H3C Technologies H3C S12500 Series Switches - Manual (Page 383)

367
Require-router-alert: disabled
# Display the MLD group information on Switch A.
[SwitchA] display mld group
Total 1 MLD Group(s).
Interface group report information
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
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.
This is usually because you have configured the shutdown command on the interface, the interface
is not correctly connected, or the IPv6 address configuration is not correctly done.
2. Use the display current-configuration command to verify that the multicast ipv6 routing-enable
command has been executed. 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.