Hi Dimitri, > -----Message d'origine----- > De : dimitri papadimitriou [mailto:[EMAIL PROTECTED] > Envoyé : vendredi 14 juillet 2006 15:44 > À : [EMAIL PROTECTED] > Objet : [Pce] P & I flags > > the comments around the P and I flags are > > o) we have two levels of optionality in listing the protocol > object and usage level of the protocol object - however it is > much more appropriate to be sure that mandatory constraints > have been taken rather than having the optional having been > taken into account
As clearly pointed out in the same setion of the draft, if a mandatory constraint cannot be handled the PCE replies with PCErr message "If the PCE does not understand an object with the P Flag set or understands the object but decides to ignore the object, the entire PCEP message MUST be rejected and the PCE MUST send a PCErr message with Error-Type="Unknown Object" or "Not supported Object". If the PCE can handle all mandatory constraints it replies with a PCRep message (either positive or negative if there is no path), else it sends a PCErr message. Hence the PCC knows whether mandatory constraints have been taken into account. > > P flag (Processing-Rule - 1-bit): the P flag allows a PCC > to specify > in a PCReq message sent to a PCE whether the object must be taken > into account by the PCE during path computation or is > just optional. > When the P flag is set, the object MUST be taken into > account by the > PCE. Conversely, when the P flag is cleared, the object > is optional > and the PCE is free to ignore it if not supported. > > o) on the I flag issue is identical why include an object > which has not considered during computation ? I don't catch your point, the PCC may want to know the constraints that were not taken into account during path computation, this sounds quite important isn'it? there are so > many things that the PCE has not taken into account during > computation so why bother ? Hum I don't follow you here "there are so many things...", What do you mean? > it is imho > more important to include the mandatory object not taken > into account If a mandatory object is not taken into account, you cannot compute the path and you send an error message. I agree with you that this would be useful to include within the PCErr the set of objects not supported, this can be clarified in next revision. > > I flag (Ignore - 1 bit): the I flag is used by a PCE in a PCRep > message to indicate to a PCC whether or not an optional object was > processed. The PCE MAY include the ignored optional object in its > reply and set the I flag to indicate that the optional object was > ignored during path computation. When the I flag is > cleared, the PCE > indicates that the optional object was processed during the path > computation. The setting of the I flag for optional objects is > purely indicative and optional. The I flag MUST be > cleared if the P > flag is set. > > o) the result of all these flags is that a PCC can be > wrapping around unknown constraints create processing churn > on the PCE; OK, if you mean that we should include the unsupported object(s) within the PCErr, then we are in sync Thanks for the comment Regards JL > > If the PCE does not understand an object with the P Flag set or > understands the object but decides to ignore the object, > the entire > PCEP message MUST be rejected and the PCE MUST send a > PCErr message > with Error-Type="Unknown Object" or "Not supported Object". > > > > _______________________________________________ > Pce mailing list > [email protected] > https://www1.ietf.org/mailman/listinfo/pce > _______________________________________________ Pce mailing list [email protected] https://www1.ietf.org/mailman/listinfo/pce
