Allied Telesis AT-S29 - Manual (Page 105)

AT-S29 Management Software User’s Guide
105
IGMP Multicast Filtering
Multicasting is used to support real-time applications such as video
conferencing or streaming audio. A multicast server does not have to
establish a separate connection with each client. It merely broadcasts its
services to the network, and any hosts which want to receive the
multicast register with their local multicast switch/router. Although this
approach reduces the network overhead required by a multicast server,
the broadcast traffic must be carefully pruned at every multicast
server/router it passed through to ensure that traffic is only passed on
the hosts which subscribed to this service.
The AT-8324SX switch uses IGMP (Internet Group Management
Protocol) to query for any attached hosts who want to receive a specific
multicast service. The switch looks up the IP Multicast Group used for
this service and adds any port which received a similar request to that
group. It then propagates the service request on to any neighboring
multicast switch/router to ensure that it will continue to receive the
multicast service.
Configuring
IGMP
This protocol allows a host to inform its local switch/router that it wants
to receive transmissions addressed to a specific multicast group. You can
use the IGMP Configuration screen to configure multicast filtering
shown below:
Note
The default values are indicated in the sample screen.
IGMP Status
IGMP Query Count (2-16)
Act as IGMP Querier Enable
IGMP Report delay (3-10)
Enable
5
5 minutes
Parameter Description
IGMP Status If enabled, the switch will monitor network traffic to determine which
hosts want to receive multicast traffic.
ACT as IGMP
Querier If enabled, the switch can serve as the “querier,” which is responsible for
asking hosts if they want to receive multicast traffic. (Not available for the
current firmware release.)
IGMP Query Count The maximum number of queries issued for which there has been no
response before the switch takes action to solicit reports.
IGMP Report Delay The time (in minutes) between receiving an IGMP Report for an IP
multicast address on a port before the switch sends an IGMP Query out
that port and removes the entry from its list.