This is the RSVP-TE Kb value, the number of refresh-timeout periods that must elapse before a session's blockade state, used during reroute events to suppress preemption, is cleared. This governs how long RSVP-TE continues protecting an in-progress reroute from being preempted by other traffic-engineering activity; too short a value risks a legitimate in-progress reroute being disrupted, while too long a value can hold blockade state well past when it's actually needed. For example, with a refresh timeout period of 90 seconds and Kb set to 4, a session's blockade state would persist for roughly 6 minutes after a reroute event before being cleared.