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Re: classful routes redux

  • From: Henk Uijterwaal
  • Date: Mon Nov 07 15:35:13 2005

At 11:57 07/11/2005, Michael.Dillon@btradianz.com wrote:

> What about those that are assigned and used but not [currently] visible
> on the public Internet [i.e., are on other internets]?

Indeed!

On Henk's slide number 5 he states:

"Each AS wants to be able to send traffic to any other AS"

This is NOT true. Many ASes explicitly do *NOT*
want to send traffic to any other AS. They only want
to send traffic to customers, vendors or business
partners of some sort.
You are right, but this was not the point I was trying to make on
this slide.

The point I was trying to make is: A site is assigned an AS if it has a
network that is connected to the global Internet and wants to send traffic somewhere. (If not, why bother to get an AS?) One of the rules in the
policies is that the AS is returned when the need disappears. So, very
naively, I'd think that for each assigned AS there is at least one
path announcing the address space in that AS to somebody else.

I immediately agree that there are cases where an AS does not want to
send traffic to another AS, or prefers not to use a path even though
it is available.

I also agree that there are cases where a network is
not visible at all on the Internet and a private AS cannot be used.
However, I do not believe that these cases account for 1/3 of the AS
out there.

Henk



 In other words, there are many
so-called extranets which are basically internets
built using exactly the same technology as the Internet
however with more restrictive interconnect policies.

One way to visualize this is to imagine the Internet
as a cloud. At the core of the cloud are the core
providers and at the edge of the cloud are the end
user organizations, many of which appear to be
singly homed. However, hidden behind this edge is
a thin layer which represents a private internet.
It also connects many networks but it does *NOT*
exchange traffic with the public Internet. All the
networks connected to these private internets are
also connected to the public Internet but they
implement strict traffic separation policies
internally. In some cases, this is an air gap but
these days it is often a bunch of firewalls.

In the 24/7 connected world of the 21st century
there is a lot of growth in these internets that
wrap around the Internet but don't exchange vital
fluids with it.

--Michael Dillon
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Henk Uijterwaal Email: henk.uijterwaal(at)ripe.net
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