Cli: Statically Configuring A Interface To Join A Group; Leaving A Multicast Group - Cisco Catalyst 2950 Software Manual

Understanding and Configuring IGMP Snooping

CLI: Statically Configuring a Interface to Join a Group

Beginning in privileged EXEC mode, follow these steps to add a port as a member of a multicast group:
Command
Step 1 configure terminal
Step 2
ip igmp snooping vlan vlan-id static
mac-address interface interface-id
Step 3
end
Step 4 show mac-address-table multicast [vlan
vlan-id] [user | igmp-snooping] [count]
Step 5 copy running-config startup-config
For CLI procedures, refer to the Cisco IOS Release 12.1 documentation on Cisco.com for additional
information and CLI procedures.

Leaving a Multicast Group

The router sends periodic IP multicast general queries, and the switch responds to these queries with one
join response per MAC multicast group. As long as at least one host in the VLAN needs multicast traffic,
the switch responds to the router queries, and the router continues forwarding the multicast traffic to the
VLAN. The switch only forwards IP multicast group traffic to those hosts listed in the forwarding table
for that IP multicast group.
When hosts need to leave a multicast group, they can either ignore the periodic general-query requests
sent by the router, or they can send a leave message. When the switch receives a leave message from a
host, it sends out a group-specific query to determine if any devices behind that interface are interested
in traffic for the specific multicast group. If, after a number of queries, the router processor receives no
reports from a VLAN, it removes the group for the VLAN from its multicast forwarding table.
Catalyst 2950 Desktop Switch Software Configuration Guide
11-6
Chapter 11
Purpose
Enter global configuration mode
Statically configure a port as a member of a multicast group:
vlan-id is the multicast group VLAN ID.
•
• mac-address is the group MAC address.
• interface-id is the member port.
Display MAC address table entries for a VLAN.
vlan-id (Optional) is the multicast group VLAN ID.
•
user displays only the user-configured multicast entries.
•
igmp-snooping displays entries learned via IGMP
•
snooping.
count displays only the total number of entries for the
•
selected criteria, not the actual entries.
(Optional) Save your configuration to the startup configuration.
Configuring IGMP Snooping and MVR
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