RuggedCom RS400 manual Router and Host Igmp Operation, Multicast Filtering

Multicast Filtering

8 Multicast Filtering

ROS™ accomplishes Multicast Filtering through the following ways:

1.Static Multicast Groups

2.Use of the Internet Group Management Protocol (IGMP) snooping.

ROS™ Multicast Filtering provides you with the following features:

•Support for up to 256 Multicast Groups (either static or dynamic).

•Ability to prioritize a Static Multicast Group via Class-of-Service

•Industry standard support of IGMP (RFC 1112, RFC 2236) versions 1 and 2 in active and passive roles.

Note: ROS™ IGMP Snooping supports multicast routers using IGMP version 2 and hosts using either IGMP version 1 or 2.

•Ability to enable or disable IGMP on a per VLAN basis.

•Multicast Routers may be statically configured or dynamically recognized by IGMP.

•“Routerless” IGMP operation.

8.1IGMP

IGMP is used by IP hosts to report their host group memberships to multicast routers. As hosts join and leave specific multicast groups, streams of traffic are directed to or withheld from that host.

The IGMP protocol operates between multicast routers and IP hosts. When an unmanaged switch is placed between multicast routers and their hosts, the multicast streams will be distributed to all ports. This may introduce significant traffic onto ports that do not require it and receive no benefit from it.

RuggedCom products with IGMP Snooping enabled will act upon IGMP messages sent from the router and the host, restricting traffic streams to the appropriate LAN segments.

8.1.1 Router and Host IGMP Operation

The following figure provides a simple example of IGMP use. One “producer” IP host (P1) is generating two IP multicast streams, M1 and M2. There are four potential “consumers” of these streams, C1 through C4.

The multicast router discovers which host wishes to subscribe to which stream by sending general membership queries to each of the segments.

RS400 195 ROS™ v3.5