SMC Networks 1000BASE-X manual Class-of-Service CoS Support, Igmp Protocol

CLASS-OF-SERVICE (COS) SUPPORT

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.

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