Wireless mesh networks are cost-efficient means to provide ubiquitous Internet access. For building large-scale wireless mesh networks, multiple access networks are joined together into one large network. In such large networks, nodes have to communicate with the Internet via multiple access gateways. The problem in such scenarios is how to make mesh nodes aware of the gateway over which data is sent towards the Internet. The goal of this paper is to propose a routing protocol-independent method that allows nodes to (i) determine when they are switching the access network; (ii) to support switching of access networks; and (iii) to support multihoming.