Re: [Anima] Alexey Melnikov's Discuss on draft-ietf-anima-grasp-12: (with DISCUSS and COMMENT)

[Brian E Carpenter <[e-mail]>]

On 30/05/2017 08:24, Alexey Melnikov wrote:
> Hi Brian,
> 
> On 29 May 2017, at 02:57, Brian E Carpenter <[e-mail]> wrote:
> 
>>> 3.5.4.3.  Discovery Procedures
>>>
>>> In 6th para:
>>>
>>>   The cache mechanism MUST include a lifetime for each entry.  The
>>>   lifetime is derived from a time-to-live (ttl) parameter in each
>>>   Discovery Response message.  Cached entries MUST be ignored or
>>>   deleted after their lifetime expires.  In some environments,
>>>   unplanned address renumbering might occur.  In such cases, the
>>>   lifetime SHOULD be short compared to the typical address lifetime and
>>>   a mechanism to flush the discovery cache MUST be implemented.
>>>
>>> How can the discovery cache be flushed?
>>
>> I think that's completely implementation-dependent, so what can we say?
>> (In the prototype, it's an API call.)
> 
> I think you just demonstrated my point that some requirements are not very clear whom they apply to. Passive voice is causing ambiguity here.
> 
> I think I would like to see more text on what different possible alternatives are and which entities need to implement the MUST.

In this case, I'm more inclined to simply delete the reference to flushing, because it's really part of a much more general problem: https://tools.ietf.org/html/rfc7010#section-7 . The previous comment about the cache lifetime is sufficient.

[In fact, renumbering would be an interesting use case for autonomics, but that's a whole topic in itself.]

    Brian


   Brian