Early Review of draft-ietf-bess-evpn-mh-pa-09
review-ietf-bess-evpn-mh-pa-09-genart-early-kyzivat-2023-11-03-00

I am the assigned Gen-ART reviewer for this draft. For background on 
Gen-ART, please see the FAQ at <https://wiki.ietf.org/group/gen/GenArtFAQ>.

Please resolve these comments along with any other comments you may receive.

Document: draft-ietf-bess-evpn-mh-pa-09
Reviewer: Paul Kyzivat
Review Date: 2023-11-10
IETF LC End Date: ?
IESG Telechat date: ?

Summary:

This draft is on the right track but has open issues, described in the 
review.

Issues: 2
Nits: 0

Note: This reviewer is not burdened with any knowledge of the subject 
matter. It is possible that the points I raise below may be entirely 
clear to a subject matter expert. Just take this as input from a fresh 
and unbiased set of eyes.

Otherwise the draft seems in good shape.

1) ISSUE: Ambiguity, Section 3.2(c):

I find the normative statement here to be ambiguous:

"PEs in the redundancy group MAY exchange only the Ethernet-Segment (ES) 
route (Route Type‑4) when ESI is configured on a Layer‑3 interface."

To what does "MAY" apply? What is the alternative? Does this mean that 
exchanging the ES route is optional? Or is this excluding exchanging 
other forms of route? Or something else?

2) ISSUE: Confusing algorithm in 4.3(2):

I find the expression:

"2. BDF(Es) = Sk| Weight(Es, Si) >= Weight(Es, Sk), and Weight(Es, Sk) 
 >= Weight(Es, Sj)."

confusing, even with the subsequent qualifier:

"BDF(Es) is defined as that PE with address Sk for which the computed 
Weight is the next highest after the Weight of the DF. j is the running 
index from 0 to N-1; i and k are selected values."

Can you find a clearer way to state this?