ATM Signaling and Connection Establishment

When an ATM device wants to establish a connection with another ATM device, it sends a signaling-request packet to its directly connected ATM switch. This request contains the ATM address of the desired ATM endpoint, as well as any QoS parameters required for the connection.

The ATM Connection-Establishment Process

ATM signaling uses the one-pass method of connection setup that is used in all modern telecommunication networks, such as the telephone network. An ATM connection setup proceeds in the following manner. First, the source end system sends a connection-signaling request. The connection request is propagated through the network. As a result, connections are set up through the network. The connection request reaches the final destination, which either accepts or rejects the connection request.

Connection-Request Routing and Negotiation

Routing of the connection request is governed by an ATM routing protocol (Private Network-Network Interface [PNNI], which routes connections based on destination and source addresses), traffic, and the QoS parameters requested by the source end system. Negotiating a connection request that is rejected by the destination is limited because call routing is based on parameters of initial connection; changing parameters might affect the connection routing. Figure the one-pass method of ATM connection establishment.