Overview
The IPv6 address scheme uses hexadecimal FF at the start of an address for IPv6
multicast. MLD is a protocol that uses these addresses. The following addresses have
specific functions:
•
You can assign only multicast addresses of global-scope (that is, containing an FFxE
prefix, where x is the flags field) to a multicast group.
•
FF02::1 is the link-scope all-nodes address—A packet sent to this address reaches all
nodes on a subnetwork.
•
FF02::2 is the link-scope all-routers address—A packet sent to this address reaches
all routers on a subnetwork.
•
FF02::16 is the link-scope all-MLDv2 routers address—A packet sent to this address
reaches all MLDv2 routers on a subnetwork.
This implementation of MLD complies with MLD versions 1 and 2. MLDv2 allows for
source-specific join and leave messages and is backward compatible with MLDv1.
Configuring MLDv1 with the SSM mapping feature provides support for source-specific
joins.
MLDv1 mode interfaces exchange the following types of messages between routers and
hosts:
•
Multicast listener queries
•
Multicast listener reports
•
Multicast listener done messages
MLDv2 mode interfaces exchange the following types of messages with MLDv2 hosts:
•
Multicast listener queries
•
MLDv2 multicast listener reports
Multicast Listener Queries
A multicast router can be a querier or a nonquerier. There is only one querier on a network
at any time. Multicast routers monitor queries from other multicast routers to determine
the status of the querier. If the querier hears a query from a router with a lower IPv6
address, it relinquishes its role to that router.
MLDv1 and MLDv2 mode interfaces send two types of multicast listener queries to hosts
on the network:
•
General queries to the all-nodes address (FF02::1)
•
Specific queries to the appropriate multicast group address
MLDv2 mode interfaces send the following type of queries to MLDv2 hosts:
Copyright © 2010, Juniper Networks, Inc.176
JunosE 11.2.x Multicast Routing Configuration Guide
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