At 5:33 AM +0000 6/27/03, Mwalie W wrote:
>Hi All,
>
>This should be a simple one.
>
>I have heard that we have Tier 1, Tier 2, Tier 3 ISPs.I do assume we only
>have Tier 1 and Tier 2 in the US, Europe and Asia (Japan, China).
>
>In a third world country, can we have Tier 1 and Tier 2? Or we just have
>Tier 3 ISPs which connect to Tier 1 and Tier 2 in the USA, etc?
>
>Okay, I ask this question because I was reading an article in Kenya about a
>local ISP there called UUNET-Kenya (www.uunet.co.ke) and they are saying
>that they are a Tier 1 ISP. I did not think that that Kenyan ISP is Tier 1,
>but I do know that its parent company (Worldcom?) is Tier 1.
>
>Was it just marketing to the locals there??
>
>Thanks for your answers
The tier concept is mostly marketing these days, although there is
some technical basis.
An essential part of the difference is the relationship of the
provider to other ISPs. Unfortunately, the terminology is awkward
here, because there are two meanings of the word "peer". The familiar
one is a BGP session, regardless of economics. The other definition
is an economic one. A "peer relationship" means that the two ISPs do
not charge one another for transit and send at least full customer
routes to each other, on the basis they are both of about the same
aize and it's to their mutual advantage to let their customers have
access to each other, without worrying about the billing.
The other relationship is a customer-provider one, where the "less
valuable" provider buys transit from the "more valuable" one. In
other words, if ISPs are peers, no money changes hands.
A tier 1 provider never buys transit. It gets all its routes from
bilateral peering arrangements. It will have a 24/7 network
operations center, and a national or intercontinental transmission
network, either leased or physically operated, of at least DS-3 (more
likely OC-3 to OC-48 these days). Its non-provider customers, if it
has them, will usually be large enterprises only -- it's really a
wholesaler.
A tier 2 provider is regional and gets all its regional routes
through peering arrangements. It does buy transit to go outside its
region, although it's likely to have significant bulk discounts. It
has 24/7 NOC and a broadband transmission network within its region.
A tier 3 provider buys transit from multiple upstreams and runs a
default-free routing table. It may or may not operate a significant
transmission network. Usually, if it doesn't have a full 24/7 NOC,
technical support remains available to other providers (not
necessarily customers) through pagers and the like.
A tier 4 provider buys transit from one or more upstreams, with
connectivity to multiple POPs of the same provider if it only uses
one upstream. It does run BGP with a substantial part of the global
table.
A tier 5 provider is a reseller, perhaps an Internet cafe. It owns or
leases ("virtual POP") end user access and buys transit.
There are lots of refinements and variations. As a shameless plug,
I'll mention my own book, _Building Service Provider Networks_.
Geoff Huston's _ISP Survival Guide_ complements it, going further
into the business model, as do the many papers on peering economics
by Bill Norton of Equinix.
Do I at least get a cup of Kenyan coffee for all this? I'm trying to
remember some of the more solid dishes. For the people in the US, if
you think "what's the best CCIE number" is bad, try a discussion
among various African cultures as to who makes the best Joloff rice!
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=71546&t=71508
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