Managing router advertisement messages to support roaming of wireless mobile client devices

摘要

Techniques are provided to manage how router advertisement messages are forwarded for ultimate wireless transmission in a wireless network. In one embodiment, a multicast router advertisement message intended for a virtual local area network is converted into individual unicast router advertisement messages directed to specific wireless mobile client devices that are part of that virtual local area network. In another embodiment, router advertisement messages are routed between controllers according to the current location of a wireless mobile client device. In still other embodiments, techniques are provided to minimize the volume of the router advertisement messages sent over a wireless network, and to proactively send a unicast router advertisement message to a mobile client device that has performed a handoff, without waiting for a router solicitation message.

主权项

1. A method comprising:
at a first controller configured to control a first virtual local area network through one or more wireless access point devices that serve wireless mobile client devices over a first wireless network, receiving a router advertisement message from a network router; determining for which of a plurality of virtual local area networks the router advertisement message is intended; storing the router advertisement message together with information identifying the virtual local area network to which the router advertisement message is intended; receiving from a particular wireless access point device a router solicitation message sent by a particular wireless mobile client device that is part of the first virtual local area network; determining whether the particular wireless access point device is among one or more wireless access point devices that serve wireless mobile client devices over the first wireless network; determining whether the router advertisement message is stored for the first virtual local area network to which the particular wireless mobile client device belongs; when the router advertisement message is stored for the first virtual local area network to which the particular wireless mobile client device belongs, responsive to a determination that the particular wireless access point device is among the one or more wireless access point devices that serve wireless mobile client devices over the first wireless network, retrieving the stored router advertisement message and sending it as a unicast message to the one or more wireless access point devices configured to serve wireless mobile client devices over the first wireless network; and responsive to a determination that the particular wireless access point device is not among the one or more wireless access point devices that serve wireless mobile client devices over the first wireless network, sending the router advertisement to a second controller that is configured to control at least one wireless access point device to which the particular wireless mobile client device has roamed.