[bess] A question regarding sections 15.2 and 15.3 of draft-ietf-bess-rfc7432bis

[Alexander Vainshtein <[e-mail]>]

Hi all,
I have a question regarding sections 15.2 and 15.3 of the 7432bis draft.<https://datatracker.ietf.org/doc/html/draft-ietf-bess-rfc7432bis-07>

Section 15.2 (which is copied from the parallel section of RFC 7432<https://www.rfc-editor.org/rfc/rfc7432.html#section-15.2>) defines "sticky" MAC addresses as addresses that are configured as static and therefore are not subject to MAC Moves.
It defines how these addresses can be identified, and requires that if such a MAC address is seen as the Source MAC address in a locally received Ethernet frame, the PE MUST alert the operator. No other actions for this case (be it the EVPN CP or EVPN DP actions)  are specified.

Section 15.3 is a new section that extends the CP mechanisms defined in Section 15.1 with DP mechanisms breaking Ethernet loops. Such loops can be created by backdoor connectivity between L2 customer sites attached to different EVPN PEs.

However, neither these sections nor RFC 9135 seem to discuss the situation when an EVPN Broadcast Domain is configured with an IRB and an Ethernet Frame with the Source MAC address matching the MAC address of this IRB is locally received by one of the PEs in which this Broadcast Domain is instantiated. Such a situation may be encountered, e.g., if the EVPN IRB in question is configured with anycast MAC address as suggested in Section 4.1 of RFC 9135<https://datatracker.ietf.org/doc/html/rfc9135#section-4.1>, and backdoor connectivity exists between different customer sites that are attached to the Broadcast Domain in question.

I would highly appreciate your answers to the following questions:

  1.  Should anycast MAC addresses configured on EVPN IRB be treated as "sticky"?
  2.  If the answer to the previous question is "Yes":
     *   Should IP-->MAC pairs of EVPN IRBs be advertised with MAC Mobility Extended Community attached and the sticky bit set? To the best of my understanding, currently only advertisement with the Default Gateway Extended Community attached is required
     *   Should a Broadcast Domain that is used by an EVPN IRB and that locally receives an Ethernet frame with the Source MAC address matching the MAC address of its IRB perform, in addition to report to the operator, perform any Loop Protection actions?

Your timely feedback would be highly appreciated.

IMHO and FWIW it would be nice if your answers (whatever they are) could be added in the next revision of the 7432bis draft.

Regards, and lots of thanks in advance,
Sasha

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