Troubleshooting Guide

Table Of Contents
Chapter 22: Multicast troubleshooting
Use the following information to troubleshoot multicast features and multicast routing.
Multicast feature troubleshooting
Use the information in this section to troubleshoot multicast feature problems.
Troubleshooting IGMP Layer 2 Querier
The following sections provide troubleshooting information for the IGMP Layer 2 Querier feature.
Querier not elected
If a Querier is not elected, use the following procedure to troubleshoot the issue.
Procedure
1. Enter Privileged EXEC mode:
enable
2. As the IGMP Layer 2 Querier is based on IGMP snoop, check whether IGMP snoop is
enabled on the VLAN:
show ip igmp interface vlan
If IGMP snoop is disabled, the Layer 2 Querier cannot work until IGMP snoop and IGMP
Layer 2 Querier are reenabled.
Example
Check whether IGMP snoop is enabled on the VLAN:
Switch:1>enable
Switch:1#show ip igmp interface vlan
================================================================================
Vlan Ip Igmp
================================================================================
VLAN QUERY QUERY ROBUST VERSION LAST PROXY SNOOP SSM FAST FAST
ID INTVL MAX MEMB SNOOP ENABLE SNOOP LEAVE LEAVE
RESP QUERY ENABLE ENABLE ENABLE PORTS
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January 2017 Troubleshooting 261
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