On Fri, Dec 18, 2015 at 3:33 AM, Robert Wilton <[email protected]> wrote:

> Hi,
>
> On 17/12/2015 23:45, Randy Presuhn wrote:
>
>> Hi -
>>
>> From: Robert Wilton
>>> Sent: Dec 17, 2015 1:12 PM
>>> To: Andy Bierman
>>> Cc: "[email protected]"
>>> Subject: Re: [netmod] NETMOD WG LC: draft-ietf-netmod-opstate-reqs-01
>>>
>> ...
>>
>>>      Your requirement is a bit too strong for my liking.
>>>
>>>      To paraphrase your requirement text, it is forcing that all
>>>      compliant NETCONF/RESTCONF servers MUST support any clients that do
>>>      not want to differentiate between intended config and applied
>>>      config.
>>>
>> Do do otherwise sound to me like an interoperability disaster,
>> and would encourage the "siloization" of toolsets.
>>
>>      However, this requires all opstate aware servers:
>>>
>>>       - To handle a mix of clients, some of which are opstate aware, and
>>>       some that are not.
>>>
>> This seems perfectly reasonable.  To do otherwise torpedoes the very
>> notion of interoperability.
>>
>>       - To potentially handle a mix of requests, some of which are
>>>       opstate aware requests, and some are not.
>>>
>> Ditto.
>>
>>      It also prevents:
>>>
>>>       - Having a server that is implemented to only support opstate aware
>>>       clients.
>>>
>> Avoiding the creation of such servers sounds like a *good* thing to me.
>>
>>       - Having a server side configuration knob to control the behaviour
>>>       (since it would affect the semantics for all clients).
>>>
>> This also sounds like something which it would be desireable to prevent.
>>
>> I think I'm squarely with Andy on this one.
>>
>
> Taking a step back ...
>
> I am probably way off the mark, but my perception is that some (perhaps
> many) of the folks in the WG still perceive that the opstate requirements
> are niche requirements for some unusual scenarios, and that everyone else
> is happy with the status quo and don't want/need them.
>
> Alas, I don't share that view.  For me, the opstate requirements can be
> summarized as saying that the operators just want to know what
> configuration the device is actually running in a format that is convenient
> for them to use.  This really doesn't appear to be unreasonable request to
> me, and if I was writing to a network manageability API then I would choose
> to use opstate because I perceive that it is a more robust and easier to
> use API.  The counter arguments appear to be that it is too hard for
> devices to provide this information, and that the operators have
> historically managed without it.
>
> However, I think that several things have changed, and hence negate these
> counter arguments: (i) the operators want to have much more automation and
> management over their devices, (ii) they have found a way to group together
> and have a more vocal voice about what they need and want, (iii) the
> operators have realized that they don't need to wait for the SDOs and can
> create defacto standard models on their own if they have to.
>
> Personally, I would like us to stop spending time churning on the
> requirements and actually get on to discussing the solutions.  To be
> honest, there has been relatively little change in my understanding of the
> requirements from reading draft-openconfig-netmod-opstate-01 back in July,
> and I was expecting to discuss the solution drafts back in September.  Here
> we are in December, and I'm not convinced that we have truly made
> significant progress.
>
> The only reason that I submitted a solution draft to this problem was
> because I thought it unlikely that OpenConfig would support a multiple
> datastore solution, and I could see strong resistance amongst the IETF
> engineers to the proposed OpenConfig solution.  I was hoping that my
> proposed solution might be seen for the compromise that it is between the
> two opposing positions.  But I care less on what the solution is, and more
> whether we can agree on one and move forward.
>
> As someone that is quite new to SDO processes, my main concern is that
> IETF (and other standards bodies) are moving too slowly here, and that by
> the time that IETF have produced a sufficiently complete set of YANG models
> to manage network devices it will be too late because the industry will
> already have converged on the OpenConfig models, which although not
> perfect, are close to being usable now, and are being evolved at a much
> quicker pace ...
>
> So my hope for the early new year is that we can reach common ground with
> OpenConfig and converge on a single set of YANG modules for managing
> network devices, and that includes having a solution to the Opstate problem.
>
> Finally, if my acquiescing to Andy's requirement is helpful to move this
> process forward then that is fine with me.  As I have previously indicated,
> I don't really think that it helps with framing or discussing the
> solutions, but equally I can live with it since I suspect that the
> solutions are likely to comply with it anyway.
>
> Apologies for the long email, and given I may not be actively reading the
> WG emails over the next couple of weeks, I'll wish you all happy holidays!
>
>

The "old manager/new agent" problem has been around for at least 3 decades.
Experience has shown that adding new features in a way that does not break
existing deployments requires forethought and planning.

The backward compatibility requirement is not hard to meet.
Simply require the client to opt-in to the new behavior.
That's it.  Problem solved.



> Thanks,
> Rob
>
>
>>

Andy


> Randy
>>
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