Troubleshooting guide

3. Troubleshooting Functional Failures During Operation
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# If the Switch is the IGMP querier, the same address is displayed for IGMP querying system and
IP Address. If any other device is the IGMP querier, the address displayed for IGMP querying
system is not the same as the address displayed for IP Address.
3.6.5 Multicast forwarding by MLD snooping is not possible
If multicast forwarding is impossible when MLD snooping is used, use the following analysis
flowchart to determine the problem and isolate the cause.
4Use the show igmp-snooping
command to check the IGMP
snooping configuration.
Check the following:
• To check whether the IGMP querier that monitors the group members
exists, make sure one of the following messages is displayed.
(1) If the IGMP querier exists, the IP address of the IGMP querier is
displayed:
IGMP querying system: 192.168.11.20*
(2) If the IGMP querier does not exist, nothing is displayed for IGMP
querying system:
IGMP querying system:
• If the Switch is the IGMP querier, make sure the IP address has been set
for the VLAN.
(1) If the IP address has been set for the VLAN, the following message
is displayed:
IP Address: 192.168.11.20*
(2) If the IP address has not been set for the VLAN, nothing is displayed
for
IP Address:
IP Address:
• If a multicast router is connected, check the Mrouter-port setting.
> show igmp-snooping 100
Date 2005/05/15 15:20:00
VLAN 100:
IP Address:192.168.11.20 Querier : enable
IGMP querying system : 192.168.11.20
Port (2): 0/1,0/3
Mrouter-port:0/1
Group Counts: 3
5Use the show igmp-snooping
command with the
group
parameter to check the IPv4
multicast group address.
Check the following:
• Make sure the joined IPv4 multicast group address is displayed by the
show igmp-snooping group command.
> show igmp-snooping group 100
Date 2005/05/15 15:20:00
VLAN 100 Group counts:3
Group Address MAC Address
224.10.10.10 0100.5e0a.0a0a
Port-list 0/1-3
225.10.10.10 0100.5e0a.0a0a
Port-list 0/1-2
239.192.1.1 0100.5e40.1606
Port-list 0/1
No. Items to check and commands Action