Re: [i2rs] Comments on Ephemeral-REQ-07 (local config vs. ephemeral)

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 20 July 2016 11:59 UTC

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Date: Wed, 20 Jul 2016 13:59:32 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: "jmh.direct" <jmh.direct@joelhalpern.com>
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Cc: i2rs@ietf.org, 'Joe Clarke' <jclarke@cisco.com>, 'Russ White' <7riw77@gmail.com>, Susan Hares <shares@ndzh.com>, "'Joel M. Halpern'" <jmh@joelhalpern.com>
Subject: Re: [i2rs] Comments on Ephemeral-REQ-07 (local config vs. ephemeral)
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The text I comment to says "individual ephemeral configuration
changes" - I was not able to infer from this that it was supposed to
imply "individual I2RS clients".

/js

On Wed, Jul 20, 2016 at 01:41:26PM +0200, jmh.direct wrote:
> 
> The reason I referred to individual I2RS clients is that different clients have different priorities.  The previous text referred to "ephemeral priority" which needed clarification.
> I referred to changes because the only time priority is relevant is when something changes.
> And the proposed new text loses the emphasis on associating a priority with local config.
> Yours,Joel
> 
> Sent via the Samsung Galaxy S® 6, an AT&T 4G LTE smartphone
> -------- Original message --------From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Date: 7/20/16  1:19 PM  (GMT+01:00) To: Susan Hares <shares@ndzh.com> Cc: "'Joel M. Halpern'" <jmh@joelhalpern.com>, 'Joe Clarke' <jclarke@cisco.com>, 'Russ White' <7riw77@gmail.com>, 	i2rs@ietf.org Subject: Re: [i2rs] Comments on Ephemeral-REQ-07 (local config vs. ephemeral) 
> What is the purpose of the word 'individual' in the sentence? Why does
> it talk about 'changes'? Isn't it simply the data that takes
> precedence? Or is the idea to have this linked to changes of data,
> i.e., how a change was carried out?
> 
> I actually find the text related to this in RFC 7921 more helpful
> since RFC 7921 provides more insight that priority is associated
> with an I2RS client. Perhaps Req-07 should just say:
> 
>   Req-07: The I2RS protocol MUST support a priority mechanism to
>   resolve any possible conflicts with local configuration as described
>   in RFC 7921.
> 
> This way we avoid having multiple definitions that may interact in
> weird ways. (This might also apply to other requirements where perhaps
> a simple pointer to RFC 7921 would be easier and safer than attempts
> to reformulate things.)
> 
> /js
> 
> PS: I do not want to further complicate things so please feel free
>     to ignore this.
> 
> On Wed, Jul 20, 2016 at 06:49:27AM -0400, Susan Hares wrote:
> > I'm fine with this revision.  Anyone else wish to change this version? 
> > 
> > Sue 
> > 
> > -----Original Message-----
> > From: i2rs [mailto:i2rs-bounces@ietf.org] On Behalf Of Joel M. Halpern
> > Sent: Wednesday, July 20, 2016 5:25 AM
> > To: Joe Clarke; Susan Hares; 'Russ White'; i2rs@ietf.org
> > Subject: Re: [i2rs] Comments on Ephemeral-REQ-07 (local config vs.
> > ephemeral)
> > 
> > That wording may well lead readers to think that Ephemeral configuration,
> > considered as a whole, has a priority.  Since that is not true, I would like
> > to further refine this.  How about:
> > 
> > Req-07: Local configuration MUST have a priority that is comparable with the
> > I2RS Agent priority for making changes.  This priority will determine
> > whether local configuration changes or individual ephemeral configuration
> > changes take precedence.  The I2RS protocol MUST support his mechanism.
> > 
> > Yours,
> > Joel
> > 
> > On 7/20/16 4:05 AM, Joe Clarke wrote:
> > > On 7/20/16 03:42, Susan Hares wrote:
> > >> Joe:
> > >> Yes - you are correct.  Can you help me state this requirement -07 
> > >> better?
> > >
> > > What about:
> > >
> > > Ephemeral-REQ-07: Ephemeral configuration and local configuration MUST 
> > > each have a priority.  This priority will determine whether ephemeral 
> > > configuration or local configuration take precedence.  The I2RS 
> > > protocol MUST support this mechanism.
> > >
> > > Is this clear and correct enough?
> > >
> > > Joe
> > >
> > >>
> > >> Sue
> > >>
> > >> -----Original Message-----
> > >> From: Joe Clarke [mailto:jclarke@cisco.com]
> > >> Sent: Wednesday, July 20, 2016 3:40 AM
> > >> To: Susan Hares; 'Russ White'; i2rs@ietf.org
> > >> Subject: Re: [i2rs] Comments on Ephemeral-REQ-07 (local config vs.
> > >> ephemeral)
> > >>
> > >> On 7/20/16 02:18, Susan Hares wrote:
> > >>> <WG hat off> <author hat on>
> > >>>
> > >>> Here's text that might replace it:
> > >>>
> > >>> Ephemeral-REQ-07: Ephemeral configuration state MUST be able to set 
> > >>> a priority on local configuration and ephemeral state.  Based on 
> > >>> this priority implementations MUST be able to provide a mechanism to 
> > >>> choose which takes precedence. The I2RS Protocol MUST be able to 
> > >>> support this
> > >> mechanisms.
> > >>>
> > >>> Any thoughts?
> > >>
> > >> I'm a bit confused by the first sentence.  I think what you're 
> > >> stating is that both ephemeral and local configurations MUST have a
> > priority.
> > >> This priority will determine whether ephemeral configuration or local 
> > >> configuration take precedence.  The I2RS protocol MUST support this 
> > >> mechanism.
> > >>
> > >> Am I correct in my interpretation?
> > >>
> > >> Joe
> > >>
> > >>>
> > >>> Sue
> > >>>
> > >>> -----Original Message-----
> > >>> From: Russ White [mailto:7riw77@gmail.com]
> > >>> Sent: Wednesday, July 20, 2016 2:09 AM
> > >>> To: 'Joe Clarke'; 'Susan Hares'; i2rs@ietf.org
> > >>> Subject: RE: [i2rs] Comments on Ephemeral-REQ-07 (local config vs.
> > >>> ephemeral)
> > >>>
> > >>>
> > >>> (wg chair hat off) --
> > >>>
> > >>>> I think the idea of extending I2RS priority to local config 
> > >>>> operators
> > >>> (e.g., CLI)
> > >>>> will still work.  Let's take knob 1.  Knob 1 is kind of like the 
> > >>>> on/off
> > >>> switch.  If I
> > >>>> don't want I2RS to have any effect on operational state, I'd have 
> > >>>> this
> > >>> off.  In
> > >>>> the I2RS priority case, by default my local config could will have 
> > >>>> the
> > >>> highest
> > >>>> priority (let's say that's 255 to make it concrete).  In this case 
> > >>>> no
> > >>> ephemeral
> > >>>> config can win.
> > >>>
> > >>> I wanted to extend Joe's remarks a bit... On reflection, I actually 
> > >>> think having priority + "this wins" bits is rather confusing, and 
> > >>> opens the door to all sorts of strange behavior. Say I have two 
> > >>> items thus --
> > >>>
> > >>> Local config item -- priority 100
> > >>> I2RS config item -- priority 200, don't overwrite bit set
> > >>>
> > >>> If the higher priority is supposed to win, then which item should 
> > >>> the operator find in the resulting running config? Should it be the 
> > >>> I2RS version, because the priority is higher, or the local config, 
> > >>> because the "don't overwrite" bit is set? There doesn't seem to be 
> > >>> any clear way to interpret such a situation.
> > >>>
> > >>> It's better to have a single "thing" that determines which 
> > >>> configuration among many wins, rather than two.
> > >>>
> > >>> -r
> > >>>
> > >>>
> > >>
> > >>
> > >
> > > _______________________________________________
> > > i2rs mailing list
> > > i2rs@ietf.org
> > > https://www.ietf.org/mailman/listinfo/i2rs
> > >
> > 
> > _______________________________________________
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> > 
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> > i2rs@ietf.org
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> 
> -- 
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>

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-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>