RuggedCom Welder RS400 用户手册

 

 

Multicast Filtering 

RS400 

195 

ROS™  v3.5 

 

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. 

™

•  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. 

 

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. 

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.