Last Call Review of draft-ietf-bess-evpn-vpws-fxc-09
review-ietf-bess-evpn-vpws-fxc-09-opsdir-lc-wu-2024-09-25-00

I have reviewed this document as part of the Operational directorate's ongoing
effort to review all IETF documents being processed by the IESG.  These
comments were written with the intent of improving the operational aspects of
the IETF drafts. Comments that are not addressed in last call may be included
in AD reviews during the IESG review.  Document editors and WG chairs should
treat these comments just like any other last call comments.

This document describes a new EVPN VPWS service type specifically for
multiplexing multiple attachment circuits across different Ethernet Segments
and physical interfaces into a single EVPN VPWS service tunnel. This document
is on the right track and ready for publication, I have a few comments and
suggestions to this draft as follows: 1.As stated in [RFC8214], 12-bit and
24-bit VPWS service instance identifiers representing normalized VIDs MUST be
right-aligned.

RFC8214 only requires 24-bit value right aligned, but doesn't provide
requirements on 12 bit value, therefore the text described here is not
consistent with what it said in RFC8214

2. Section 2 said:
"
In absence of
   updating the BGP path list, the traffic for that VPWS service tunnel
   will be black-holed.
"
3. Section 5.2 said:
"
      Default FXC (Figure 1): in the default mode, a VLAN or AC failure
      is not signaled.  Consequently, in case of an AC failure such as
      VID1 on CE2, there is nothing to prevent PE3 from directing
      traffic from CE4 to PE1, leading to a potential black hole.
"
I am wondering whether this black hole issue is security issue and need to
document as security consideration.

4.Section 3 said:
"
This translation of VIDs
   into unique VIDs (either single or double) is referred to as "VID
   normalization".
"
I see VID normalization as a new term, it will be nice to introduce the term
defintion in section 1.1.

5.Section 3 said:
"
   When a single normalized VID is used, the lower 12 bits of the
   Ethernet tag field in EVPN routes MUST be set to that VID.  When a
   double normalized VID is used, the lower 12 bits of the Ethernet tag
   field MUST be set to the inner VID, while the higher 12 bits are set
   to the outer VID.
"
I am wondering how does disposition PE know when single normalized VID is used
and when a double normalized VID is used, e.g., if single normalized VID is
used, the higher 12 bits will be set to all zeros? No?

6.Section 3 said:
“
   Since the VID lookup (single or double) needs to be performed at the
   disposition PE, VID normalization MUST be completed prior to MPLS
   encapsulation on the ingress PE.
”
One suggestion to this paragraph is to make clear who does VID normalization.
I believe it is imposition PE, the question is whether imposition PE and
ingress PE are the same box? I suggest to add two definition in the terminology
section to clarify the relation between imposition PE and ingress PE, the
relation between disposition PE and egress PE.

7. Section 3.3.1 said:
"
This method of
   prioritizing locally switched traffic aligns with the baseline EVPN
   principles described in [RFC7432]
"
Can you be more specific which section in RFC7432 to introduce baseline EVPN
principles?