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Cisco Multicast Routing on IOS-XR v1

February 2021

Multicast is almost as old as unicast. IP multicast was invented in order to provide an efficient delivery of the same traffic to multiple receivers at the same time. For instance, if you were to deliver a TV stream to 1000 receivers by using unicast, the source would need to send out 1000 streams. This is not efficient usage of the network bandwidth. With IP multicast, the source sends out only one IP stream, which is replicated at network branches (routers) until the stream reaches all the receivers that showed interest in receiving the stream.

The multicast solution has the following parts:

  • Source
  • Receivers
  • Routers, replicating the multicast traffic

Multicast is a complete set of features, such as PIM, IGMP, MSDP, multicast forwarding, Rendezvous Point, multicast routing table, and multicast forwarding table. In this demo, we cover these features in order for you to become familiar with the basics of IP multicast on the Cisco IOS-XR. The focus of this lab is on the multicast part of the IOS-XR routers. Upon completion of this lab you, you will be able to:

  • Configure multicast on IOS-XR routers
  • Troubleshoot basic multicast routing on IOS-XR
  • Understand the basic operation of IOS-XR multicast routing and understand the differences with IOS(-XE) multicast routing


  • Scenario 1. IGMP/Receivers
  • Scenario 2. SSM
  • Scenario 3. Sparse Mode (Shared Tree Only)
  • Scenario 4. Sparse Mode (Source Tree aka Shortest Path Tree)
  • Scenario 5. Sparse Mode (Anycast RP)
  • Scenario 6. Multicast Troubleshooting