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 does it matter? And how does it work?
- A LAB demo shows the Bidir PIM configuration in Nexus switches.
Summary
- 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.