[RTG-DIR] Rtgdir review of draft-ietf-sfc-ioam-nsh-10

[Mach Chen <[e-mail]>]

Hello,
I have been selected as the Routing Directorate reviewer for this draft. The Routing Directorate seeks to review all routing or routing-related drafts as they pass through IETF last call and IESG review, and sometimes on special request. The purpose of the review is to provide assistance to the Routing ADs. For more information about the Routing Directorate, please see http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir
Although these comments are primarily for the use of the Routing ADs, it would be helpful if you could consider them along with any other IETF Last Call comments that you receive, and strive to resolve them through discussion or by updating the draft.

Document: draft-ietf-sfc-ioam-nsh-10
Reviewer: Mach Chen
Review Date: 2022-08-22
IETF LC End Date: 
Intended Status: Standards Track

Summary:
I have some minor concerns about this document that I think should be resolved before publication. 

Comments:
The draft is well written and easy to read.

Section 3,
"The O-bit MUST be handled following the rules in [I-D.ietf-sfc-oam-packet]." 

According to [I-D.ietf-sfc-oam-packet], a NSH-encapsulated packet with IOAM will not be considered as OAM packet. Thus, it's better to state that "the O-bit MUST NOT be set" for packet with IOAM header in this document. 

Major Issues:
No major issues found.

Minor Issues:
Quoted from Section 2.2, last paragraph of RFC 8300, it says:
"...Packets with Next Protocol values not supported SHOULD be silently dropped
      by default, although an implementation MAY provide a configuration
      parameter to forward them."

With above requirement, when insert an IOAM header to a NSH-encapsulated packet, the encapsulating node MUST make sure that every nodes (e.g., SFF, SF) along the service path supports IOAM, otherwise, the packet will be silently dropped. IMHO, this should be discussed in the document to make this more explicit. 

Nits:
None.

Best regards,
Mach