Hi, 

I have been selected to do a routing directorate “early” review of this draft:
https://datatracker.ietf.org/doc/draft-ietf-bess-extended-evpn-optimized-ir

The routing directorate will, on request from the working group chair,
perform an “early” review of a draft before it is submitted for
publication to the IESG. The early review can be performed at any time
during the draft’s lifetime as a working group document.

For more information about the Routing Directorate, please see
https://wiki.ietf.org/en/group/rtg/RtgDir

Document: https://datatracker.ietf.org/doc/draft-ietf-bess-extended-evpn-optimized-ir-04
Reviewer: Nicolai Leymann
Review Date: Nov 19, 2023
Intended Status: Standards Track

Overall the draft is in good shape and extends the existing optimzed ingress replication in multihoming scenarios. For such networks the draft  provides a solution and also optimized ingress replication for the EVPN overlay. 

The draft assumes that the reader is familiar with the details of the underlying specs such as "Optimized Ingress Replication solution for EVPN". There are a few things which would help to make the document more readable. 

In general I recommend to extend abbreviation such as "A-D", "RNVE", "BD" (at first occurence in the document). The first part of the draft describes handling of BUM traffic, later BM is used (for Multicast/Broadcast) only; the solution itself refers to BUM again. Please clarify a more in detail what the solution/document is addressing. Section 2 gives an detailed description of a scenario used throughout the document but a figure as additional information and reference would be really helpful to better understand the problem as well as the solution (also because the scenario is referred from other sections such as 4.2.1, making the draft hard to read).

Other Nits:
Section 2 and following
  - inconsistent use of "split horizon" and "split-horizon"
  - inconsistent use of "extended optimized-IR" and "extended Optimized-IR" and "Extended Optimized-IR"

Section 2.2 
  - "[EVPN-AR] specifies an optimized ingress replication procedures for" to
    "[EVPN-AR] specifies an optimized ingress replication procedure" for

Section 3.1
  - "it MUST informs"
  - "it MUST inform"
  - "The changes in the control plane and forwarding [...] is further explained in detail in section 5.2."
  - "The changes in the control plane and forwarding [...] are further explained in detail in section 5.2."
  - "It may also applies to Unknown unicast traffic."
  - "It may also apply to Unknown unicast traffic.

Section 3.2
  - consider explaining/extending "BD"
  - "Consider an EVPN NVO network with a tenant domain consists of a set of m AR-LEAFs in BD X: AR-LEAF1, AR-LEAF2, AR-LEAF3, ..."
    -> would be easier to understand with a figure showing the network being described

Section 3.3
  - "The extended Optimized-IR procedures specified in this document greatly reduces ..."
    Rest of the section is written in a way that it's only one procedure but not several
 
Section 4.1.1
  - consider explaining/extending "EVI"
  - "EVPN Multicast Flags Extended Community" should be used consitently throughout the draft (vs. "multicast flags extended community")