Establishment of a reservation

We assume that no reservation is currently recorded by the RSVP process and that no ATM connection is in place.

1. $\EuScript{A}$ sends a Path message to $\EuScript{X}$.

   The switch eventually receives the RSVP message. An entry is added in the path state, recording the Path message received. The message is then forwarded to $\EuScript{X}$.

2. $\EuScript{X}$ sends a Resv message to $\EuScript{A}$.

   When the switch receives the message, it looks for a corresponding entry in the path state. Having found it, and no entry existing in the reservation state, it creates a new block in it. It finally calls Traffic Control to set up the connection and forwards the message to $\EuScript{A}$.

The state of the switch after these two messages can be seen in figure , together with the output of the RSVP process. This result is viewed using the command line interface (section ). The reservation is made twice. At first, it is deleted by the time-out handler because it has expired: the path state block expires and is thus deleted, and then the corresponding reservation state block is found and deleted; finally, Traffic Control updates the switch state according to those deletions, i.e. it tears down the ATM connection that it made.

Figure: Output and result of a reservation