looping traceroutes

Wed Sep 19 04:31:39 UTC 2001

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