Communication device, and method, in an internet protocol network, of controlling a communication device

A communication device comprising a controller and a memory, said controller being arranged for managing a communication session, in an Internet Protocol network, with a communication partner using a session level connection identifier for referring to a transport connection used in said communication session, where the session level connection identifier is independent of a transport layer connection identifier so a value of the transport layer connection identifier can be changed while retaining the session level connection identifier so a session manager can continue to handle the communication session as occurring on a same connection, although conditions at the transport layer have changed, thereby allowing a change of IP address of the communication device on the session level without having to modify procedures at the transport layer, and for keeping a link record in said memory for associating a recorded value of said session level connection identifier with a recorded value of a transport layer connection identifier.