IGMP-Connected Group Membership

IGMP-Connected Group Membership

Group Address

Interface

Uptime

Expires

Last Reporter

225.250.250.1

ethernet 0

03:05:59

Never

172.16.4.3

group-address

Multicast group address

interface

Interface where the group joined

Uptime

How long the group has been joined on the interface in hours, minutes, and seconds

Expires

The time when the group is removed from the table in hours, minutes, and seconds

Last Reported

IP address of the last host to report membership

The current state of IGMP on an interface along with IGMP timer values can be shown using the Exec command:

router#show ip igmp interface ?

Ethernet

IEEE 802.3

Loopback

Loopback interface

Null

Null interface

Serial

Serial

|

Output modifiers

<cr>

An individual interface can be displayed using

router#show ip igmp interface ethernet 0

ethernet 0 is up; line protocol is up

Internet address is 172.16.4.3/24

IGMP is enabled on interface

Current IGMP version is 2

CGMP is disabled on interface

IGMP query interval is 60 seconds

IGMP querier timeout is 120 seconds

IGMP max query response time is 10 seconds

Inbound IGMP access group is not set

IGMP activity: 1 joins, 0 leaves

Multicast routing is disabled on interface

Multicast TTL threshold is 0

Multicast groups joined (number of users): 225.250.250.1(1)

Finally, the operation of IGMP can be monitored using the debug ip igmp command:

router#debug ip igmp

05:09:55: IGMP: Received v2 Query from 172.16.4.1 (ethernet 0)

05:09:55: IGMP: Set report delay time to 7.0 seconds for 225.250.250.1 on ethernet 0

05:10:02: IGMP: Send v2 Report for 225.250.250.1 on ethernet 0

05:10:02: IGMP: Received v2 Report from 172.16.4.3 (ethernet 0) for 225.250.250.1

05:10:15: IGMP: Send Leave for 225.250.250.1 on ethernet 0

References

RFC 1054, “Host Extensions for IP Multicasting,” S. Deering, Stanford University, 1988

RFC 1112, “Host Extensions for IP Multicasting,” S. Deering, Stanford University, 1989

RFC 2236, “Internet Group Management Protocol—Version 2,” W. Fenner, Xerox PARC, 1997 cp4