Extreme Networks ExtremeWare XOS 11.3, Manual

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ExtremeWare XOS 11.3 Concepts Guide
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31 IPv6 Multicast Routing
This chapter covers the following topics:
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Overview on page 587
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MLD Overview on page 587
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MLD Snooping on page 587
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Static MLD on page 588
Overview
IPv6 multicast routing is a function that allows a single IPv6 host to send a packet to a group of IPv6
hosts. This group of hosts can include devices that reside on or outside the local network, or within or
across a routing domain.
IPv6 multicast routing consists of the following functions:
●
A router that can forward IPv6 multicast packets
●
A router-to-router multicast protocol [for example, Protocol Independent Multicast (PIM)]
●
A method for the IPv6 host to communicate its multicast group membership to a router [for
example, Multicast Listener Discovery (MLD)]
NOTE
In the current release of ExtremeWare XOS (11.3), IPv6 multicast packets are flooded to VLANs that receive the
traffic.
MLD Overview
MLD is a protocol used by an IPv6 host to register its IP multicast group membership with a router.
Periodically, the router queries the multicast group to see if the group is still in use. If the group is still
active, a single IP host responds to the query, and group registration is maintained.
MLD is the IPv6 equivalent to IGMP. MLDv1 is equivalent to IGMPv2, and MLDv2 is equivalent to
IGMPv3. MLDv1 is currently supported on the switch.
MLD Snooping
MLD snooping is a Layer 2 function of the switch; it does not require multicast routing to be enabled. In
MLD snooping, the Layer 2 switch keeps track of MLD reports and only forwards multicast traffic to
that part of the local network that requires it. MLD snooping optimizes the use of network bandwidth
and prevents multicast traffic from being flooded to parts of the local network that do not need it.