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Re: looping traceroutes

  • From: Stephen J. Wilcox
  • Date: Wed Sep 19 05:19:31 2001

the most interesting thing is that the rtt increases.. 

and it does so by regular amounts, about 30ms in each hop

i'd guess there is a routing loop going on there for sure, i'd also guess
its between two routers that are 30ms apart!

perhaps it could be being caused by some sort of nat on the router so
there are actually two routers looping but one or both of the addresses
get nat'd as the replies come to you

Steve

On Tue, 18 Sep 2001, Ratul Mahajan wrote:

> 
> 
> 
> while playing around with traceroutes for a measurement study of bgp, i
> often come across the traceroute outputs similar to those appended below.  
> i don't have a reasonable explanation of such behaviour (i don't think
> these are routing loops; they are not transient in any case). i am hoping
> someone on the list has a hang of traceroute implementations, and provide
> insights into under what circumstances this might happen.
> 
> 	thanks,
> 	-- ratul
> 
> --------------
> 
> $ traceroute 200.13.39.1
> traceroute to 200.13.39.1 (200.13.39.1), 30 hops max, 38 byte packets
>  1  regina-GE1-2.cac.washington.edu (128.95.219.100)  1.098 ms  1.233 ms  
>  2  uwbr2-GE3-0.cac.washington.edu (140.142.153.24)  0.349 ms  0.377 ms  
>  3  cnsp1-wes-GE1-0.pnw-gigapop.net (198.107.150.1)  1.561 ms  1.005 ms  
>  4  so-1-2-2.a07.sttlwa01.us.ra.verio.net (204.203.3.1)  21.690 ms  6.076 
>  5  ge-6-2-0.r03.sttlwa01.us.bb.verio.net (129.250.28.1)  8.481 ms  8.756 
>  6  p4-7-2-0.r06.plalca01.us.bb.verio.net (129.250.3.138)  29.934 ms  
>  7  p16-3-0-0.r00.plalca01.us.bb.verio.net (129.250.2.162)  26.740 ms  
>  8  p4-0.francetelecom.plalca01.us.bb.verio.net (129.250.9.134)  23.058 ms  
>  9  P4-3.DALBB1.Dallas.opentransit.net (193.251.132.221)  84.523 ms  
> 10  P5-1.FWHBB2.Fort-worth.opentransit.net (193.251.132.213)  86.653 ms  
> 11  Sr9-0-0.FWHAR1.Fort-worth.opentransit.net (193.251.132.227)  88.507 ms  
> 12  193.251.133.117 (193.251.133.117)  115.472 ms *  116.554 ms
> 13  193.251.133.117 (193.251.133.117)  145.386 ms  147.224 ms  148.333 ms
> 14  193.251.133.117 (193.251.133.117)  178.751 ms  172.224 ms *
> 15  193.251.133.117 (193.251.133.117)  208.640 ms  203.841 ms  199.946 ms
> 16  193.251.133.117 (193.251.133.117)  231.618 ms  233.234 ms  229.844 ms
> 17  193.251.133.117 (193.251.133.117)  259.227 ms  258.488 ms  262.034 ms
> 18  193.251.133.117 (193.251.133.117)  288.661 ms  292.598 ms  288.129 ms
> 19  193.251.133.117 (193.251.133.117)  321.982 ms  320.806 ms  318.364 ms
> 20  193.251.133.117 (193.251.133.117)  350.245 ms  349.834 ms  540.883 ms
> 21  193.251.133.117 (193.251.133.117)  539.971 ms  410.838 ms  419.743 ms
> 22  193.251.133.117 (193.251.133.117)  468.291 ms  409.761 ms  406.256 ms
> 23  193.251.133.117 (193.251.133.117)  432.990 ms  439.589 ms  434.184 ms
> 24  * 193.251.133.117 (193.251.133.117)  466.399 ms  465.287 ms
> 25  193.251.133.117 (193.251.133.117)  500.719 ms  498.601 ms  499.957 ms
> 26  193.251.133.117 (193.251.133.117)  530.089 ms  527.642 ms  528.999 ms
> 27  193.251.133.117 (193.251.133.117)  556.208 ms  555.552 ms  557.387 ms
> 28  193.251.133.117 (193.251.133.117)  586.776 ms  584.171 ms  586.944 ms
> 29  193.251.133.117 (193.251.133.117)  608.677 ms  610.789 ms  618.232 ms
> 30  193.251.133.117 (193.251.133.117)  641.141 ms  643.149 ms  639.050 ms
> 
> ----------
> 
> $ traceroute 198.146.21.26
> traceroute to 198.146.21.26 (198.146.21.26), 30 hops max, 38 byte packets
>  1  regina-GE1-2.cac.washington.edu (128.95.219.100)  4.395 ms  0.986 ms  
>  2  uwbr2-GE2-0.cac.washington.edu (140.142.155.24)  0.326 ms  0.310 ms  
>  3  cnsp1-wes-GE1-0.pnw-gigapop.net (198.107.150.1)  1.305 ms  1.113 ms  
>  4  so-1-2-2.a07.sttlwa01.us.ra.verio.net (204.203.3.1)  4.219 ms  4.308 
>  5  ge-6-2-0.r03.sttlwa01.us.bb.verio.net (129.250.28.1)  4.096 ms  6.462 
>  6  p4-5-0-0.r06.plalca01.us.bb.verio.net (129.250.3.89)  25.469 ms  
>  7  p4-0-0.r05.plalca01.us.bb.verio.net (129.250.2.129)  23.593 ms  22.371 
>  8  svl-brdr-01.inet.qwest.net (205.171.4.45)  24.093 ms  25.967 ms  
>  9  svl-core-03.inet.qwest.net (205.171.14.109)  27.487 ms  22.669 ms  
> 10  svl-core-01.inet.qwest.net (205.171.14.121)  22.500 ms  24.719 ms  
> 11  chi-core-03.inet.qwest.net (205.171.8.50)  62.208 ms  55.153 ms  
> 12  chi-core-01.inet.qwest.net (205.171.20.173)  57.742 ms  54.672 ms  
> 13  chi-edge-01.inet.qwest.net (205.171.20.34)  54.261 ms  58.971 ms  
> 14  208.46.63.202 (208.46.63.202)  88.583 ms  69.619 ms  67.605 ms
> 15  208.63.128.3 (208.63.128.3)  70.551 ms  67.581 ms  69.375 ms
> 16  208.63.128.1 (208.63.128.1)  65.115 ms  70.951 ms  66.083 ms
> 17  208.63.128.3 (208.63.128.3)  67.628 ms  65.488 ms  68.418 ms
> 18  208.63.128.1 (208.63.128.1)  72.197 ms  71.422 ms  69.517 ms
> 19  208.63.128.3 (208.63.128.3)  68.539 ms  68.976 ms  67.911 ms
> 20  208.63.128.1 (208.63.128.1)  72.373 ms  67.838 ms  66.468 ms
> 21  208.63.128.3 (208.63.128.3)  67.040 ms  69.136 ms  67.631 ms
> 22  208.63.128.1 (208.63.128.1)  66.317 ms  83.947 ms  70.693 ms
> 23  208.63.128.3 (208.63.128.3)  66.865 ms  69.521 ms  69.760 ms
> 24  208.63.128.1 (208.63.128.1)  69.604 ms  67.534 ms  70.447 ms
> 25  208.63.128.3 (208.63.128.3)  68.285 ms  69.772 ms  67.721 ms
> 26  208.63.128.1 (208.63.128.1)  71.915 ms  69.530 ms  72.403 ms
> 27  208.63.128.3 (208.63.128.3)  111.475 ms  69.670 ms  69.267 ms
> 28  208.63.128.1 (208.63.128.1)  68.883 ms  67.147 ms  72.106 ms
> 29  208.63.128.3 (208.63.128.3)  69.842 ms  67.889 ms  66.944 ms
> 30  208.63.128.1 (208.63.128.1)  70.986 ms  73.124 ms  68.452 ms
> 
> 
> 
> 

-- 
Stephen J. Wilcox
IP Services Manager, Opal Telecom
http://www.opaltelecom.co.uk/
Tel: 0161 222 2000
Fax: 0161 222 2008