Method of subnet roaming within a network
View Patent ↗Disclosed is an apparatus and method of client device roaming from a home subnet to a foreign subnet of a network. The method includes the client device accessing the network through a first access node of the home subnet, and the client device roaming 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.
1. A method of a wireless 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 wireless access to the network;
each gateway of the network maintaining a list of other gateways on 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 wirelessly 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;
resolving the fixed client IP address of the client device from a MAC address of the client device, wherein resolving the fixed client IP address comprises:
the foreign gateway of the foreign subnet sending a request to designated gateways of all other subnets of the network;
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 home gateway receiving a relayed DHCP request; and
the home gateway relaying the DHCP request to a local DHCP server.
2. The method of claim 1 , further comprising the client device maintaining a MAC address of a default gateway as the client device roams from first access node to the second access node.
3. The method of claim 1 , wherein the fixed client IP address of the client device is maintained at a home gateway of the client device.
4. The method of claim 1 , wherein when the client device roams to the second access node, the client device performs an authentication and association with the foreign gateway of the foreign subnet.
5. The method of claim 4 , wherein the authentication and association is according to an 802.11 protocol.
6. The method of claim 4 , further comprising the client device issuing a DHCP renew request if an IP address lease of the client is due to expire.
7. The method of claim 6 , further comprising:
the second access node intercepting the DHCP renew request, and the second access node identifying the home subnet of the client device from a locally stored AARP entry from the client device.
8. The method of claim 7 , further comprising:
the second access node relaying the home subnet to the home gateway of the home subnet.
9. The method of claim 1 , wherein the request is an AARP request.
10. The method of claim 1 , further comprising:
the home gateway of the home subnet of the client device responding to the request with the fixed client IP address of the client device.
11. The method of claim 10 , further comprising:
the home gateway of the home subnet of the client device responding to the request with the default gateway IP address and IP subnet attachment.
12. The method of claim 1 , further comprising:
each access node along a path from the client device to the foreign gateway setting up a route to the client device through the network.
13. The method of claim 1 , further comprising:
the foreign gateway setting up routes to the client device through the network.
14. The method of claim 1 , further comprising:
the home gateway relaying a DHCP response to an access node the client device is attached, renewing the client device IP address.
15. A wireless network that allows a client device to roam from a home subnet to a foreign subnet of the network, the network comprising a plurality of gateways and a plurality of access nodes, comprising:
a first access node of the home subnet of the network providing the client device wireless access to the network;
each gateway of the network maintaining a list of other gateways on 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 wirelessly 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 resolving the fixed client IP address of the client device from a MAC address of the client device, wherein resolving the fixed client IP address comprises: the foreign gateway of the foreign subnet sending a request to designated gateways of all other subnets of the network; 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 home gateway receiving a relayed DHCP request; and
the home gateway relaying the DHCP request to a local DHCP server.