Re: [netmod] 6021 ipv4-prefix
Ladislav Lhotka <lhotka@nic.cz> Mon, 29 April 2019 08:26 UTC
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From: Ladislav Lhotka <lhotka@nic.cz>
To: "Acee Lindem (acee)" <acee@cisco.com>, Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>, Kristian Larsson <kristian@spritelink.net>
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References: <alpine.DEB.2.20.1904181128480.3490@uplift.swm.pp.se> <20190418102604.y5wyqflcudiywj2i@anna.jacobs.jacobs-university.de> <alpine.DEB.2.20.1904181251000.3490@uplift.swm.pp.se> <20190418111241.5csf5kkgwgxwtsnm@anna.jacobs.jacobs-university.de> <227a2452-69f9-6786-2643-822e70dc636d@spritelink.net> <20190425215134.pabdl3bbbjoivbaj@anna.jacobs.jacobs-university.de> <24fff697cde3ac2e0c9a09cf2dfa1153ca61bd90.camel@nic.cz> <5d6b915d-2b6b-2844-6343-5e42abe01e3b@spritelink.net> <20190426111829.6wkml53a72swxt4b@anna.jacobs.jacobs-university.de> <56a9b51c-d143-6436-7ebe-8db5f66b2fff@spritelink.net> <20190426153623.wpb4owuqsdfjc5q5@anna.jacobs.jacobs-university.de> <B2FAF932-0BD9-42BF-BBCA-38A37F6B33C9@cisco.com>
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Date: Mon, 29 Apr 2019 10:25:53 +0200
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Subject: Re: [netmod] 6021 ipv4-prefix
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"Acee Lindem (acee)" <acee@cisco.com> writes: > Hi Juergen, > > On 4/26/19, 11:36 AM, "netmod on behalf of Juergen Schoenwaelder" <netmod-bounces@ietf.org on behalf of j.schoenwaelder@jacobs-university.de> wrote: > > On Fri, Apr 26, 2019 at 05:07:52PM +0200, Kristian Larsson wrote: > > > > I think the canonical representation is quite clear as is the part that the > > server must return data (and conceptually store) in canonical format. What > > is much less clear is the allowed input formats which then includes > > 2001:db8::1/64. I think it could be worthwhile to explicitly state this as > > it is a bit surprising. Unlike say the uintX types, there is no "lexical > > representation" section for ip-prefix (I presume because they are not > > basetypes and so the lexical presentation follows the base, string in this > > case + the pattern) that explains things in any detail. Do you think we > > could add some clarifications, perhaps to the description of the type about > > this? Or could we even add a lexical representation section with examples? > > Or just an examples section? > > > > I have added text along these lines in my sources (goes behind the > definition of the canonical format): > > The definition of ipv6-prefix does not require that bits, > which are not part of the prefix, are set to zero. However, > implementations have to return values in canonical format, > which requires non-prefix bits to be set to zero. This means > that 2001:db8::1/64 must be accepted as a valid value but it > will be converted into the canonical format 2001:db8::/64. This just says how the canonical format works, and this is already defined in RFC 7950. I know this particular type is a hot topic right now, but there are other places where the canonical format may come into play. I think that YANG readers should just understand what it is about. Perhaps it would suffice to add a reference to the corresponding RFC 7950 section: OLD The canonical format of an IPv[46] prefix has all bits of ... NEW The canonical format (see sec. 9.1 of RFC 7950) of an IPv[46] prefix has all bits of ... > > I have added similar text to the definition of ipv4-prefix. I hope > that text like this clarifies the situation inline in the type > definition. > > I must admit that I think this is the worst possible > outcome. Independent of the original intent, at a high level it is > just not a good idea to accept the non-canonical prefix format and > return the canonical format. But this is how the canonical format is supposed to work! There are other types with multiple lexical formats, and the canonical format is basically just the Postel principle applied to the server: Be liberal in what you accept, and conservative in what you send. The expected server behaviour in this case can be a problem only if the ipv[46]-prefix is (mis)used as IP address & network prefix length combo. Lada > > Thanks, > Acee > > > > /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/> > > _______________________________________________ > netmod mailing list > netmod@ietf.org > https://www.ietf.org/mailman/listinfo/netmod > > > _______________________________________________ > netmod mailing list > netmod@ietf.org > https://www.ietf.org/mailman/listinfo/netmod -- Ladislav Lhotka Head, CZ.NIC Labs PGP Key ID: 0xB8F92B08A9F76C67
- [netmod] 6021 ipv4-prefix 7riw77
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Acee Lindem (acee)
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Lou Berger
- Re: [netmod] 6021 ipv4-prefix William Lupton
- Re: [netmod] 6021 ipv4-prefix Acee Lindem (acee)
- Re: [netmod] 6021 ipv4-prefix Kristian Larsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Kristian Larsson
- Re: [netmod] 6021 ipv4-prefix Jeff Tantsura
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Kristian Larsson
- Re: [netmod] 6021 ipv4-prefix Acee Lindem (acee)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Kristian Larsson
- Re: [netmod] 6021 ipv4-prefix Kristian Larsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Acee Lindem (acee)
- Re: [netmod] 6021 ipv4-prefix tom petch
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Martin Bjorklund
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Randy Presuhn
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Juergen Schoenwaelder
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Randy Presuhn
- Re: [netmod] 6021 ipv4-prefix tom petch
- Re: [netmod] 6021 ipv4-prefix Mikael Abrahamsson
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- Re: [netmod] 6021 ipv4-prefix Rob Wilton (rwilton)
- Re: [netmod] 6021 ipv4-prefix Ladislav Lhotka
- [netmod] convert it and not throw an error was Re… tom petch
- Re: [netmod] convert it and not throw an error wa… Christian Hopps