Chapter 12 Mld Configuration; Mld Overview - Zte ZXR10 5900E Configuration Manual

Chapter 12
MLD Configuration
Table of Contents

MLD Overview..........................................................................................................12-1

Configuring MLD ......................................................................................................12-2
Maintaining MLD ......................................................................................................12-6
MLD Configuration Examples ...................................................................................12-8
12.1 MLD Overview
MLD originate from IGMP. MLDv1 corresponds to IGMPv2, and MLDv2 corresponds to
IGMPv3. Different from IGMP which uses message type of IP protocol number 2, MLD
uses message type of ICMPv6 (the IP protocol number is 58), including MLD Query
message (type value is 130, MLDv1 Report message (type value is 131), MLDv1 Leaving
message (type value is 132) and MLDv2 Report message (type value is 143). MLD acts
completely the same as IGMP does excepts for the message structure.
MLD provides the information that is needed in the last state to forward a multicast packet
to the destination. The multicast router exchanges information with the host receiving the
multicast data. The information is collected from the group members of hosts that connect
to the multicast router directly.
MLD mainly uses two types of messages, group member query message and group
member report message. The multicast router sends group member query messages to
all hosts periodically to know the group members on the interconnected subnets. Each
host replies with a member report message to report the multicast group which it belongs
to. When a host joins a new group, it sends a join message immediately instead of waiting
for a query in case it is the first member of the group.
When a host begins to receive information as a member of a group, the multicast router
will query the group periodically to check whether there is any member in the group. As
long as there is one host, the multicast router continues forwarding data.
When a host leaves a group, the multicast router receives a leaving message, and then it
queries whether there is any other active member in the group immediately. If there is any,
the multicast router continue forwarding data. Otherwise, it will not forward data any more.
At present, there are two versions of MLD. MLDv1 corresponds to IGMPv2, and it provides
the fast leaving mechanism of group members. MLDv2 corresponds to IGMPv3, and it
provides to receive or refuse to receive packets from designated multicast sources, thus
to support SSM.
12-1
SJ-20150114102049-011|2015-01-15 (R1.0) ZTE Proprietary and Confidential