Re: [netmod] 6021 ipv4-prefix

"Rob Wilton (rwilton)" <rwilton@cisco.com> Mon, 29 April 2019 14:53 UTC

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From: "Rob Wilton (rwilton)" <rwilton@cisco.com>
To: Ladislav Lhotka <lhotka@nic.cz>, "netmod@ietf.org" <netmod@ietf.org>
Thread-Topic: [netmod] 6021 ipv4-prefix
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Date: Mon, 29 Apr 2019 14:53:40 +0000
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References: <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> <20190426173014.klub4kxbzucgfmyc@anna.jacobs.jacobs-university.de> <f582ccc854ae446291d6020822fae9dd@XCH-RCD-007.cisco.com> <20190429100213.vukmmbdsz5zlw6w5@anna.jacobs.jacobs-university.de> <bbf252aaca86418ca80b3bf04a910aff@XCH-RCD-007.cisco.com> <20190429103451.yink4bdvvmlh7ohe@anna.jacobs.jacobs-university.de> <c03aa9a27ed544c5be88fd0750d782e3@XCH-RCD-007.cisco.com> <20190429134615.f32zkbia6fqwk3to@anna.jacobs.jacobs-university.de> <b404565930694fd8af93326b5e754a2b@XCH-RCD-007.cisco.com> <0c4265d31adbf208a680f76216cc4bc42c766eae.camel@nic.cz>
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Subject: Re: [netmod] 6021 ipv4-prefix
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Hi Lada,

> -----Original Message-----
> From: netmod <netmod-bounces@ietf.org> On Behalf Of Ladislav Lhotka
> Sent: 29 April 2019 15:24
> To: netmod@ietf.org
> Subject: Re: [netmod] 6021 ipv4-prefix
> 
> On Mon, 2019-04-29 at 14:02 +0000, Rob Wilton (rwilton) wrote:
> > > -----Original Message-----
> > > From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
> > > Sent: 29 April 2019 14:46
> > > To: Rob Wilton (rwilton) <rwilton@cisco.com>
> > > Cc: Acee Lindem (acee) <acee@cisco.com>om>; netmod@ietf.org
> > > Subject: Re: [netmod] 6021 ipv4-prefix
> > >
> > > On Mon, Apr 29, 2019 at 01:33:22PM +0000, Rob Wilton (rwilton) wrote:
> > > > But I'm not convinced that allowing ipv4-prefix values in the non-
> > > > canonical
> > > format is necessarily the right thing to do.  If we were defining
> > > these as a new type today then would we make the same choice of
> > > typedef definition?
> > > >
> > > > Or is a significant part of your proposal/reasoning to ensure
> > > > backwards
> > > compatibility with what we have today?
> > >
> > > I am trying to clarify what the existing definition says since there
> > > apparently have been different interpretations.
> >
> > Given the definition of ipv6-prefix already contains:
> >
> >       " The IPv6 address should have all bits that do not belong
> >        to the prefix set to zero."
> >
> > I think that a better solution might be to add the equivalent text to
> > the ipv4-prefix definition:
> >
> >       " The IPv4 address should have all bits that do not belong
> >        to the prefix set to zero."
> 
> But this still essentially permits the client to send a value with those bits set, and
> the server has to be prepared to handle it.

My aim with this text is to:
 - encourage clients to use canonical format, since that seems to cause the least problems.
 - align the v4 and v6 definitions.
 - retain the existing flexibility for servers to choose what they support, noting that any change in behaviour here will be non-backwards compatible.

Thanks,
Rob


> 
> If the goal is to get rid of the difference between ipv4- and ipv6-prefix, which
> makes sense, then I prefer to remove this sentence from ipv6-prefix.

> 
> Lada
> 
> >
> > Thanks,
> > Rob
> >
> >
> > > /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
> --
> Ladislav Lhotka
> Head, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
> 
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