Monitoring IGMP for Multicast Groups

Purpose

Display the IGMP membership information for multicast groups and (S, G) channels. You can specify the tracked keyword to view the interface information only for interfaces where explicit host tracking is enabled.

Action

To display IGMP membership information for multicast groups and (S, G) channels:

host1# show ip igmp membership
Flags: M – Uses Oifmap  S– SSM mapped  T – tracked 
       1,2,3 – The version of IGMP the group is in
Reporter:
<ip-address> - last reporter if the group is not explicitly tracked
<n>/<m> - <n> reporters include mode, <m> reporters in exclude
Group            Source             Reporter         ExpTim    Flags     Interface
---------------  ---------------    -------------    ------    ------    ---------------
224.0.1.40           *              10.10.1.1        02:41     2S        FastEthernet2/1
224.0.1.50                          1/2              02:56     3MT       FastEthernet2/2 
                                    11.10.0.21       02:56
                                    11.10.2.22       02:30      
                 20.30.0.11         
                                    11.10.0.23       02:48     
                 20.30.0.12         
                                    11.10.0.21       02:56     
                 20.30.0.13         
                                    11.10.0.21       02:56 
                                    11.10.0.22       02:30     
                                    11.10.0.23       02:48     
224.0.1.60                          20.20.0.1        01:56     3        FastEthernet2/3
                 10.30.0.100                         02:45
                 10.30.0.101                         02:35 
                 10.30.0.102                         02:15 
                 10.30.0.104                         stop
224.0.1.70                          30.20.0.1        stop      3        FastEthernet2/4
                 40.30.0.100                         01:10
                 40.30.0.101                         01.24
239.0.1.80                          2/0              stop      3T       FastEthernet2/5 
                 50.30.0.100        
                                    10.10.0.10       02:48     
                 50.30.0.101        
                                    10.10.0.20       02:56     
                                    10.10.0.10       02:48     
                 50.30.0.102        10.10.0.20       02:56     
235.0.1.90                          0/3              02:56     2T       FastEthernet2/6 
                      *             
                                    12.10.0.10       02:48     
                                    12.10.0.20       02:56     
                                    12.10.0.30       02:48 

Meaning

Table 21 lists the output fields of the show ip igmp membership command.

Table 21: show ip igmp membership Output Fields

Field Name

Field Description

Group

Multicast group or (S, G) channel

Source

(S, G) entries that are forwarding traffic

Reporter

Hosts that requested including sources or have not requested excluding sources. If listed under a group, host that sent exclude reports for the group. If listed under a source, host that requested traffic from this source for the group. For any (S, G), if listed under a source, hosts interested in the traffic for this (S, G).

Flags

  • M—Uses Oifmap
  • S—SSM mapped
  • T—Tracked
  • 1, 2, 3—IGMP version that the group is in

ExpTim

Expiration time

Interface

Type of interface and interface specifier. For details about interface types and specifiers, see Interface Types and Specifiers in the JunosE Command Reference Guide.

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