Configuring Mld - HP FlexNetwork 7500 Series Configuration Manual

Configuring MLD

Overview
Multicast Listener Discovery (MLD) establishes and maintains IPv6 multicast group memberships
between a Layer 3 multicast device and the hosts on the directly connected subnet.
MLD has the following versions:
•
MLDv1 (defined by RFC 2710), which is derived from IGMPv2.
•
MLDv2 (defined by RFC 3810), which is derived from IGMPv3.
MLDv1 and MLDv2 support the ASM model. MLDv2 can directly implement the SSM model. MLDv2
can directly implement the SSM model, but MLDv1 must work with the MLD SSM mapping feature to
implement the SSM model. For more information about the ASM and SSM models, see
overview."
How MLDv1 works
MLDv1 implements IPv6 multicast listener management based on the query and response
mechanism.
Electing the MLD querier
All IPv6 multicast routers that run MLD on the same subnet can monitor MLD listener report
messages (often called reports) from hosts. However, only one router can act as the MLD querier to
send MLD query messages (often called queries). A querier election mechanism determines which
router acts as the MLD querier on the subnet.
Initially, every MLD router assumes itself as the querier. Each router sends MLD general query
1.
messages (often called general queries) to all hosts and routers on the local subnet. The
destination address of the general queries is FF02::1.
After receiving a general query, every MLD router compares the source IPv6 address of the
2.
query with its own link-local interface address. The router with the lowest IPv6 address
becomes the querier. All the other routers become non-queriers.
All the non-queriers start the other querier present timer. If a router receives an MLD query from
3.
the querier before the timer expires, it resets this timer. Otherwise, it considers that the querier
has timed out. In this case, the router initiates a new querier election process.
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"Multicast