Reserve Bandwidth on an Interface

For each interface on which RSVP is enabled, by default RSVP permits all the interface's bandwidth (100 percent) to be used for RSVP reservations.

Oversubscription on an interface occurs when the aggregate demand of all RSVP sessions is allowed to exceed physical capacity of the link. You can use oversubscription to take advantage of the statistical nature of traffic patterns and to permit higher utilization of links. In particular, you can use oversubscription in places where peak utilizations of traffic do not coincide in time.

Undersubscription on an interface occurs when the total demand of all RSVP sessions is always less than the physical capacity of the link. You can use undersubscription to bound utilization of links and reduce congestion.

You can modify the link bandwidth used for RSVP reservations, either decreasing it below 100 percent or oversubscribing the interface. To do this, include the subscription statement:

subscription percentage; 

You can configure this statement at the following hierarchy levels:

• [edit logical-routers logical-router-name protocols rsvp interface interface-name]
• [edit protocols rsvp interface interface-name]

percentage is the percentage of the interface's bandwidth that RSVP allows to be used for reservations. It can be a value from 0 through 65,000 percent. If you specify a value greater than 100, you are oversubscribing the interface.

You can use the subscription factor to shut down new RSVP sessions on a per-interface basis. If you set the percentage to 0, no new sessions (including those with zero bandwidth requirements) are permitted on the interface. Existing RSVP sessions are not affected by changing the subscription factor. To clear an existing session, issue the clear rsvp session command.