding relationship between the EID of the MN and the NRLOC.

Preferably, after the OETR saves the binding relationship between the EID and the NRROC for a predetermined time, the binding relationship between the EID and the NRROC is deleted. To solve the above technical problem, the present invention further provides a tunnel router, where the tunnel router includes:

 A switching management unit, configured to: obtain, as NETR, a routing location (ORLOC) of an old egress tunnel router (OETR) attached before a mobile node (MN) handover;

 a forwarding tunnel establishing unit, configured to: when a new egress tunnel router (NETR) is used, establish a forwarding tunnel by interacting with an OETR attached before the MN handover; and as an OETR, establishing a forwarding tunnel by interacting with the NETR attached after the MN handover ;

 The message forwarding unit is configured to: when the OETR is used, forward the destination terminal identifier (EID) to the MN through the forwarding tunnel to the NETR.

 In the embodiment of the present invention, the LISP-PMIP scheme is extended. When the terminal moves from the OETR to the NETR when the terminal moves, the forwarding tunnel is established between the OETR and the NETR, and the OETR needs to forward the packet to the MN through the NETR. The forwarding tunnel between the two is forwarded, so that the LISP mobility solution is more complete, and the LISP network has no seamless routing and routing. BRIEF abstract

 Figure 1 is a schematic diagram of a LISP network structure;

 Figure 2 is a schematic diagram of the LISP data forwarding process;

 FIG. 3 is a schematic structural diagram of a mobile management network based on LISP-PMIP;

 Figure 4 is a schematic diagram showing the structure of a PMIP mobile management network;

 Figure 5 is a schematic diagram of a PMIP handover management signal flow;

 FIG. 6 is a schematic diagram of a flow chart of a method for implementing mobility based on LISP according to the present invention; FIG. 7 is a schematic diagram of a network structure of a method for implementing mobility based on LISP according to the present invention; FIG. 8 is a schematic diagram of mobility implementation based on LISP according to the present invention; Signal flow chart of method embodiment 2; FIG. 9 is a schematic diagram of a unit structure of a tunnel router based on LISP according to an embodiment of the present invention. Preferred embodiment of the invention

In order to solve the LISP protocol can not support the lack of mobility and personal draft LISP-PMIP technology The invention provides a method for implementing mobility management based on LISP. Embodiments of the invention are based on LISP and PMIP. The architecture of the solution of the embodiment of the present invention is as shown in FIG. 6, and includes a LISP network, a communication node MN, an ETR, an ITR, and a mapping server MS and MAG. The mapping server MS is a mapping between the stored EID and the RLOC address of the ETR.

MAG is a functional device introduced by LISP-PMIP, and ETR is equivalent to LMA in PMIP.

 The switch between the different MAGs in the same ETR directly uses the existing PMIP protocol. The process is shown in Figure 5, which is a problem in the prior art, and the packets sent by different ETRs cannot be correctly forwarded. The invention expands the LISP-PMIP scheme, and when the terminal moves from the OETR to the NETR when the terminal moves, the forwarding tunnel is established between the OETR and the NETR, and the OETR needs to forward the packet to the MN through the NETR. The forwarding tunnel is forwarded, so that the LISP mobility solution is more complete, and the LISP network has no seamless routing and routing.

 Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

 As shown in FIG. 6, the LISP-based mobility implementation method embodiment includes: Step 601: A new egress tunnel router (NETR) obtains a routing location of an old egress tunnel router (OETR) attached before a mobile node (MN) handover After (ORLOC), a forwarding tunnel is established with the OETR;

 The establishment of the forwarding tunnel between the NETR and the OETR requires that the initiator of the tunnel must know the IP address of the peer, that is, the RLOC where the peer is located. Before the NETR establishes the forwarding tunnel, the method further includes: The gateway (NMAG) sends a Proxy Binding Update (PBU) message to the NETR, which carries the EID of the MN. The NETR queries the mapping server (MS) to obtain the ORLOC according to the EID of the MN sent by the new mobile access gateway (NMAG), and establishes a forwarding tunnel between the ORLOC and the OETR.

 Preferably, when the NETR queries the mapping server (MS) according to the EID to obtain the ORLOC, the NETR registers with the MS to update a binding relationship between the EID and a routing location (NRLOC) of the NETR.

Preferably, NETR can request query and registration simultaneously by using one message, and of course, two messages can be separately queried and registered. After the NETR receives the binding update message of the NMAG in the above steps, the NETR registers the EID with the NRROC (the IP address of the NETR) in the MS, and the NETR queries the EID of the MS and the ORLOC by the EID of the MN. To obtain ORLOC, that is, NETR obtains the ORLOC of the IP address where the OETR is located by the MN's EID query.

 Step 602: The OETR forwards the packet whose destination address is the terminal identifier (EID) of the MN to the NETR through the forwarding tunnel.

 The step of the OETR forwarding the packet with the destination terminal identifier (EID) to the MN to the NETR through the forwarding tunnel includes:

 The OETR receives the first packet, the outer destination address of the first packet is ORLOC, and the inner layer destination address is the EID of the MN;

 The OETR decapsulates the outer address of the first packet and re-encapsulates it into a second file, and the outer destination address of the second packet is NRLOC;

 The OETR forwards the second packet to the NETR through the forwarding tunnel.

 In the mobility management process of the LISP, the NETR queries to obtain the ORLOC where the OETR is located by registering the updated EID/NRLOC mapping in the MS, and establishes a tunnel between the new ETR and the old ETR, and moves through the NETR after the handover. Sending packets, seamlessly switching the LISP network without routing and routing.

 In this method, the EID is obtained through static configuration. In the LISP network, the EID of the MN remains unchanged before and after the handover. When the mobile node MN moves from one location to another, the MN switches from the connected OETR to the NETR, and the IP addresses of the OETR and the NETR are different, that is, the routing addresses of the MN are ORLOC and NLROC, respectively, but the MN The identity indicator EID is unchanged, that is, before and after the MN moves, the MN communicates with the opposite CN by using different RLOCs, but the user indicates that the EID is unchanged, and the seamless handover of the LISP network is ensured.

 Example 2

 The MN transmits and receives data through the OMAG and its anchor OETR before the mobile handover.

 After the MN moves, the signal flow of the LISP-based mobility implementation method is as shown in FIG. 7 and FIG. 8, and includes:

Step 701a: proxy binding update (PBU); The MN switches from the OMAG to the NMAG and switches from the OETR to the NETR. The NMAG sends a PBU message to the NETR where it is located. (This message carries the EID of the MN, the address of the ETR is NNROC, notifies the NERT mobile node that a mobile handover occurs, requesting to update the NLROC and the EID. The binding relationship and the binding relationship between NLROC and NMAG's proxy-CoA.

 Step 701b: Proxy binding confirmation (PBA);

 After the NETR receives the binding update message, the NETR updates the binding between the NRLOC and the EID and sends a binding confirmation message to the NMAG, indicating that the binding update information has been received.

 Steps: 702a: NETR sends a registration request to the MS, requests registration of the binding relationship between the NRLOC and the EID, and queries the ORLOC of the OETR;

 NETR will register the NRLOC/EID in the MS, and NETR will query the ORLOC where the OETR is located through the EID;

 Step 702b: The MS updates its stored ORLOC and EID binding to the binding of the NRLOC and the EID, and returns a registration and query response, and the message carries the EID of the ORLOC and the MN;

 Step 703a: After step 702b, the NETR sends a forwarding tunnel establishment request to the OETR according to the obtained ORLOC, where the message carries the EID and the NRLOC;

 Step 703b: After receiving the forwarding tunnel establishment request, the OETR establishes a tunnel with the NETR according to the mobility related message (establishing a tunnel refers to saving the correspondence between the EID and the NRLOC), and returning the forwarding tunnel establishment response to the NETR;

 Step 704: The OETR forwards the EID of the MN whose destination address is the MN to the NETR through the established forwarding tunnel, and the subsequent packet forwarding is performed by the NETR.

 The OETR first encapsulates the packet with the destination NRLOC. After the packet arrives at the NETR, the NETR decapsulates the packet.

 The step of the OETR forwarding the packet with the destination terminal identifier (EID) to the MN to the NETR through the forwarding tunnel includes:

 The OETR receives the first packet, the outer destination address of the first packet is ORLOC, and the inner layer destination address is the EID of the MN;

The OETR decapsulates the outer address of the first packet, and re-encapsulates the second packet according to the binding relationship between the EID of the MN and the NLROC, and the outer destination of the second packet Address is NNROC;

 The OETR forwards the second packet to the NETR through the forwarding tunnel.

 The OETR enables a timer t locally while establishing a forwarding tunnel. When the timing expires, the binding relationship between the EID and the NLROC cached in the OETR is deleted, that is, the tunnel is removed, so as to avoid long-term switching between the NETR and the OETR. Packet forwarding is performed through the OETR, causing route bypass.

 Preferably, the MS can notify the ITR attached to the sending end of the MN after the registration of the binding relationship between the NRLOC and the EID is completed, so that the ITR sends the message to the NETR in time.

 After the mobile switch, the MN sends and receives data through the NMAG and its anchor NETR. To achieve the above method, the present invention also provides a tunnel router. As shown in FIG. 9, the tunnel router includes:

 The switching management unit, when used as the NETR, is used to obtain the routing location (ORLOC) of the old egress tunnel router (OETR) attached before the mobile node (MN) handover;

 The forwarding tunnel establishing unit, when acting as a new egress tunneling router (NETR), is configured to establish a forwarding tunnel in interaction with the OETR attached before the MN handover; and as an OETR, to establish a forwarding tunnel by interacting with the NETR attached after the MN handover ;

 The message forwarding unit, when the OETR is used, forwards the destination terminal identifier (EID) to the MN through the forwarding tunnel to the NETR.

 Preferably, the handover management unit is further configured to receive a proxy binding update (PBU) message sent by a new mobile access gateway (NMAG), where the EID of the MN is carried.

 Preferably, the handover management unit acquires the ORLOC from a mapping server (MS) according to an EID of the MN, and the forwarding tunnel establishing unit establishes a forwarding tunnel according to the ORLOC and the OETR.

 Preferably, the text forwarding unit includes:

 The message receiving module, when the OETR is used, is configured to receive the first packet, where the outer layer destination address of the first packet is ORLOC, and the inner layer destination address is the EID of the MN;

a packet processing module, when used as an OETR, to decapsulate an outer address of the first packet, And re-encapsulating into the second text, the outer destination address of the second text is NNROC;

 The message sending module, when the OETR is used, is configured to forward the second packet to the NETR by using the forwarding tunnel.

 Preferably, the forwarding tunnel establishing unit includes:

 a tunneling message sending module, as a NETR, configured to send a forwarding tunnel establishment request to the OETR according to the ORLOC, where the forwarding tunnel establishment request carries a routing location (NRLOC) of the NETR and an EID of the MN; Used to send a forwarding tunnel establishment response to the NETR;

 a tunnel message receiving module, configured to receive a forwarding tunnel establishment request sent by the NETR when the OETR is used, and a forwarding tunnel establishment response for receiving the OETR transmission when the NETR is used, and a binding relationship maintenance module, when used as an OETR, And binding a binding relationship between the EID of the MN and the NLROC according to the forwarding tunnel establishment request.

 Preferably, the packet processing module encapsulates the second packet according to the binding relationship between the EID of the MN and the NRLOC in the binding relationship maintenance module.

 Preferably, when the OETR is used as the OETR, the binding relationship maintenance module is further configured to delete the binding relationship between the EID of the MN and the NRLOC after a predetermined time.

 The above description focuses on the different functional units of the tunnel router and the prior art. It is understood that the tunnel router of the present invention further includes other functional units in the prior art that do not conflict with the present invention.

 The foregoing method and the embodiment of the tunnel router are described based on the architecture shown in FIG. 7. It can be understood that, in the architecture without the MAG or in the new architecture that evolves later, if the ETR handover occurs, the present invention The same applies.

One of ordinary skill in the art will appreciate that all or a portion of the above steps may be performed by a program to instruct the associated hardware, such as a read only memory, a magnetic disk, or an optical disk. Alternatively, all or part of the steps of the above embodiments may also be implemented using one or more integrated circuits. Correspondingly, each unit/module in the foregoing embodiment may be implemented in the form of hardware, or may be implemented in the form of a software functional unit. The invention is not limited to any specific form of combination of hardware and software. Industrial applicability

 In the embodiment of the present invention, the LISP-PMIP scheme is extended. When the terminal moves from the OETR to the NETR when the terminal moves, the forwarding tunnel is established between the OETR and the NETR, and the OETR needs to forward the packet to the MN through the NETR. The forwarding tunnel between the two is forwarded, so that the LISP mobility solution is more complete, and the LISP network has no seamless routing and routing.

Claims

Claim A method for implementing a mobility separation protocol (LISP), the method comprising: a new egress tunnel router (NETR) obtaining a routing location of an old egress tunnel router (OETR) attached before a handover of a mobile node (MN) (ORLOC) After establishing a forwarding tunnel with the OETR;  The OETR forwards the packet with the destination terminal identifier (EID) to the MN to the NETR through the forwarding tunnel. 2. The method of claim 1, wherein before the NETR acquires the ORLOC, the method further comprises: a new mobile access gateway (NMAG) transmitting a Proxy Binding Update (PBU) message to the NETR, wherein Carrying the EID of the MN. The method according to claim 1 or 2, wherein the NETR queries the mapping server (MS) to obtain the ORLOC according to the EID of the MN. 4. The method according to claim 3, wherein the NETR queries the mapping server (MS) to obtain the ORLOC according to the EID of the MN, and registers with the MS to update the EID of the MN and the NETR. Binding relationship of the routing location (NRLOC). The method of claim 1, wherein the step of the OETR forwarding the packet with the destination terminal identifier (EID) to the MN to the NETR through the forwarding tunnel comprises:  The OETR receives the first packet, the outer destination address of the first packet is ORLOC, and the inner layer destination address is the EID of the MN;  The OETR decapsulates the outer address of the first packet and re-encapsulates it into a second file, and the outer destination address of the second packet is NRLOC;  The OETR forwards the second packet to the NETR through the forwarding tunnel. The method according to claim 1 or 5, wherein the step of establishing a forwarding tunnel between the ORLOC and the OETR according to the NETR includes: The NETR sends a forwarding tunnel establishment request to the OETR according to the ORLOC, Carrying the routing location (NRLOC) of the NETR and the EID of the MN;  And the OETR returns a tunneling response to the NETR, and saves a binding relationship between the EID of the MN and the NRLOC. The method of claim 6, wherein the OETR encapsulates the second packet according to a binding relationship between an EID of the MN and the NRLOC. The method of claim 6, wherein the OETR saves the binding relationship between the EID and the NRLOC after the binding relationship between the EID and the NRLOC is deleted. 9. A tunnel router, the tunnel router comprising:  A switching management unit, configured to: obtain, as NETR, a routing location (ORLOC) of an old egress tunnel router (OETR) attached before a mobile node (MN) handover;  a forwarding tunnel establishing unit, configured to: when a new egress tunnel router (NETR) is used, establish a forwarding tunnel by interacting with an OETR attached before the MN handover; and as an OETR, establishing a forwarding tunnel by interacting with the NETR attached after the MN handover ;  The message forwarding unit is configured to: when the OETR is used, forward the destination terminal identifier (EID) to the MN through the forwarding tunnel to the NETR. The tunnel router according to claim 9, wherein the handover management unit is further configured to: receive a proxy binding update (PBU) message sent by a new mobile access gateway (NMAG), where the EID of the MN is carried . The tunnel router according to claim 9 or 10, wherein the handover management unit is configured to: query the mapping server (MS) to obtain the ORLOC according to the EID of the MN. The tunnel router according to claim 11, wherein the forwarding tunnel establishing unit is configured to: establish a forwarding tunnel between the ORLOC and the OETR. The tunnel router according to claim 9, wherein the packet forwarding unit comprises: a message receiving module, configured to: when the OETR is received, receive the first packet, and the outer destination of the first packet The address is ORLOC, and the inner layer destination address is the EID of the MN; a packet processing module, configured to: when the OETR is used, decapsulate the outer address of the first packet, and re-encapsulate the second packet, and the outer destination address of the second packet is NNROC;  The message sending module is configured to: when the OETR is used, forward the second packet to the NETR through the forwarding tunnel. The tunnel router according to claim 9 or 12, wherein the forwarding tunnel establishing unit comprises:  The tunnel message sending module is configured to: when the NETR is used, send a forwarding tunnel establishment request to the OETR according to the ORLOC, where the forwarding tunnel establishment request carries the routing location (NRLOC) of the NETR and the EID of the MN; Sending a forwarding tunnel establishment response to the NETR;  The tunnel message receiving module is configured to: when the OETR is used, receive the forwarding tunnel establishment request sent by the NETR; when the NETR is received, receive the forwarding tunnel establishment response sent by the OETR; and the binding relationship maintenance module is set to: And, according to the forwarding tunnel establishment request, the binding relationship between the EID of the MN and the NLROC is saved. The tunnel router according to claim 14, wherein the message processing module is configured to: encapsulate the number according to a binding relationship between an EID of the MN and the NNROC according to the binding relationship maintenance module Two messages. The tunnel router according to claim 14, wherein the binding relationship maintenance module is further configured to: delete the binding relationship between the EID of the MN and the NRLOC after a predetermined time as the OETR.