| Dear WG, We discussed some time ago about the use of existing objects (e.g. RSVP) in PCEP messages so as to specify constraints, return computed paths and so on. There were two possible approaches: (1) Define a PCEP object that would carry non PCEP object. (2) Specify an identical object with a PCEP codepoint. (1) was rejected because of potential ambiguity in the interpretation of the non PCEP object in a PCEP context, thus we elected to adopt the (2) approach. For example, in the current PCEP ID: 7.8. ERO Object The ERO object is used to encode a TE LSP path. If can either be carried within a PCReq message to specify the existing path of a TE LSP to be reoptimize or within a PCRep message to provide a computed TE LSP. The contents of this object are identical in encoding to the contents of the Explicit Route Object defined in [RSPV-TE], [GRSVP] and [RSVP- UNNUM]. That is, the object is constructed from a series of sub- objects. Any RSVP ERO sub-object already defined or that could be defined in the future for use in the ERO is acceptable in this object. PCEP ERO sub-object types correspond to RSVP ERO sub-object types. Since the explicit path is available for immediate signaling by the MPLS or GMPLS control plane, the meanings of all of the sub-objects and fields in this object are identical to those defined for the ERO. ERO Object-Class is to be assigned by IANA (recommended value=7) ERO Object-Type is to be assigned by IANA (recommended value=1) 7.9. RRO Object The RRO object is used to record the route followed by a TE LSP. The PCEP RRO object is exclusively carried within a PCReq message so as to specify the route followed by a TE LSP for which a reoptimization is desired. The contents of this object are identical in encoding to the contents of the Route Record Object defined in [RSPV-TE], [G-RSVP] and [RSVP- UNNUM]. That is, the object is constructed from a series of sub- objects. Any RSVP RRO sub-object already defined or that could be defined in the future for use in the RRO is acceptable in this object. The meanings of all of the sub-objects and fields in this object are identical to those defined for the RRO. PCEP RRO sub-object types correspond to RSVP RRO sub-object types. RRO Object-Class is to be assigned by IANA (recommended value=8) RRO Object-Type is to be assigned by IANA (recommended value=1) There are other examples such as the PROTECTION object (draft-ietf-ccamp-gmpls-recovery-e2e-signaling-03.txt ), <CLASSTYPE> (RFC4124), ... It would be a good idea to have a separate ID to get PCEP codepoint for these objects (for which the format is likely to remain unchanged) and potentially (if needed) clarify the interpretation of these objects in a PCEP context. Any volunteer to drive this ? Thanks, JP and Adrian. |
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