[145753] in North American Network Operators' Group
Re: BGP Peers as basis of available routes
daemon@ATHENA.MIT.EDU (Bill Woodcock)
Wed Oct 19 12:54:20 2011
From: Bill Woodcock <woody@pch.net>
In-Reply-To: <4E9E7236.5000403@stluke.com.ph>
Date: Wed, 19 Oct 2011 09:53:15 -0700
To: Nathanael C. Cariaga <nccariaga@stluke.com.ph>
Cc: NANOG Mailing List <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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On Oct 18, 2011, at 11:46 PM, Nathanael C. Cariaga wrote:
> Is it safe to conclude that the web hosting provider's available =
routes would would depend on the peers who are advertising their AS / =
network? (i.e if web hosting provider claims that they are peering with =
telco a, b, c but as seen from a third party looking glass, only C is =
seen advertising the web hosting provider network that would mean web =
hosting provider is effectively utilizing c as their upstream??)
Modulo a lot of nit-picking caveats, this would indicate that they are =
purchasing transit from C, while they may or may not be peering with A =
and B. If a customer of A or B is able to reach them in a single =
AS-hop, but A and B are not advertising a route to C to looking-glasses =
or their own peers or transit providers, then A and B are peers, but not =
transit providers, to the web host.
> I would need to determine the web hosting provider who has the most =
number of peers and most number of transit providers?
A large number of transit providers has been shown, both theoretically =
and experimentally, to _decrease_ uptime, because of greater =
route-convergence times when there are more parallel paths to a =
destination. Your mileage may vary, but the optimum number is usually =
somewhere around three transit providers. The number of peers, though, =
and more to the point, the number of routes acquired through peering, is =
an excellent measure of how large and how long an ISP (in this case a =
web-hoster) has been in business. That shouldn't be your only measure =
of quality, however. It may be that reliability of power, competence of =
remote-hands, and flexibility to accommodate your needs are more =
important than how the packets get delivered.
-Bill
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