Chapter 21
| Multicast Filtering Commands
IGMP Snooping
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ip igmp snooping vlan
immediate-leave
This command immediately deletes a member port of a multicast service if a
leave packet is received at that port and immediate-leave is enabled for the
parent VLAN. Use the
no
form to restore the default.
Syntax
ip igmp snooping vlan
vlan-id
immediate-leave
[
by-host-ip
]
no
ip igmp snooping vlan
vlan-id
immediate-leave
vlan-id
- VLAN ID (Range: 1-4094)
by-host-ip
- Specifies that the member port will be deleted only
when there are no hosts joining this group.
Default Setting
Disabled
Command Mode
Global Configuration
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 timeout period. (The timeout for this
release is defined by Last Member Query Interval (fixed at one second) *
Robustness Variable (fixed at 2) as defined in RFC 2236.)
◆
If immediate-leave is used, the switch 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.
◆
If the “by-host-ip” option is used, the router/querier will not send out a
group-specific query when an IGMPv2/v3 leave message is received. But
will check if there are other hosts joining the multicast group. Only when all
hosts on that port leave the group will the member port be deleted.
◆
This command is only effective if IGMP snooping is enabled, and IGMPv2
or IGMPv3 snooping is used.
Example
The following shows how to enable immediate leave.
Console(config)#ip igmp snooping vlan 1 immediate-leave
Console(config)#