SMC Networks 6924MT, Management Manual

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information, and configures multicast filters accordingly. IGMP Snooping
generates no additional network traffic, allowing you to significantly reduce
the multicast traffic passing through your switch.
IGMP Protocol
The Internet Group Management Protocol (IGMP) runs between hosts
and their immediately neighboring multicast router/switch. IGMP is a
multicast host registration protocol that allows any host to inform its local
router that it wants to receive transmissions addressed to a specific
multicast group.
A router, or multicast-enabled switch, can periodically ask their hosts is
they want to receive multicast traffic. If there is more than one router/
switch on the LAN performing IP multicasting, one of these devices is
elected “querier” and assumes the responsibility of querying the LAN for
group members.
Based on the group membership information learned from IGMP, a
router/switch can determine which (if any) multicast traffic needs to be
forwarded to each of its ports. At Layer 3, multicast routers use this
information, along with a multicast routing protocol such as DVMRP, to
support IP multicasting across the Internet.
Note that IGMP neither alters nor routes any IP multicast packets. A
multicast router/switch must be used to deliver IP multicast packets across
different subnetworks.
Class-of-Service (CoS) Support
The TigerStack 100 provides two transmit queues on each port, with a
weighted round-robin scheme. This function can be used to provide
independent priorities for various types of data such as real-time video or
voice, and best-effort data.