Comcast - Stuck route in Chicago directing MN traffic via Denver

Eric Spaeth eric at spaethco.com
Sun Jun 1 23:57:06 CDT 2008


For the last couple weeks there has been a route stuck in the Chicago 
wan/core that is directing some Minnesota-bound traffic through Denver, 
even though Chicago and the Roseville, MN aggregation remain up and 
directly connected.  This has the dual benefit of unnecessarily 
increasing the load on Comcast's internal backbone as well as increasing 
latency for Minnesota subscribers connecting to "east of the 
Mississippi" destinations by ~20ms.

I'm hoping Comcast engineers read this list, or someone in the carrier 
community can help poke one of their Comcast contacts to help get this 
resolved.

Thanks in advance! 

"Wedged" route -  76.113.128.0/17
Correct route - 69.180.128.0/18

Example trace from Chicago source to 76.113.128.0/17:
=========================================
traceroute to 76.113.128.1 (76.113.128.1), 30 hops max, 40 byte packets
 1  69.65.40.62 (69.65.40.62)  0.542 ms  0.511 ms  0.508 ms
 2  so2-0-0-0.er1.Chi1.Servernap.net (69.39.239.169)  1.632 ms  1.642 
ms  2.121 ms
 3  ge-6-20.car1.Chicago1.Level3.net (4.79.65.49)  1.605 ms  1.608 ms  
1.619 ms
 4  ae-2-54.edge1.Chicago2.Level3.net (4.68.101.115)  1.604 ms  1.602 
ms  1.600 ms
 5  COMCAST-IP.edge1.Chicago2.Level3.net (4.71.248.26)  2.735 ms  2.741 
ms  2.739 ms
 6  pos-0-8-0-0-cr01.denver.co.ibone.comcast.net (68.86.85.114)  27.284 
ms  27.398 ms  27.387 ms
 7  te-9-4-ar02.roseville.mn.minn.comcast.net (68.86.91.154)  44.177 ms * *
 8  te-0-2-0-5-ar03.roseville.mn.minn.comcast.net (68.87.174.73)  28.352 
ms  28.352 ms  28.349 ms
 9  te-2-1-ur01.sims.mn.minn.comcast.net (68.87.174.74)  28.826 ms * *
10  te-8-3-ur02.sims.mn.minn.comcast.net (68.87.174.78)  28.959 ms * *
11  te-2-1-ur01.newport.mn.minn.comcast.net (68.87.174.82)  29.267 ms * 
te-2-1-ur01.newport.mn.minn.comcast.net (68.87.174.82)  28.700 ms
12  c-76-113-128-1.hsd1.mn.comcast.net (76.113.128.1)  28.638 ms  28.673 
ms  28.667 ms
=========================================

Example trace from Chicago source to working route 69.180.128.0/18
=========================================
traceroute to 69.180.130.1 (69.180.130.1), 30 hops max, 40 byte packets
 1  69.65.40.62 (69.65.40.62)  0.482 ms  0.450 ms  0.446 ms
 2  so2-0-0-0.er1.Chi1.Servernap.net (69.39.239.169)  1.595 ms  2.082 
ms  2.082 ms
 3  ge-6-20.car1.Chicago1.Level3.net (4.79.65.49)  1.568 ms  1.569 ms  
1.579 ms
 4  ae-2-52.edge1.Chicago2.Level3.net (4.68.101.51)  1.562 ms  1.563 ms  
1.560 ms
 5  COMCAST-IP.edge1.Chicago2.Level3.net (4.71.248.22)  2.708 ms  2.713 
ms  2.711 ms
 6  te-0-1-0-7-ar03.roseville.mn.minn.comcast.net (68.87.174.21)  13.144 
ms  11.919 ms  11.877 ms
 7  68.87.174.22 (68.87.174.22)  11.824 ms * *
 8  te-8-3-ur02.brooklynpark.mn.minn.comcast.net (68.87.174.26)  12.333 
ms * *
 9  te-2-1-ur01.newhope.mn.minn.comcast.net (68.87.174.30)  12.012 ms * *
10  c-3-0-ubr02.newhope.mn.minn.comcast.net (69.180.130.1)  11.963 ms  
12.018 ms  11.973 ms
=========================================

-Eric




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