1 / 7

Objective Functions Encoding in PCE Communication and Discovery Protocols

This draft presents updates regarding the encoding of objective functions (OF) in the PCE communication and discovery protocols. It discusses both unsynchronized and synchronized computations for Traffic Engineering Label Switching Paths (TE-LSPs) under various objective functions, enabling a Path Computation Client (PCC) to discover supported OFs. Additionally, it defines extensions for the PCE and PCEP, including a new Objective Function Code Point Registry for management by IANA. These advancements aim to enhance the capabilities for path computation requests and response handling.

dore
Télécharger la présentation

Objective Functions Encoding in PCE Communication and Discovery Protocols

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Encoding of Objective Functions in PCE Communication and Discovery Protocolsdraft-leroux-pce-of-00.txtJ.L. Le Roux (France Telecom) J.P. Vasseur (Cisco Systems) Y. Lee (Huawei) IETF 68, PCE WG, Prague

  2. Overview • The computation of one or a series of TE-LSPs is subject to an objective function (OF) • Unsynchronized computations: Minimum cost path, shortest widest path, widest shortest path, etc. • Synchronized computation: Minimize the load on the most loaded link, minimize the global bandwidth consumption, etc. • As spelled out in RFC 4674, it may be useful for a PCC to discover the set of objective functions supported by a PCE • As spelled out in RFC 4657, a PCC must be able to indicate in a request a required objective function as well as optional parameters • This draft covers these requirements • PCED extensions allowing a PCE to advertise a list of supported OF • PCEP extensions allowing to carry an OF in a request/response

  3. PCE OF Code Point Registry • An Objective Function is identified by a 16 bit code point • A common Objective Function Code Point Registry is defined for both PCE communication and discovery protocols • To be managed by IANA • Values 32768-65535 for private use • A document that defines an objective function will request a code point from this registry • e.g. draft-lee-pce-concurrent-optimization

  4. PCE Discovery Extensions • IS-IS and OSPF based PCE Discovery defined in draft-ietf-pce-disco-proto-{isis | ospf} • PCED TLV carried in OSPF Router Information LSA and IS-IS Router Capability TLV • Extension to PCED TLV, that allows a PCE to advertise a list of supported objective functions • A new sub-TLV of the PCED TLV is defined: the OF-List sub-TLV • carries a list of 16-bit Objective Function identifiers • Indicates objective functions supported by the PCE

  5. PCEP Extensions • A new PCEP Object is defined, the OF Object, to be carried in PCReq and PCRep messages • carries a 16-bit objective function identifier + Optional TLVs to encode parameters • When carried in a PCReq it indicates a desired/required objective function • If P bit = 1 this is required, else this is desired • If the OF object applies to a synchronize computation, it MUST be carried just after the SVEC object and MUST not be repeated for each elementary request • When carried in a PCRep it indicates the objective function actually applied • Useful if there is no OF in the PCReq or if the PCE applied another OF than the desired one • A new flag defined in the RP object, used in a PCReq to indicate that the objective function that will be actually applied by the PCE should be provided in the PCRep • New PCEP error codes/values • Error code "Objective Function Error". Values: unknown/unsupported OF • New values for the error code "Policy Violation": "Unauthorized OF", "OF bit in RP"

  6. Next Steps • Straightforward PCED and PCEP extensions • Shall we define objective functions in this draft? • Jerry asked for the definition of objective functions listed in 4657 • Discussion on the list and offline • Conclusion => They will be added in next revision • Need for WG feedback • Adopt as WG doc?

  7. ThanksQuestions?

More Related