6.2 - Problems with R6 !

I'm now going through the torture with this 6.2 multicast task (after the R2/R3 redistribution loop disaster) and have resolved the issue with the preference path via R2 to avoid the route pointing to R3.  I have full reachability between the RP and all mcast routers and all ip subnets involved.  Now my final issue is with R6.

I'm using dynamips and R6 is configured as a router on a stick as in the SG.  Both IFs ping and being pinged by the rest of the network withour any problems.  Now, after I joint gp 228.28.28.28 on SW1's VLAN IF and ping from R6, I first have two replies.  Ping again and gets one reply.  Then ping again have no reply.  The mroute table then shows the out IF to 132.1.26.0 was pruned.  When I wait long enough for mcast to flush the table or whatever, I can ping again and the above mentioned behavior cycles again.  I'm beginning to wonder if this is a problem with R6 and the SW2's FA1/6 been setup as a router on a stick (same physical media on both vlans causing RPF failing, and then vlan26 was pruned ???)  Any insight on this ???

Below is the show output:-

Rack1R6#ping 228.28.28.28 source 132.1.6.6

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 228.28.28.28, timeout is 2 seconds:
Packet sent with a source address of 132.1.6.6

IP(0): s=132.1.6.6 (Ethernet0/0.6) d=228.28.28.28 id=80, ttl=254, prot=1, len=114(100), mroute olist null
IP(0): s=132.1.26.6 (Ethernet0/0.26) d=228.28.28.28 id=80, ttl=254, prot=1, len=114(100), mroute olist null
Reply to request 0 from 132.1.17.7, 392 ms
Reply to request 0 from 132.1.17.7, 464 ms
Rack1R6#ping 228.28.28.28 source 132.1.6.6

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 228.28.28.28, timeout is 2 seconds:
Packet sent with a source address of 132.1.6.6

IP(0): s=132.1.6.6 (Ethernet0/0.6) d=228.28.28.28 (Ethernet0/0.26) id=81, ttl=254, prot=1, len=100(100), mforward
Reply to request 0 from 132.1.17.7, 368 ms
Rack1R6#ping 228.28.28.28 source 132.1.6.6

Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 228.28.28.28, timeout is 2 seconds:
Packet sent with a source address of 132.1.6.6
.
Rack1R6#sh ip mroute 228.28.28.28

(*, 228.28.28.28), 00:06:12/stopped, RP 150.1.2.2, flags: SPF
  Incoming interface: Ethernet0/0.26, RPF nbr 132.1.26.2
  Outgoing interface list: Null

(132.1.6.6, 228.28.28.28), 00:01:41/00:01:57, flags: FT
  Incoming interface: Ethernet0/0.6, RPF nbr 0.0.0.0
  Outgoing interface list:
    Ethernet0/0.26, Forward/Sparse, 00:01:41/00:02:48

(132.1.26.6, 228.28.28.28), 00:01:41/00:01:27, flags: PFT
  Incoming interface: Ethernet0/0.26, RPF nbr 0.0.0.0
  Outgoing interface list: Null

Thanks,

-AC

Comments

  • Ok. Again, the problem seems to have resolved after my original posting.

    I have already spotted the "more then one" replies when pinging the mcast address.  When I ping 228.28.28.28 on R2, I actually got 3 replies.  So, after thinking about it for a little while, I moved on to task 6.3 which talk about unwanted mcast traffic received on other routers.  So, I thought, hmm.....maybe the problem in 6.2 is due to mcast packets bouncing withing the FR network and got pruned ?  So, I put that NBMA line in the R2's IF and it solved the problem completely.  Exactly how it stopped the problem is still not fully understood (of course in my little brain's perspective) and I have to definitely spend more time studying mcast.  Got a pile of cisco mcast while papers printed out already........

    I think for the most of us, after we resolve the "preferred the R2 path" issue and the pinging works, we just move on to do task 6.3.  Then the solution in task 6.3 natually solves the problem I spotted earlier.  I think I just happened to re-ping a few times on R6 to observe the problem.

    -AC

Sign In or Register to comment.