actions and in section (i.e. reservation of endpoint SAP, and callback operation respectively).
Consider Figure . If the Sandman-1 MCA wants to setup a connection to a destination in Sandman-2, it knows that the pseudo-endpoint of L1 is the via parameter for this connection and hence that this where the appropriate callback operations reside. It will set up the connection in its own domain and (if successful) call the callback operations in both endpoint 1 and the pseudo-endpoint. The pseudo-endpoint now replicates the connection setup request and sends it to the Sandman-2 MCA, specifying itself as the source endpoint and specifying the vpi-vci value it received from Sandman-1 as the starting vci-vpi for link L1 for this connection. The Sandman-2 MCA tries to set up the connection with the specified vpi-vci value and if successful, returns the boolean value true to the pseudo-endpoint, which in turn returns true to the Sandman-1 MCA. We have now established and end-to-end connection between two endpoints in different Sandman domains. In this case the pseudo-endpoints works as a signalling bridge between the two MCA. The tear down of connections proceeds in roughly the same way. Observe that all this takes place on the control path. The datapath is untouched. For this reason, such pseudo-endpoints are sometimes called control gateways.