Patent ID: 7649866

Claim:
A method of a network allowing a client device to roam from a home subnet to a foreign subnet of the network, comprising: a first access node of the home subnet of the network providing the client device access to the network; each gateway of the network maintaining a list of all other gateways on all of a plurality of subnets of the network wherein gateways of different subnets are connected to different edge routers, the list comprising an IP address of each of the other gateways, a gateway status of each of the other gateways, and at least one subnet associated with each of the other gateways; a foreign gateway of the foreign subnet forming an IP-in-IP tunnel to a home gateway of the home subnet allowing the client device to roam to a second access node of the foreign subnet, the client device accessing the network through the second access node, the client device maintaining a fixed client IP address, default gateway IP address and IP subnet attachment as the client device roams from the first access node to the second access node; the foreign gateway periodically checking a status of the home gateway˜wherein the home gateway is connected to a different edge router than the foreign gateway; the client device generating a DHCP request; the second access node relaying the DHCP request to the foreign gateway of the foreign subnet; the foreign gateway further relaying the DHCP request to the home gateway of the home subnet: the home gateway proxying the DHCP request to a local DHCP server; the DHCP server sending a DHCP acknowledgement to the home gateway; the home gateway proxying the DHCP acknowledgement to the second access node; the second access node relaying the DHCP acknowledgement to the client device; the home gateway mapping a transaction identifier to an IP address of the second access node, and using the mapping to proxy the DHCP acknowledgement back to the second access node.