Rps unable to join spt in pim-sm, Symptom, Analysis – H3C Technologies H3C S7500E Series Switches User Manual

Page 200: Solution

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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

z

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 a specific group is mapped to the same RP. Otherwise, multicast forwarding will fail.

z

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 register with the RP.

Analysis

z

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.

z

In addition, if the BSR does not have a unicast router 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.

z

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.

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