Hi Mirja,

See responses inline.

> On Sep 25, 2018, at 2:32 AM, Mirja Kuehlewind (IETF) <[email protected]> 
> wrote:
> 
> Hi Mahesh,
> 
> please see below.
> 
>> Am 25.09.2018 um 00:56 schrieb Mahesh Jethanandani <[email protected]>:
>> 
>> 
>> 
>>> On Sep 21, 2018, at 6:47 AM, Mirja Kühlewind <[email protected]> wrote:
>>> 
>>> Mirja Kühlewind has entered the following ballot position for
>>> draft-ietf-netmod-acl-model-19: Discuss
>>> 
>>> When responding, please keep the subject line intact and reply to all
>>> email addresses included in the To and CC lines. (Feel free to cut this
>>> introductory paragraph, however.)
>>> 
>>> 
>>> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
>>> for more information about IESG DISCUSS and COMMENT positions.
>>> 
>>> 
>>> The document, along with other ballot positions, can be found here:
>>> https://datatracker.ietf.org/doc/draft-ietf-netmod-acl-model/
>>> 
>>> 
>>> 
>>> ----------------------------------------------------------------------
>>> DISCUSS:
>>> ----------------------------------------------------------------------
>>> 
>>> 1) The tcp options element is type uint32, however, the option field in the 
>>> TCP
>>> header can be up to 40 bytes.
>> 
>> You are right that the options field can be up to 40 bytes long.
>> 
>> To the WG - We have two options in front of us. Take the field out 
>> completely or change the type to binary, and add a ‘length’ restriction of 
>> 40. Unless there is a objection, we will go with the latter option.
> 
> Not sure what exactly you mean but change the type to binary and add a length 
> restriction but I’ll leave it to you to have the appropriate change.

Ok.

> 
>> 
>>> 
>>> 2) Why are only TCP and UDP supported? What's about SCTP and DCCP?
>> 
>> There has been no requirement to support either of those protocols. Support 
>> for those protocols can be added as augmentations to the base model in the 
>> future if such a need arises.
> 
> That’s do bad. However, the document must at least say that it’s scope is 
> restricted to TCP and UDP only and it would also be nice to reason why that 
> restriction is and what would need to be done to extend it in future.

To the contrary. The model is not restricted to TCP and UDP. In Section 2, the 
document states that:

   ACL implementations in every device may vary greatly in terms of the
   filter constructs and actions that they support.  Therefore this
   draft proposes a model that can be augmented by standard extensions
   and vendor proprietary models.


It is a different matter that it has chosen not to support SCTP and DCCP. That 
is because implementations today have not felt the market need to add support 
for those protocols. But that does not prevent anyone from adding support for 
them.

As far as an example for how the model can be extended in the future, see 
Appendix A - Extending ACL model examples.

> 
>> 
>>> 
>>> 3) The icmp rest-of-header can also be larger than 4 bytes but the type is
>>> uint32 again.
>> 
>> You are right that the rest-of-header can be more than 4 bytes, but in 
>> reality we have not had a requirement to support more than 4 bytes. 
>> 
>> To the WG - We will give it the same treatment as above - two options. Take 
>> it out completely, or change this to binary also. The only difference is 
>> that there does not seem to be a length restriction on the size of the 
>> field, so the field will be left unbounded. Unless there is a objection, we 
>> will go with the conversion to binary option.
> 
> Again, leaving it to you to apply the appropriate fix.

Ok.

Thanks.

> 
> Mirja
> 
> 
> 
>> 
>> Cheers.

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