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T1 vs. T2 [WAS: Apology: [Tier-2 reachability and multihoming]]

  • From: Patrick W Gilmore
  • Date: Sun Mar 27 11:32:05 2005 
On Mar 26, 2005, at 11:21 PM, Randy Bush wrote:
forget this concept of tier1, 2, 3 .. they are little more than terms used
by salesmen.
at least t1 and t2, also permeate academic papers where the real
topology is actually measured.  but we should not let demonstrable
measurements get in the way of our defense of the position of our
smaller networks by marketing people.
And how, pray tell, does one actually "measure" T1 vs. T2 networks? (Assuming you are not talking about two of the Terminator movies. ;-)

If someone is paying Network A, but sends communities to be treated as a peer, are they T1 or T2?

If someone buys from Network B, but peers with all of Network B's peers, and therefore does not appear in a path through Network B in those peers' BGP tables (except at the actual peering router), are they T1 or T2?

If someone "peers" with Network C, but is out-of-balance and pays a settlement fee every month, are they T1 or T2?

Assume someone else is out-of-balance with Network C, but in the other direction, does that make Network C a T2? Even if the network in question still pays Network C?

Etc., etc., etc.

There might be a way to define "Tier 1" and "Tier 2" sufficiently well as to disambiguate all the variations, but I do not think you could do it without seeing (NDA'ed) contracts and/or actual router configurations - neither of which are likely without the help of the network in question. And if you have their help, you can just ask. :-)

Back on a more operational topic, it really doesn't matter what "tier" you are, it just matters how good your connectivity is. There is no need to 'defend' the 'smaller networks'. Some of the "tier 1" networks have totally suck ass connectivity. (Yes, 'suck ass' is a technical term. =)

--
TTFN,
patrick