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3 mld, 1 introduction to mld – Accton Technology ES4626 User Manual

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Switch#show ipv6 pim rp mapping

PIM Group-to-RP Mappings

This system is the Bootstrap Router (v2)

Group(s): ff00::/8

RP: 2000:1:111::100

Info source: 2000:1:111::100, via bootstrap, priority 192

Uptime: 00:10:24, expires: 00:02:06

Group(s): ff00::/8, Static

RP: 2000:1:111::100

Uptime: 00:11:01

Displayed Information

Explanations

Group(s)

Group address range of RP

Info source

Source of Bootstrap messages

Priority

Priority of Bootstrap messages

17.3 MLD

17.3.1 Introduction to MLD

MLD (Multicast Listener Discovery) is the multicast group member (receiver)

discovery protocol serving IPv6 multicast. It is similar to IGMP Protocol in IPv4 multicast

application. Correspondingly, MLD Protocol version1 is similar to IGMP Protocol version2,

and MLD Protocol version2 is similar to IGMP Protocol version3. Current firmware only

supports MLDv1.

The IPv6 multicast hosts can join or leave from multicast group at any location, any

time, regardless of the total number of group members. It is unnecessary and impossible

for multicast switch to store the relationship among all host members. Multicast switch

simply finds out via MLD protocol if there are receivers of certain multicast group on the

network segment connected to each port. The only thing host need to do is to keep the

record of which multicast groups it joined.

MLD is unsymmetrical between host and switch: the host needs to respond the MLD

query message of multicast switch with membership report message; the switch

periodically sends membership query message and determines if there is host joining a

specific group in its subnetworks according to the response message received, and after

it receives the report of a host quitting from the group, it sends out the query for the group

to confirm if there is no member left in it.

There are three types of protocol messages of MLD Protocol, that is, Query, Report

and Done (which is corresponding to Leave of IGMPv2). Like IGMPV2, the Query

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