Methods and apparatus for handling wireless roaming among and across wireless area networks

Abstract

Wireless roaming in a computer network may be handled through a solution provided on one or more switches in the network. A roam request sent by a switch corresponding to the user's new location may be received by the other switches in the network. If the user is known to any of these switches, then they may execute steps to accommodate the roaming. The tasks performed may vary based on whether the roaming is on layer 2 or layer 3, whether the switch is a home agent for the client, and/or whether the switch already corresponds to the user's new location.

What is claimed is: 
     
         1 . A method comprising:
 receiving, by a first switch in a mobility domain of switches, a first request from an access point associated with the first switch, the first request indicating that a mobile client has connected to the access point; and   in response to the first request, sending, by the first switch, a second request to all other switches in the mobility domain and to the first switch itself, the second request indicating that the mobile client has roamed to the access point from another access point.   
     
     
         2 . The method of  claim 1  wherein the access point is in a first Layer  2  network and wherein the another access point is in a second Layer  2  network distinct from the first Layer  2  network. 
     
     
         3 . The method of  claim 2  wherein the another access point is associated with the first switch. 
     
     
         4 . The method of  claim 2  wherein the another access point is associated with a second switch in the mobility domain distinct from the first switch. 
     
     
         5 . The method of  claim 1  wherein the access point is in a first Layer  3  network and wherein the another access point is in a second Layer  3  network distinct from the first Layer  3  network. 
     
     
         6 . The method of  claim 5  wherein the another access point is associated with the first switch. 
     
     
         7 . The method of  claim 5  wherein the another access point is associated with a second switch in the mobility domain distinct from the first switch. 
     
     
         8 . The method of  claim 1  wherein each switch in the mobility domain is configurable to, upon receiving the second request:
 handle the second request to determine whether the switch is a home agent for the mobile client; and 
 return a first reply to the first switch. 
 
     
     
         9 . The method of  claim 8  further comprising, upon receiving the first reply:
 if the first reply indicates that the second request was successfully handled, setting the first switch as a foreign agent for the mobile client. 
 
     
     
         10 . The method of  claim 9  further comprising, if the first reply indicates that the second request was successfully handled:
 trapping an Address Resolution Protocol (ARP) packet received from the mobile client via the access point; and 
 sending an ARP reply to the mobile client identifying the first switch's default router address. 
 
     
     
         11 . The method of  claim 10  further comprising, if the first reply indicates that the second request was successfully handled:
 sending a second reply to the access point that includes a new VLAN identifier for the mobile client. 
 
     
     
         12 . The method of  claim 11  wherein the access point is configurable to, upon receiving the second reply, tag all traffic for the mobile client with the new VLAN identifier. 
     
     
         13 . The method of  claim 8  further comprising, upon receiving the first reply:
 if the first reply indicates that the second request was not successfully handled, sending a second reply to the access point indicating failure. 
 
     
     
         14 . The method of  claim 1  wherein the first request is a Switch Access Point Protocol (SAPP) move message. 
     
     
         15 . The method of  claim 1  wherein the second request is an Inter Switch Roaming Protocol (ISRP) roam request. 
     
     
         16 . The method of  claim 1  wherein each switch in the mobility domain is configured with an IP address of every other switch in the mobility domain. 
     
     
         17 . A network switch usable in a mobility domain of switches, the network switch comprising:
 a processor; and   a non-transitory computer readable storage medium having stored thereon instructions that, when executed by the processor, cause the processor to:
 receive a first request from an access point associated with the network switch, the first request indicating that a mobile client has connected to the access point; and 
 in response to the first request, send a second request to all other switches in the mobility domain and to the network switch itself, the second request indicating that the mobile client has roamed to the access point from another access point. 
   
     
     
         18 . A non-transitory computer readable storage medium having stored thereon instructions executable by a network switch in a mobility domain of switches, the instructions comprising:
 instructions that cause the network switch to receive a first request from an access point associated with the network switch, the first request indicating that a mobile client has connected to the access point; and   instructions that cause the network switch to, in response to the first request, send a second request to all other switches in the mobility domain and to the network switch itself, the second request indicating that the mobile client has roamed to the access point from another access point.