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Odd Routing to Chicago POP

Started by cybrmatt, November 19, 2008, 09:26:35 AM

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I'm setting up a tunnel to my home in the Chicagoland area, and was glad to see a Chicago PoP to connect to.  To my surprise, the Chicago PoP actually demonstrated higher latency to my comcast connection than did the one in NY.  A quick traceroute suggests that both connections are passing through the east cost; the Chicago PoP making a round trip before it even starts its way back to me:

-New York PoP-
traceroute to (, 30 hops max, 40 byte packets
1  * * *
ge-1-46-ur01.romeoville.il.chicago.comcast.net (  20.779 ms  20.838 ms  20.955 ms
te-8-2-ur02.romeoville.il.chicago.comcast.net (  20.467 ms  20.562 ms  20.536 ms
te-8-3-ar02.elmhurst.il.chicago.comcast.net (  20.125 ms  20.336 ms  20.227 ms
te-8-2-ar02.elmhurst.il.chicago.comcast.net (  19.743 ms  19.708 ms  19.701 ms
te-2-1-ar01.area4.il.chicago.comcast.net (  20.326 ms  19.359 ms  19.165 ms
7 (  20.252 ms  20.155 ms  20.060 ms
TenGigabitEthernet2-3.ar5.CHI1.gblx.net (  19.568 ms  19.574 ms  19.679 ms
HURRICANE-ELECTRIC-LLC-Ashburn.TenGigabitEthernet4-4.ar3.DCA3.gblx.net (  55.294 ms  55.776 ms  55.833 ms
10  10gigabitethernet1-2.core1.nyc4.he.net (  55.598 ms  55.550 ms  50.787 ms
11  tserv4.nyc4.ipv6.he.net (  55.266 ms  60.093 ms  60.073 ms

-Chicago PoP-
traceroute to (, 30 hops max, 40 byte packets
1  * * *
ge-1-46-ur01.romeoville.il.chicago.comcast.net (  17.937 ms  17.998 ms  18.137 ms
te-8-2-ur02.romeoville.il.chicago.comcast.net (  17.783 ms  17.658 ms  17.655 ms
te-8-3-ar02.elmhurst.il.chicago.comcast.net (  17.174 ms  17.155 ms  17.171 ms
te-8-2-ar02.elmhurst.il.chicago.comcast.net (  16.591 ms  16.951 ms  16.853 ms
te-2-1-ar01.area4.il.chicago.comcast.net (  19.650 ms  10.434 ms  14.892 ms
pos-0-13-0-0-cr01.chicago.il.ibone.comcast.net (  20.901 ms  20.990 ms  20.977 ms
TenGigabitEthernet2-2.ar5.CHI1.gblx.net (  20.285 ms  20.288 ms  20.267 ms
HURRICANE-ELECTRIC-LLC-Ashburn.TenGigabitEthernet4-4.ar3.DCA3.gblx.net (  57.170 ms  57.228 ms  57.183 ms
10  10gigabitethernet1-2.core1.nyc4.he.net (  56.880 ms  56.004 ms  51.237 ms
11  10gigabitethernet1-2.core1.chi1.he.net (  76.054 ms  72.770 ms  78.027 ms

12  tserv9.chi1.ipv6.he.net (  78.013 ms  77.941 ms  77.779 ms

Is this normal?


Hurricane peers aggressively at over 23 different exchange points globally.

Comcast peers where Comcast wants and Comcast routes how they want.

If you are a Comcast customer perhaps you could persuade them to buy transit from or peer with Hurricane in Chicago and other locations.


Could you explain how you can tell that this is an issue with the Comcast connection?  (Genuine curiosity)

I just tracerouted to the Seattle, Miami, Ashburn, and Dallas PoPs from the same location, and none of them took this detour.  Does this mean that out of all the locations I've tried, Chicago is the only one Comcast is not peering with?  (I assume the peering takes place on the Global Crossing network, because that's where the discrepancy is.  Comcast's routers appear to be staying within IL.)


Edit: To further confuse myself,  I just did a quick trace from my Verizon WAN card as well.  It did not transit global crossing, nor use the comcast network, yet the trace to chicago still hits nyc4.he.net before it hits chi1.he.net, and again miami and dallas did not. :\


Comcast does not appear to peer with HE. It instead determines that the best path is through GBLX, whom HE peers with. (Actually, I believe HE buys transit from GBLX, but don't quote me on that.) They apparently don't peer with each other in Chicago, so GBLX has to send it to New York to reach HE's network.

I wouldn't really say that it is an issue with Comcast, but you would get a shorter route if Comcast peered with HE in Chicago, or even if GBLX peered with HE in Chicago.

Oh, and just so you know, peering does not all take place on GBLX. GBLX is just another network. If Comcast were to peer with HE, you would bypass GBLX entirely.