In the compatible mode MVR does not learn multicast groups, but they
have to be configured by administrator and protocol does not forward joins
from the hosts to the router. To work in this mode the IGMP router has to
be configured to transmit required multicast streams to the network with
the MVR switch.
Enabling MVR and IGMP on the Same Interface
MVR and IGMP snooping operate independently and could both be enabled
on an interface. When both MVR and IGMP snooping are enabled, MVR
listens to the IGMP join and report messages for static multicast group
information, and IGMP snooping manages dynamic multicast groups.
When Are L3 Multicast Features Required?
In addition to L2 multicast features, the switch suports IP and IPv6 multicast
features. You configure the IP/IPv6 multicast features if the switch functions
as a multicast router that can route multicast traffic between VLAN routing
interfaces. In this case, you must enable a multicast routing protocol on the
switch, such as PIM-SM. For information about L3 multicast features, see
"Managing IPv4 and IPv6 Multicast" on page 1149.
If you enable IGMP Snooping on the switch to listen to IGMP traffic, you do
not need to enable IGMP, a layer 3 multicast protocol. If the switch functions
as a multicast router, it is possible to enable both IGMP and IGMP Snooping
so that the switch routes IGMP traffic between VLANs and examines the
IGMP packets for join and leave information.
If MVR is enabled, IP Multicast should be disabled. Multicast routing and
MVR cannot coexist on a switch.
For information about configuring a PowerConnect
M6220/M6348/M8024/M8024-k switch as a mutlicast router that also
performs IGMP snooping, see "Configuring Multicast VLAN Routing With
IGMP and PIM-SM" on page 1223.
Configuring L2 Multicast Features