[e2e] What's wrong with this picture?

[David P. Reed]

I should not have been so cute - I didn't really want to pick on the 
operator involved, because I suspect that other 3G operators around the 
world probably use the same equipment and same rough configuration.

The ping and traceroute were from Chicago, using an ATT Mercury data 
modem, the same channel as the Apple iPhones use, but it's much easier 
to run test suites from my netbook.

Here's the same test from another time of day, early Sunday morning, 
when things were working well.

Note that I ran the test over the entire labor day weekend at 
intervals.   The end-to-end ping time was bimodal.  Either it pegged at 
over 5000 milliseconds, or happily sat at under 200 milliseconds.   
Exactly what one would expect if TCP congestion control were disabled by 
overbuffering in a router preceding the bottleneck link shared by many 
users.

------------------------------

$ ping lcs.mit.edu
PING lcs.mit.edu (128.30.2.121) 56(84) bytes of data.
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=1 ttl=44 
time=209 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=2 ttl=44 
time=118 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=3 ttl=44 
time=166 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=4 ttl=44 
time=165 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=5 ttl=44 
time=224 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=6 ttl=44 
time=183 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=7 ttl=44 
time=224 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=8 ttl=44 
time=181 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=9 ttl=44 
time=220 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=10 ttl=44 
time=179 ms
64 bytes from zermatt.csail.mit.edu (128.30.2.121): icmp_seq=11 ttl=44 
time=219 ms
^C
--- lcs.mit.edu ping statistics ---
11 packets transmitted, 11 received, 0% packet loss, time 10780ms
rtt min/avg/max/mdev = 118.008/190.547/224.960/31.772 ms
$ traceroute lcs.mit.edu
traceroute to lcs.mit.edu (128.30.2.121), 30 hops max, 60 byte packets
  1  * * *
  2  172.26.248.2 (172.26.248.2)  178.725 ms  178.568 ms  179.500 ms
  3  * * *
  4  172.16.192.34 (172.16.192.34)  187.794 ms  187.677 ms  207.527 ms
  5  12.88.7.205 (12.88.7.205)  207.416 ms  208.325 ms  69.630 ms
  6  cr84.cgcil.ip.att.net (12.122.152.134)  79.425 ms  89.227 ms  90.083 ms
  7  cr2.cgcil.ip.att.net (12.123.7.250)  98.679 ms  90.727 ms  91.576 ms
  8  ggr2.cgcil.ip.att.net (12.122.132.137)  72.728 ms  89.628 ms  88.825 ms
  9  192.205.33.186 (192.205.33.186)  89.787 ms  89.794 ms  80.918 ms
10  ae-31-55.ebr1.Chicago1.Level3.net (4.68.101.158)  79.895 ms  70.927 
ms  78.817 ms
11  ae-1-5.bar1.Boston1.Level3.net (4.69.140.93)  107.820 ms  156.892 
ms  140.711 ms
12  ae-7-7.car1.Boston1.Level3.net (4.69.132.241)  139.638 ms  139.764 
ms  129.853 ms
13  MASSACHUSET.car1.Boston1.Level3.net (4.53.48.98)  149.595 ms  
154.366 ms  152.225 ms
14  B24-RTR-2-BACKBONE.MIT.EDU (18.168.0.23)  146.808 ms  129.801 ms  
89.659 ms
15  MITNET.TRANTOR.CSAIL.MIT.EDU (18.4.7.65)  109.463 ms  118.818 ms  
91.727 ms
16  trantor.kalgan.csail.mit.edu (128.30.0.246)  91.541 ms  88.768 ms  
85.837 ms
17  zermatt.csail.mit.edu (128.30.2.121)  117.581 ms  116.564 ms  103.569 ms
$