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Debugging with mtr

For diagnostics and debugging in the Fastly network, we think the mtr tool offers a great way to test network speed, evaluate performance, and perform connection diagnostics. The program's source and installation instructions live in GitHub.

While mtr provides a number of practical uses for network engineering needs, the following command works well:

mtr -c 20 -w -r www.example.com

Be sure to replace www.example.com with the hostname of the domain you're working with. The command will generate the network hops to the destination you specify, any packet loss experienced, and aggregate connection statistics.

For example, if we wanted to test the network connection from Fastly's San Francisco office to the CDN, we would use the above command for www.fastly.com. The following output would appear:

~  mtr -c 20 -w -r www.fastly.com
Start: Mon Feb  2 15:27:20 2015
HOST: test-local-machine.local                Loss%   Snt   Last   Avg  Best  Wrst StDev
  1.|-- 10.100.20.2                            0.0%    20    2.1   2.2   1.6   4.3   0.5
  2.|-- ge-4-3-4.mpr4.sfo7.us.zip.zayo.com     0.0%    20    2.3   2.4   1.8   5.2   0.6
  3.|-- ae5.cr2.sjc2.us.zip.zayo.com           0.0%    20    4.6   6.5   2.9  35.3   7.7
  4.|-- ae10.mpr4.sjc7.us.zip.zayo.com         0.0%    20    4.7   4.8   3.6  14.5   2.3
  5.|-- be6461.ccr21.sjc03.atlas.cogentco.com  5.0%    20    5.1   5.9   4.2  15.3   2.6
  6.|-- fastly-inc.edge2.sanjose3.level3.net   0.0%    20    5.0   4.7   4.2   8.2   0.8
  7.|-- ???                                   100.0    20    0.0   0.0   0.0   0.0   0.0
  8.|-- 23.235.47.184                          0.0%    20    4.7  14.3   3.8  74.6  20.3