Re: [Cbor] Supporting IPv6 Link-Local with scope (was Re: Éric Vyncke's Discuss on draft-ietf-cbor-network-addresses-09: (with DISCUSS and COMMENT))

[Jürgen Schönwälder <[e-mail]>]

Yes, there are two things, recognizing that there is a need to
disambiguate addresses and then what you choose to disambiguate
them. Back in SNMP times, everything was commonly identified by
numbers. When we moved to YANG, we started to prefer using names as
there was a push to move closer to what people use on their CLIs
instead of what a kernel may be using internally. (The ifTable was
indexed by the numeric ifIndex, the YANG interfaces list is keyed by
interface names.) I guess as part of this transition, we moved from
using numeric zone indexes (that usually are simply ifIndex values) to
zone names (that are usually interface names).

/js

On Thu, Oct 07, 2021 at 11:41:52AM +0200, Carsten Bormann wrote:
> Thank you!
> 
> I can’t find zones in 2851, but InetAddressIPv4z is in 3291 (of 2002 vintage, which also mentions InetAddressIPv6z in the Section 9, Changes) and 4001 (which we could reference alongside RFC 6991).  SNMP InetAddressIPv4z (or InetAddressIPv6z) only supports a numeric zone index, which is a 32-bit (Unsigned32 as per RFC4001 InetZoneIndex, which is mentioned in the RFC 4001 Section 8, Changes) number, but I think the generality of RFC 6991 (and the symmetry of the IP versions) wins here.
> 
> (RFC 3291 mentions v4-mapped IPv6 addresses as a source of zoned IPv4 addresses.  Thinking about it, that’s exactly where I have used them.)
> 
> Grüße, Carsten
> 
> 
> > On 2021-10-07, at 08:43, Jürgen Schönwälder <[e-mail]> wrote:
> > 
> > On Thu, Oct 07, 2021 at 03:40:24AM +0200, Carsten Bormann wrote:
> >> On 7. Oct 2021, at 00:44, Brian E Carpenter <[e-mail]> wrote:
> >>> 
> >>> That's probably because there are none. As far as I know, there is no
> >>> "Scoped architecture for IPv4" RFC. I don't know why there is YANG support.
> >> 
> >> Zones are this gift that keeps on giving.
> >> 
> >> If we are doing zones, we need to do them like YANG.
> >> I would have a strong objection against including them but then doing them differently.
> >> Maybe we should simply reference RFC 6991 as well.
> >> 
> >> Jürgen:  Do you remember why ipv4-address has a zone ID (called “zone index”)?
> >> 
> > 
> > The YANG definitions were derived from the SNMP definitions. I think
> > the first RFC having support for zoned IPv4 addresses in the network
> > management world was RFC 2851 (published June 2000). I vaguely recall
> > that we had several side meetings during the draft writing stage where
> > people pointed to other work (that may have led to things like RFC
> > 3927 later on) and/or they pointed out that the need to disambiguate
> > IP addresses also exists in the IPv4 world. I think people also
> > pointed to routers running multiple links using the same non-global
> > (e.g., private) address spaces.
> > 
> > /js
> > 
> > -- 
> > Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> > Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
> > Fax:   [phone]         <https://www.jacobs-university.de/>
> > 
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> 

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <https://www.jacobs-university.de/>