[arin-ppml] 2-byte ASN policy

Job Snijders job at ntt.net
Mon Apr 4 17:17:11 EDT 2016

On Mon, Apr 04, 2016 at 08:56:34PM +0000, David Huberman wrote:
> ARIN has traditionally had a large number of AS numbers (almost all
> 2-byte) in the "hold" bucket. These are ASNs which have been revoked
> for years due to non-payment and separation from the RSA.  But they're
> still found in the DFZ.
> Can't ARIN ask requestors who say they need 2-bytes if they'd be
> willing to accept a 2-byte ASN that may have route announcements
> present in the DFZ, and due to circumstances blah blah blah?  It boils
> down to "we have 2-byte ASNs, but they're not quite as clean as one
> might expect - is that ok?", because I'm pretty sure the answer will
> always be "HECK YEAH!"

> ASNs aren't quite like IP addresses in this context.  There's no
> conflict I know of unless the new registrants tries to directly
> exchange routes with the old registrant, which is mathematically
> highly improbable.

(Assuming at least one of two parties is running their network with
default settings..)

Indrect route exchange will also fail due to AS_PATH loop prevention.
("Phase 2: Route Selection" RFC4271).

The idea is interesting, but I wonder if there will be cases where the
new ASN holder just can't get the old ASN holder's peers & upstreams to
disconnect the illegitimately user of the ASN, causing operational

Kind regards,


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