3Com Switch 8800 Advanced Software V5 Configuration Guide

606 CHAPTER 42: PIM CONFIGURATION
Multicast Data
Abnormally Terminated
on an Intermediate
Device
Symptom
An intermediate device can receive multicast data successfully, but the data cannot
reach the last hop device. An interface on the intermediate device receives data
but no corresponding (S, G) entry is created in the PIM routing table.
Analysis
■ If a multicast forwarding boundary has been configured through the multicast
boundary command, any multicast packet will be kept from crossing the
boundary, and therefore no routing entry can be created in the PIM routing
table.
■ In addition, the source-policy command is used to filter received multicast
packets. If the multicast data fails to pass the ACL rule defined in this
command, PIM cannot create the route entry, either.
Solution
1 Check the multicast forwarding boundary configuration. Use the display
current-configuration command to check the multicast forwarding
boundary settings. Use the multicast boundary command to change the
multicast forwarding boundary settings.
2 Check the multicast filter configuration. Use the display
current-configuration command to check the multicast filter configuration.
Change the ACL rule defined in the source-policy command so that the
source/group address of the multicast data can pass ACL filtering.
RPs Unable to Join SPT in
PIM-SM
Symptom
An RPT cannot be established correctly, or the RPs cannot join the SPT to the
multicast source.
Analysis
■ As the core of a PIM-SM domain, the RPs serve specific multicast groups.
Multiple RPs can coexist in a network. Make sure that the RP information on all
devices is exactly the same, and a specific group is mapped to the same RP.
Otherwise, multicast forwarding will fail.
■ If the static RP mechanism is used, the same static RP command must be
executed on all the devices in the entire network. Otherwise, multicast
forwarding will fail.
Solution
1 Check that a route is available to the RP. Carry out the display ip
routing-table command to check whether a route is available on each
device to the RP.
2 Check the dynamic RP information. Use the display pim rp-info command
to check whether the RP information is consistent on all devices.
3 Check the configuration of static RPs. Use the display pim rp-info
command to check whether the same static RP address has been
configured on all the devices in the entire network.