CVS: Using VLANs to Counteract the Effect of Topology Changes in Quasi-Static Mesh Access Networks

Mesh networks are candidate to play the role of switched Ethernet LANs over extended areas and with a sensibly higher flexibility. Actually, mesh networks can exploit both Ethernet and wireless technologies, e.g. Wi-Fi and/or free-space optical links, to provide a high degree of redundancy in an access network, and to provide users with powerful means to connect with each other. By using such technologies, the mesh topology remains stable for hours, so that the mesh topology can be considered quasi-static. However, large meshes require a heavy overhead in the network control plane as for the management of end-to-end paths, which can change due to mobility of users and due to occasional failure of wireless links. In this paper we show that a mesh network can be endowed with dynamically-managed VLANs in order to tackle the impairment caused by topology changes. In fact, the availability of multiple VLANs offers redundancy enough to hide network changes to end users. However, a continuous rearrangement of unused (redundant) VLANs is strictly required. We call that approach CVS (Controlled VLANs Switching), since network traffic should be run-time switched to different VLANs, depending on the active network topology.