1. A method of processing a data connection for exchanging data between two communication devices within a fault tolerant apparatus having an active host and a stand-by host; the active host being arranged to support a communication protocol stack comprising at least a first protocol layer, providing connection management signals, for establishing and managing the data connection between the two communication devices, including a disconnect signal for terminating the data connection, and a second protocol layer having an associated connection context; the first protocol layer being at a higher level within the communication protocol stack relative to the second protocol layer; the method comprising the steps of establishing a data connection between the two communication devices using at least the connection management signals of the first protocol layer and establishing a connection context for the second protocol layer; replicating the connection context of the second protocol layer to the stand-by host; implementing the communication stack protocol on the standby host in response to detection of an event associated with the active host; receiving, at the standby host, from one of the two communication devices, an associated connection management signal other than a disconnect signal; and issuing to at least one of the two communication devices a disconnect signal in response to receipt of the associated call management signal.