RtgDir Early review: draft-ietf-mpls-sr-epe-oam-08.txt

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draft. https://datatracker.ietf.org/doc/draft-foo-name/

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Document: draft-ietf-mpls-sr-epe-oam-08.txt
Reviewer: Matthew Bocci
Review Date: 8th August 2023
Intended Status: Standards Track

Summary: 

I have some minor concerns about this document that I think should be resolved before it
is submitted to the IESG. 


Comments:

The draft is generally very readable - thanks! There are one or two paragraphs, 
particularly in the introduction where the definite article (the/a, etc) is missing or not
used correctly. I have tried to capture some examples in my list of 'nits' below.

In general, I don't have an issue with the mechanism described in the draft. However, 
it does rely on the head end of the SR Policy / SR-TE LSP knowing the types of the SIDs
along the path. This is a challenge if the segment list is just specified as a raw sequence
of MPLS labels, for example in a PCEP S-ERO. Although the draft mentions in Section 2 that
this is out of scope, I think it should be much more up-front about this limitation 
and provide an informational reference to mitigating mechanisms such as the use of the
NIL FEC, as an example.
  


Other Comments:

1.  Introduction

   Egress Peer Engineering (EPE) as defined in [RFC9087] is an effective
   mechanism to select the egress peer link based on different criteria.
   The EPE-SIDs provide means to represent egress peer links.  Many
                                                  ^^^^^^^^^^
MB>                                    ...and nodes and sets of nodes

 
   network deployments have built their networks consisting of multiple
   Autonomous Systems either for ease of operations or as a result of
   network mergers and acquisitons.  The inter-AS links connecting any
   two Autonomous Systems could be traffic engineered using EPE-SIDs in
   this case as well.  It is important to be able to validate the
             ^^^^^^^
MB>      As well as what?   
   
   
   control plane to forwarding plane synchronization for these SIDs so
   that any anomaly can be detected easily by the operator.

[...]

Introduction, second paragraph: 
"When there is a multi-hop EBGP session between the ASBRs, PeerNode SID is
   advertised and traffic would be load-balanced between the interfaces
   connecting the two nodes. "

MB> That really depends on local policy. I suggest replacing "...would be load-balanced" 
with "..MAY be load balanced"

[...]

Section 2. Theory of operation. Second Paragraph.
"The procedures to operate EBGP sessions in a scenario with
   unnumbered interfaces is not very well defined in [RFC9086] and hence
   out of scope for this document."

MB> This is quite a subjective statement. Perhaps you could rephrase as:
"[RFC9086] does not define the detailed procedures to operate EBGP sessions in a scenario with
   unnumbered interfaces. Therefore, these scenarios are 
   out of scope for this document."
   

     

Nits:

- Introduction, Second paragraph is missing the definite article in some sentences. Please
go through and double check the grammar.

- Section 4.1, last paragraph: 
s/optional descriptors and use them /optional descriptors and using them 

- Section 4.2. This refers to the Downstream Detailed Mapping TLV as "DDMT". However,
I believe RFC8029 abbreviates this to "DDMAP TLV", and indeed that is how I think it is more
commonly referred to in the industry. I suggest replacing "DDMT" with "DDMAP TLV" throughout.

- Section 5.1. "Set the Best-return-code to 10, "Mapping for this FEC is not the
   given label at stack-depth if any below conditions fail:. The text in the draft is missing closing
   quotation marks.