WB1 8.2 Multicast RPF Failure

8.2 Multicast RPF Failure

• Disable PIM on the Serial link between R4 and R5 and activate it on the Frame-Relay connection between R4 and R5.
• Ensure that R6 can still ping the group 224.10.10.10.
• Set R5’s periodic RPF checks interval to 6 seconds.
• To reduce the load on the router’s CPU configure R5 to perform triggered RPF checks 10 ms after a topology change but don’t allow the delay to ever be longer than 200ms.

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R4:
interface Serial 0/1/0
no ip pim dense-mode
!
interface Serial 0/0/0.1
ip pim dense-mode

R5:
interface Serial 0/1/0
no ip pim dense-mode
!
interface Serial 0/0/0
ip pim dense-mode
!
ip multicast rpf interval 6
ip multicast rpf backoff 10 200

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Rack1R6#ping 224.10.10.10 repeat 100 會timeout...

Rack1R5#show ip mroute

Check the multicast routing table on R5. Notice that the (S,G) state for our flow has no Incoming Interface field (it’s Null) this means the traffic is not arriving on the RPF interface.

R5:

interface Serial 0/0
 no ip mroute-cache
!

Rack1R5#debug ip mpacket
IP multicast packets debugging is on
Rack1R5#
IP(0): s=155.1.146.6 (Serial0/0/0) d=224.10.10.10 id=300, ttl=253, prot=1, len=104(100), not RPF interface

Rack1R5(config)#ip mroute 0.0.0.0 0.0.0.0 155.1.0.4

這是因為根據RPF的檢查Source 155.1.146.6的路由應該來自於Serial0/1 155.1.45.4...........所以我們只好自己補上mroute