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Rapidly-variable routing on the time scale of seconds to minutes?

  • From: Charles Shen
  • Date: Mon Jan 31 04:21:52 2005

We did a "traceroute" end-to-end routing measurement in 2004 and found about
5-10% of measuremnts exhibiting rapidly-variable routing on the time scale
of a single traceroute (seconds to minutes). In other words, the packets
belonging to a single traceroute took multiple paths. 

Vern Paxson mentioned in 1997 one mechanism that can lead to this "route
fluttering" behavior as "route splitting", which is explicity allowed in
RFC1812 - Requirements for IP version 4 Routers. 

Route change in such a short scale for packets in the same flow could be
troublesome. But the occurrence of such behavior does not seem to have
reduced over the past years at least from our measurements. Does anyone know
how to explain this behavior? Thanks!

An example traceroute record containing the fluttering is shown below (see
the 5th hop)

 Fri Apr 09 09:35:35 2004

 1  cisfhfb.fh-friedberg.de (212.201.24.1)  1.095 ms  0.402 ms  0.321 ms
 2  ar-frankfurt2.g-win.dfn.de (188.1.42.9)  120.105 ms  198.766 ms  200.040
ms
 3  cr-frankfurt1-ge5-0.g-win.dfn.de (188.1.80.1)  2.093 ms  2.142 ms  2.087
ms
 4  so-6-0-0.ar2.FRA2.gblx.net (208.48.23.141)  2.461 ms  2.349 ms  2.333 ms
 5  pos5-0-2488M.cr2.FRA2.gblx.net (67.17.65.53)  2.448 ms
pos6-0-2488M.cr1.FRA2.gblx.net (67.17.65.77)  2.368 ms  2.281 ms
 6  so3-0-0-2488M.ar2.FRA3.gblx.net (67.17.65.82)  2.676 ms  2.750 ms
so2-0-0-2488M.ar2.FRA3.gblx.net (67.17.65.58)  2.569 ms
 7  ge-7-2.Frankfurt1.Level3.net (195.122.136.245)  10.971 ms  10.967 ms
10.882 ms
 8  ae-0-55.mp1.Frankfurt1.Level3.net (195.122.136.97)  11.488 ms  11.417 ms
11.353 ms
 9  so-0-0-0.mp1.London2.Level3.net (212.187.128.61)  27.203 ms  27.042 ms
27.048 ms
10  so-1-0-0.bbr1.Washington1.Level3.net (212.187.128.138)  91.004 ms
91.006 ms  90.977 ms
11  ge-0-0-0.mpls1.Honolulu2.Level3.net (4.68.128.13)  212.254 ms  212.321
ms  212.351 ms
12  so-7-0.hsa1.Honolulu2.Level3.net (4.68.112.90)  212.407 ms  212.250 ms
212.365 ms
13  s1.lavanet.bbnplanet.net (4.24.134.18)  212.609 ms  212.372 ms  213.270
ms
14  malasada.lava.net (64.65.64.17)  212.260 ms  212.460 ms  212.226 ms

Best regards,

Charles