PLANET SGSD-1022 - Manual (Page 214)

User’s Manual of SGSD-1022 / SGSD-1022P
SGSW-2840 / SGSW-2840P
• 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
• IGMP Version Sets the protocol version for compatibility with other devices on the network.
Range: 1-3;
Default: 2
1. All systems on the subnet must support the same version.
2. Some attributes are only enabled for IGMPv2 and/or v3, including Act as IGMP
Querier, IGMP Report Delay and IGMP Query Timeout.
4.9.1.2 IGMP Immediate Leave
The Managed 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 immediate-leave function is enabled for the parent VLAN. This allows the Managed witch to remove a port
from the multicast forwarding table without first having to send an IGMP group-specific query to that interface.
Command Usage
• If immediate leave is not used, a multicast router (or querier) will send a group-specific 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. Note that the timeout period is determined by the IGMP Query Report Delay (see
“Configuring IGMP Snooping and Query Parameters”).
• If immediate leave is enabled, the Managed witch assumes that only one host is connected to the interface. Therefore,
immediate 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.
• Immediate leave is only effective if IGMP snooping is enabled, and IGMPv2 or IGMPv3 snooping is used.
• Immediate leave does not apply to a port if the Managed witch has learned that a multicast router is attached to it.
• Immediate leave can improve bandwidth usage for a network which frequently experiences many IGMP host add and leave
requests.
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