Re: [Sidrops] I-D Action: draft-ietf-sidrops-rpki-prefixlist-01.txt

[Job Snijders <[e-mail]>]

On Thu, Jan 25, 2024 at 09:32:09AM -0500, Russ Housley wrote:
> > On Wed, Jan 24, 2024 at 04:07:06PM -0500, Russ Housley wrote:
> >> I am confused by this change in the syntax:
> >> 
> >>   IPv4Prefixes ::= SEQUENCE (SIZE(1..MAX)) OF AddressPrefix{32}
> >>   IPv6Prefixes ::= SEQUENCE (SIZE(1..MAX)) OF AddressPrefix{128}
> >> 
> >>   AddressPrefix {INTEGER: len} ::= BIT STRING (SIZE(0..len))
> >> 
> >> What does it mean when the prefix is a zero length BIT STRING?
> > 
> > That would be 0.0.0.0/0 or ::/0, right?
> > 
> > As I understand it a BIT STRING value can have any length, including
> > zero. Same approach is used in draft-ietf-sidrops-rfc6482bis.
>
> I was trying to figure out where rpki-prefixlist would use 0.0.0.0/0
> or ::/0.

To me that is an open question, one I intended to address after some
proof-of-concept software materalizes :-).

The question at hand being whether the working group would want
Autonomous Systems to document the possible origination of default
routes, or make that more implicit. If the WG prefers to not having to
append ::/0 and 0.0.0.0/0 to a Signed Prefix List, it indeed would make
sense to change "SIZE(0..ub)" to "SIZE(1..ub)".

However, related to the above, a suggestion was shared with me at
IETF118 whether 'ge' (greater than or equal), and 'le' (less than or
equal) constructs [1] or 'longer', 'orlonger', 'through', 'upto'-style
constructs [2] could be introduced in Signed Prefix Lists to make
makking to existing infrastructure in Router's Routing Policy Language
Engines easier. With that kind of complication in mind, it seems
plausible that zero-length address prefix BIT STRINGS would be a
necessity to support.

For me it still is up in the air whether the above mentioned 'advanced'
routing policy constructs should be made part of the Signed Prefix List
profile, and I'd like to let a bit of experimentation guide us.

Kind regards,

Job

[1]: https://learningnetwork.cisco.com/s/question/0D56e0000CcXAD0CQO/prefix-lists-what-are-ge-and-le-used-for
[2]: https://www.juniper.net/documentation/us/en/software/junos/routing-policy/topics/concept/policy-configuring-route-lists-for-use-in-routing-policy-match-conditions.html