Tier 2 - Lease?

Valdis.Kletnieks at vt.edu Valdis.Kletnieks at vt.edu
Wed May 3 06:16:00 UTC 2006

On Tue, 02 May 2006 22:38:22 PDT, Robert Sherrard said:
> What make a provider a tier 2, versus a tier 1 provider...

Usually it's defined as "Tier 1's don't buy transit, Tier 2's do".  Of course,
it gets a lot more complicated, because you can easily have a "Tier2" that's
peering for 95% of its prefixes, and buying transit for 5% of not-often-used
prefixes simply because it's expensive to get a peer for that 5%.  But said
Tier2 may be bigger than some "tier 1s", and be better on any *rational*
comparison criteria (price, support, throughput, latency, jitter, downtime/SLA,
path diversity, etc....)

If a company is "almost a Tier1", but buys transit for several hundred prefixes
coming from Korea and Nigeria (say, 0.2% out of the 180K or whatever the
routing table is this week), why do you *care*, unless you have (or *seriously*
plan to have) lots of packets coming and going to those 2 countries?

In general, the people who *really* care about Tier 1/2 already know if they
are a 1 or a 2 themselves.  Almost everybody else falls into 2 categories:

1) People who are using 1/2 as a shortcut for doing a *proper* analysis of the options.
2) People who feel a marketing need to say "we peer with X Tier-1s".

(OK, where's my asbestos long-johns? ;)

> Is it possible to determine who a tier 2 (i.e. Cogent) leases fiber from?

Try asking? :) (And the answer will probably depend on which exact leg of their
network you're asking about - it's almost certainly a patchwork....)

It probably doesn't matter unless you're trying to buy connectivity over
diverse paths - in which case you're going to have to ask *both* providers
what the exact fiber routing is.  It's possible the tier2 and the tier1 are
both leasing previously-dark fiber in the same conduit - but leasing it from
2 different companies.

And of course, it's quite possible that *this* week, that tier 2 is routing
your packets over fiber they own, and next week, some traffic engineering puts
your packets on fiber leased from A - and last week, it was on fiber leased from B.

(Disclaimer: we're neither a Tier 1 or 2.  And most of the routes we receive via
a regional provider that treats us *very* nicely - mostly because we have them
by the short-and-curlies.  They piss us off too much, we turn off the phones in
their NOC. ;)
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