Re: [Idr] WGLC on draft-ietf-idr-as-private-reservation-00 concluded, extended to consider ASN range

[Jon Mitchell <[e-mail]>]

On Thu, Dec 20, 2012 at 10:47:54AM -0600, David Farmer wrote:
> On 12/19/12 08:57 , Jon Mitchell wrote:
> 
> >Maybe some others would like to weigh in on one of the above options now
> >that it's a focused discussion (otherwise I plan to make the small edits
> >discussed in previous threads and move the start of range to
> >42xxxxxxxx so we can close this out...)
> 
> 
> The idea is to allow the simple regexp of 42???????? to match
> private use ASNs.  However, this makes a few assumptions.

Human identifiable range was the primary concern raised with regex
implementation another given justification for changing the
recommendation to IANA for the start of range.

> 
> 1. While not part of the Private Use ASN range, the intended regexp
> also matches the reserved ASN 4294967295, and therefore 4294967295
> can never be a valid ASN in an AS_PATH.

The draft does not state how to construct a regex, this is out of scope
for the draft.  Some operators may not even choose or need to filter
private use ASN's inbound or outbound based on their
requirements/design.

> 
> 2. The intended regexp would select ASNs beyond the 32bit ASN range,
> if they were valid, that is 4294967296 through 4299999999.
> Therefore, if the ASN range were ever expanded to make these valid
> ASNs, the private use ASN range would also need to be expanded to be
> included these ASNs as well.

Certainly something operators should concern themselves with when
discussions start on moving beyond 4 byte ASNs (maybe a note about it
could be attached to that draft).  On a side note, do you plan on this
before or after IPv6 exhaustion? 

> If we want to use 4.2B as the starting point to simplify regexp
> matching of the private use range then these assumptions need to be
> explicitly stated in the draft.

I disagree, I prefer not delving how to construct regex's properly or
stating how they work in various implementations in a simple IANA
reservation draft.