Multicasting on N5K & N7K

[linguancheng]

Hi, I have questions regarding the command "switch(config-vlan)# ip igmp snooping querier IP-address"

It says that "Configures a snooping querier when you do not enable PIM because multicast traffic does not need to be routed. The IP address is used as the source in messages."

My question is does any IP address within the VLAN can be used here as the querier IP? Does it need to be an unused IP address in the VLAN to avoid IP conflict? Or is it just used as the source in messages and won't cause IP conflict?

Also, if the vlan is trunked among a few N5Ks and N7Ks, does the command "switch(config-vlan)# ip igmp snooping querier IP-address" needs to be configured on each one of the N5Ks and N7Ks?

Thanks.

Guan

[Jerry Ye]

You can use any IP address, and I usually use an unused one to avoid confusion.

You only need to configure it on 1 Nexus switches, usually the N7K aggregation (not access layer).

HTH,

jerry

[sbhadrav@cisco.com]

IGMP snooping immediate-leave processing allows the switch to remove an interface from the forwarding-table entry without first sending out IGMP group-specific queries to the interface. The VLAN interface is pruned from the multicast tree for the multicast group specified in the original IGMP leave message. Immediate-leave processing ensures optimal bandwidth management for all hosts on a switched network, even when multiple multicast groups are being used simultaneously.

When a switch with IGMP snooping enabled receives an IGMPv2 or IGMPv3 leave message, it sends an IGMP group-specific query from the interface where the leave message was received to determine when other hosts are attached to that interface that are interested in joining the MAC multicast group. If the switch does not receive an IGMP join message within the query response interval, the interface is removed from the port list of the (MAC-group, VLAN) entry in the Layer 2 forwarding table.
To display the IGMP version on a particular VLAN, use the show ip igmp snooping querier vlan command.

To display whether the switch supports IGMPv3 snooping, use the show ip igmp snooping vlan command.

To enable immediate-leave for IGMPv2, use the ip igmp snooping immediate-leave command.
To display querier information, perform this task:

Command
Purpose
Switch# show ip igmp snooping querier [vlan vlan_ID]

Displays multicast router interfaces.

This example shows how to display the IGMP snooping querier information for all VLANs on the switch:

 Switch# show ip igmp snooping querier
 Vlan      IP Address     IGMP Version        Port
 ---------------------------------------------------
 2         10.10.10.1     v2                  Router
 3         172.20.50.22   v3                  Fa3/15
This example shows how to display the IGMP snooping querier information for VLAN 3:

 Switch# show ip igmp snooping querier vlan 3
 Vlan      IP Address     IGMP Version        Port
 ---------------------------------------------------
 3         172.20.50.22   v3                  Fa3/15
To display host membership information, perform this task:
Switch# show ip igmp snooping membership [interface interface_num][vlan vlan_ID] [reporter a.b.c.d] [source a.b.c.d group a.b.c.d]