A question about the draft-wang-bess-sbfd-discriminator

[Greg Mirsky <[e-mail]>]

Hi Haibo and the Authors,
thank you for updating the draft. I've read the new version and have a
question about the use case presented in the document. There are three PEs
with two of them providing redundant access to a CE. It appears that a more
general case would be if both CEs use redundant connections to the EVPN.
Asume, PE4 is added and connected to CE2. In that case, it seems reasonable
that each PE is monitoring remote PEs, i.e., PE1 monitors PE3 and PE4, PE2
- PE3 and PE4, PE3 - PE1 and PE2, and PE4 - PE1 and PE2. So, now there are
pairs of S-BFD sessions between PEs connected to CE1 and CE2 respectively.
That seems like too many sessions and that number can be reduced if one
uses BFD instead of S-BFD. Would you agree? To simplify operations, it
might be helpful to use the technique described in
draft-ietf-bfd-unsolicited
<https://datatracker.ietf.org/doc/html/draft-ietf-bfd-unsolicited-09>. In
the recent discussion of the draft on the BFD WG ML, the authors noted that
they are working on extending the scope to include the multi-hop BFD.
Greatly appreciate your thoughts about the number of S-BFD sessions.

Regards,
Greg