Configuring Timers for RSVP Refresh Messages

RSVP uses two related timing parameters:

refresh-time—The refresh time controls the interval between the generation of successive refresh messages. The default value for the refresh time is 45 seconds. This number is derived from the refresh-time statement’s default value of 30, multiplied by a fixed value of 1.5. This computation differs from RFC 2205, which states that the refresh time should be multiplied by a random value in the range from 0.5 through 1.5.
Refresh messages include path and Resv messages. Refresh messages are sent periodically so that reservation states in neighboring nodes do not time out. Each path and Resv message carries the refresh timer value, and the receiving node extracts this value from the messages.
keep-multiplier—The keep multiplier is a small, locally configured integer from 1 through 255. The default value is 3. It indicates the number of messages that can be lost before a particular state is declared stale and must be deleted. The keep multiplier directly affects the lifetime of an RSVP state.

To determine the lifetime of a reservation state, use the following formula:

lifetime = (keep-multiplier + 0.5) x (1.5 x refresh-time)

In the worst case, (keep-multiplier – 1) successive refresh messages must be lost before a reservation state is deleted.

We do not recommend configuring a short RSVP hello timer. If quick discovery of a failed neighbor is needed, configure short IGP (OSPF or IS-IS) hello timers.

By default, the refresh timer value is 30 seconds. To modify this value, include the refresh-time statement:

refresh-time seconds;

You can include this statement at the following hierarchy levels:

[edit protocols rsvp]
[edit logical-systems logical-system-name protocols rsvp]

The default value of the keep multiplier is 3. To modify this value, include the keep-multiplier statement:

keep-multiplier number;

You can include this statement at the following hierarchy levels:

[edit protocols rsvp]
[edit logical-systems logical-system-name protocols rsvp]