Reviewer: Mike McBride
Review result: Ready with nits

I have been selected to do a routing directorate early review of this draft which has passed SPRING WG Last Call (copied to SFC WG) , but would benefit from a larger review.

Document: draft-ietf-spring-nsh-sr
Review Date: 28 June 2021
Intended Status: Standards Track

Summary:

A couple of nits found but otherwise this document is ready to proceed to the IESG.

Comments:

The document is well written. Aside from the following recommended changes its good to go.

There are a couple of long semi-awkward sentences. They still make sense but, for readability, it would help to reword them. 
And there are a couple of recommended grammar related changes.

1. The 3rd paragraph, in the Abstract, says: 

"The integration described in this document demonstrates that NSH and
SR can work jointly and complement each other leaving the network
operator with the flexibility to use whichever transport technology
makes sense in specific areas of their network infrastructure, and
still maintain an end-to-end service plane using NSH."

I would recommend rewording this to:

"This integration demonstrates that NSH and SR can work 
cooperatively with each other and provide the network
operator with the flexibility to use whichever transport technology
makes sense in specific areas of their network infrastructure while
still maintaining an end-to-end service plane using NSH."

2. In the section 1.1. SFC Overview and Rationale I would recommend changing this:

"Particularly, cascading SFs at the so-called Third Generation
Partnership Project (3GPP) Gi interface (N6 interface in 5G
architecture) in the context of mobile network infrastructure, have
shown their limitations, such as the same redundant classification
features must be supported by many SFs to execute their function,
some SFs receive traffic that they are not supposed to process (e.g.,
TCP proxies receiving UDP traffic), which inevitably affects their
dimensioning and performance, an increased design complexity related
to the properly ordered invocation of several SFs, etc."

to this:

"For instance, cascading SFs at the 3GPP (Third Generation
Partnership Project) Gi interface (N6 interface in 5G
architecture) has shown limitations such as 1) redundant classification
features must be supported by many SFs to execute their function,
2) some SFs receive traffic that they are not supposed to process (e.g.,
TCP proxies receiving UDP traffic) which inevitably affects their
dimensioning and performance, 3) an increased design complexity related
to the properly ordered invocation of several SFs."

3. Need a comma after "problems":

"In order to solve those problems and to decouple the services
topology from the underlying physical network while allowing for
simplified service delivery, Service Function Chaining (SFC)
techniques have been introduced [RFC7665]."

4. Probably can scratch the "Indeed" and just start with "SFC...":

"Indeed, SFC allows to dynamically create service
planes that can be used by specific traffic flows"