Hi Dan,

Thank you for the review. Please see comments inline with [PC].

Regards,
Pablo.

-----Original Message-----
From: Dan Romascanu via Datatracker <[email protected]> 
Sent: jueves, 20 de agosto de 2020 11:43
To: [email protected]
Cc: [email protected]; [email protected]; 
[email protected]; [email protected]
Subject: Opsdir last call review of 
draft-ietf-spring-srv6-network-programming-17

Reviewer: Dan Romascanu
Review result: Has Issues

This document together with the companion document 
[I-D.filsfils-spring-srv6-net-pgm-illustration] defines the SRv6 Network 
Programming concept and specifies the main segment routing behaviors to enable 
the creation of interoperable overlays with underlay optimization (Service 
Level Agreement).

The document is Ready.  There are a number of issues from an Operations and 
Management perspective that need further work, and it is assumed that they will 
be subject to work in the future. Some clarification on these issues would be 
however welcome before document approval.

There are several references that are work-in-progress. For example basic 
concepts need to be understood from 
[I-D.filsfils-spring-srv6-net-pgm-illustration]. 

[PC] The illustrations used to be part of this document originally but were 
moved to a separate informational document based on WG feedback. 

The control plane interaction is based on BGP-LS  [I-D.ietf-idr-bgpls-srv6-ext] 
or on BGP IP/VPN/EVPN [I-D.ietf-bess-srv6-services]. These documents are listed 
as Informative References probably in order to avoid a downref for this 
Standards Track document, but actually this document cannot be implemented or 
even understood without stable versions of the later.

[PC] After re-reading section 8 I don't see a need for the informative 
references to ietf-idr-bgpls-srv6-ext and ietf-bess-srv6-services. We will 
remove those two. This document specifies a set of SRv6 SID behaviors for 
supporting of TE and overlay services using SRv6; these TE and overlay services 
themselves are not new (e.g. they are available with MPLS data plane) and the 
document includes references to them. Control plane extensions are covered by 
documents progressing in other RTG WGs.

>From the operators point of view I would like to draw the attention on 
>Sections 6 and 8. 

- Section 6 (Operation) recommends the implementation of a implement a combined 
traffic counter (packets and bytes) per local SID entry. There is no indication 
how an operator would retrieve this information and if and how the values of 
these counters could be used for operational purposes. Adding such information 
would be useful. 

[PC] These counters are included in the draft draft-raza-spring-srv6-yang that 
was just recently adopted by the Spring WG. I'll update this section to 
indicate that retrieval of these counters via MIB, NETCONF/YANG or other means 
is outside the scope of this document.
 
- Section 8 (Control Plane) describes how the controllers can explicitly 
provision the SIDs and/or discover them as part of a service discovery 
function. Subsections describe the usage of IGP, BGP-LS, and BGP IP/VPN/EVPN 
for these purposes. Operators should be aware that one or more of these 
protocols also need to be supported in an SDN deployment.

[PC] I would propose the following diff
<old>
This section provides a high level overview of the control-plane protocols 
involved with SRv6 and their specification.
</old>
<new>
While not necessary for an SDN control plane, the remainder of this section 
provides a high-level illustrative overview of how control-plane protocols may 
be involved with SRv6. Their specification is outside the scope of this 
document.
</new>



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