[address-policy-wg] 2023-01 New Policy Proposal (Reducing IXP IPv4 assignment default size to a /26)

* Angela Dall'Ara

> A new RIPE Policy Proposal, 2023-01, "Reducing IXP IPv4 assignment 
> default size to a /26"
> is now available for discussion.
> 
> The goal of this proposal is to extend the lifetime of the IXP IPv4 
> address pool and to motivate IXPs to implement the exchange of IPv4 
> routing information over IPv6.

Hi,

This proposal is a step in the right direction, although I feel it
should have gone further. I've already elaborated on why in the «IXP
pool lower boundary of assignments» thread, so I don't seek to re-hash
that whole thread, but for the record I'll repeat the gist of it in the
formal proposal thread:

Since IPv4 is a finite resource that needs to last "forever", it seems
wasteful to willfully assign too large prefixes to IXPs that do not
need them. According to https://github.com/mwichtlh/address-policy-wg,
a /26 would be excessively large for a majority of IXPs.

I would rather see a policy that did not specify a default size at all,
but rather instructed the NCC to right-size each assignment according
to the "at least 50% utilisation after a year" rule. 

Note that this should not be considered an objection to this proposal,
as I mentioned before it is a step in the right direction, after all.

With that out of the way, I have a few questions/comments:

1) Regarding «New IXPs will be initially assigned a /26 by default.
Upon request, a /25 can be assigned initially. If the initial
assignment has been utilised by at least 50%, IXPs can request the
assignment of a /24»:

This is somewhat difficult to decipher. Does it mean that:

a) a new IXP can simply ask for an initial /25 and receive it, no
questions asked?
b) an existing IXP that has used 50% of an initial /26 will be able to
upgrade straight to a /24, i.e., bypassing a /25? (Or even %50-of-
/27→/24, in an unlikely but not impossible corner case.)

To improve clarity, I would suggest not to mix the conditions for new
IXPs / initial assignments with the conditions for already existing
IXPs that seek to upgrade a previous assignment.


2) Regarding «Assignments strictly larger than a /24 will only be made
to IXPs that offer the exchange of IPv4 routing information over IPv6
at their route servers»:

a) What is the purpose / meaning of the word «strictly» here? I assume
it is there for a reason, but removing it does not seem to me to change
the meaning of the sentence in any way (but then again, I am not a
native English speaker).

b) Depending on whether one considers an assignment from the NCC to the
IXPs as to be a continuous state or as a one-time event, this may cause
an instant obligation on current holders of larger-than-/24 IXP
prefixes to implement IPv4-over-IPv6 routing in their route servers. Is
that the intention?

Tore