[ppml] Proposed Policy: 4-Byte AS Number Policy Proposal

Geoff Huston gih at apnic.net
Tue Dec 13 14:28:11 EST 2005

At 01:46 AM 14/12/2005, Rich Emmings wrote:
>On Tue, 13 Dec 2005, Geoff Huston wrote:
>[regarding separation of policy proposals on documentation/private space]
>No real objection to that.
> > While I have heard of folk indicating that the private IPv4 address 
> space is
> > too small, I have not heard of anyone saying that the 1023 AS numbers
> > reserved for private use is too small. [ balance deleted]
> >
>More thinking that 1023 could perceived as some as being too large a
>reservation of the top two bytes.
> >
> >>         b) administrative ease is addressed here by using the same range,
> >> at the possible expense of "c"
> >>         c) efficiency of allocation is not -- could be with a small range
> >> at the top, at the expense of "b"
> >
> >
> > it is unclear to me what your point is here.
> >
>Reservation of the top 1023 2 bytes in 4 byte space is a larger chunk of
>space, than is probably needed, but using the same numbers as in 2 byte
>space is easier to remember -- administrative ease.  The other side is to
>only strip off a few addresses at the top, say: 65520.x - 65534.x, instead
>of 1023 (in the first 2 bytes of the 4.)

This policy proposal says absolutely nothing about expansion of the private 
AS number space. Currently the AS numbers 0 (or 0.0 in a 4 byte notation), 
23456 (0.23456) and 65535 (0.65535) are reserved by IANA, and the range 
64512 - 65534 (0.64512 - 0.65534) are designated for private use 
(http://www.iana.org/assignments/as-numbers) Neither the IETF 4 Byte draft 
nor this proposal say anything about extending this set of reserved or 
designated numbers in any way. i.e. in a 4byte AS world private AS numbers 
will still be the range of AS numbers from 0.64512 to 0.65534.

>AS2 -> AS4 transition will mirror what will happen in IPv6 implementation.
>Won't happen until/if forced, workarounds allowing the continued use of AS2
>space will probably be developed ala some of the tools which extended the
>IPv4 lifetime (both good and ugly), they'll be some things that won't leave
>IPv4 space for 10+ years, if ever, and they'll be grumbling all over.  In
>other words, same as always.  (but no reason not to get started now)

I have to disagree with this assertion. As noted in the 4byte AS draft, and 
as noted in http://www.potaroo.net/ispcol/2005-08/as.html, the transition 
is entirely different to that associated with IPv6. In this case existing 
players in the inter-domain routing space have no requirement to do 
anything now, or in the future. Let me say it again: Folk who have 2 byte 
AS numbers need do _nothing_ , i.e. the transition allows for "the 
continued use of AS2  space" indefinitely. Please read these references, as 
they are intended to describe the transition situation in as comprehensive 
manner as possible.



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