Configuring Layer 2 Multicast IGMP Snooping Configuration
User Guide    225
Step 6 ip igmp snooping vlan-config 
vlan-id-list
 immediate-leave
(Optional) Enable the Fast Leave for the VLANs. By default, it is disabled. IGMPv1 does not 
support fast leave.
Without Fast Leave, after a receiver sends an IGMP leave message to leave a multicast group, 
the switch will forward the leave message to the Layer 3 device (the querier). 
From the point of view of the querier, the port connecting to the switch is a member port of the 
corresponding multicast group. After receiving the leave message from the switch, the querier 
will send out a configured number (Last Member Query Count) of group-specific queries on 
that port with a configured interval (Last Member Query Interval), and wait for IGMP group 
membership reports. If there are other receivers connecting to the switch, they will response 
to the queries before the Last Member Query Interval expires. If no reports are received 
after the response time of the last query expires, the querier will remove the port from the 
forwarding list of the corresponding multicast group.
That is, if there are other receivers connecting to the switch, the one sent leave message have 
to wait until the port ages out from the switch’s forwarding list of the corresponding multicast 
group (the maximum waiting time is decided by the Member Port Aging Time).
With Fast Leave enabled on a VLAN, the switch will remove the (Multicast Group, Port, VLAN) 
entry from the multicast forwarding table before forwarding the leave message to the querier. 
This helps to reduce bandwidth waste since the switch no longer sends the corresponding 
multicast streams to the VLAN of the port as soon as the port receives a leave message from 
the VLAN. 
You should only enable Fast Leave for a VLAN when there is a single receiver belongs to this 
VLAN on every port of the VLAN.
vlan-id-list: 
Specify the ID or the ID list of the VLAN(s).
Step 7 ip igmp snooping vlan-config 
vlan-id-list
 rport interface { fastEthernet 
port-list
 | 
gigabitEthernet 
port-list
 | ten-gigabitEthernet 
port-list
| port-channel 
lag-list
 }
(Optional) Specify the static router ports for the VLANs. Static router ports do not age.
vlan-id-list: 
Specify the ID or the ID list of the VLAN(s).
port-list
: The number or the list of the Ethernet port that need to be configured as static router 
ports.
lag-list
: The ID or the list of the LAG that need to be configured as static router ports.
Step 8 ip igmp snooping vlan-config 
vlan-id-list
 router-ports-forbidden interface { fastEthernet 
port-list
 | gigabitEthernet 
port-list
 | ten-gigabitEthernet 
port-list
| port-channel 
lag-list
 }
(Optional) Specify the ports to forbid them from being router ports in the VLANs.
vlan-id-list: 
Specify the ID or the ID list of the VLAN(s).
port-list
: The number or the list of the Ethernet port that need to be forbidden from being 
router ports.
lag-list
: The ID or the list of the LAG that need to be forbidden from being router ports.
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