User manual

HAPTER

| Configuring the Switch

IGMP Snooping

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If IGMP snooping cannot locate the IGMP querier, you can manually

designate a port which is connected to a known IGMP querier (i.e., a

multicast router/switch). This interface will then join all the current

multicast groups supported by the attached router/switch to ensure

that multicast traffic is passed to all appropriate interfaces within the

switch.

◆ Fast Leave - Immediately deletes a member port of a multicast service

if a leave packet is received at that port. (Default: Disabled)

The switch can be configured to immediately delete a member port of a

multicast service if a leave packet is received at that port and the Fast

Leave function is enabled. This allows the switch to remove a port from

the multicast forwarding table without first having to send an IGMP

group-specific (GS) query to that interface.

If Fast Leave is not used, a multicast router (or querier) will send a

GS-query message when an IGMPv2/v3 group leave message is

received. The router/querier stops forwarding traffic for that group only

if no host replies to the query within the specified timeout period.

If Fast Leave is enabled, the switch assumes that only one host is

connected to the interface. Therefore, Fast Leave should only be

enabled on an interface if it is connected to only one IGMP-enabled

device, either a service host or a neighbor running IGMP snooping.

Fast Leave is only effective if IGMP snooping is enabled, and IGMPv2 or

IGMPv3 snooping is used.

Fast Leave does not apply to a port if the switch has learned that a

multicast router is attached to it.

Fast Leave can improve bandwidth usage for a network which

frequently experiences many IGMP host add and leave requests.

◆ Throttling - Limits the number of multicast groups to which a port can

belong. (Range: 1-10; Default: unlimited)

IGMP throttling sets a maximum number of multicast groups that a port

can join at the same time. When the maximum number of groups is

reached on a port, any new IGMP join reports will be dropped.