400
# Display the MLD group information on Switch A.
[SwitchA] display mld group
Total 1 MLD Group(s).
Interface group report information of VPN-Instance: public net
Vlan-interface100(2001::1):
Total 1 MLD Groups reported
Group Address Last Reporter Uptime Expires
ff3e::101 2001::2 00:02:04 00:01:15
The output shows that the MLD reports sent from the hosts are forwarded to Switch A through the
proxy interface, VLAN-interface 100 of Switch B.
Troubleshooting MLD
This section describes details about troubleshooting MLD.
No member information exists on the receiver-side router
Symptom
When a host sends a message to announce its joining IPv6 multicast group G, no member
information of multicast group G exists on the intermediate router.
Analysis
•
The correctness of networking and interface connections and whether the protocol layer of the
interface is up directly affect the generation of IPv6 group member information.
•
IPv6 multicast routing must be enabled on the router and MLD must be enabled on the interface
connecting to the host.
•
If the MLD version on the router interface is lower than that on the host, the router will not be
able to recognize the MLD report from the host.
•
If the
mld group-policy
command has been configured on an interface, the interface cannot
receive report messages that fail to pass filtering.
Solution
1.
Use the
display mld interface
command to verify that the networking, interface connections,
and IP address configuration are correct. If no information is output, the interface is in an
abnormal state. The reason is that you have configured the
shutdown
command on the
interface, that the interface is not properly connected, or that the IPv6 address configuration is
not correctly done.
2.
Use the
display current-configuration
command to verify that the IPv6 multicast routing is
enabled. If not, use the
multicast ipv6 routing-enable
command in system view to enable
IPv6 multicast routing. In addition, enable MLD on the corresponding interface.
3.
Use the
display mld interface
command to verify that the MLD 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 IPv6 multicast group G. If an IPv6 ACL is
configured to restrict the host from joining IPv6 multicast group G, the ACL must be modified to
allow IPv6 multicast group G to receive report messages.
