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Re: dup packets

  • From: Alex P. Rudnev
  • Date: Mon Mar 15 14:03:02 1999

I recommend to 'ping' every host in 'traceroute' chain and check _when_ 
does this duping appear. It can result from some important 
misconfiguration in your own network, but can be result of some 
unimportant effect.

Anyway, it looks suspiciows. I'v checked this addresses, and can't see 
'dup's in my 'ping tests'. Looks as the dup's source somewhere in your 
network. For example, it can be ccaused by the broken interface card in 
your router, or by the broken switch, or result from the internal loop in 
your (or some intermediate) LAN.

You should pay attention to this effect - in can indicate a serious lost 
of throughput.

Run 'tcpdump', open some 'ftp' session and look - if you see dup TCP 
packets you can get complain to your provider (or youself) about _bad 
network behaviour_. 

Alex.

On Mon, 15 Mar 1999, cache22 wrote:

> Date: Mon, 15 Mar 1999 13:33:47 -0500
> From: cache22 <cache22@webkorner.com>
> To: nanog@merit.edu
> Subject: dup packets
> 
> i reported a problem with packet duplication to the gridnet
> (worldcom) noc, and they checked it and they said everything
> is fine, some hosts give duplicate echo replies to pings.  i
> get either one or three duplicates.  are there any hosts,
> routers, firewalls, load balancers, etc. that do this?  i
> couldn't find anything in the archives on this subject.
> 
> when i tried pinging from locations on other backbones i
> didn't receive dups so i feel the problem is within
> gridnet.  i am reporting here as i would like to know if any
> others are suffering this problem.  also, many hosts and
> networks may be receiving unnecessary traffic from duplicate
> acks as there is duplication of tcp packets also.
> 
> most of the problems are through connections from east to
> west coast on atm circuits--see traces below.
> 
> other unfriendly behavior--their default route appears to be
> pb-nap.eni.net.  most unroutable packets, including reserved
> and rfc1918, are routed there--traces below.  this morning,
> when g.root-servers.net was unreachable for a few minutes
> (via gridnet, did anyone else see it disappear?) i watched
> those packets go to eni.  (sorry, didn't capture the
> trace.)  are they selling /dev/rj0 service?
> 
> this (everything above) has been happening for at least
> several months.
> 
> matt sommer
> sysadmin
> webkorner.com  
> 
> 
> 
> PING route-server.cerf.net (192.215.254.5): 56 data bytes
> 64 bytes from 192.215.254.5: icmp_seq=0 ttl=248 time=150.6
> ms
> 64 bytes from 192.215.254.5: icmp_seq=0 ttl=248 time=151.1
> ms (DUP!)
> 64 bytes from 192.215.254.5: icmp_seq=0 ttl=248 time=151.9
> ms (DUP!)
> 64 bytes from 192.215.254.5: icmp_seq=0 ttl=248 time=152.4
> ms (DUP!)
> 64 bytes from 192.215.254.5: icmp_seq=1 ttl=248 time=129.1
> ms
> 
> --- route-server.cerf.net ping statistics ---
> 2 packets transmitted, 2 packets received, +3 duplicates, 0%
> packet loss
> round-trip min/avg/max = 129.1/147.0/152.4 ms
> 
> traceroute to route-server.cerf.net (192.215.254.5), 30 hops
> max, 40 byte packets
>  1  nemo.webkorner.com (207.53.77.1)  3.039 ms  2.013 ms 
> 1.728 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.749 ms 
> 19.756 ms  17.061 ms
>  3  core-snfx1-atm9-0.2.grid.net (206.80.170.70)  79.949 ms 
> 81.523 ms  81.564 ms
>  4  snfc1.grid.net (198.32.136.48)  79.668 ms  93.924 ms 
> 79.515 ms
>  5  atm8-0-155M.sjc-bb3.cerf.net (134.24.29.38)  97.64 ms 
> 90.751 ms
> f1-0-0.sjc-bb1.cerf.net (134.24.88.55)  106.49 ms
>  6  atm0-0-155M.sfo-bb2.cerf.net (134.24.29.21)  114.862 ms
> atm8-0-155M.sjc-bb3.cerf.net (134.24.29.38)  101.439 ms
> atm0-0-155M.sfo-bb2.cerf.net (134.24.29.21)  105.387 ms
>  7  pos0-2-155M.sfo-bb3.cerf.net (134.24.29.197)  93.883 ms 
> 97.39 ms  97.007 ms
>  8  atm10-0-155M.lax-bb1.cerf.net (134.24.29.41)  110.238
> ms  113.954 ms  107.834
> ms
>  9  atm1-0-1-622M.san-bb6.cerf.net (134.24.29.141)  106.82
> ms
> atm10-0-155M.lax-bb1.cerf.net (134.24.29.41)  190.6 ms
> atm1-0-1-622M.san-bb6.cerf.net (134.24.29.141)  135.938 ms
> 10  pos10-0-0-155M.san-bb2.cerf.net (134.24.29.105)  114.09
> ms  100.856 ms
> 103.303 ms
> 11  pos1-0-155M.san-hq5.cerf.net (134.24.29.54)  112.1 ms 
> 118.083 ms  104.277 ms
> 12  pos1-0-155M.san-hq5.cerf.net (134.24.29.54)  105.645 ms 
> 106.927 ms  113.921
> ms
> 13  * route-server.cerf.net (192.215.254.5)  122.29 ms *
> 
> 
> PING cerf.net (192.102.249.3): 56 data bytes
> 64 bytes from 192.102.249.3: icmp_seq=0 ttl=247 time=178.2
> ms
> 64 bytes from 192.102.249.3: icmp_seq=0 ttl=247 time=178.9
> ms (DUP!)
> 64 bytes from 192.102.249.3: icmp_seq=0 ttl=247 time=179.2
> ms (DUP!)
> 64 bytes from 192.102.249.3: icmp_seq=0 ttl=247 time=179.7
> ms (DUP!)
> 64 bytes from 192.102.249.3: icmp_seq=1 ttl=247 time=126.5
> ms
> 
> --- cerf.net ping statistics ---
> 2 packets transmitted, 2 packets received, +3 duplicates, 0%
> packet loss
> round-trip min/avg/max = 126.5/168.5/179.7 ms
> 
> traceroute to cerf.net (192.102.249.3), 30 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  1.978 ms  1.959 ms 
> 1.724 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  29.475 ms 
> 17.064 ms  18.406 ms
>  3  core-snfx1-atm9-0.2.grid.net (206.80.170.70)  80.843 ms 
> 89.331 ms  82.987 ms
>  4  snfc1.grid.net (198.32.136.48)  85.938 ms  78.285 ms 
> 82.579 ms
>  5  f0-0-0.sjc-bb2.cerf.net (134.24.88.5)  85.739 ms  88.796
> ms  90.437 ms
>  6  pos0-0-155M.san-bb6.cerf.net (134.24.29.130)  104.53 ms 
> 102.469 ms  102.327
> ms
>  7  pos0-0-155M.san-hq5.cerf.net (134.24.29.113)  102.044 ms
> pos0-0-155M.san-bb6.cerf.net (134.24.29.130)  100.354 ms
> pos0-0-155M.san-hq5.cerf.net (134.24.29.113)  101.231 ms
>  8  pos0-0-155M.san-hq5.cerf.net (134.24.29.113)  103.14 ms 
> 98.93 ms  100.854 ms
>  9  pos9-0-0-155M.san-hq1.cerf.net (134.24.29.126)  108.44
> ms  104.816 ms  104.518
> ms
> 10  nic.cerf.net (192.102.249.3)  102.09 ms  110.655 ms 
> 103.239 ms
> 
> 
> PING cisco.com (192.31.7.130): 56 data bytes
> 64 bytes from 192.31.7.130: icmp_seq=0 ttl=246 time=89.0 ms
> 64 bytes from 192.31.7.130: icmp_seq=0 ttl=246 time=89.5 ms
> (DUP!)
> 64 bytes from 192.31.7.130: icmp_seq=0 ttl=246 time=90.0 ms
> (DUP!)
> 64 bytes from 192.31.7.130: icmp_seq=0 ttl=246 time=90.5 ms
> (DUP!)
> 64 bytes from 192.31.7.130: icmp_seq=1 ttl=246 time=104.7 ms
> 
> --- cisco.com ping statistics ---
> 2 packets transmitted, 2 packets received, +3 duplicates, 0%
> packet loss
> round-trip min/avg/max = 89.0/92.7/104.7 ms
> 
> traceroute to cisco.com (192.31.7.130), 30 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  1.946 ms  5.717 ms 
> 2.183 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.692 ms 
> 25.742 ms  40.845 ms
>  3  core-snfx1-atm5-0.4.grid.net (206.80.187.29)  98.354 ms 
> 85.901 ms  82.039 ms
>  4  snfc1.grid.net (198.32.136.48)  79.189 ms  107.082 ms 
> 79.548 ms
>  5  p2-0.sanjose1-nbr1.bbnplanet.net (4.0.3.193)  85.506 ms 
> 100.916 ms  105.923
> ms
>  6  p2-0.sanjose1-nbr1.bbnplanet.net (4.0.3.193)  92.522 ms 
> 96.826 ms  100.667 ms
>  7  p4-0.paloalto-nbr2.bbnplanet.net (4.0.1.1)  91.881 ms 
> 110.78 ms  106.679 ms
>  8  h1-0.cisco.bbnplanet.net (131.119.26.10)  95.844 ms 
> 89.91 ms  89.474 ms
>  9  h1-0.cisco.bbnplanet.net (131.119.26.10)  92.13 ms
> pigpen.cisco.com
> (192.31.7.40)  98.463 ms h1-0.cisco.bbnplanet.net
> (131.119.26.10)  114.123 ms
> 10  cio-sys.cisco.com (192.31.7.130)  97.249 ms
> pigpen.cisco.com (192.31.7.40)
> 99.075 ms  95.722 ms
> 
> 
> PING enmu.edu (192.94.216.250): 56 data bytes
> 64 bytes from 192.94.216.250: icmp_seq=0 ttl=51 time=322.1
> ms
> 64 bytes from 192.94.216.250: icmp_seq=0 ttl=51 time=322.7
> ms (DUP!)
> 64 bytes from 192.94.216.250: icmp_seq=1 ttl=51 time=239.1
> ms
> 
> --- enmu.edu ping statistics ---
> 2 packets transmitted, 2 packets received, +1 duplicates, 0%
> packet loss
> round-trip min/avg/max = 239.1/294.6/322.7 ms
> 
> traceroute to enmu.edu (192.94.216.250), 30 hops max, 40
> byte packets
>  1  nemo.webkorner.com (207.53.77.1)  2.014 ms  1.927 ms 
> 2.617 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  19.161 ms 
> 27.238 ms  16.684 ms
>  3  core-snfx1-atm5-0.4.grid.net (206.80.187.29)  81.792 ms 
> 82.091 ms  80.942 ms
>  4  t8-0.San-Francisco.t3.ans.net (198.32.128.10)  95.598
> ms  83.259 ms  83.83 ms
>  5  pacbell-nap.ans.net (198.32.128.67)  110.493 ms  97.621
> ms  85.529 ms
>  6  h13-1.t16-0.Los-Angeles.t3.ans.net (140.223.9.14) 
> 106.263 ms  119.991 ms
> 99.344 ms
>  7  h14-1.t112-0.Albuquerque.t3.ans.net (140.223.17.10) 
> 136.081 ms  120.616 ms
> 119.887 ms
>  8  f0-0.cnss116.Albuquerque.t3.ans.net (140.222.112.196) 
> 138.032 ms  122.725 ms
> 125.71 ms
>  9  h1-0.enss191.t3.ans.net (192.103.74.42)  126.823 ms 
> 131.757 ms  130.943 ms
> 10  198.83.5.4 (198.83.5.4)  158.435 ms  144.432 ms  154.82
> ms
> 11  192.65.78.82 (192.65.78.82)  175.607 ms  160.103 ms 
> 168.386 ms
> 12  EM0X.ENMU.EDU (192.94.216.250)  244.882 ms  172.999 ms 
> 183.95 ms
> 
> 
> PING e.root-servers.net (192.203.230.10): 56 data bytes
> 64 bytes from 192.203.230.10: icmp_seq=0 ttl=251 time=112.5
> ms
> 64 bytes from 192.203.230.10: icmp_seq=0 ttl=251 time=114.3
> ms (DUP!)
> 64 bytes from 192.203.230.10: icmp_seq=1 ttl=251 time=117.3
> ms
> 
> --- e.root-servers.net ping statistics ---
> 2 packets transmitted, 2 packets received, +1 duplicates, 0%
> packet loss
> round-trip min/avg/max = 112.5/114.7/117.3 ms
> 
> traceroute to e.root-servers.net (192.203.230.10), 30 hops
> max, 40 byte packets
>  1  nemo.webkorner.com (207.53.77.1)  2.072 ms  2.964 ms 
> 1.746 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  17.125 ms 
> 17.129 ms  16.715 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  81.316 ms 
> 69.578 ms  81.366 ms
>  4  mae-east.nsn.nasa.gov (192.41.177.125)  98.22 ms  87.618
> ms  91.117 ms
>  5  s-ARC1-ATM.NSN.NASA.GOV (128.161.10.1)  116.303 ms 
> 112.699 ms  113.355 ms
>  6  E.ROOT-SERVERS.NET (192.203.230.10)  123.275 ms * 
> 111.486 ms
> 
> 
> PING l.root-servers.net (198.32.64.12): 56 data bytes
> 64 bytes from 198.32.64.12: icmp_seq=0 ttl=244 time=174.9 ms
> 64 bytes from 198.32.64.12: icmp_seq=0 ttl=244 time=175.1 ms
> (DUP!)
> 64 bytes from 198.32.64.12: icmp_seq=1 ttl=244 time=157.6 ms
> 
> --- l.root-servers.net ping statistics ---
> 2 packets transmitted, 2 packets received, +1 duplicates, 0%
> packet loss
> round-trip min/avg/max = 157.6/169.2/175.1 ms
> 
> traceroute to l.root-servers.net (198.32.64.12), 30 hops
> max, 40 byte packets
>  1  nemo.webkorner.com (207.53.77.1)  3.558 ms  3.419 ms 
> 1.765 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  18.912 ms 
> 25.015 ms  17.186 ms
>  3  core-wash1-atm8-0.3.grid.net (206.80.180.34)  94.471 ms 
> 87.77 ms  95.625 ms
>  4  * f6.peer1.wdc1.genuity.net (192.41.177.147)  109.531
> ms  140.935 ms
>  5  h5-0-1.core1.wdc1.genuity.net (207.240.1.233)  136.672
> ms *  154.67 ms
>  6  * core1.lax1.genuity.net (207.240.0.5)  169.329 ms 
> 181.559 ms
>  7  fe-5-0.peer1.lax1.genuity.net (207.240.1.142)  244.746
> ms  164.322 ms  184.965
> ms
>  8  sandbox.ep.net (198.32.146.11)  168.058 ms  159.353 ms *
>  9  * l.root-servers.net (198.32.64.12)  159.825 ms  170.084
> ms
> 
> 
> PING altavista.com (204.123.2.66): 56 data bytes
> 64 bytes from 204.123.2.66: icmp_seq=0 ttl=54 time=96.8 ms
> 64 bytes from 204.123.2.66: icmp_seq=0 ttl=54 time=97.3 ms
> (DUP!)
> 64 bytes from 204.123.2.66: icmp_seq=1 ttl=54 time=99.8 ms
> 
> --- altavista.com ping statistics ---
> 2 packets transmitted, 2 packets received, +1 duplicates, 0%
> packet loss
> round-trip min/avg/max = 96.8/97.9/99.8 ms
> 
> traceroute to altavista.com (204.123.2.69), 30 hops max, 40
> byte packets
>  1  nemo.webkorner.com (207.53.77.1)  1.96 ms  3.553 ms 
> 1.782 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.567 ms 
> 19.488 ms  21.282 ms
>  3  peer-atl-uunet-fddi.grid.net (206.80.190.201)  25.164
> ms  17.09 ms  61.332 ms
>  4  104.ATM2-0.XR1.ATL1.ALTER.NET (146.188.232.50)  18.564
> ms  17.982 ms  17.676
> ms
>  5  295.ATM2-0.TR1.ATL1.ALTER.NET (146.188.232.90)  17.736
> ms  86.312 ms  36.625
> ms
>  6  109.ATM6-0.TR1.SCL1.ALTER.NET (146.188.136.66)  74.736
> ms  80.162 ms  83.007
> ms
>  7  199.ATM7-0.XR1.PAO1.ALTER.NET (146.188.147.117)  75.24
> ms  107.525 ms  86.392
> ms
>  8  189.ATM10-0-0.GW3.PAO1.ALTER.NET (146.188.147.249) 
> 78.844 ms  81.42 ms  85.98
> ms
>  9  208.195.253.18 (208.195.253.18)  94.185 ms  81.601 ms 
> 84.882 ms
> 10  core-gw1.pa-x.dec.com (204.123.1.1)  81.878 ms  81.915
> ms  82.955 ms
> 11  altavista.com (204.123.2.69)  90.244 ms  86.355 ms 
> 84.804 ms
> 
> 
> ***	default route stuff	***
> 
> 
> traceroute to 192.168.0.1 (192.168.0.1), 7 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  2.109 ms  1.987 ms 
> 1.725 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.876 ms 
> 17.136 ms  16.879 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  80.955 ms 
> 69.07 ms  84.384 ms
>  4  206.80.168.178 (206.80.168.178)  108.509 ms  108.005 ms 
> 108.684 ms
>  5  pb-nap.eni.net (198.32.128.39)  116.592 ms  108.99 ms 
> 108.275 ms
>  6  pb-nap.eni.net (198.32.128.39)  108.28 ms !H * *
>  7  * * *
> 
> 
> [they blackholed this one, oddly enough]
> 
> traceroute to 172.16.0.1 (172.16.0.1), 7 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  1.956 ms  1.996 ms 
> 1.695 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.623 ms 
> 17.005 ms  20.315 ms
>  3  core-snfc1-hssi11-0.1.grid.net (206.80.180.214)  78.943
> ms  76.954 ms  78.453
> ms
>  4  * * *
>  5  * * *
>  6  * * *
>  7  * * *
> 
> traceroute to 172.17.0.1 (172.17.0.1), 7 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  2.184 ms  2.169 ms 
> 1.69 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  17.204 ms 
> 17.49 ms  96.326 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  73.894 ms 
> 80.646 ms  72.661 ms
>  4  206.80.168.178 (206.80.168.178)  114.916 ms  111.088 ms 
> 107.569 ms
>  5  pb-nap.eni.net (198.32.128.39)  110.934 ms  109.213 ms 
> 109.857 ms
>  6  * * *
>  7  * * *
> 
> traceroute to 172.32.0.1 (172.32.0.1), 7 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  2.002 ms  3.351 ms 
> 1.696 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  17.148 ms 
> 16.834 ms  18.726 ms
>  3  core-wash1-atm8-0.3.grid.net (206.80.180.34)  94.444 ms 
> 94.4 ms  99.834 ms
>  4  206.80.168.178 (206.80.168.178)  140.235 ms  140.247 ms 
> 137.033 ms
>  5  pb-nap.eni.net (198.32.128.39)  127.318 ms  133.545 ms 
> 124.439 ms
>  6  * * *
>  7  * * *
> 
> 
> traceroute to 10.0.0.1 (10.0.0.1), 7 hops max, 40 byte
> packets
>  1  nemo.webkorner.com (207.53.77.1)  2.998 ms  1.933 ms 
> 2.636 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  16.79 ms 
> 17.42 ms  17.519 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  83.64 ms 
> 80.487 ms  98.335 ms
>  4  206.80.168.178 (206.80.168.178)  126.873 ms  111.404 ms 
> 110.231 ms
>  5  pb-nap.eni.net (198.32.128.39)  127.533 ms  109.746 ms 
> 111.201 ms
>  6  pb-nap.eni.net (198.32.128.39)  114.215 ms !H * *
>  7  * * *
> 
> 
> traceroute to 1.0.0.1 (1.0.0.1), 7 hops max, 40 byte packets
>  1  nemo.webkorner.com (207.53.77.1)  2.053 ms  2.003 ms 
> 1.685 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  30.512 ms 
> 17.147 ms  18.741 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  76.457 ms 
> 89.586 ms  69.123 ms
>  4  206.80.168.178 (206.80.168.178)  110.383 ms  117.309 ms 
> 112.722 ms
>  5  pb-nap.eni.net (198.32.128.39)  112.76 ms  112.733 ms 
> 111.573 ms
>  6  * * *
>  7  * * *
> 
> traceroute to 0.0.0.1 (0.0.0.1), 7 hops max, 40 byte packets
>  1  nemo.webkorner.com (207.53.77.1)  2.025 ms  2.825 ms 
> 1.753 ms
>  2  core-atln1-hssi4/0.9.grid.net (207.205.2.1)  20.68 ms 
> 17.356 ms  20.616 ms
>  3  core-wash1-atm4/0.4.grid.net (206.80.188.33)  73.731 ms
> core-wash1-atm8-0.3.grid.net (206.80.180.34)  94.608 ms
> core-wash1-atm4/0.4.grid.net (206.80.188.33)  68.392 ms
>  4  206.80.168.178 (206.80.168.178)  121.929 ms  107.539 ms 
> 120.781 ms
>  5  pb-nap.eni.net (198.32.128.39)  112.065 ms  122.983 ms 
> 109.885 ms
>  6  * * *
>  7  pb-nap.eni.net (198.32.128.39)  111.42 ms !H * *
> 
> 

Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)






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