Re: [netmod] 6991bis: address-with-prefix-length

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Thu, 18 April 2019 12:03 UTC

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Date: Thu, 18 Apr 2019 14:03:53 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Ladislav Lhotka <lhotka@nic.cz>
CC: <netmod@ietf.org>
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Subject: Re: [netmod] 6991bis: address-with-prefix-length
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On Thu, Apr 18, 2019 at 10:41:11AM +0200, Ladislav Lhotka wrote:
> > > 
> > > I am not in favour of adding this type. Having ip-prefix next to
> > > ip-address-and-prefix is confusing.
> > 
> > Confusing or not, they are NOT interchangeable and actually do different 
> > things, which is why both are needed. There's plenty of precedence to
> 
> I actually agree with you. It is a historical accident that these
> two different things got mixed up (and some vendors contributed to
> this). I would argue that
>
> - IP prefix is a set of IP addresses, and as such can be thought of
>   as a single entity.
> 
> - IP address and subnet mask/prefix are two separate things, the
>   latter being an instruction for routing to *other* destination
>   addresses.

I think we should be pragmatic. There are other common types that are
in fact constructed out of simpler types, date-and-time is a prime
example of a type constructed out of a date value and a time value. It
is sometimes convenient to treat something that is in fact constructed
as an atomic value.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <https://www.jacobs-university.de/>