North American Network Operators Group

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Re: classful routes redux

  • From: Michael.Dillon
  • Date: Tue Nov 08 05:48:20 2005

> >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.

> 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?) 

Many companies get an AS in order to exchange traffic
with other companies across an internetwork that
IS NOT THE GLOBAL INTERNET!!! There are many internetworks
separate from the global Internet. These internetworks
carry traffic between many companies using globally unique
IP addresses and global unique AS numbers. But these companies
do not want any of this traffic to transit any part of the
global Internet and they don't want any form of peering
with the global Internet.

Some people seem to think that IP addresses were created 
in order to allow people to run networks connected to
the global Internet and that ASes were invented in order
for such networks to exchange routing policy details on
the global Internet. THIS IS *NOT* TRUE!

IP (Internetwork Protocol) addresses were created to allow
devices to communicate using IP regardless of whether they are
all connected to a single global Internet or not. And AS numbers
were created to allow IP networks to exchange routing policy 
details across any IP network, not just the global Internet.

RFC1918 IP addresses were set aside for the special 
case in which someone is building a *PRIVATE* network.
Once two organizations interconnect their networks,
the two networks are no longer private and must use
globally unique addresses to avoid conflicts. Similarly
private AS numbers were created for people to build
private internetworks such as in a lab environment or
at the edge of the global Internet where the private
ASes would disappear when routes are aggregated towards
the core. But if many companies wish to connect their
networks in an internetwork, separate from the global
Internet then private AS numbers are required to avoid

So, to answer your question, "Why bother to get an AS?". 
In order to exchange routing policy details with other
organizations on one of the many internetworks that 

It is important for RIR policymakers to understand
that the RIRs are not managing Internet resources. 
They are managing IP (Internetwork Protocol) resources
that are absolutely essential for ALL users of IP and
related protocols. These users may not be part of the
Internet but they still have a right to use these resources
in order to build their networks.

> One of the rules in the
> policies is that the AS is returned when the need disappears.

Excellent rule and it should be more widely enforced.

> 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.

I agree. I would guess that there are no more than a
few hundred ASes in use on private internetworks. So
that still leaves almost 10,000 ASes that could be
recovered and reused.

On the other hand, it may be cheaper in the long run
to just go to a 4-byte AS number and forget about lost
AS numbers entirely. Is "waste" really a relevant word
when we have IPv6 and 4-byte ASNs on the horizon?

--Michael Dillon