[bess] A controversy in draft-ietf-bess-rfc7432bis

[Alexander Vainshtein <[e-mail]>]

Hi,
I think that I have found a controversy in the latest version of the 7432bis<https://datatracker.ietf.org/doc/html/draft-ietf-bess-rfc7432bis-09> draft.

Section 5 of the draft contains the following text:

If a bridged network does not connect to the PEs using a LAG, then only one of the links between the bridged network and the PEs must be the active link for a given <ES, EVI>. In this case, the set of Ethernet A-D per ES routes advertised by each PE MUST have the "Single-Active" bit in the flags of the ESI Label extended community set to 1.


Section 8.2.1 of the draft conatis the following text:
The ESI Label extended community MUST be included in the route. If All-Active redundancy mode is desired, then the "Single-Active" bit in the flags of the ESI Label extended community MUST be set to 0 and the MPLS label in that Extended Community MUST be set to a valid MPLS label value.
…
If Single-Active redundancy mode is desired, then the "Single-Active" bit in the flags of the ESI Label extended community MUST be set to 1 and the ESI label SHOULD be set to a valid MPLS label value.

Section 8.4 of the draft mentions “the "Single-Active" bit in the flags of the ESI Label extended community”.


Section 14.1.1 of the draft contains the following text (copied verbatim from the namesake section of RFC 7432<https://datatracker.ietf.org/doc/html/rfc7432>)

For a given ES, if a remote PE has imported the set of Ethernet A‑D per ES routes from at least one PE, where the "Single-Active" flag in the ESI Label extended community is set, then that remote PE MUST deduce that the ES is operating in Single-Active redundancy mode.

Similarly, Section 14.1.2 of the draft contains the following text:

For a given ES, if the remote PE has imported the set of Ethernet A-D per ES routes from one or more PEs and none of them have the "Single‑Active" flag in the ESI Label extended community set, then the remote PE MUST deduce that the ES is operating in All-Active redundancy mode.



The problem with all these (and, possibly, some other) fragments is that the “Single-Active bit” (or flag) in the Flags field of the ESI Label extended community that has been defined in RFC 7432 does not exist in the 7432bis draft. Instead, Section 7.5 of the dratf defines a two-bit RED subfield in the Flags field of the ESI Label Extended Community, and defines two (out of 4) possible values for this field. (Yet another value is defined in the Layer 2 EVPM Multi-Homing Mechanism for Layer 2 Protocol Gateways draft<https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-l2gw-proto-04>.)

Hopefully, these notes will be helpful.

Regards,
Sasha

Disclaimer

This e-mail together with any attachments may contain information of Ribbon Communications Inc. and its Affiliates that is confidential and/or proprietary for the sole use of the intended recipient. Any review, disclosure, reliance or distribution by others or forwarding without express permission is strictly prohibited. If you are not the intended recipient, please notify the sender immediately and then delete all copies, including any attachments.