Question

A service provider deploys PIM Bidirectional (Bidir-PIM) in a data-center distribution segment to support a many-to-many financial multicast application where every host is both a source and a receiver. On a multi-access LAN segment that connects to the rendezvous point (RP) tree, the engineer notices that multicast traffic sourced on the segment is being forwarded upstream toward the RP by more than one router, causing duplicate packets. Which Bidir-PIM mechanism is responsible for electing a single router per link to forward traffic toward the RP, and what must the engineer verify?

Accepted Answer

The Designated Forwarder (DF) election; verify that exactly one DF is elected per RPF link based on the best unicast metric to the RP address

Answer

The PIM Designated Router (DR) election; verify that the highest-IP-address router became DR and is registering sources to the RP

Answer

The IGMP querier election; verify that the lowest-IP-address router is acting as querier to suppress duplicate forwarding

Answer

The Assert mechanism used in PIM Sparse Mode; verify that the router with the lowest administrative distance wins the assert on the shared segment