Client roaming from a first access node to a second access node within a wireless network

• US 7,586,879 B2
• Filed: 01/17/2006
• Issued: 09/08/2009
• Est. Priority Date: 06/24/2003
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited (Hitachi, Ltd.)
• Original Assignee: Tropos Networks Incorporated (ABB Limited)
• Inventors: Srikrishna, Devabhaktuni, Chari, Amalavoyal
• Primary Examiner(s): Moore; Ian N
• Application Number:
  US11/333,776
• Publication Number:
  US 20060133341A1
• Time in Patent Office: 1,330 Days
• Field of Search: 370/389, 370/310, 370/310.1, 370/312, 370/351, 370/314, 370328-345, 370/395.2, 370/442, 370/355, 370/326, 370/238, 370/469, 455/433, 455/436, 455/437, 455/439, 455/442, 455/445, 709/238, 709/239, 709/226, 709/230
• US Class Current: 370/331
• CPC Class Codes: H04L 12/2856 Access arrangements, e.g. Internet access asynchronous transfer mode networks H04L12/5601; broadband local area networks H04L12/2801; optical access or distribution networks H04Q11/0067; access to open networks H04L12/5691; digital subscriber line end-user equipment and bit-level processing of data on a PSTN-based network H04M11/00; home network gateways H04L12/2834; wireless access networks H04W
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 61/5014 using dynamic host configuration protocol [DHCP] or bootstrap protocol [BOOTP]
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 40/32 for defining a routing cluster membership
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A method that includes a client roaming from the first access node to a second access node is disclosed. The second wireless access node detects the client seeking access to the system. The second wireless access node is able to connect to the backbone network. Client information is obtained. The second wireless node provides the client a communication path to and from the destination. The communication path is able to include wired and wireless communication links. Routing of information through the communication path between the client and the destination is aided based upon detection of the client. The wireless connection between the second access node and the backbone network can include at least one wireless hop between the second access node and a fourth access node.

Claims

1. A method of allowing a client to roam from a first wireless access node to a second wireless access node within a wireless network, the method comprising:

providing the client by a first access node, a first communication path to and from a destination;

the client roaming from the first wireless access node to the second wireless access node;

detecting the client by the second access node, seeking access to the system, the second wireless access node wirelessly connected to a back bone network through a second gateway;

requesting client information by the second access node, including an IP address of the client from the second gateway, the request including a MAC address of the client;

performing a look up by the second gateway, of an anti-address resolution protocol (AARP) table, obtaining the IP address of the client based on the MAC address of the client;

receiving by the second wireless access node, the IP address of the client from the second gateway;

providing by the second wireless access node, the client a second communication path to and from the destination, the second communication path able to include wired and wireless communication links; and

aiding in routing of information through the second communication path between the client and the destination based upon detection of the client;

wherein

if the second gateway does not have the client information, then the second gateway requests the client information from another gateway; and

wherein

if none of the gateways have information regarding the client, then an IP address of the client is obtained by the first wireless access node by at least one of;

pinging the broadcast address, snooping IP datagrams originating from a MAC address of the client, the first wireless access node inspecting a DHCP acknowledgment packet.

2. The method of claim 1, wherein the wireless connection between the second wireless access node and the back bone network comprises at least one wireless hop.

3. The method of claim 1, wherein the first wireless access node and the second wireless access node belong to a common cluster.

4. The method of claim 1, wherein the first wireless access node belongs to a first cluster, and the second wireless access node belongs to a second cluster.

5. The method of claim 1, wherein the first cluster is connected to a first subnet, and the second cluster is connected to a second subnet.

6. The method of claim 1, wherein the second wireless access node allows the client to maintain a same default gateway IP address as the client roams from the first wireless access node to the second wireless access node.

7. The method of claim 1, wherein the second wireless access node allows the client to maintain a same default gateway MAC address as client roams from the first wireless access node to the second wireless access node.

8. The method of claim 1, wherein a first gateway maintains information pertaining to the client.

9. The method of claim 1, wherein the second gateway is within a same cluster as the second wireless access node.

10. The method of claim 1, wherein at least a third gateway not within a same cluster as the second wireless access node maintains information pertaining to the client.

11. The method of claim 1, wherein the second wireless access node references at least one of:

a second gateway within a same cluster as the second wireless access node, and a third gateway, to obtain client information regarding the client.

12. The method of claim 1, wherein the requests of the second gateway are transmitted over a back haul interface of the second gateway.

13. The method of claim 1, wherein information of the second gateway is updated with the obtained client information.

14. The method of claim 1, wherein if none of the gateways have information regarding the client, then a default gateway IP address of the client is obtained by interception and inspection by the second wireless access node of a DHCP acknowledgment packet sent to the client.

15. The method of claim 1, wherein the second gateway provides a proxy ARP so that a device outside of the wireless network is spoofed into sending frames addressed to the client IP address to a MAC address of the second gateway.

16. The method of claim 5, wherein the second gateway gratuitously sends an ARP to an edge router upon the client roaming from the first cluster to the second cluster so that an ARP cache within the edge router is updated.

17. The method of claim 6, wherein an IP-in-IP tunnel is created between a first gateway of the first cluster and the second gateway of the second cluster.

18. The method of claim 6, wherein information destined for the client through the first gateway is rerouted to the second gateway through an IP-in-IP encapsulated tunnel.

19. The method of claim 17, wherein the first gateway and the second gateway are maintained by a network management system, and the network management system controls creation, maintenance, and removal, of an IP-in-IP tunnel formed between the first gateway and the second gateway.

20. The method of claim 17, wherein data traffic for the client is received by the first gateway, encapsulated within an IP datagram having a same destination IP address as the second gateway, and routed through the tunnel.

21. The method of claim 20, wherein the second gateway decapsulates the IP datagram by stripping an IP header, and routes the data traffic based upon an IP destination address.

22. The method of claim 1, wherein both the IP address and a default gateway route on the client remain fixed as the client roams within a cluster, both the IP address and the default gateway route on the client remain fixed as the client roams between clusters having a common subnet, both the IP address and the default gateway route on the client remain fixed as the client roams between clusters having different subnets.

23. The method of claim 1, wherein aiding in a routing of information through the second communication path between the client includes updating a routing table for each of the access nodes and gateways that exist in the second communication path between the first wireless access node and the destination.