Bidir PIM in Simple Steps: How It Works With LAB Demo

Bidirectional PIM (often referred to as Bidir PIM or Bidirectional Multicast) is a PIM operating mode that enhances traditional ASM PIM by creating bidirectional multicast distribution trees. Unlike unidirectional trees (RPT & SPT), where traffic flows only from sources to receivers or RPs, bidirectional trees allow communication in both directions.

  • This video article covers the following:
    • What is Bidir PIM? Why it matters? And how it works?
    • LAB demo shows the Bidir PIM configuration in Nexus switches.


  • ASM works efficiently with a relatively small number of multicast senders. However, it becomes less efficient with a large number of senders, receivers, and multicast group addresses.
  • Bidirectional PIM solves the ASM scale inefficiency by slightly changing the rules used by PIM-SM ASM.
  • Bidir uses bidirectional shared trees, whereas ASM relies on unidirectional shared and source trees.
  • Bidir PIM RFC-5015.
  • Bidir PIM RP redundancy is achieved by the Phantom RP mechanism.

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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