Re: [Isis-wg] Alexey Melnikov's Discuss on draft-ietf-isis-rfc4971bis-03: (with DISCUSS and COMMENT)

[Alexey Melnikov <[e-mail]>]

Hi Alia,

On Tue, Aug 16, 2016, at 05:03 PM, Alia Atlas wrote:
> Hi Alexey,
>
> On Tue, Aug 16, 2016 at 11:43 AM, Alexey Melnikov
> <[e-mail]> wrote:
>>
>>
>>  ----------------------------------------------------------------
>>  ------
>>  DISCUSS:
>>  ----------------------------------------------------------------
>>  ------
>>
>>  I would like to get clarification on the following points before
>>  recommending approval of this document:
>>
>>  1) How do multiple CAPABILITY TLVs from the same source treated, if
>>     they
>>  have the same S and D flags, but different subTLV? Are the
>>  cumulative? Or
>>  this is not allowed?
>>  I am sorry if I missed where this was described, let me know if
>>  I did.
>
> The end of Section 3 says " Where a receiving system has two copies of
> a CAPABILITY TLV from the same system that have different settings for
> a given attribute, the procedure used to choose which copy shall be
> used is undefined."

Ok, I wasn't sure that this was talking about the same thing.

So just to double check: using multiple CAPABILITY TLVs with different
S and D flags is Ok (and described), but use of multiple CAPABILITY
TLVs with identical S and D flags is undefined as per the sentence you
quoted above?

>
> This bis is to update the handling for IPv6; there was no discussion
> about changing the basic details (such as this)
> in the updated version.
>
>> 2) In Section 4, 1st sentence: how can this specification have
>>  requirements on implementation that don't support this extension?
>>  If this
>>  behaviour is already prescribed by another specification, then you
>>  should
>>  not use RFC 2118 keyword and you should reference the relevant
>>  specification.
>
> RFC1195 says
> "   Any codes in a received PDU that are not recognised shall
> be ignored
>    and, for those packets which are forwarded (specifically Link State
>    Packets), passed on unchanged."
>
> A reference would be fine - but this is basic well-known behavior
> for IS-IS.
> The authors may have more details.

My problem was that the document seemed to impose new requirements. I
think the sentence needs to be reworded to say "As per RFC 1195, ..."
and don't use RFC 2119 language.

>
>> ---------------------------------------------------------------
>> -------
>>  COMMENT:
>>  ----------------------------------------------------------------
>>  ------
>>
>>  Should subTLVs have an IANA registry? Or is there an existing one
>>  already?
>
> It's already there -
> http://www.iana.org/assignments/isis-tlv-codepoints/isis-tlv-codepoints.xhtml#isis-tlv-codepoints-242
> but it does look like an updated reference to rfc4971bis would be a
> good idea.
Indeed.