3-12
Configuring the Switch
Configurable Features
Configuring the Switch
IP Multicast (IGMP) Service Features—Multimedia
Traffic Control
The IGMP (Internet Group Management Protocol) feature helps to reduce
network congestion and improve security by reducing unnecessary multicast
traffic on a per-port basis. This is useful in multimedia applications such as
LAN TV, desktop conferencing, and collaborative computing, where there is
multipoint communication; that is, communication from one to many hosts,
or communication originating from many hosts and destined for many other
hosts. In such multipoint applications, IGMP will be configured on the hosts,
and multicast traffic will be generated by one or more servers (inside or
outside of the local network). Switches in the network (such as the Switch
800T or the B-version of the Switch 2000) can then be configured to direct the
multicast traffic to only the ports where needed.
In the factory default state (IGMP disabled), the switch forwards all IGMP
traffic. When IGMP is enabled, you can configure the switch to any of the
following states on a per-port basis:
■ Automatic (the default): Causes the switch to interpret IGMP packets and
to filter IP multicast traffic based on the IGMP packet information for that
port.
■ Blocking: Causes the switch to drop all IGMP transmissions received and
block all outgoing IP Multicast packets for that port.
■ Forwarding: Causes the switch to forward all IGMP and IP multicast
transmissions through the port.
For more information on IGMP and how to configure it, refer to “IP Multicast
(IGMP)” on 7-23.
SEDONA.BK : sed_3.fm5 Page 12 Thursday, February 27, 1997 10:11 AM
