Understanding Cisco IOS XR PIM Sparse Mode

This section explains the mechanics involved with the multicast forwarding of IOS XR using PIM SM. The configuration details are not presented yet; however, the control plane behavior is discussed with the help of show commands. Configuration details are discussed in the “Configuring Cisco IOS XR Multicast” section of this chapter.

Figure 10-2 shows a network that is preconfigured for PIM SM multicast routing. All the CRS-1 and GSR routers shown in the topology are running Release 3.6.0 of Cisco IOS XR software. The 7200-Paris router running IOS is configured for bootstrap router (BSR) and functions as a rendezvous point for this network. The GSR1-SJC router receives an IGMP join for a multicast group 231.1.1.1. Example 10-1 shows the IGMP and MRIB debugs and illustrates the process of creating multicast route entry when an IGMP join is received on an IOS XR router configured for PIM SM.