In a typical IPTV network, there are several high demand basic channels. At any instant there is at least one viewer for each of these channels (streams), and they should always be available at the core (ring). When a user requests one of these channels, it is quickly pulled locally from the multicast VLAN (Virtual LAN). You have the option to use the static router configuration in each of the switches in the core. But this will cause all the channels to be available in the core, which may not be desired. For example, on an Extreme Networks router, you can use the following commands:
configure igmp snooping {vlan} vlan_name ports port_list add static router
You can use the static MVR configuration and choose the groups for which the multicast stream should be flooded. If a multicast stream 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.
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 (Internet Group Management Protocol) 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. You can use a dynamic MVR configuration, and choose the groups for which the IGMP join requests should be proxied over the MVR VLAN. Thus, in Basic MVR Deployment, 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 does not need to configure static IGMP on the router for each of these channels.
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