PIM Phantom RP Demystified: Why and How to deploy it?

The Phantom RP is the RP redundancy mechanism for PIM-BiDir. The PIM Anycast RP and Anycast RP with MSDP are the mechanisms used for RP redundancy in the PIM ASM (Any Source Multicast).

In this video, I explain the PIM phantom RP with a LAB demonstration using Cisco Nexus switches.

Summary

  • Phantom RP means the RP address (RPA) does not belong to any physical router’s interface but only to a reachable network.
  • Phantom RP is provided using loopback interfaces configured in multiple routers, each with a different subnet mask for the RP address (none of them is the exact /32 address).
  • The unicast routing longest match rule is used to choose the active RP.
  • If the active RP fails, the secondary RP with the shorter mask, still advertising the RP subnet, will appear in the routing table as the best route.
  • For more information: RP Redundancy with PIM Bidir – Phantom RP

I hope this article was useful. For comprehensive content, you can refer to my CCIE Data Center (v3.1) – Multicast Udemy course.

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SALEM
SALEM
13 days ago

If I configure a phantom RP on each device in IPN with 4 routers (2 routers in each POD) : 2 phantom RP /30 in POD 1 and 2 phantom RP /29 in POD2 , what will be the behavior? Or you advice me to configure only 2 phantom RP (one in each pod)?

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