Telecommunications routing

• US 7,339,925 B2
• Filed: 10/26/2001
• Issued: 03/04/2008
• Est. Priority Date: 10/26/2000
• Status: Expired due to Fees

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: O'Neill, Alan W, Corson, Mathew S
• Primary Examiner(s): Jung; Min
• Application Number:
  US10/381,939
• Publication Number:
  US 20040048618A1
• Time in Patent Office: 2,321 Days
• Field of Search: 370/328, 370/329, 370/331, 370/400, 370/401, 370/356, 455/445
• US Class Current: 370/356
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/28 for reactive routing
• CPC Class Codes: H04W 40/30 for proactive routing
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

In a packet switched network, first said network address are allocated to a first mobile node being served via a communications link by a first access node, at least a first routing path in related infrastructure being directed to the first access node for the first network address.

Routing in said infrastructure is altered when the first mobile node receives service from a second access node, such that at least a second routing path in the infrastructure is directed to the second access node for the first network address, the second routing path being defined at least in part by one or more host-specific routing entries. During a period of subsequent inactivity, the one or more host-specific routing entries are removed from the infrastructure such that the mobile node has no current routing path. During the period of inactivity, two separate states are provided for the mobile node: a) a state in which the mobile node retains the first network address; and b) a state in which the first network address may be reallocated to a different mobile node.

Claims

1. A method of controlling routing of packets in a packet switched network including an infrastructure of packet switching nodes interconnected by packet transport links, and a plurality of access nodes to which a routing path, defined by routing entries held in packet switching nodes located along said routing path, may be directed in said infrastructure for a given network address, said method comprising:

allocating a first said network address to a first mobile node being served via a communications link by a first access node, at least a first routing path in said infrastructure being directed to said first access node for said first network address;

altering routing in said infrastructure when said first mobile node receives service from a second access node, such that at least a second routing path in said infrastructure is directed to said second access node for said first network address, said second routing path being defined at least in part by one or more host-specific routing entries;

during a period of subsequent inactivity, removing said one or more host-specific routing entries from said infrastructure such that said mobile node has no current routing path in said network; and

during said period of inactivity, providing two separate states for said mobile node;

a) a state in which said mobile node retains said first network address; and

b) a state in which said first network address may be reallocated to a different mobile node.

2. A method according to claim 1, wherein said step of removing host-specific routing is conducted by a routing erase message propagated from said second access node.

3. A method according to claim 2, wherein said step of removing host-specific routing is initiated by the second access node.

4. A method according to claim 2, wherein said step of removing host-specific routing is initiated by the mobile node.

5. A method according to claim 1, wherein in state a) the mobile node is arranged to re-establish host-specific routing by initiating a route injection process at a new access node when the mobile node again becomes active.

6. A method according to claim 1, wherein in state b) the mobile node is arranged to request the allocation of a new network address when the mobile node again becomes active.

7. A method according to claim 1, wherein entry into states a) and b) is controlled by timers.

8. A method according to claim 7, wherein state a) is arranged to precede state b).

9. A method according to claim 1, wherein said communications links is a wireless link.

10. A method according to claim 1, wherein said network address is an Internet Protocol (IP) address.

11. Routing apparatus comprising:

a plurality of routers respectively associated with packet switching nodes interconnected by packet transport links and arranged to carry out the steps of the method of claim 1.