Connections among ASes

Chengchen Hu huc at
Fri Nov 30 04:11:01 UTC 2007


Although they are not absolute cases, are they "typical" cases, i.e., do 
they apply to most of the cases? I know "typical" is not well defined, but 
I am kind of curious about the likelihood of the happening.

A related question. Is there any sources I can look more about such 


From: Randy Bush
Data: 2007-11-29 19:24:12
To: Chengchen Hu
CC: nanog
Subject: Re: Connections among ASes

> 1) there is no such a direct link between two routers located in two
> Internet eXchange Points-IXPs (even in same city) if they are from 
> different ASes. For example, a router A belongs to AS x located in 
> IXP1, and router B belongs to AS y located in IXP2, there is no link
> between A and B.

it is not safe to assume that routers A & B, each belonging to a
different isp and each in a different colo in the same city are not
otherwise interconnected.

> 2) small AS will not use one router to connect to 2 different
> providers in differnet IXPs. It is much cheaper using one router to
> connect with different ASes in a same IXP.

what if the two providers to which i want to connect are not at the same
ix but i can get a cheap L2 transport to the second ix?


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