3Com S7902E, Руководство по настройке

Страница: 1364 / 2621

1-15
Configuring MLD Snooping Querier
Configuration Prerequisites
Before configuring MLD snooping querier, complete the following task:
z
Enable MLD snooping in the VLAN.
Before configuring MLD snooping querier, prepare the following data:
z
MLD general query interval,
z
MLD last-member query interval,
z
Maximum response time for MLD general queries,
z
Source IPv6 address of MLD general queries, and
z
Source IPv6 address of MLD multicast-address-specific queries.
Enabling MLD Snooping Querier
In an IPv6 multicast network running MLD, a multicast router or Layer 3 multicast switch is responsible
for sending periodic MLD general queries, so that all Layer 3 multicast devices can establish and
maintain multicast forwarding entries, thus to forward multicast traffic correctly at the network layer. This
router or Layer 3 switch is called MLD querier.
However, a Layer 2 multicast switch does not support MLD, and therefore cannot send MLD general
queries by default. By enabling MLD snooping querier on a Layer 2 switch in a VLAN where multicast
traffic needs to be Layer-2 switched only and no Layer 3 multicast devices are present, the Layer 2
switch will act as the MLD querier to send periodic MLD queries, thus allowing multicast forwarding
entries to be established and maintained at the data link layer.
Follow these steps to enable the MLD snooping querier:
To do... Use the command... Remarks
Enter system view system-view —
Enter VLAN view vlan vlan-id —
Enable the MLD snooping
querier
mld-snooping querier
Required
Disabled by default
It is meaningless to configure an MLD snooping querier in an IPv6 multicast network running MLD.
Although an MLD snooping querier does not take part in MLD querier elections, it may affect MLD
querier elections because it sends MLD general queries with a low source IPv6 address.
For details about MLD querier, see MLD Configuration of the IP Multicast Volume .
Configuring MLD Queries and Responses
You can tune the MLD general query interval based on actual condition of the network.
Upon receiving an MLD query (general query or multicast-address-specific query), a host starts a timer
for each IPv6 multicast group it has joined. This timer is initialized to a random value in the range of 0 to