The DR_Priority option allows a network administrator to give preference to a particular router in the DR election process by giving it a numerically larger DR Priority. The DR_Priority option is included in every Hello message, even if no DR Priority is explicitly configured on that interface. This is necessary because priority-based DR election is only enabled when all neighbors on an interface advertise that they are capable of using the DR_Priority Option. The default priority is 1.
DR Priority is a 32-bit unsigned number, and the numerically larger priority is always preferred. A router's idea of the current DR on an interface can change when a PIM Hello message is received, when a neighbor times out, or when a router's own DR Priority changes. If the router becomes the DR or ceases to be the DR, this will normally cause the DR Register state machine to change state. Subsequent actions are determined by that state machine.
configure pim {ipv4 | ipv6} {vlan} [vlan_name] dr-priority priority
Print
this page
Email this topic
Feedback
View PDF
Download EPUB