Re: [OPSAWG] Suresh Krishnan's No Objection on draft-ietf-opsawg-nat-yang-16: (with COMMENT)

[Suresh Krishnan <[e-mail]>]

Hi Med,
  Thanks for the clarification. The lw4over6 use case clarifies both the lack of a default and the psid-offset not being mandatory.

Regards
Suresh

> On Sep 27, 2018, at 1:58 AM, <[e-mail]> <[e-mail]> wrote:
> 
> Hi Suresh, 
> 
> Please see inline. 
> 
> Cheers,
> Med
> 
>> -----Message d'origine-----
>> De : Suresh Krishnan [mailto:[e-mail]]
>> Envoyé : mercredi 26 septembre 2018 15:26
>> À : BOUCADAIR Mohamed IMT/OLN
>> Cc : The IESG; [e-mail]; [e-mail]; opsawg-
>> [e-mail]
>> Objet : Re: [OPSAWG] Suresh Krishnan's No Objection on draft-ietf-opsawg-nat-
>> yang-16: (with COMMENT)
>> 
>> Hi Med,
>> 
>>> On Sep 26, 2018, at 12:47 AM, <[e-mail]>
>> <[e-mail]> wrote:
>>> 
>>> Hi Suresh,
>>> 
>>> Adding that default value would make sense if port restriction is only
>> reserved to NATs deployed in combination with MAP-E BRs. The document does
>> not make that assumption.
>> 
>> Are there any other expected consumers for this feature (other than MAP-E)?
>> An example would be great.
> 
> [Med] Without citing other examples such as closed infrastructures in which only a subset of ports are allowed, let's focus on the A+P flavors.
> 
> The algorithm approach for identifying port sets is not specific to MAP-E, but is used by other mechanisms such as lightweight 4over6. RFC 7596 says the following:
> 
> "For lw4o6, the number of
>   a-bits SHOULD be 0, thus allocating a single contiguous port set to
>   each lwB4."
> 
> I would think the offset bits (for the system port
>> exclusion) and the PSID are fairly specific for MAP-E.
> 
> [Med] see above.  
> 
> If there are other
>> consumers, how do you ensure that  the value of the ‘a’ bits (i.e. A) needs
>> to be greater than zero since I assumed the A>0 check will be done by the
>> MAP-E implementation.
> 
> [Med] The range of allowed values is clear about this:
> 
>          type uint8 {
>            range 0..15;
>          }
> 
>> 
>> Thanks
>> Suresh
>