91
The output shows that Switch A is the RPF neighbor of Switch C and the multicast data from Switch
A is delivered over a GRE tunnel to Switch C.
Troubleshooting multicast routing and forwarding
This section describes details about troubleshooting multicast routing and forwarding.
Static multicast route failure
Symptom
No dynamic routing protocol is enabled on the routers, and the physical status and link layer status of
interfaces are both up, but the static multicast route fails.
Analysis
•
If the static multicast route is not configured or updated correctly to match the current network
conditions, the route entry and the configuration information of static multicast route do not exist
in the multicast routing table.
•
If a better route is found, the static multicast route might also fail.
Solution
1.
Use the
display multicast routing-table static
command to view the information of static
multicast routes to verify that the static multicast route has been correctly configured and that
the route entry exists in the multicast routing table.
2.
Verify the type of the next-hop interface of the static multicast route. If the interface is not a
point-to-point interface, be sure to specify the next hop address for the outgoing interface when
you configure the static multicast route.
3.
Verify that the static multicast route matches the specified routing protocol. If a protocol was
specified in static multicast route configuration, use the
display ip routing-table
command to
verify that an identical route was added by the protocol.
4.
Verify that the static multicast route matches the specified routing policy. If a routing policy was
specified when the static multicast route was configured, use the
display route-policy
command to verify the configured routing policy.
Multicast data fails to reach receivers
Symptom
The multicast data can reach some routers but fails to reach the last-hop router.
Analysis
If you have configured a multicast forwarding boundary by using the
multicast boundary
command,
any multicast packet is kept from crossing the boundary.
Solution
1.
Use the
display pim routing-table
command to verify that the corresponding (S, G) entries
exist on the router. If so, the router has received the multicast data. Otherwise, the router has
not received the data.
2.
Use the
display multicast boundary
command to view the multicast boundary information on
the interfaces. Use the
multicast boundary
command to change the multicast forwarding
boundary setting.
3.
In PIM-SM, use the
display current-configuration
command to verify the BSR and RP
information.
