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
This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:13:25 EDT