An upper-bound on the time thate stale routes will be retained by a router after a session is restarted. If an End-of-RIB (EOR) marker is received prior to this timer expiring stale-routes will be flushed upon its receipt - if no EOR is received, then when this timer expires stale paths will be purged. This timer is referred to as the Selection_Deferral_Timer in RFC4724