H3C Technologies H3C S10500 Series Switches - Manual (Page 217)

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RPs cannot 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 routers is exactly the same and that 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 routers
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 router 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 routers.
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 routers in the entire network.
RPT establishment failure or source registration failure in
PIM-SM
Symptom
C-RPs cannot unicast advertise messages to the BSR. The BSR does not advertise bootstrap messages
containing C-RP information and has no unicast route to any C-RP. An RPT cannot be established correctly,
or the DR cannot perform source registration with the RP.
Analysis
• The C-RPs periodically send C-RP-Adv messages to the BSR by unicast. If a C-RP has no unicast route
to the BSR, the BSR cannot receive C-RP-Adv messages from that C-RP and the bootstrap message
of the BSR will not contain the information of that C-RP.
• In addition, if the BSR does not have a unicast route to a C-RP, it will discard the C-RP-Adv messages
from that C-RP, and therefore the bootstrap messages of the BSR will not contain the information of
that C-RP.
• The RP is the core of a PIM-SM domain. Make sure that the RP information on all routers is exactly
the same, a specific group G is mapped to the same RP, and unicast routes are available to the RP.
Solution
1. Check whether routes to C-RPs and the BSR are available. Carry out the display ip routing-table
command to check whether routes are available on each router to the RP and the BSR and whether
a route is available between the RP and the BSR. Make sure that each C-RP has a unicast route to
the BSR, the BSR has a unicast route to each C-RP, and all the routers in the entire network have a
unicast route to the RP.
2. Check the RP and BSR information. PIM-SM needs the support of the RP and BSR. Use the display
pim bsr-info command to check whether the BSR information is available on each router, and then
use the display pim rp-info command to check whether the RP information is correct.