Re: [i2rs] comments on draft-ietf-i2rs-ephemeral-state-10

[Robert Wilton <[e-mail]>]

Hi,


On 23/06/2016 16:47, Susan Hares wrote:
> Juergen and Robert:
>
> I will use the following for Ephemeral-REQ-03.
>
> Ephemeral-REQ-03: Ephemeral state must be able to utilized temporary
>   operational state (e.g.  MPLS LSP-ID or a BGP IN-RIB) as a
>   constraints.
That is the original text.  Am I correct in assuming that you meant this 
text instead?:

Ephemeral-REQ-03: Ephemeral state must be able to utilize operational state
(e.g. MPLS LSP-ID or BGP In-RIB) as a constraint.

If so, this proposed text is OK with me.


>
> On Ephemeral-REQ-04,
>
>> Ephemeral-REQ-04: Ephemeral state MAY refer to non-ephemeral state
>> for purposes of implementing constraints.
> Non-ephemeral state is both configuration state (config true), and
> operational state (config false).
>
> I believe these are two different requirements.
Yes.  Given that REQ-03 covers using operational state as a constraint, 
then would it be sufficient to word REQ-04 as:

Ephemeral-REQ-04: Ephemeral state MAY refer to non-ephemeral configuration
for purposes of implementing constraints.

Or perhaps to relate it more closely to REQ-03, as:

Ephemeral-REQ-03: Ephemeral state must be able to utilize non-ephemeral
configuration as a constraint.

Or is this missing something out?

Thanks,
Rob


>
> Sue
>
> -----Original Message-----
> From: i2rs [mailto:[e-mail]] On Behalf Of Juergen Schoenwaelder
> Sent: Thursday, June 23, 2016 11:42 AM
> To: Robert Wilton
> Cc: [e-mail]
> Subject: Re: [i2rs] comments on draft-ietf-i2rs-ephemeral-state-10
>
> On Thu, Jun 23, 2016 at 03:12:50PM +0100, Robert Wilton wrote:
>> Hi,
>>
>> On 23/06/2016 13:02, Juergen Schoenwaelder wrote:
>>> Hi,
>>>
>>> here are few comments on the latest version.
>>>
>>>      Ephemeral-REQ-03: Ephemeral state must be able to utilized temporary
>>>      operational state (e.g.  MPLS LSP-ID or a BGP IN-RIB) as a
>>>      constraints.
>>>
>>> I am not sure what 'must be able to utilized temporary operational
>>> state as constraints' means. The text in the parenthesis does not
>>> help me understand this better. Did you want to say something like:
>>> 'Ephemeral configuration state may have constraints that refer to
>>> operational state'? I am using 'ephemeral configuration state' since
>>> this is used in other places (although sometimes worded slightly
>>> different).
>> I asked a similar question in the I2RS  interim meeting yesterday, I
>> think that Sue's spoken explanation of the requirement was effectively:
>>
>>     Ephemeral-REQ-03: Ephemeral state may have constraints that refer
>>     to operational state, this includes potentially fast changing or
>>     short lived operational state nodes, such as MPLS LSP-ID or a BGP
> IN-RIB.
>> Perhaps this wording is more clear?
> Yes, this is clearer. One question of course is what is expected to happen
> if constraints are becoming false due to (fast) operational state changes,
> that is, what the expected consequence of this is.
>
>>>      Ephemeral-REQ-04: Ephemeral state MAY refer to non-ephemeral state
>>>      for purposes of implementing constraints.
>>>
>>> Hm, now I wonder whether this is just a special case of
>>> Ephemeral-REQ-03 and if so it is not clear why we need this as a
>>> separate requirement. If this is not the case but something
>>> different, then likely my interpretation of Ephemeral-REQ-03 is wrong.
>> I think that ephemeral state could also use configuration nodes as a
>> constraint, so it isn't just operational state covered by REQ-3.
> Well, the Ephemeral-REQ-04 text says 'non-ephemeral state' - if your
> interpretation is correct than this phrase is wrong or possibly misleading.
>
> /js
>