Hi Reshad, I agree with you that if in all the deployment scenarios there's always only one node in a pair of nodes that needs to be aware of the path continuity to the remote system, then S-BFD has an advantage compared to "classic" RFC 5880-style BFD. I think that the use case presented in the document is not generic. In the more general case, as I imagine, PEs connected to CE1 and CE2 would benefit from monitoring the undelay network continuity between them. Hence, my suggestion to use RFC 5880-style BFD rather than S-BFD.
Regards, Greg On Mon, Mar 14, 2022 at 7:36 PM Reshad Rahman <res...@yahoo.com> wrote: > Hi Greg, authors, > > > Greg, is your point is that instead of having a pair of S-BFD sessions > between 2 PEs, we can have 1 (traditional) BFD session between 2 PEs? In > general I agree that S-BFD is better suited when only 1 side needs to > perform continuity tests. > > Authors, in section 3.1 3rd paragraph, last sentence, I'm not sure I fully > understand. Instead of having 2 S-BFD sessions on PE3 (as initiator) to PE1 > and PE2 (the responders), how are you merging this into 1 single session? > > Also, I think the document would be clearer if the terms initiator and > responder (as per RFC7880) are used in the document. > > Regards, > Reshad. > > > On Monday, March 14, 2022, 12:44:55 PM EDT, Greg Mirsky < > gregimir...@gmail.com> wrote: > > > 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 >
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