Abstract: A communication network (100) comprises a roaming network node (109) which may move within the network. The network node (109) comprises a network interface (201) for receiving data from a first node (107) of the network (100). The received data may be multicast data or unicast data. The network node (109) further comprises a multicast processor (205) which determines a multicast characteristic of the first node (107) and an address update processor (207) for selecting between a dynamic address update mode and a non-dynamic address update mode in response to the multicast characteristic. In particular, the network node (109) may operate an address update process, such as a route optimisation or a correspondent registration process, conditionally on whether the foreign network (105) is a multicast node or not. This may improve performance and reduce the signalling overhead associated with route optimisation in a communication network.