1. Multicast Listener Discovery
Lesson 7
Multicast Listener Discovery

2. Lesson Objectives Multicast Listener Discovery (MLD) protocol
Multicast communication for IPv6 hosts and routers
MLD messages

3. Overview of Multicast Listener Discovery
IPv6 equivalent of Internet Group Management Protocol version 2 (IGMPv2) for IPv4
Enables routers to discover the set of multicast addresses for which there are listening nodes for each attached interface

4. IPv6 Multicast Overview
Multicast provides one-to-many delivery
The set of hosts listening on a specific IPv6 multicast address is called a multicast group
Multicast group membership is dynamic, and hosts can join and leave the group at any time
There are no limitations to the size of a multicast group
A multicast group can span IPv6 routers across multiple subnets
A host can send traffic to a multicast address without being a member of the group

5. Host Support for Multicast
To send multicast packets:
Determine the IPv6 multicast address to use
Place the IPv6 multicast packet on the medium
To receive multicast packets:
Inform IPv6 to receive multicast traffic
Register the multicast MAC address with the network adapter
Inform local routers

6. Router Support for Multicast
Receive all IPv6 multicast traffic
Forward IPv6 multicast traffic
Receive and process MLD Multicast Listener Report and Multicast Listener Done messages
Query attached subnets for host membership status
Communicate group membership to other IPv6 multicast routers

7. Structure of an MLD Message Packet
IPv6 Header
Next Header = 0
(Hop-by-hop Options)
Hop-by-Hop Options Header
IPv6 Router Alert Option
Next Header = 58 (ICMPv6)
MLD Message

8. Structure of the Multicast Listener Query Message
Type
Code
Checksum
Maximum Response Delay
Unused
Multicast Address
= 130
= 0
= 0

9. Structure of the Multicast Listener Report Message
Type
Code
Checksum
Maximum Response Delay
Unused
Multicast Address
= 131
= 0
= 0
= 0

10. Structure of the Multicast Listener Done Message
Type
Code
Checksum
Maximum Response Delay
Unused
Multicast Address
= 132
= 0
= 0
= 0

11. Review Multicast Listener Discovery (MLD) protocol
Multicast communication for IPv6 hosts and routers
MLD messages