Multicast Routing on IOS-XR

Configuring multicast on IOS-XR uses different command syntax, as you can imagine. The following are condensed study notes that detail configuration and show commands. The principals of PIM work the same on IOS-XR as on IOS-XE.

Configuration

Enable multicast routing for each interface that connects to a receiver, router, or source. This takes place of the ip multicast-routing command in IOS-XE. IOS-XR separates the multicast-routing function and PIM function per-interface into two separate processes. On IOS-XE you enable PIM on each interface even if it connects to a receiver or source.

multicast-routing
 address-family ipv4
  interface gi0/0/0/0
   enable
  ! or
  interface all enable

Enable PIM in “routing protocol” configuration style. You only need to enable PIM on interfaces that connect to other PIM neighbors.

router pim
 address-family ipv4
  interface gi0/0/0/0
   enable

By default, IGMPv3 is used on all interfaces enabled for multicast-routing. IGMPv3 is backwards compatible with IGMPv2 so usually you can leave it on the default. But if needed, you configure this under a separate configuration stanza.

router igmp
 version 2

IOS-XR cannot run PIM-DM. By enabling PIM, you enable PIM-SM, PIM-SSM and PIM-BiDir implicitly. PIM-SSM uses the default 232/8 range but you can change it:

multicast-routing
 address-family ipv4
  ssm range <ACL>

You can configure the RP on IOS-XR as follows. By default it will accept BSR RP mappings just like IOS-XE.

router pim
 address-family ipv4
  ! Static
  rp-address ip-address [bidir]

  ! BSR
  bsr candidate-bsr ip-address-of-interface 
  bsr candidate-rp ip-address-of-interface [bidir] [group-list acl]

  ! AutoRP
  auto-rp candidate-rp interface scope ttl [group-list acl] [bidir]
  auto-rp mapping-agent interface scope ttl

Show commands

show mrib route ! Similar to show ip mroute
show mfib route ! Harder to read, contains information only necessary for forwarding
show pim topology
show pim neighbor
show pim rp mapping
show igmp groups gi0/0/0/0 detail