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# Display the IGMP group information on Router A.
[RouterA] display igmp group
Total 1 IGMP Group(s).
Interface group report information of VPN-Instance: public net
Ethernet1/1(192.168.1.1):
Total 1 IGMP Groups reported
Group Address Last Reporter Uptime Expires
224.1.1.1 192.168.1.2 00:02:04 00:01:15
The output shows that IGMP reports from the hosts are forwarded to Router A through the proxy interface,
Ethernet 1/1 of Router B.
Troubleshooting IGMP
This section describes common IGMP problems and how to troubleshoot them.
No membership information exists on the receiver-side router
Symptom
When a host sends a report for joining multicast group G, no membership information of the multicast
group G exists on the router closest to that host.
Analysis
•
The correctness of networking and interface connections and whether the protocol layer of the
interface is up directly affect the generation of group membership information.
•
Multicast routing must be enabled on the router, and IGMP must be enabled on the interface that
connects to the host.
•
If the IGMP version on the router interface is lower than that on the host, the router will not be able
to recognize the IGMP report from the host.
•
If you have configured the
igmp group-policy
command on the interface, the interface cannot
receive report messages that fail to pass filtering.
Solution
1.
Use the
display igmp interface
command to verify that the networking, interface connection, and
IP address configuration are correct. If no information is output, the interface is in an abnormal
state. The reason might be that you have configured the
shutdown
command on the interface, that
the interface is not correctly connected, or that the IP address configuration is not correctly
completed.
2.
Use the
display current-configuration
command to verify that multicast routing is enabled. If not,
use the
multicast routing-enable
command in system view to enable IP multicast routing. In
addition, check that IGMP is enabled on the corresponding interfaces.
3.
Use the
display igmp interface
command to verify that the IGMP version on the interface is lower
than that on the host.
4.
Use the
display current-configuration interface
command to verify that no ACL rule has been
configured to restrict the host from joining the multicast group G. If the host is restricted from
joining the multicast group G, the ACL rule must be modified to allow receiving the reports for the
multicast group G.