Apparatus for transferring packet data incorporates a "hand-off" feature
that allows the transfer of an existing PPP connection from one packet server to
another packet server. Such a hand-off control message or call continue transaction
can be initiated by any of the servers involved in the transactions. For instance,
assume an initial arrangement where a point-to-point call is set up and in progress
between a user and a private network via a first packet server (e.g., a first Serving
LAC) and a second packet server (e.g., an Anchor LAC). If, for example, the user
moves out of the region served by the first packet server into a region served
by a third packet server (e.g., a second Serving LAC), then a hand-off control
message transaction, according to the invention, is initiated. Either the second
Serving LAC or the Anchor LAC may initiate the call continue transaction. Alternatively,
radius servers respectively associated with the packet servers may be employed
to perform the call continue transaction. Furthermore, assuming that a communication
path is not yet established between the second packet server (e.g., Anchor LAC)
and the third packet server (e.g., the second Serving LAC), a communication path
(e.g., tunnel), set-up control message transaction may be performed concurrent
with the call continue transaction. Still further, at least one packet server (e.g.,
the Anchor LAC) monitors state variables associated with the packet servers (e.g.,
the second Serving LAC and the private network) from which it receives packet data.
