On 3/8/06, Todd Underwood <todd-nanog@renesys.com> wrote:
On Wed, Mar 08, 2006 at 01:56:00AM -0500, alex@pilosoft.com wrote:
(from Marty)
From a global perspective[1], the top 12 (I stopped at Cogent since you are asking about them) service providers whose customers and peering partners reach the largest number of networks are listed below. You can make some fairly interesting assumptions on your own: <snip>
This gotta be the most meaningless metric ever. What does "reach" mean?
now, that's a bit harsh. 'incompletely specified in this email', perhaps, but 'meaningless'? come on. :-)
the marketing description for those rankings is: "Identify service providers who are responsible for meeting Internet transit needs (directly or indirectly) of significant numbers of large customer networks within a given market, including both customer and peering relationships."
in actual, technical detail, what that means is that we take global routing data (routeviews-style), determine the relationship of every edge (customer, provider, peer), and weight the 'downstream cone' (a caida term that is useful here) of each provider by the scaled prefix space and the degree to which that provider actually provided transit to that prefix space over the course of time. it's critical to integrate across time and across lots of peers in this process. otherwise, the position of your peers and leaks come to dominate the equation.
this metric (one of several that we've begun calculating daily) isn't perfect, but we've found that for large SPs it matches expectations of people familiar with traffic flows.
Note that many Cogent customers, while using Cogent for outbound, prefer not to announce any routes to Cogent for political reasons (or prepend or depref their routes). So, that metric won't be exactly helpful.
this is, in fact, a useful point. detecting and compensating for asymmetric routing is difficult in a metric such as this, although it's probably not impossible.
t.
-- _____________________________________________________________________ todd underwood +1 603 643 9300 x101 renesys corporation chief of operations & security todd@renesys.com http://www.renesys.com/blog
Drew: What i would do is construct an RFP with specific questions about capacity, availability and locations (plus other things i can't remember right now) so that I knew what i was getting into with any provider on if they were congested. We see them all the time for large deals, and i'm sure other providers do too. A decision to purchase from supplier A vs. B should not be done lightly, and without some due diligence pertaining to where YOUR traffic may be coming from or going to. Perhaps a spread sheet of some sort that allows you to consolidate all the responses. Good Luck Peter Cohen