Protocol Action: 'BGP EVPN Multi-Homing Extensions for Split Horizon Filtering' to Proposed Standard (draft-ietf-bess-evpn-mh-split-horizon-11.txt)

[The IESG <[e-mail]>]

The IESG has approved the following document:
- 'BGP EVPN Multi-Homing Extensions for Split Horizon Filtering'
  (draft-ietf-bess-evpn-mh-split-horizon-11.txt) as Proposed Standard

This document is the product of the BGP Enabled ServiceS Working Group.

The IESG contact persons are Gunter Van de Velde, Jim Guichard and John
Scudder.

A URL of this Internet-Draft is:
https://datatracker.ietf.org/doc/draft-ietf-bess-evpn-mh-split-horizon/




Technical Summary

   Ethernet Virtual Private Network (EVPN) is commonly used with Network
   Virtualization Overlay (NVO) tunnels, as well as MPLS and Segment
   Routing tunnels.  The multi-homing procedures in EVPN may vary based
   on the type of tunnel used within the EVPN Broadcast Domain.
   Specifically, there are two multi-homing Split Horizon procedures
   designed to prevent looped frames on multi-homed Customer Edge (CE)
   devices: the ESI Label-based procedure and the Local Bias procedure.
   The ESI Label-based Split Horizon is applied to MPLS-based tunnels,
   such as MPLSoUDP, while the Local Bias procedure is used for other
   tunnels, such as VXLAN.

   Current specifications do not allow operators to choose which Split
   Horizon procedure to use for tunnel encapsulations that support both
   methods.  Examples of tunnels that may support both procedures
   include MPLSoGRE, MPLSoUDP, GENEVE, and SRv6.  This document updates
   the EVPN multi-homing procedures described in RFC 8365 and RFC 7432,
   enabling operators to select the appropriate Split Horizon procedure
   for a given tunnel based on their specific requirements.

Working Group Summary

   Was there anything in the WG process that is worth noting?
   For example, was there controversy about particular points 
   or were there decisions where the consensus was
   particularly rough? 

Strong concurrence of a few active EVPN contributors.
It took a while for the AD review to complete. 

Document Quality

   Are there existing implementations of the protocol?  Have a 
   significant number of vendors indicated their plan to
   implement the specification?  Are there any reviewers that
   merit special mention as having done a thorough review,
   e.g., one that resulted in important changes or a
   conclusion that the document had no substantive issues?  If
   there was a MIB Doctor, Media Type, or other Expert Review,
   what was its course (briefly)?  In the case of a Media Type
   Review, on what date was the request posted?

WG has probed for implementations (documented in the Shepherd writeup).
Current AD processed the document to enhance readability of the document and technical intent and procedures.

No requirement for MIB Doctor, YANG Doctor, media type, and URI type reviews. There is no yang model.


Personnel

   The Document Shepherd for this document is Zhaohui (Jeffrey) Zhang. The
   Responsible Area Director is Gunter Van de Velde.

IANA Note

   This document creates a registry called "EVPN ESI Label Extended
   Community Flags" for the 1-octet Flags field in the ESI Label
   Extended Community [RFC7432].  Initial registrations are made for the
   "Multihoming redundancy mode" field in bits 0 and 1, and the "Split
   Horizon Type" field in bits 6 and 7, as follows:

      +==============+=============================+===============+
      | Bit Position | Name                        | Reference     |
      +==============+=============================+===============+
      | 0-1          | Multihoming redundancy mode | [RFC7432]     |
      +--------------+-----------------------------+---------------+
      | 2-5          | Unused                      |               |
      +--------------+-----------------------------+---------------+
      | 6-7          | Split Horizon Type          | This Document |
      +--------------+-----------------------------+---------------+

                                 Table 2

   In addition, the "Multihoming redundancy mode" field is initialized
   as follows:


                  +=======+=============================+
                  | Value | Multihoming redundancy mode |
                  +=======+=============================+
                  | 00    | All-Active mode             |
                  +-------+-----------------------------+
                  | 01    | Single-Active mode          |
                  +-------+-----------------------------+
                  | 10    | Unused                      |
                  +-------+-----------------------------+
                  | 11    | Unused                      |
                  +-------+-----------------------------+

                                  Table 3

   And the field "Split Horizon Type" is initialized as follows:

                   +=======+===========================+
                   | Value | Split Horizon Type value  |
                   +=======+===========================+
                   | 00    | Default SHT               |
                   +-------+---------------------------+
                   | 01    | Local Bias                |
                   +-------+---------------------------+
                   | 10    | ESI Label based filtering |
                   +-------+---------------------------+
                   | 11    | Unused                    |
                   +-------+---------------------------+

                                  Table 4

   New registrations in the "EVPN ESI Label Extended Community Flags"
   registry will be made through the "IETF Review" procedure defined in
   [RFC8126].  This registry is located in the "Border Gateway Protocol
   (BGP) Extended Communities" registry.