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

[Alia Atlas <[e-mail]>]

On Tue, Aug 16, 2016 at 12:16 PM, Alexey Melnikov <[e-mail]>
wrote:

> 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?
>

They have to have the same attribute - which could be a sub-TLV.

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.
>
>