Owner's Manual

Chapter 27. Multicast Routing and Switching | 751
NETGEAR 8800 User Manual
If a multicast packet for a group in the static MVR range is received on an MVR enabled
VLAN, it is always flooded on the MVR VLAN. This allows the neighbor switch in the ring to
receive all the static MVR streams.
Dynamic MVR
In contrast, since a video content provider would like to provide a variety of on-demand and
other premium channels, there are often many lower demand (fewer viewers) premium
channels that cannot all be made available simultaneously at the core network. These should
be streamed from the router only if requested by a host.
IGMP is the standard method used by a host to request a stream. However, IGMP packets
are constrained to a VLAN. Thus, subscribers' IGMP join requests on the VLAN cannot be
forwarded onto other VLANS. With MVR, a VLAN sends proxy IGMP join messages on
behalf of all the subscriber VLANs on the switch. Thus, in
Figure 89, McastVlan sends join
and leave messages on behalf of Vlan2, Vlan3, and Vlan4. The router receives the
messages on McastVlan and streams corresponding channels onto the core network. This
provides on-demand service, and an administrator doesn't need to configure static IGMP on
the router for each of these channels.
Configuring Static and Dynamic MVR
By default, all MVR streams are static. You can specify which groups are static by using the
following command:
configure mvr vlan <vlan-name> static group {<policy-name> | none}
Any other groups in the MVR address range are dynamic. You can specify the MVR address
range by using the following command:
configure mvr vlan <vlan-name> mvr-address {<policy-name> | none}
By using these two commands together, you can specify which groups are static and which
are dynamic. If you want all the groups to be dynamic, specify a policy file for the static group
command that denies all multicast addresses.
MVR Forwarding
The goal for MVR is to limit the multicast traffic in the core Layer 2 network to only the
designated multicast VLAN. If the backbone Layer
2 port is tagged with multiple VLANs, as
shown in
Figure 90, a set of rules is needed to restrict the multicast streams to only one
VLAN in the core.