KR100596383B1 - Route optimazation method using prefix delegation protocol - Google Patents

Abstract

A route optimization method using a prefix delegation protocol is disclosed. In a method for optimizing a communication path between a mobile node and a corresponding node, a mobile router associated with the mobile node is assigned a predetermined prefix from an access router of the access network. The mobile router transmits the prefix to at least one mobile node connected to the mobile router, and generates a first temporary address CoA based on the prefix received by the mobile node receiving the prefix. The binding is performed based on the first temporary address CoA generated by the mobile node. Thus, when the mobile node communicates with the correspondent node, it is possible to establish a communication path through which the mobile node and the correspondent node can communicate directly without using a bidirectional tunnel between the mobile node and the home agent of the mobile node.

Mobile Router, Access Router, Prefix, Temporary Address (CoA), Binding

Description

Route optimization method using prefix delegation protocol

1 is a diagram illustrating a network topology before two mobile routers move from a home link to an external link.

2 is a diagram illustrating a network topology after a mobile router moves to an access router link.

3 is a diagram illustrating a network topology including a path optimization method using a prefix delegation protocol according to the present invention;

4 is a diagram illustrating an embodiment of a delegation prefix option format used in a path optimization method using a prefix delegation protocol according to the present invention;

5 is a flowchart illustrating a path optimization method using a prefix delegation protocol according to the present invention.

The present invention relates to a method for optimizing a communication path between a mobile node and a correspondent node in an IPv6-based mobile network environment, and more specifically, using a prefix delegation protocol. The present invention relates to a path optimization method for establishing a direct communication path between a mobile node and a corresponding node without tunneling between a mobile router and a home agent.

The Network Engineering Mobility (NEMO) Working Group of the Internet Engineering Task Force (IETF) proposes a basic routing scheme for mobility support in IPv6 mobile networks. The basic routing technique of mobile networks supports Internet connectivity to allow Internet users to receive Internet services while using mobile nodes such as buses, cars, subways, airplanes, and ships. Such mobile transportation is a network including one or more terminals, and there may be another mobile network in the mobile network.

Conventional mobile network routing schemes establish a bidirectional tunnel between the mobile router and its home agent and allow all nodes in the mobile network to communicate with other nodes on the Internet through that tunnel.

When the mobile router detects the movement, it sends a binding update message to its home agent and creates a mobile network prefix binding entry. That is, a packet transmitted by a Correspondent Node to a node in a mobile network is transmitted to the home network of the mobile router, and has a binding for transmitting the mobile network prefix to a care of address (CoA) of the mobile router. The home agent intercepts this packet and encapsulates the CoA of the mobile router in the destination address and sends it.

Therefore, as the external link visited by the mobile network moves away from the home network, the delay time due to tunneling increases, and the mobile router encapsulates and decapsulates the packets for all nodes in the mobile network.

Prefix Delegation Protocol is a mechanism for automatic delegation of IPv6 network prefixes from the upper router to the lower router. In other words, the requesting router performs the function of requesting a specific size prefix to the delegating router and informs the delegating router of the routing protocols that it can support so that the delegating router can determine the routing mechanisms supported by the requesting router and each other. do.

Several message formats are defined to support this feature, which includes the prefix request message used to request prefix delegation and the prefix delegation used to announce new prefixes and lifetimes, routing protocol information, or error information. Messages, etc.

Conventional prefix delegation protocols include APD (Automaic Prefix Delegation), RA-PD (Router Advertisement-Prefix Option), DHCPv6, and the like. These methods need to be extended to be applied to the hierarchical network structure of IPv6.

An object of the present invention is to establish a path in which communication between a mobile node and a corresponding node can communicate directly without using a bidirectional tunnel between the mobile node and the home agent of the mobile node in communication between the mobile node and the corresponding node. To provide a route optimization method using a prefix delegation protocol.

In order to achieve the above technical problem, an embodiment of a path optimization method using a prefix delegation protocol according to the present invention is a method for optimizing a communication path between a mobile node and a corresponding node, wherein the mobile router is connected to the mobile node. Is assigned a prefix from an access router of the access network; Transmitting, by the mobile router, the prefix to at least one mobile node connected to the mobile router; Generating, by the mobile node receiving the prefix, a first temporary address (CoA) based on the prefix; And performing binding by the mobile node based on the generated first temporary address CoA.

Thus, when the mobile node communicates with the correspondent node, it is possible to establish a communication path through which the mobile node and the correspondent node can communicate directly without using a bidirectional tunnel between the mobile node and the home agent of the mobile node.

Hereinafter, a path optimization method using a prefix delegation protocol according to the present invention will be described in detail with reference to the accompanying drawings.

First, the terms used in the present invention are defined as follows.

A home network is a network in which a mobile node communicates with a home address that follows the home link prefix before moving.

A home agent is a router that has registration information of a mobile node among routers in a home network of the mobile node and sends a datagram to the current location of the mobile node when the mobile node leaves the home network.

A mobile network is a network composed of one or more IP subnets connected to the Internet through one or more mobile routers, and refers to a mobile network that moves as a unit capable of dynamically changing a point of attachment (POA).

A mobile router is a router that can dynamically change the POA while connecting a mobile network and the Internet. An interface connected to the mobile network is called an ingress interface, and an interface connected to an internet link is called an egress interface.

Local Mobile Nodes (LMNs) are hosts or routers whose home links can move on the topology of a mobile router belonging to a mobile network. A visiting mobile node (VMN) is a host or router that a home link can move on to a topology of a mobile router that does not belong to a mobile network. A Correspondent Node is a host or router that communicates with a mobile node.

An access network is a network to which a mobile router moves and is currently connected. An access router is a router connected to a mobile router in an access network to which the mobile router connects.

The binding matches the CoA registered in the home agent with the home address of the node when the mobile node moves to the external network. If the mobile node does not update within a certain lifetime, it is invalidated.

The AAA server stands for Authentication, Authorization, and Accountion Server. It is a server that prevents illegal use of the service, grants and verifies the subscriber's authority level, and measures network usage for billing and resource planning.

The present invention is a path optimization technique for mobile nodes in a mobile network. The mobile router in charge of the mobile network advertises it into the mobile network by delegating the correct IPv6 prefix from the access network to which it is connected. The mobile node generates a CoA that can communicate using the prefix and performs a binding update with the corresponding node, whereby data packets can be exchanged through an optimized path.

Even if the mobile router manages the mobile network and moves to another network, the mobile router guarantees the connection of all nodes in the mobile network by supporting the mobile network basic routing scheme. In the present invention, the mobile router is extended as follows to support path optimization of the mobile node in the mobile network.

(1) The administrator can set the mobile router on whether to support path optimization.

(2) If it is set not to support path optimization, it operates according to basic routing technique.

(3) If it is set to support route optimization, it must receive IPv6 prefix block through Prefix Delegation Protocol after detecting movement.

(4) If it is set to support route optimization, if the access router fails to find the prefix delegator, the mobile network basic routing scheme is applied.

(5) The mobile routers may be a prefix request router or a prefix delegate router that is delegated an IPv6 prefix from the access network.

(6) A mobile router that has been delegated an IPv6 prefix advertises its prefix information by sending a Router Advertisement Message containing a Delegated Prefix Option into its own mobile network. At this time, the prefix is included in the prefix field of the Delegated Prefix Option.

The mobile node of the mobile network is composed of a local mobile node (LMN) and a visited mobile node (VMN). The following operations are extended for mobile nodes equipped with Mobile IPv6 function for path optimization in mobile network.

(1) Delegate the prefix prefix option, which is a new router advertisement option. The mobile node uses the prefix to generate CoA.

(2) The CoA is used as the primary CoA.

(3) Even if the local mobile node is in the home link, if it receives the delegation prefix option, it should process the above (1) (2) and delete the binding information performed when the mobile node returns to the home link. Do not perform deregistration.

After creating the Primary CoA, the binding update message may be transmitted to its home agent and the corresponding node as described in the Mobile IPv6 protocol, and then communicated with the corresponding node through an optimal path.

1 is a diagram illustrating a network topology before two mobile routers move from a home link to an external link.

Referring to FIG. 1, a network topology includes a corresponding node 110, a home agent 120 of a first mobile router, a home agent 120 of a second mobile router, and an access router 140 around the Internet 100. Connected. Each home agent 120, 130 includes at least one mobile router 122, 132, and each mobile router 122, 132 includes at least one local mobile node 124, 134 or visited mobile node 126, 136.

When the first mobile router 122 and the second mobile router 132 are on their home links, each mobile router 122, 132 has its own mobile network prefix as 1: 1 :: and 2, respectively. Use the: 1 :: prefix. Here, 1: 1 :: and 2: 1 :: are used to simply express a prefix having a predetermined bit length, and use the form of prefix :: address. That is, the prefix of the home agent 120 of the first mobile router 122 is 1 ::, and the mobile nodes 124 and 126 of the first mobile router 122 have a 1: 1 :: prefix.

The access router 140 is a router connected to the mobile routers 122 and 132 when the mobile routers 122 and 132 move.

2 is a diagram illustrating a network topology after a first mobile router and a second mobile router move to an access router link.

Referring to FIG. 2, a network topology includes a corresponding node 210, a home agent 220 of a first mobile router, a home agent 230 of a second mobile router, and an access router 240 around the Internet 200. Connected. The first mobile router 250 moves and is connected to the access router 240 link, and the second mobile router 260 is moved and connected to the link of the first mobile router 250.

The first mobile router 250 and the mobile nodes 252 and 254 connected to the first mobile router 250 generate a care of address (CoA) as a prefix of the visited link. In addition, the first mobile router 250 and the second mobile router 260 attempt to receive the prefix using the prefix delegation protocol according to the present invention. That is, the first mobile router 250 and the second mobile router 260 search for the prefix delegator, and if it fails to find the prefix delegator, it supports mobility using the basic routing technique of the mobile network.

The second mobile router 260 moving to the link of the first mobile router 250 generates a temporary address CoA based on the prefix of the first mobile router 250 link. Since the mobile network prefix of the first mobile router 250 is 1: 1 ::, the second mobile router 260 generates 1: 1 :: 3 as a temporary address. The second mobile router also attempts to be assigned a prefix using the prefix delegation protocol according to the present invention.

Accordingly, the first mobile router 250 and the second mobile router 260 generate CoA according to the prefix of the link to which each is connected, and generate CoA using the prefix delegation protocol according to the present invention. This will be described in detail with reference to FIG. 3.

3 is a diagram illustrating a network topology including a path optimization method using a prefix delegation protocol according to the present invention.

Referring to FIG. 3, the network topology includes the corresponding node 310, the home agent 320 of the first mobile router, the home agent 330 of the second mobile router, and the access router, as shown in FIG. 2. 340 is connected. The first mobile router 350 moves and is connected to the link of the access router 340, and the second mobile router 360 is moved and connected to the link of the first mobile router 350.

When the first mobile router 350 moves from the home agent 320 to the access router 340, the first mobile router 350 generates a temporary address CoA based on the prefix of the link of the access router 340. That is, the first mobile router 350 generates the address 3: 1 including the prefix 3 :: of the access router 340 as a temporary main coA. The home address HoA and the mobile network prefix of the first mobile router 350 are generated based on the prefix of the home agent 320 of the first mobile router to which the first mobile router 350 is connected prior to the movement. .

The mobile nodes 352 and 354 connected to the first mobile router 350 generate a temporary address CoA based on the mobile network prefix of the mobile router. Here, since the mobile network prefix of the first mobile router is 1: 1 ::, the temporary addresses CoAs generated by the mobile nodes 353 and 354 are 1: 1 :: 5 and 1: 1 :: 6, respectively.

In the prefix delegation protocol according to the present invention, the prefix is delegated from the access router 340 or the upper mobile router 350 to which the respective mobile routers 350 and 360 are connected in addition to the generation of the temporary address CoA. The mobile router 350 may request the prefix delegation to the direct access router 340, or the access router 340 may directly delegate the prefix when the mobile router 350 is connected.

Referring to FIG. 3, the first mobile router 350 makes a prefix delegation request to the access router 340, and then prefixes 3: 1:: of the access network including the current access router 340 from the access router 340. Is delegated. The second mobile router 360 makes a prefix delegation request to the first mobile router 350 to receive the prefix 3: 1: 1 :: from the first mobile router 350. That is, the first mobile router 350 performs both operations of the prefix request router and the prefix delegation router.

In the present invention, a delegated prefix option format is defined and used to inform delegated prefix information to respective mobile nodes, and the delegated prefix information is carried in the prefix field of this option. The delegation prefix option format will be described in detail with reference to FIG. 4.

The first mobile router 350 and the second mobile router 360 transmit the router advertisement message including the delegation prefix option to each mobile node after delegating the prefix.

When each mobile node 352, 354, 362, 364 receives a Router Advertisement message including the delegation prefix option, it processes the delegation prefix option first. That is, the mobile nodes generate CoAs using the delegation prefix and perform binding updates on their home agents 320 and 330 and the corresponding nodes 310. If the mobile node does not have a delegation prefix option in the router advertisement message, it generates a CoA in a conventional manner and performs binding updates to the home agent and the corresponding node.

As shown in FIG. 3, CoA1 generated using a delegate prefix is used as the first CoA. This process has no effect on local fixed nodes. After performing the prefix delegation protocol, each router's routing table is updated with the routing protocol. This is possible because each router has information about the delegation prefix.

4 is a diagram illustrating an embodiment of a delegation prefix option format used in a path optimization method using a prefix delegation protocol according to the present invention.

Referring to FIG. 4, the delegation prefix option format 400 used in the present invention includes a type field 402, a length field 404, a prefix length field 406, and an L field. 408, A field 410, first reserved field 412, valid lifetime field 414, preferred lifetime field 416, second reserved field 418, and prefix field 420.

The type field 402 is a field for displaying a predefined type value to distinguish a delegate prefix option. The length field 404 indicates the length of the delegation prefix option format. The prefix length field 406 indicates the length of the prefix.

L field 408 is used to determine whether the prefix is used on-link or off-link. A field 410 determines whether the prefix is used for autonomous address configuration.

The Valid Lifetime field 414 indicates how long the prefix is valid for on-link determination. Preferred Lifetime field 416 indicates a period during which addresses generated from a prefix by Stateless address autoconfiguratin remain preferential.

Prefix field 420 represents a delegation prefix according to the present invention, where the first reserved field 412 and the second reserved field 418 are fields reserved for future use.

5 is a flowchart illustrating a path optimization method using a prefix delegation protocol according to the present invention.

Referring to FIG. 5, when the mobile router 350 moves from the home agent 320 link to the link of the access router 340, the mobile router 350 requests the access router 340 for delegation of prefix and from the access router. Prefix is assigned (S500). The mobile router 350 may detect movement by the neighbor discovery protocol of Mobile IPv6.

The mobile router 350 acts as a prefix delegation router when another second mobile router 360 is connected to its mobile network. That is, the second mobile router 360 requests the prefix delegation to the mobile router 350, and the mobile router 350 delegates the prefix to the second mobile router 360.

When the mobile router 350 detects the movement, the mobile router 350 may be assigned a prefix from the access router 340 after the authentication process using the AAA server.

By updating the routing table of each router using the routing protocol after the execution of the prefix delegation protocol according to the present invention, the path is optimized because the mobile node is connected to the corresponding node without bypassing the home agent and the bidirectional tunnel.

The mobile router 350 transmits the prefix allocated from the access router 340 to its mobile network using the router advertisement message (S510). The router advertisement message includes a delegation prefix option for supporting the prefix delegation protocol according to the present invention. The delegation prefix option has been described with reference to FIG. 4.

Each of the mobile nodes 352, 354, and 360 existing in the mobile network of the mobile router 350 generates a CoA by using the delegation prefix option of the received router advertisement message (S520).

Accordingly, the mobile node generates two CoAs, a first CoA generated based on the delegation prefix of the mobile router according to the present invention, and a second CoA generated based on the access router link. The mobile node selects the first CoA generated based on the delegation prefix according to the present invention as the primary CoA, and binds it based on the CoA (S530).

If the mobile router 350 does not support the route optimization method using the delegation prefix according to the present invention, or if the mobile nodes 352 and 354 do not support the method according to the present invention, the access router 340 generates the link based on the access router 340 link. Binding with the second CoA.

The local mobile node 352 uses the CoA generated based on the delegation prefix when receiving the delegation prefix option even though it is on the home link. In addition, when the mobile node 352 returns from the external link to the home link, the mobile node 352 does not perform deregistration to delete the binding information. Each of the mobile nodes 352 and 354 performs a binding update on the home agent 320 and the corresponding node 310 using the CoA generated using the delegation prefix.

The correspondent node 310 checks its binding cache information for the packet to be transmitted to the mobile nodes 352 and 354, sets the destination address of the packet as the temporary address (CoA) of the mobile node, and sends the home address in the routing header. do. In this case, the temporary addresses of the mobile nodes 352 and 354 are routed to the corresponding network because they have the prefix of the network in which the mobile node is currently located. Since the routing tables are updated, the packets transmitted from the corresponding node 310 The mobile nodes 352 and 354 are transmitted to the network where the mobile nodes are located (S540).

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the present invention, when a mobile node in a mobile network communicates with a corresponding node, a prefix generated from the access network to which the mobile node belongs does not go through a bypass path through a bidirectional tunnel between the mobile router and the home agent of the mobile router. By using the address of the mobile network as CoA, it can communicate through the optimized path. Thus, data packet exchange over optimized paths minimizes data transmission latency, increases communication efficiency, and reduces the load and dependence of mobile routers and home agents.

Claims (9)

In the method for optimizing the communication path between the mobile node and the corresponding node, A mobile router connected to the mobile node assigned a predetermined prefix from an access router of an access network; Transmitting, by the mobile router, the prefix to at least one mobile node connected to the mobile router; Generating, by the mobile node receiving the prefix, a first temporary address (CoA) based on the prefix; And And performing binding by the mobile node on the basis of the generated first temporary address (CoA). The method of claim 1, And the step of assigning a prefix comprises assigning a network prefix on an actual topology of the mobile router connected to the access router. 2. The method of claim 1, prior to the prefix assignment step. Detecting, by the mobile router, a movement from a home network to the access network; And Requesting protocol delegation from the access router when the movement is detected. The method of claim 1, Updating a routing table of the mobile router using a routing protocol. The method of claim 1, The generating of the CoA includes generating a second temporary address (CoA) based on the prefix of the access router link, The performing of the binding may include binding to a home agent and the access router based on the first temporary address or the second temporary address. The method of claim 5, And wherein the performing of the binding comprises first selecting the first temporary address to perform a binding. The method of claim 1, And the transmitting step includes transmitting the prefix in a router advertisement message. The method of claim 1, And maintaining the binding result when the mobile node returns to the home network. The method of claim 1, The prefix assignment step includes the step of assigning the prefix from the access router after the mobile router is authenticated by the AAA server.

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