Re: [netmod] 6021 ipv4-prefix

Mikael Abrahamsson <swmike@swm.pp.se> writes:

> On Wed, 1 May 2019, Randy Presuhn wrote:
>
>> Hi -
>>
>> On 5/1/2019 12:46 PM, Mikael Abrahamsson wrote:
>> ....
>>> Where is the text that tells the server implementor whether to throw an
>>> error when client commits non-zero bits, or to just throw the bits away
>>> and store the value in the canonical format?
>>
>> Such text would be an inappropriate constraint the server's
>> internal representation.  We should only specify
>> the externally-visible behaviour: that the reported value
>> will be in the canonical format.  Whether an implementation
>> preserves extraneous cruft in its internal representation is
>> purely an implementation decision, and not subject to standardization.
>
> I am talking about what goes on the wire. If the client does an 
> edit-config with ipv6-prefix 2001:db8::1/64, should the server convert 
> this into 2001:db8::/64 or throw an error on the edit-config operation.
>
> Jurgen seems to say it should convert it and not throw an error, and I'd 
> like text to say that indeed, this is proper behaviour. Nobody has so far 
> been able to tell me where this text currently is, so that's why I'm

If we agree that a type defines the set of legal on-the-wire values
(possibly modulo representation - JSON/XML/...), then section 4.2.2.1 in
RFC 7950 says:

[A leaf instance] has exactly one value of a particular type ...

So why should a server throw an error if this is satisfied?

Lada

> asking for it to be added. Either this should go into an update to 
> https://tools.ietf.org/html/rfc7950#section-9.1 or it should go into each 
> and every definition of types (or both of them).
>
>>> It seems it should "fix it", so we should
>>> have text that reflects this.
>>
>> False dichotomy.  An implementation might actually preserve
>> those bits, though of course they'd never be seen again (at
>> least not on a netconf interface) since the netconf server
>> will always behave as though the value were in its canonical
>> form, regardless of the internal representation.
>
> Again, I am talking about what goes on the wire, what is seen when issuing 
> "get" or "edit-config" etc.
>
> -- 
> Mikael Abrahamsson    email: swmike@swm.pp.se
>
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-- 
Ladislav Lhotka
Head, CZ.NIC Labs
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