Rps Cannot Join The Spt In Pim-Sm - HP A8800 Configuration Manual

Analysis
When a router receives a multicast packet, it decrements the TTL value of the multicast packet by 1
•
and recalculates the checksum value. The router then forwards the packet to all outgoing interfaces.
If the multicast minimum-ttl command is configured on the outgoing interfaces, the TTL value of the
packet must be larger than the configured minimum TTL value. Otherwise, the packet will be
discarded.
• If a multicast forwarding boundary has been configured through the multicast boundary command,
any multicast packet will be kept from crossing the boundary, and no routing entry can be created
in the PIM routing table.
In addition, the source-policy command filters 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. Use the display current-configuration command to check the minimum TTL value for multicast
forwarding. Increase the TTL value or remove the multicast minimum-ttl command configured on
the interface.
2. Use the display current-configuration command to verify the multicast forwarding boundary
settings. Use the multicast boundary command to change the multicast forwarding boundary
settings.
3. Use the display current-configuration command to verify 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 cannot join the 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 routers is exactly the same and that a specific
group is mapped to the same RP. Otherwise, multicast forwarding fails.
If the static RP mechanism is used, the same static RP command must be executed on all the routers
•
in the entire network. Otherwise, multicast forwarding fails.
Solution
1. Use the display ip routing-table command to verify that a route to the RP is available on each
router.
2. Use the display pim rp-info command to verify that the dynamic RP information is consistent on all
routers.
3. Use the display pim rp-info command to verify that the same static RP address has been configured
on all the routers in the entire network.
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