Exception processing for wireless roaming

A client device detects when it roams between subnets and signals to a device in the subnet being entered. The client may detect roaming by monitoring subnet identifiers included in beacon signals transmitted by access points. When the client detects a beacon with a new subnet identifier and at the same time no longer detects a beacon with the original subnet identifier then roaming is indicated. When roaming is indicated the client responds by setting a tag, such as an IEEE 802.1q VLAN tag, in packets transmitted by the client. The tagged packets provide an indication to devices in the new subnet that the client has roamed into that new subnet. Devices in the new subnet, such as access points and switches, recognize the tagged packets and establish a path to the original subnet in response. For example, the tagged packets transmitted by the client may be encapsulated pursuant to a Layer 3 protocol and tunneled from a switch associated with the subnet being entered to a switch in the original subnet. If the client roams to other subnets the path is established from the new subnet to the original subnet, rather than an intermediate subnet.