Dhruv, Hi! Thanks for the response! Please see inline..
Regards, -Pavan On Wed, Jan 11, 2023 at 12:03 PM Dhruv Dhody <[email protected]> wrote: > Hi Pavan, > > On Wed, Jan 11, 2023 at 11:02 AM Vishnu Pavan Beeram < > [email protected]> wrote: > >> I would like to get some clarification on the text below (understand that >> a publication request has been made for the draft). >> >> ** >> From Section 5: >> >> When L-flag is not set and E-flag is not set then PCE SHOULD consider >> the protection eligibility as UNPROTECTED PREFERRED but MAY consider >> protection eligibility as UNPROTECTED MANDATORY constraint. >> >> When L-flag is not set and E-flag is set then PCE MUST consider the >> protection eligibility as UNPROTECTED MANDATORY constraint. >> >> >> >> ** >> For the scenario where both the L-flag and the E-flag are not set (first >> statement above), it seems okay to just say >> that the "PCE MUST consider the protection eligibility as UNPROTECTED >> PREFERRED". Is there a good reason >> for both the "SHOULD (UNPROTECTED PREFERRED)" and "MAY (UNPROTECTED >> MANDATORY)" clauses to >> be included here (and keep things ambiguous)? >> >> > Dhruv: If I recall correctly (and the authors can confirm that), this was > done for the sake of backward compatibility. I remember it being discussed > on the mailing list as well. > > [VPB] Thanks for the pointer to the mailing list thread (should have searched there first; apologies for re-opening the topic) -- it was useful! However, the backwards compatibility section (5.1) seems to be silent about this particular scenario. If a PCEP speaker does not understand this document (and thus ignores the E > flag) and L flag is set to 0, would behave as per RFC 5440 where the > concept of enforcement is undefined and some implementation could > understand it to be handled as UNPROTECTED MANDATORY instead of UNPROTECTED > PREFERRED. And the text allows for it. > [VPB] I understand that there was ambiguity with how the (presence/absence of the) L-flag was interpreted prior to this draft. I was hoping that there would be no ambiguity left when this draft is implemented -- but that doesn't seem to be the case. Let's say a PCC implementation assumes [L 0, E 0] to mean "UNPROTECTED PREFERRED" (SHOULD clause), while the PCE implementation assumes it to mean "UNPROTECTED MANDATORY" (MAY clause) -- this may result in no path being returned (if only protected SIDs are available on some links along the viable paths). Do we need to retain this ambiguity? > > Happy to get additional eyes and confirm if it still makes sense! > > Thanks! > Dhruv > > > >> Regards, >> -Pavan >> _______________________________________________ >> Pce mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/pce >> >
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