Multicast Listener Discovery

Jeffrey ZhouSW2ZyXEL Communications, Inc04/06/2006

Outline

• IPv6 multicast overview

• The purpose of IPv6 MLD protocol

• MLD packet structure

• MLD message classification

• Summary of MLD

• Q & A

IPv6 IPv6 mmulticast ulticast ooverviewverview

• 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

IPv6 IPv6 mmulticast ulticast ooverviewverview

• 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

Unicast

Multicast

Source

Source

Router

Router

Host Host ssupport for upport for mmulticastulticast

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

Router Router ssupport for upport for mmulticastulticast

• 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

Router 1

Subnet 2

Subnet 1

Router 2

Host B

Host C

Multicast: FF02::21CB:6255 FF05::86CB:1153

Multicast: FF05::86CB:1153

Subnet 3

Host D

Host A

Multicast: FF02::21CB:6255 FF05::86CB:1153

Multicast: FF02::21CB:6255 FF05::86CB:1153

Source

Router 3

The purpose of IPv6 MLD protocolThe purpose of IPv6 MLD protocol

• IPv6 equivalent of Internet Group Management Protocol version 2 (IGMPv2) for IPv4

• Multicast Listener Discovery enables routers to discover the set of multicast addresses for which there are listening nodes for each attached interface

MLD MLD ppacket acket sstructuretructure

An MLD message packet consists of an IPv6 header, a Hop-by-Hop Options extension header, and the MLD message.

The Hop-by-Hop Options extension header contains the IPv6 Router Alert Option described in RFC 2711. It is used to ensure that routers process MLD messages that are sent to multicast addresses for which the router is not a group member.

MLD MLD ppacket acket sstructuretructure

IPv6 HeaderNext Header = 0 (Hop-by-hop Options)

MLD MessageHop-by-Hop Options HeaderIPv6 Router Alert OptionNext Header = 58 (ICMPv6)

MLD message MLD message classificationclassification

• Multicast Listener Query message

• Multicast Listener Report message

• Multicast Listener Done message

Multicast Listener Query Multicast Listener Query mmessageessage

• Function

An IPv6 multicast-capable router uses the Multicast Listener Query message to query a link for multicast group membership. It is equivalent to the IGMPv2 Host Membership Query message.

Multicast Listener Query Multicast Listener Query mmessageessage

TypeCode

ChecksumMaximum Response Delay

UnusedMulticast Address

= 0= 130

• Structure:

Multicast Listener Query Multicast Listener Query mmessageessage

• Classification:1. General query

The general query is used to periodically query all hosts on a subnet for the presence of multicast group members of any multicast address, except the link-local scope all-nodes multicast address (FF02::1). Multicast address is ::

2. Multicast-address-specific query The multicast-address-specific query is used

to query all hosts on a subnet that are members of a specific multicast group.

Multicast Listener Query Multicast Listener Query mmessageessage

Host A Host B

Router

Ethernet II: Destination: 33:33:00:00:00:01 IP Header: Destination address: ff02::1ICMP v6: Type: 130 Code: 0 Checksum: 0x9a2f (correct) Maximum response delay: 10000 Multicast Address: ::

Multicast listener query

MAC: 00:13:46:ec:87:d5

IP: fe80::213:46ff:feec:87d5

Multicast Address: ff02::1:ffec:87d5

Address derivationAddress derivation

MAC :

00:13:46:ec:87:d5

IPv6 address (Unicast)

fe80::213:46ff:feec:87d5

Solicited-Node Address (Multicast)ff02::1:ffec:87d5

Ethernet II, Src: 00:e0:4e:10:6e:f8, Dst: 33:33:00:00:00:01

Destination: 33:33:00:00:00:01 (IPv6-Neighbor-Discovery_00:00:00:01)

Source: 00:e0:4e:10:6e:f8 (SanyoDen_10:6e:f8) Type: IPv6 (0x86dd)Internet Protocol Version 6 Version: 6 Traffic class: 0x00 Flowlabel: 0x00000 Payload length: 24 Next header: ICMPv6 (0x3a) Hop limit: 1 Source address: fe80::2e0:4eff:fe10:6ef8 Destination address: ff02::1

Internet Control Message Protocol v6

Type: 130 (Multicast listener query)

Code: 0

Checksum: 0x9a2f (correct)

Maximum response delay: 10000

Multicast Address: ::

Multicast Listener Report Multicast Listener Report mmessageessage

• FunctionThe Multicast Listener Report

message is used by a listening node to either immediately report its interest in receiving multicast traffic at a specific multicast address or respond to a Multicast Listener Query message (either a general or multicast-address-specific query).

It is equivalent to the IGMPv2 Host Membership Report message.

Multicast Listener Report Multicast Listener Report mmessageessage

TypeCode

ChecksumMaximum Response Delay

UnusedMulticast Address

= 0= 131

= 0

= 0

• Structure:

Multicast Listener Report Multicast Listener Report mmessageessage

Host A Host B

Router

Ethernet II: Destination: 33:33:ff:ec:87:d5 Source: 00:13:46:ec:87:d5IP Header: Source Address : fe80::213:46ff:feec:87d5 Destination Address: ff02::1:ffec:87d5ICMP v6: Type: 131 Multicast Address: ff02::1:ffec:87d5

Multicast listener report

MAC: 00:13:46:ec:87:d5

IP: fe80::213:46ff:feec:87d5

Multicast Address: ff02::1:ffec:87d5

Address derivationAddress derivation

MAC :

00:13:46:ec:87:d5

IPv6 address (Unicast)

fe80::213:46ff:feec:87d5

Solicited-Node Address (Multicast) ff02::1:ffec:87d5

Multicast Ethernet Address 33:33:ff:ec:87:d5

Ethernet II, Src: 00:13:46:ec:87:d5, Dst: 33:33:ff:ec:87:d5

Destination: 33:33:ff:ec:87:d5 (IPv6-Neighbor-Discovery_ff:ec:87:d5)

Source: 00:13:46:ec:87:d5 (00:13:46:ec:87:d5) Type: IPv6 (0x86dd)Internet Protocol Version 6 Version: 6 Traffic class: 0x00 Flowlabel: 0x00000 Payload length: 32 Next header: IPv6 hop-by-hop option (0x00) Hop limit: 1 Source address: fe80::213:46ff:feec:87d5 Destination address: ff02::1:ffec:87d5

Hop-by-hop Option Header Next header: ICMPv6 (0x3a) Length: 0 (8 bytes) Router alert: MLD (4 bytes) PadN: 2 bytesInternet Control Message Protocol v6 Type: 131 (Multicast listener report) Code: 0 Checksum: 0xa0ca (correct) Maximum response delay: 0 Multicast Address: ff02::1:ffec:87d5

Multicast Listener Done Multicast Listener Done mmessageessage

• FunctionThe Multicast Listener Done message

is equivalent to the IGMPv2 Leave Group message and is used to inform the local routers that there might not be any more group members of a specific multicast address on the subnet.

A local router verifies that there are no more group members on the subnet.

Multicast Listener Done Multicast Listener Done mmessageessage

TypeCode

ChecksumMaximum Response Delay

UnusedMulticast Address

= 0= 132

= 0

= 0

• Structure:

Multicast Listener Done Multicast Listener Done mmessageessage

• Step 1:

Host AHost B

Router

Multicast Listener Done

MAC: 00:13:46:ec:87:d5IP: fe80::213:46ff:feec:87d5

Multicast Address:

ff02::23b1:7480

ff02::1:ffec:87d5

ff02::1

MAC: 00:90:27:66:c1:40IP: fe80::213:46ff:fe66:c140

Multicast Address:

ff02::23b1:7480

ff02::1:ff66:c140

ff02::1

Internet Control Message Protocol v6 Type: 132 (Multicast listener Done) Code: 0 Checksum: 0x25ca (correct) Maximum response delay: 0 Multicast Address: ff02::23b1:7480

Multicast Listener Done MessageMulticast Listener Done Message

Host AHost B

Router

Multicast Listener Query

MAC: 00:13:46:ec:87:d5IP: fe80::213:46ff:feec:87d5

Multicast Address:

ff02::1:ffec:87d5

ff02::1

MAC: 00:90:27:66:c1:40IP: fe80::213:46ff:fe66:c140

Multicast Address:

ff02::23b1:7480

ff02::1:ff66:c140

ff02::1

Internet Control Message Protocol v6 Type: 130 (Multicast listener query) Code: 0 Checksum: 0x9a2f (correct) Maximum response delay: 10000 Multicast Address: ff02::23b1:7480

• Step 2:

Multicast Listener Done MessageMulticast Listener Done Message

• Step 3:

Host AHost B

Router

Multicast Listener Report

MAC: 00:13:46:ec:87:d5IP: fe80::213:46ff:feec:87d5

Multicast Address:

ff02::1:ffec:87d5

ff02::1

MAC: 00:90:27:66:c1:40IP: fe80::213:46ff:fe66:c140

Multicast Address:

ff02::23b1:7480

ff02::1:ff66:c140

ff02::1

Internet Control Message Protocol v6 Type: 131 (Multicast listener report) Code: 0 Checksum: 0xa0ca (correct) Maximum response delay: 0 Multicast Address: ff02::23b1:7480

Summary of MLD Summary of MLD

IGMPv2 Message MLD Equivalent Host Membership Query Multicast Listener Query

Host Membership Report Multicast Listener Report

Leave Group Multicast Listener Done

Date Subject Lecturer

Introduction to IPv6

IPv6 Addressing

IPv6 Header & Extensions

Neighbor Discovery Protocol

Multicast Listener Discovery

IPv6 Routing

ICMPv6

Address Autoconfiguraton

Joe Zhao

Milo Liu

Joe Zhao

Feng Zhou

Billy Bian

Jeffrey Zhou

Feng Zhou

Milo Liu

03/10

03/16

03/23

03/27

03/30

04/06

04/11

04/13

Date Subject Lecturer

Setting Up an IPv6 Test Lab

IPv6 Migration Mechanisms

IPv6 Mobility

Joe Zhao

Milo Liu

04/20

04/27

Q & AQ & A