Router apparatus, route information distributing method, and communications system

• US 20050047348A1
• Filed: 08/18/2004
• Published: 03/03/2005
• Est. Priority Date: 08/27/2003
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Suzuki, Toshihiro, Ishida, So
• Granted Patent: US 7,729,312 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 2101/659 Internet protocol version 6 [IPv6] addresses
• CPC Class Codes: H04L 2101/668 Internet protocol [IP] address subnets
• CPC Class Codes: H04L 2101/677 Multiple interfaces, e.g. multihomed nodes
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 61/50 Address allocation

Abstract

A router apparatus used in an IPv6 multihome network and capable of exchanging a network prefix as route information with an adjacent router is disclosed. The router apparatus comprises a pair information generator (52) configured to associate a prefix assigned from the network with a default route to generate a pair information item, and a routing protocol processor (51) configured to distribute the pair information item of the prefix and the associated default route to the adjacent router using a routing protocol.

Claims

1. A router apparatus used in an IPv6 multihome network and capable of exchanging a network prefix as route information with an adjacent router, the router apparatus comprising:

a pair information generator configured to associate a prefix assigned from the network with a default route to generate a pair information item; and

a routing protocol processor configured to distribute the pair information item of the prefix and the associated default route to the adjacent router using a routing protocol.

2. The router apparatus of claim 1, further comprising:

a routing table configured to set an address generation availability bit and a default route availability bit for the prefix, wherein the routing protocol processor is configured to read the address generation availability bit and the default route availability bit from the routing table, and determine a route based on the reading result.

3. The router apparatus of claim 2, wherein the routing protocol processor enters the default route, together with the prefix and a next hop of a packet, in the routing table when the default route availability bit indicates the availability of the default route.

4. The router apparatus of claim 1, wherein the routing protocol processor is configured to check the prefix of a received packet, compare predetermined upper bits of the source address of the received packet with the pair information item if the prefix of the received packet represents the default route, and transmit the received packet to the default route that is consistent with the predetermined upper bits.

5. A router apparatus located in a mobile network that is connected to a node in a core network and is moving dynamically while changing the node, the router apparatus comprising:

prefix changing means configured to update only a prefix assigned hierarchically to a mobile terminal located in the mobile network whenever the node changes as the mobile network moves.

6. The router apparatus of claim 5, further comprising:

distribution means configured to distribute a pair information item of the updated prefix and an associated default route to an adjacent router in the mobile network using a routing protocol.

7. A method of distributing route information used in an IPv6 multihome network capable of exchanging a prefix as route information among adjacent routers, the method comprising the steps of:

associating the prefix assigned from the network with a default route to generate a pair information item; and

distributing the pair information item to the adjacent routers using a routing protocol.

8. A route information distributing method comprising the steps of:

connecting a mobile network to a connection node of a core network;

updating only a prefix assigned hierarchically to a mobile terminal located in the mobile network whenever the connection node changes as the mobile network moves;

associating the updated prefix with a default route to make a pair; and

distributing the pair to an adjacent router in the mobile network using a routing protocol.

9. A communications system including multiple routers in an IPv6 multihome network, the system comprising:

a router apparatus configured to receive a prefix from the network, associtate the prefix with a default route to generate a pair information item, and distribute the pair information item to an adjacent router.