Evaluating Tier 1 Internet providers

Richard A Steenbergen ras at e-gerbil.net
Fri Aug 30 03:46:48 UTC 2013


On Thu, Aug 29, 2013 at 08:25:41PM -0700, Luke S. Crawford wrote:
> 
> I have no idea how to solve this sort of problem automatically. 
> Ideally, if someone has a congested or down link, I'd prefer that they 
> not announce routes to that part of the internet, as I do have a 
> backup, but that isn't how it works.

BGP best path routing decisions are made by completely irrelevent 
criteria like AS-PATH lengths and lower router-id's, and are completely 
blind to things that actualy matter like latency, capacity, packet loss, 
etc. Fundamentally it's impossible to fix automatically with the current 
routing protocols, and at best the protocol extensions like BGP AIGP 
(which could help at least convey some of the data, like the "oh crap I 
just got rerouted to a different exit with much higher latency" 
situation you mentioned) are still a long way from being practically 
usable. At best you can aim your default/tie breaks towards networks you 
have "more faith in", but that doesn't mean much in practice. :) 

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)



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