[arin-ppml] Policy Proposal: Extend 16 bit ASN Assignments

Ted Mittelstaedt tedm at ipinc.net
Fri May 8 19:42:06 EDT 2009

> -----Original Message-----
> From: arin-ppml-bounces at arin.net 
> [mailto:arin-ppml-bounces at arin.net] On Behalf Of Robert E. Seastrom
> Sent: Friday, May 08, 2009 3:39 PM
> To: Aaron Hughes
> Cc: arin-ppml at arin.net
> Subject: Re: [arin-ppml] Policy Proposal: Extend 16 bit ASN 
> Assignments
> Aaron Hughes <aaronh at bind.com> writes:
> > It is entirely unnecessary.  The only change that should be 
> made IMHO 
> > is to revert to default 16bit assignments until Jan 1 2010 or
> > 11 to prevent the 90% return of 32bit ASNs.  That should be enough 
> > time to get better vendor support.
> How about better education *now*?  Might get that return rate 
> down substantially if there were some information out there 
> about common platforms and their support for 4-byte ASNs.  I 
> asked at the meeting if anyone knew of any "bgp for dummies" 
> style books that talk about 4-byte ASNs and there was not a 
> peep from the audience.  Let's FIX that information gap.

The audience doesn't need to know.

At this point all the major router vendors have corrected their
ASN handling code so that 4 byte AS numbers are not a problem
unless you want to use one yourself.

The very last one to get caught was Quagga, which happened a week
ago, here's the writeup:


they patched it in hours and things got back to normal.

So, it's understandable that 4 byte ASNs are going to draw
blanks, because most people don't NEED to know - they aren't
affected by it.

If I asked the audience at the meeting if they knew what a
downstream O2 sensor in a car did I'd get the same sea of blank

The people who need to know are the people requesting ASNs

And the problem is that if ARIN asks everyone requesting an
AS if they really, really, really, really!!! are sure they
can use a 4 byte ASN, because it MIGHT NOT WORK with their
gear, why then requestors are simply going to say "fine,
then gimmie a 2 byte ASN" and they won't even bother learning
anything more about it.

Most AS requestors still are not going to be able to use a
32 bit AS number right off the bat.

Either they are going to have to update firmware, or they
are going to have to replace equipment.  If they have a 32 bit
AS number in hand from ARIN, and they discover that they have
to update firmware to use it, they will have the choice of
either having to return the ASN and go through the work again to
re-request it, or updating firmware.  Most likely they will
update firmware because that will be less work.

If ARIN tells them in advance that a 16 bit AS will work with
everything and a 32 bit AS won't, and all they need to do to
get a 16 bit AS is to check the box on the form, well then
what do you think they are going to do?  Most people will check the
box and get the 16 bit AS.  Only a few will bother to check
and see if they can update firmware to support 32-bit ASNs.

The folks who get the 32 bit AS and find out after the fact that
they have to replace hardware to use it, will hopefully be mad enough
to call their router vendor and scream at them for not releasing
a firmware update for their gear.  Which, is really what we want -
since the router vendors have all had plenty of time to add in
support for these, now.


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