SMC Networks SMC TigerAccess SMC7824M/FSW - Manual (Page 319)

L
AYER
2 IGMP (S
NOOPING AND
Q
UERY
)
15-3
Only IGMPv3 hosts can request service from a specific multicast source.
When downstream hosts request service from a specific source for a
multicast service, these sources are all placed in the Include list, and traffic
is forwarded to the hosts from each of these sources. IGMPv3 hosts may
also request that service be forwarded from all sources except for those
specified. In this case, traffic is filtered from sources in the Exclude list,
and forwarded from all other available sources.
Notes: 1. When the switch is configured to use IGMPv3 snooping, the
snooping version may be downgraded to version 2 or version
1, depending on the version of the IGMP query packets
detected on each VLAN.
2. IGMP snooping will not function unless a multicast router
port is enabled on the switch. This can accomplished in one of
two ways. A static router port can be manually configured (see
“Specifying Static Interfaces for a Multicast Router” on page
15-8). Using this method, the router port is never timed out,
and will continue to function until explicitly removed. The
other method relies on the switch to dynamically create
multicast routing ports whenever multicast routing protocol
packets or IGMP query packets are detected on a port.
3. A maximum of up to 255 multicast entries can be maintained
for IGMP snooping and 255 entries for Multicast Routing
when both of these features are enabled. If the table’s capacity
is exceeded, then IGMPv3 snooping will not support multicast
source filtering, but will forward multicast traffic from all
relevant sources to the requesting hosts.
Static IGMP Router Interface – If IGMP snooping cannot locate the
IGMP querier, you can manually designate a known IGMP querier (i.e., a
multicast router/switch) connected over the network to an interface on
your switch (page 15-8). This interface will then join all the current
multicast groups supported by the attached router/switch to ensure that
multicast traffic is passed to all appropriate interfaces within the switch.