T1 vs. T2 [WAS: Apology: [Tier-2 reachability and multihoming]]
Patrick W Gilmore
patrick at ianai.net
Tue Mar 29 15:46:24 UTC 2005
On Mar 29, 2005, at 1:24 AM, Richard A Steenbergen wrote:
> On Tue, Mar 29, 2005 at 02:23:06AM +0100, Stephen J. Wilcox wrote:
>>
>> 701 is not the most connected, it has only customers and a restrictive
>> set of peers?
>
> Ok, I'm just bored enough to bite. If we're talking about a contest to
> see
> who has the most number of directly connected ASNs, I think UU might
> still
> win, even with a restrictive set of peers.
>
> Taking a look at a count of customer ASNs behind some specific
> networks of
> note, I come up with the following (some data a couple weeks out of
> date,
> but the gist is the same):
>
> Network ASN Count
> ------- ---------
> 701 2298
> 7018 1889
> 1239 1700
> 3356 1184
> 209 1086
> 174 736
> 3549 584
> 3561 566
> 2914 532
> 2828 427
> 6461 301
> 1299 243
>
> Which begs the question, what is the largest number of ASNs that
> someone
> peers with? Patrick? :) Somehow I suspect that 701's customer base (702
> and 703 aren't included in the above count BTW) overpower even the most
> aggressively open of peering policies, in this particular random
> pointless
> and arbitrary contest at any rate.
Of course. There is a difference between "most peers" and "most
adjacent ASes".
But it is non-trivial to see which of those adjacencies are transit and
which are peering. (Nearly impossible if you define such things on
Layer 8, but not impossible if you only include which ASes are
propagated to which other ASes.)
At the end of the day, an AS with a LOT of downstream ASes can always
beat a well peered AS - there just aren't that many ASes which peer.
--
TTFN,
patrick
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