Hi,

I have a few questions:

   On the S-PEs, the pseudowires from the Access PEs are terminated onto
   VRFs, such that all pseudowires within a given redundancy set
   terminate on a single IP endpoint on the S-PEs. To achieve this, the
   S-PEs in a given Redundancy Group are configured with the same
   Anycast IP and MAC addresses on the virtual (sub)interface
   corresponding to the VRF termination point.

Is the virtual interface (like) an IRB interface?

   Since the S-PEs are running in EVPN single-active redundancy mode,
   the S-PEs would advertise an Ethernet AD route per vES with the
   single-active flag set per [RFC7432]. Since only the DF S-PE has its
   access pseudowire in Active state, only that device would establish
   an eBGP session with the CE and receive control and data traffic.

Will the IRB/virtual interface on a non-DF PE be up? I assume it is - even 
though the PW is not active. Would the non-DF PE keeps trying to establish the 
eBGP session with the CE? Would that cause issue to the session between CE and 
the DF PE?

   The
   DF S-PE advertises host prefixes that it receives, from the CE over
   the eBGP session, to other PEs in the EVI using EVPN route type-5,
   with the proper ESI set. Remote PEs learn the host prefixes and
   associate them with the ESI, using the advertising PE as the next-hop
   for forwarding.

Would he DF S-PE advertise other prefixes received on the eBGP session? I 
assume so but the text only says host prefixes.

   Other S-PEs in the same Redundancy Group as the advertising PE will
   receive the same EVPN route type-5 advertisement, and will recognize
   the associated ESI as a locally attached vES.

What is the RT that limits the routes to be imported only the PEs in the same 
redundancy group? Is it that all PEs in the same EVPN instance will import the 
routes? Or is it that different redundancy groups will have different EVPN 
instances? I assume it's latter (since we need one IRB interface for each 
redundancy group?).

   The withdrawal of the Ethernet
   Segment route serves as an indication to the backup S-PE to go active
   (i.e. act as a backup DF), and activate its pseudowires to the Access
   PE. The withdrawal of the Ethernet A-D route triggers a "mass
   withdraw" on the remote PEs: these PEs adjust their next-hop
   associated with the prefixes that were originally advertised by the
   failed PE to point to the "backup path" per [RFC7432].

Can you elaborate the procedure for the PEs to adjust their next-hop?

I don't see reference to draft-ietf-bess-evpn-vpws. Is that used at all?

Thanks.
Jeffrey

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