[spring] Usage of End.DX2 SID in EVPN-VPWS

[Alexander Vainshtein <[e-mail]>]

Hi,
I have a question about usage of End.DX2 SID (as defined in Section 4.9 of RFC 8986<https://datatracker.ietf.org/doc/html/rfc8986#section-4.9>in EVPN-VPWS.


  *   The definition of this endpoint behavior says that "The End.DX2 SID MUST be the last segment in an SR Policy, and it is associated with one outgoing interface I"
  *   If the upper-layer header type is Ethernet, the IPv6 header and all extension headers are stripped, and the resulting Ethernet frame is forwarded to the outgoing interface I.

EVPN-VPWS as defined in RFC 8214 is explicitly mentioned as one of possible applications in this section,  and Section 6.1.2 of RFC 9252<https://datatracker.ietf.org/doc/html/rfc9252#section-6.1.2> explicitly mentions End.DX2 as one of possible behaviors of the SID signaled in per-EVI Ethernet A-D routes (along with End.X2V and End.DT2U).


I think that End.X2  behavior as defined above is not compatible with one of the advantageous features of EVPN-VPWS as described in the last para of Section 5 of RFC 8214<https://datatracker.ietf.org/doc/html/rfc8214#section-5>:
<quote>
   Finally, EVPN may employ data-plane egress link protection mechanisms
   not available in VPWS.  This can be done by the primary PE (on local
   AC down) using the label advertised in the per-EVI Ethernet A-D route
   by the backup PE to encapsulate the traffic and direct it to the
   backup PE.
<end quote>

(For the reference, implementing fast egress protection against AC failure  in "classic" VPWS has been defined in RFC 8104).

What, if anything, did I miss? Do you think that a new Endpoint behavior should be defined?

Regards, and lots of thanks in advance,
Sasha

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