Installation manual

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SIGNAMAX LLC • www.signamax.eu
Configuring IGMP Snooping and Query Parameters
You can configure the switch to forward multicast traffic intelligently. Based on the IGMP
query and report messages, the switch forwards traffic only to the ports that request
multicast traffic. This prevents the switch from broadcasting the traffic to all ports and
possibly disrupting network performance.
Command Usage
• IGMP Snooping – This switch can passively snoop on IGMP Query and Report packets
transferred between IP multicast routers/switches and IP multicast host groups to
identify the IP multicast group members. It simply monitors the IGMP packets passing
through it, picks out the group registration information, and configures the multicast
filters accordingly.
Note:
Unknown multicast traffic is flooded to all ports in the VLAN for several seconds when
first received. If a multicast router port exists on the VLAN, the traffic will be filtered by
subjecting it to IGMP snooping. If no router port exists on the VLAN or the multicast
filtering table is already full, the switch will continue flooding the traffic into the VLAN.
• IGMP Querier – A router, or multicast-enabled switch, can periodically ask their hosts if
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
role of querying the LAN for group members. It then propagates the service requests on
to any upstream multicast switch/router to ensure that it will continue to receive the
multicast service.
Note: Multicast routers use this information, along with a multicast routing protocol such as
DVMRP or PIM, to support IP multicasting across the Internet.
Command Attributes
• IGMP Status — When enabled, the switch will monitor network traffic to determine
which hosts want to receive multicast traffic. This is also referred to as IGMP Snooping.
(Default: Enabled)
• Act as IGMP Querier — When enabled, the switch can serve as the Querier, which is
responsible for asking hosts if they want to receive multicast traffic. This feature is not
supported for IGMPv3 snooping. (Default: Disabled)
• IGMP Query Count — Sets the maximum number of queries issued for which there has
been no response before the switch takes action to drop a client from the multicast
group. (Range: 2-10; Default: 2)
• IGMP Query Interval — Sets the frequency at which the switch sends IGMP host-query
messages. (Range: 60-125 seconds; Default: 125)
• IGMP Report Delay — Sets the time between receiving an IGMP Report for an IP
multicast address on a port before the switch sends an IGMP Query out of that port and
removes the entry from its list. (Range: 5-25 seconds; Default: 10)
• IGMP Query Timeout — The time the switch waits after the previous querier stops
before it considers the router port (i.e., the interface which had been receiving query
packets) to have expired. (Range: 300-500 seconds; Default: 300)