What happens on a traceroute??
Barry
At 05:21 PM 12/1/2001 -0800, Jim Warner wrote:
>When I ping to a particular router my reply packets are
>getting duplicated. It looks like:
>
>bash-2.03$ ping 137.164.12.33
>PING 137.164.12.33 (137.164.12.33): 56 data bytes
>64 bytes from 137.164.12.33: icmp_seq=0 ttl=250 time=24.924 ms
>64 bytes from 137.164.12.33: icmp_seq=0 ttl=250 time=25.013 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=0 ttl=248 time=25.247 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=0 ttl=248 time=25.698 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=1 ttl=250 time=24.084 ms
>64 bytes from 137.164.12.33: icmp_seq=1 ttl=250 time=24.594 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=1 ttl=248 time=24.825 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=1 ttl=248 time=25.030 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=2 ttl=250 time=24.330 ms
>64 bytes from 137.164.12.33: icmp_seq=2 ttl=250 time=24.544 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=2 ttl=248 time=24.750 ms (DUP!)
>64 bytes from 137.164.12.33: icmp_seq=2 ttl=248 time=25.173 ms (DUP!)
>
>Not shown here, but this effect happens when I pass through this
>router. Anything beyond it is replicated.
>
>I have seen routing loops cause things that are similar, but
>not the same as this. But here the duplication is always the
>same. I think that my packets to the router are being replicated,
>and then each of the replies is getting replicated -- which is
>why I see four responses to everything I send.
>
>I am curious to hear what sorts of pathologies might result in
>this kind of packet copying. There is ATM in the path. Could
>it be the culprit? I am pretty sure that the equipment doing the
>packet copying is made by Cisco. The same way that I can't imagine
>that a bad packet would cause a fan to fail, I can't imagine how a
>packet could be copied a fixed number of times.
>
>I know this would be easier if there was a map of the topology.
>Is anyone willing to speculate without one?
>
>Thanks. -jim warner, UC santa cruz
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