CCIE RS – L3 Multicast – Describe IPv6 Multicast

Describe IPv6 Multicast


  • FF00::/8
  • All nodes (link local)
    • FF02::1
  • All routers (link-local)
    • FF02::2

Signaling is done through MLD

  • Routers use MLD to learn members of groups
  • Hosts send joins with a MLD report message
  • Discovers multicast listeners

MLD – Multicast Listener Discovery

  • Version 1 – based on IGMPv2
  • Version 2 – Based on IGMPv3
    • Fully backwards compatible with v1
  • Used for disocovering local group and source specific group membership
  • Automatically control and limit multicast traffic throughout the network
  • Uses ICMP to carry messages
  • All messages are link-local
    • Hop limit of 1
  • Message Types
    • Query – General, group specific and multicast address specific
      • General query learns which multicast addresses have listeners on the attached link
    • Report – Mutlicast address field is that of a speceific IPv6 multicast address to which sender is listening
    • Done – Multicast address field is that of a specific IPv6 multicast address to which the source of the MLD is no longer listening


IPv6 Multicast Addresses

Multicast – FF00::/8

  • All Nodes, Link Local: FF02::1
  • All Routers, Link Local: FF02::1
  • All OSPF Routers: FF02::5
  • All OSPF DR routers: FF02::6
  • All ISIS routers: FF02::8
  • All RIP Routers: FF02::9
  • All EIGRP routers: FF02::A
  • All PIM routers: FF02::D
  • MLDv2 Reports: FF02::16



PIM will get enabled on all IPv6 enabled interfaces after issuing the ipv6 multicast-routing in global config


  • Used between routers to track multicast packets to forward
  • Provides reverse path information for multicast tree building
    • Initially uses shared tree
    • Requires use of RP
  • No dependent on any particular unicast routing protocol
  • Designated router
  • Ipv6 pim dr-priority
  • Rendezvous Point (RP)
    • Embedded RP
    • Learn RP information using multicast group destination instead of statically configured RP
  • IPv6 BSR
    • Configure RP mapping
    • Announce scope to RP mapping from BSR


  • Ability to report interest in receiving packets from specific source addresses
  • MLDv2 is required



ipv6 multicast-routing

Static RP: 
ipv6 pim [vrf name] rp-address [ipv6] [acl] [bidir]

PIM Options:

ipv6 pim [vrf vrf-name] spt-threshold infinity [group-list access-list-name]
ipv6 pim [vrf vrf-name] accept-register {list access-list | route-map map-name}

ipv6 pim dr-priority   [value] 
ipv6 pim hello-interval   [seconds] 
ipv6 pim join-prune-interval   [seconds]

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