IBM SG24-4817-00 manual Basic ATM Signalling, ATM Call Establishment

This soft copy for use by IBM employees only.

Because ATM allows for dynamic registration of resources, signalling processes have been established to provide for initial registration, connection setup, and connection teardown, whether the connection is native ATM, ATM

Forum-Compliant LAN Emulation, or Classical IP (CIP).

1.1.4.1 Basic ATM Signalling

Figure 3. ATM Call Establishment

For an endstation to communicate in a switched environment such as ATM, it must register with the network, request a connection when necessary, and clear the connection when through. For native ATM endstations, this is done by the following:

Initial Registration: When an endstation wishes to enter the network, it must first register its full ATM address with its associated switch. This signalling process is described in ATM UNI Specification 3.0 (based on ITU-T Q.93B recommendations), or more recently, in ATM UNI Specification 3.1 (based on ITU-T Q.2931 recommendations) and is performed when the endstation is activated. During this process, the workstation receives its 13-byte network prefix from the switch, appends its own local address (ESI plus selector), and registers its complete ATM address with the switch.

Connection Setup: When an endstation wishes to communicate with another endstation, it must first establish a connection to it. It does this by issuing a SETUP request to the ATM network.

If the requested address is local, the switch acknowledges the request by issuing a CALL PROCEEDING response to the requesting endstation and forwarding the SETUP request to the requested endstation, which acknowledges receipt with a CALL PROCEEDING response.

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