Multicast problem in my lab

From: huangyinxiao@gmail.com
Date: Thu Apr 12 2007 - 10:53:36 ART


Hi all,

I have two multicase problems when I am doing labs.

Topology:
R4-(FR multipoint)-R1----R5-(FR point-to-point)-R2

R4 is RP and R1 is mapping agent. Sparse-dense-mode and auto-rp are used, and R4 loopback 0 join-group 239.8.8.30. Ip pim dm-fallback is enabled.
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Two problem for me in this senario:

1. It is very odd that R5 fail to ping 239.8.8.30 in first time and later it is success. After a little while, R5 ping again and it also fail to ping at the beginning, and then it is success.

2. R2 cannot ping 239.8.8.30, but after R2 loopback0(150.4.8.1) enable sparse-dense-mode, R2 can ping 239.8.8.30.
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And I found some different in "sh ip mroute" on R2. The incoming and outgoing interface seems right when enable sparse-dense-mode on loopback.

Without enable sparse-dense-mode on R2 loopback:

(*, 224.0.1.39), 00:00:08/stopped, RP 0.0.0.0, flags: D
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0, Forward/Sparse-Dense, 00:00:08/00:00:00
    FastEthernet0, Forward/Sparse-Dense, 00:00:08/00:00:00

(8.8.4.4, 224.0.1.39), 00:00:08/00:02:51, flags: T
  Incoming interface: Serial0, RPF nbr 8.8.13.1
  Outgoing interface list:
    FastEthernet0, Forward/Sparse-Dense, 00:00:09/00:00:00

(*, 224.0.1.40), 00:00:33/stopped, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0, Forward/Sparse-Dense, 00:00:33/00:00:00
    FastEthernet0, Forward/Sparse-Dense, 00:00:33/00:00:00
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With enable sparse-dense-mode on R2 loopback:
(*, 239.8.8.30), 00:07:14/stopped, RP 8.8.4.4, flags: SPF
  Incoming interface: Serial0, RPF nbr 8.8.13.1
  Outgoing interface list: Null

(150.4.8.1, 239.8.8.30), 00:00:12/00:03:22, flags: FT
  Incoming interface: Loopback1, RPF nbr 0.0.0.0, Registering
  Outgoing interface list:
    Serial0, Forward/Sparse-Dense, 00:00:12/00:03:17

(*, 224.0.1.39), 03:49:53/stopped, RP 0.0.0.0, flags: D
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0, Forward/Sparse-Dense, 03:49:53/00:00:00
    FastEthernet0, Forward/Sparse-Dense, 03:49:53/00:00:00

(8.8.4.4, 224.0.1.39), 03:49:53/00:02:41, flags: T
  Incoming interface: Serial0, RPF nbr 8.8.13.1
  Outgoing interface list:
    FastEthernet0, Forward/Sparse-Dense, 03:49:53/00:00:00

(*, 224.0.1.40), 03:50:31/stopped, RP 0.0.0.0, flags: DCL
  Incoming interface: Null, RPF nbr 0.0.0.0
  Outgoing interface list:
    Serial0, Forward/Sparse-Dense, 03:50:31/00:00:00
    FastEthernet0, Forward/Sparse-Dense, 03:50:31/00:00:00

(8.8.1.1, 224.0.1.40), 03:18:06/00:02:30, flags: LT
  Incoming interface: Serial0, RPF nbr 8.8.13.1
  Outgoing interface list:
    FastEthernet0, Forward/Sparse-Dense, 03:18:06/00:00:00
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Can someone tell me what's reason will lead to two problems happening? How can R2 ping 239.8.8.30 without enabling pim sparse-dense-mode on loopback 0?

Thank you for any reply!
Laurence



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