Re: [core] [Cbor] Interface names (Re: changes in draft-ietf-cbor-network-addresses-05.txt)

Brian E Carpenter <brian.e.carpenter@gmail.com> Tue, 27 July 2021 20:01 UTC

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To: =?UTF-8?Q?Christian_Ams=c3=bcss?= <christian@amsuess.com>, Carsten Bormann <cabo@tzi.org>
Cc: Erik Kline <ek.ietf@gmail.com>, cbor@ietf.org, 6MAN <6man@ietf.org>, core@ietf.org
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From: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Date: Wed, 28 Jul 2021 08:01:41 +1200
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Subject: Re: [core] [Cbor] Interface names (Re: changes in draft-ietf-cbor-network-addresses-05.txt)
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On 27-Jul-21 21:55, Christian Amsüss wrote:
> Hello Carsten, groups,
> 
>> Interface names are local, so it doesn’t make a lot of sense to carry
>> them around between systems, which is where CBOR is mostly used these
>> days.
> 
> two applications come to mind:
> 
> * RD introspection[1] uses zone identifiers in what may be described as
>   debug output: Usually an RD won't show you a resource on a fe80::
>   address not on your link, but as an administrator you may need the
>   birds-eye view.

Yes, that is an operational use case, as also considered in RFC6874(bis)
 
> * Many network devices offer a remote way to run a ping; when the
>   process is started via CBOR, it'd be useful to give an interface
>   identifier.

How does host A know the Zone IDs (interface names) used on
host B?

(Answer: only if B has previously told A. So the use case is quite
complex.)
 
> I'm not particularly advocating that we add zone identifiers to the new
> tags (as I can use URIs or even work around completely in the former,
> and don't have a pressing need for the latter) -- but with those
> examples, a statement like "we don't specify interface identifiers
> because they shouldn't be serialized anyway" would be overreaching.

They shouldn't be on the wire except in rather special use cases.

    Brian

> 
> BR
> c
> 
> [1]: https://www.ietf.org/archive/id/draft-amsuess-core-resource-directory-extensions-05.html#name-zone-identifier-introspecti
> 
> 
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