Subject: [mpls] Comments of draft-bocci-mpls-miad-adi-requirements

From: Yingzhen Qu <[email-masked]>
Date: Sun, 5 Dec 2021 23:05:12 -0800

Hi authors,

Thank you for writing the draft. I’ve reviewed version -00 and have the following comments.

General comment: the key words from RFC 2119 are not used consistently. More discussions are needed especially when “MUST” or “MUST NOT” is used.
Detail comment (line numbers generated from idnits):
191	   o  Any solutions to these requirements MUST not restrict the
192	      generality of MPLS architecture.
MUST not/MUST NOT
Would you please add some details or a reference for “the generality of MPLS architecture”?

200	   o  Neither an ADI or ancilliary data must be delivered to a node that
201	      is not capable of processing it.
what about transit node? Where neither ADI or ancillary data need to be processed.

229	   o  A mechanism is REQUIRED to enable an LER inserting ADIs to
230	      determine whether LSRs along the path can parse the label stack
231	      and process the ADI at the location it is inserted.

233	   o  A mechanism is REQUIRED to enable an LER inserting ADIs to
234	      determine if the ADI will be processed by LSRs along the path.
it seems to me that these two bullet points are somewhat duplicate. Am I missing something here?
253	   o  ADIs can only be inserted at LERs, but may be processed at LSRs
254	      and LERs.  If it is required to insert an ADI at a transit router
255	      on an LSP, then a new label stack must be pushed. .
These two sentences seem to conflict. Or maybe in this case, the transit router inserting an ADI should be considered as LER?

261	   o  It MUST be possible to insert new ADIs for new applications on the
262	      same LSP.[Ed note: neet to clarify]
Definitely need clarifications on this. What’s the definition of the same LSP? 

270	   o  The solution MUST support slow path processing of ancilliary data.

272	   o  The solution MUST support fast path processing of ancilliary data.

When an ancillary data is defined/standardized, should it also include whether it should be slow/fast path processed?

284	   o  In order to prevent unnecesary scanning of the packet, care needs
285	      to be taken in the location of the ancillary data, for example it
286	      should be located as close to the label stack as possible.
This should be discussed further more. The location of ancillary data might vary case by case. It’s possible that ancillary data is good to be located after label stack.
288	   o  A solition must be provided to verify the authenticity of
289	      ancillary data processed to LSRs.
This probably is “should be provided”.

Thanks,
Yingzhen