Two phase local mobility scheme for wireless access to packet based networks

• US 6,763,007 B1
• Filed: 12/11/1998
• Issued: 07/13/2004
• Est. Priority Date: 12/11/1998
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Murakami, Kazutaka, Ramjee, Ramachandran, Varadhan, Kannan, La Porta, Thomas F., Thuel, Sandra R.
• Primary Examiner(s): Sam, Phirin
• Application Number:
  US09/209,705
• Time in Patent Office: 2,041 Days
• Field of Search: 370/389, 370/310, 370/310.1, 370/310.2, 370/312, 370/351, 370/314, 370/352, 370/328, 370/329, 370/331, 370/332, 370/336, 370/338, 370/345, 370/395.52, 370/442, 370/355, 370/353, 370/356, 370/386, 370/238, 370/469, 455/433, 455/436, 455/437, 455/439, 455/442, 455/445
• US Class Current: 370/331
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04W 8/082 for traffic bypassing of mobility servers, e.g. location registers, home PLMNs or home agents
• 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

Local mobility within a subnet is supported by classifying wireless base stations, and the routers used to forward packets to those base stations, within defined domains. Domains are defined to incorporate a subnet having a plurality of base stations. Base stations are used by mobile devices to attach to the wired portion of a packet-based network, such as the Internet, and exchange packets thereover with a correspondent node. Packets sent from the correspondent node to the mobile device have a packet destination address corresponding to the mobile device. The mobile device retains this address for the duration of time it is powered up and attached to the Internet via any base station within a given domain. Host-based routing is utilized to update routing table entries corresponding to the mobile device at routers incorporated within a single domain. The routing table entries are established and updated via path setup schemes to convey packets destined for the mobile device along the proper established path through the domain routers and base stations, regardless of the domain base station through which the mobile device is attached. Path setup schemes utilize power up, refresh, and handoff path setup messages to maintain the proper relationship between router interfaces and packet addresses for routing table entries.

Claims

1. A method of establishing a routing path for packet delivery to a destination node within a packet-based subnet, said destination node having a destination node address, said method comprising the steps of:

launching a path setup message from said destination node;

receiving said path setup message over a first interface at a first router; and

creating a first routing table entry for a first routing table, said first routing table entry associating a second interface and said destination node address with said first interface,

wherein a packet, subsequently received over said second interface and having said destination node address as a packet header destination address, is forwarded from said first router over said first interface after said first router associates said second interface and said destination node address with said first routing table entry, and

wherein said first router is incorporated within a first wireless base station, further including forwarding a handoff path setup message, for handoffs processed at a network layer, from a second wireless base station to said first wireless base station if said wireless device is handed off from said first wireless base station to said second wireless base station, said handoff update path setup message used to alter routing table entries for a plurality of subnet routers and

further comprising the step of maintaining said first routing table entry as a soft state in said first router, said first routing table entry overwritten with a default entry if a refresh path setup message is not received at said router within a specified period of time.

2. The method in accordance with claim 1 wherein said destination node is a wireless device.

3. The method in accordance with claim 2 wherein said wireless device is a TDMA device.

4. The method in accordance with claim 1 wherein said first router is incorporated within a first wireless base station.

5. The method in accordance with claim 1 wherein said packet-based subnet is an Internet Protocol subnet.

6. A method of establishing a routing path for packet delivery to a destination node within a packet-based subnet, said destination node having a destination node address, said method comprising the steps of:

launching a path setup message from said destination node;

receiving said path setup message over a first interface at a first router; and

creating a first routing table entry for a first routing table, said first routing table entry associating a second interface and said destination node address with said first interface,

wherein a packet, subsequently received over said second interface and having said destination node address as a packet header destination address, is forwarded from said first router over said first interface after said first router associates said second interface and said destination node address with said first routing table entry, and

wherein said first router is incorporated within a first wireless base station, further including forwarding a handoff path setup message, for handoffs processed at a network layer, from a second wireless base station to said first wireless base station if said wireless device is handed off from said first wireless base station to said second wireless base station, said handoff update path setup message used to alter routing table entries for a plurality of subnet routers, and

wherein during a first handoff phase, data packets continue to arrive at an old base station and are then forwarded from the old base station to a new base station, and

during a second handoff phase, a dynamically determined cross-over router forwards the packets to the new base station.

7. The method in accordance with claim 6 wherein said plurality of subnet routers include at least said first wireless base station and said second wireless base station.

8. The method in accordance with claim 6 wherein said handoff path setup message is initiated from said wireless device.

9. A method for forwarding a received packet from a router, said method comprising the steps of:

forwarding said received packet over a first interface if said received packet includes a first packet header destination address and was received over a second interface; and

forwarding said received packet over a third interface if said received packet includes said first packet header destination address and was received over an interface other than said second interface,

wherein said router is incorporated within a first wireless base station, further including forwarding a handoff path setup message, for handoffs processed at a network layer, from a second wireless base station to said first wireless base station if said wireless device is handed off from said first wireless base station to said second wireless base station, said handoff update path setup message used to alter routing table entries for a plurality of subnet routers,

wherein said forwarding is performed in response to a lookup of a routing table entry in said routing table, said routing table entry including said first packet header destination address as a first field value and an interface over which said received packet arrives at said router as an ingress interface field value, and an egress interface field value.

10. The method in accordance with claim 9 wherein said second and third interfaces are the same interface.

11. The method in accordance with claim 9 wherein said routing table entry is formed in response to receiving a power up path setup message.

12. The method in accordance with claim 9 wherein said routing table entry is maintained as a valid entry in response to receiving a refresh path setup message.

13. The method in accordance with claim 12 wherein said router is a soft state router.

14. The method in accordance with claim 9 wherein said router is incorporated within a wireless base station.

15. The method in accordance with claim 9 wherein said wireless base station is a TDMA base station.

16. The method in accordance with claim 9 wherein said router is an Internet Protocol (IP) packet router.

17. A method for forwarding a received packet from a router, said method comprising the steps of:

forwarding said received packet over a first interface if said received packet includes a first packet header destination address and was received over a second interface;

forwarding said received packet over a third interface if said received packet includes said first packet header destination address and was received over an interface other than said second interface,

wherein said router is incorporated within a first wireless base station, further including forwarding a handoff path setup message, for handoffs processed at a network layer, from a second wireless base station to said first wireless base station if said wireless device is handed off from said first wireless base station to said second wireless base station, said handoff update path setup message used to alter routing table entries for a plurality of subnet routers, and

utilizing a dynamically determined cross-over router to forward packets to a new base station during a handoff process.

18. A method for forwarding a received packet from a router, said method comprising the steps of:

forwarding said received packet over a first interface if said received packet includes a first packet header destination address and was received over a second interface; and

forwarding said received packet over a third interface if said received packet includes said first packet header destination address and was received over an interface other than said second interface,

wherein said router is incorporated within a first wireless base station, further including forwarding a handoff path setup message, for handoffs processed at a network layer, from a second wireless base station to said first wireless base station if said wireless device is handed off from said first wireless base station to said second wireless base station, said handoff update path setup message used to alter routing table entries for a plurality of subnet routers, and

further including the step of maintaining said routing table entries as a soft state, said routing table entries overwritten with a default entry if a refresh path setup message is not received within a specified period of time.