[mpls] MPLS-RT review on draft-ninan-mpls-spring-inter-domain-oam-02

Mach Chen <mach.chen@huawei.com> Wed, 02 June 2021 03:59 UTC

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From: Mach Chen <mach.chen@huawei.com>
To: "draft-ninan-mpls-spring-inter-domain-oam@ietf.org" <draft-ninan-mpls-spring-inter-domain-oam@ietf.org>
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Thread-Topic: MPLS-RT review on draft-ninan-mpls-spring-inter-domain-oam-02
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Date: Wed, 02 Jun 2021 03:59:14 +0000
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Subject: [mpls] MPLS-RT review on draft-ninan-mpls-spring-inter-domain-oam-02
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I am selected as a MPLS-RT reviewer of draft-ninan-mpls-spring-inter-domain-oam.

After review, I think the problem that the draft is trying to address is valid and useful. The solution is overall workable. My comments are mainly about Type 3 and Type 4 segment sub-TLV, I think it's better to address these comments before the adoption.

Type 3 and 4 sub-TLVs are supposed to be used when the headend/PMS does not have the labels or SRGB information of the remote nodes, and assume that the receiving node (egress node) can derive the MPLS labels according to the IPv4/IPv6 addresses. This assumption may not hold, because given that the headend/PMS does not have the information, it is very likely that the receiving node has no the information either. So the draft should add more text to clarify the use cases of type 3, 4 sub-TLVs, or just remove them.

In addition, given type 3 and 4 have valid use case, the optional SID fields of type 3 and 4 are redundant, I think that they should be removed. 

Section 4, 
"Below types of segment sub-TLVs are applicable for the Reverse Path
   Segment List TLV."

Should the "Reverse Path Segment List TLV" be "Return Path TLV"?

Best regards,