Cisco IE 4000, Руководство по настройке программного обеспечения

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Configuring IGMP Snooping and MVR
Information About IGMP Snooping and MVR

The IGMP snooping querier supports IGMP Versions 1 and 2.

When administratively enabled, the IGMP snooping querier moves to the nonquerier state if it detects the presence
of a multicast router in the network.

When it is administratively enabled, the IGMP snooping querier moves to the operationally disabled state under these
conditions:
— IGMP snooping is disabled in the VLAN.
— PIM is enabled on the SVI of the corresponding VLAN.
IGMP Report Suppression
IGMP report suppression is enabled by default. When it is enabled, the switch forwards only one IGMP report per
multicast router query. When report suppression is disabled, all IGMP reports are forwarded to the multicast routers.
Multicast VLAN Registration
Note: To use this feature, the switch must be running the LAN Base image.
Multicast VLAN Registration (MVR) is designed for applications using wide-scale deployment of multicast traffic across
an Ethernet ring-based service-provider network (for example, the broadcast of multiple television channels over a
service-provider network). MVR allows a subscriber on a port to subscribe and unsubscribe to a multicast stream on the
network-wide multicast VLAN. It allows the single multicast VLAN to be shared in the network while subscribers remain
in separate VLANs. MVR provides the ability to continuously send multicast streams in the multicast VLAN, but to isolate
the streams from the subscriber VLANs for bandwidth and security reasons.
MVR assumes that subscriber ports subscribe and unsubscribe (join and leave) these multicast streams by sending out
IGMP join and leave messages. These messages can originate from an IGMP Version-2-compatible host with an Ethernet
connection. Although MVR operates on the underlying mechanism of IGMP snooping, the two features operate
independently of each other. One can be enabled or disabled without affecting the behavior of the other feature.
However, if IGMP snooping and MVR are both enabled, MVR reacts only to join and leave messages from multicast
groups configured under MVR. Join and leave messages from all other multicast groups are managed by IGMP snooping.
The switch CPU identifies the MVR IP multicast streams and their associated IP multicast group in the switch forwarding
table, intercepts the IGMP messages, and modifies the forwarding table to include or remove the subscriber as a receiver
of the multicast stream, even though the receivers might be in a different VLAN from the source. This forwarding behavior
selectively allows traffic to cross between different VLANs.
You can set the switch for compatible or dynamic mode of MVR operation:

In compatible mode, multicast data received by MVR hosts is forwarded to all MVR data ports, regardless of MVR
host membership on those ports. The multicast data is forwarded only to those receiver ports that MVR hosts have
joined, either by IGMP reports or by MVR static configuration. IGMP reports received from MVR hosts are never
forwarded from MVR data ports that were configured in the switch.

In dynamic mode, multicast data received by MVR hosts on the switch is forwarded from only those MVR data and
client ports that the MVR hosts have joined, either by IGMP reports or by MVR static configuration. Any IGMP reports
received from MVR hosts are also forwarded from all the MVR data ports in the switch. This eliminates using
unnecessary bandwidth on MVR data port links, which occurs when the switch runs in compatible mode.
Only Layer 2 ports take part in MVR. You must configure ports as MVR receiver ports. Only one MVR multicast VLAN per
switch is supported.