1 / 8

Background

Encoding of Objective Functions in PCE Communication and Discovery Protocols draft-leroux-pce-of-01.txt J.L. Le Roux (France Telecom) J.P. Vasseur (Cisco Systems) Y. Lee (Huawei). Background.

penney
Download Presentation

Background

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-01.txtJ.L. Le Roux (France Telecom) J.P. Vasseur (Cisco Systems) Y. Lee (Huawei) IETF 69, PCE WG, Chicago

  2. Background • The computation of one or a series of TE-LSPs is subject to an objective function (OF) • Unsynchronized computation: 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. Solution Overview • A common Objective Function Code Point Registry is defined for both PCE communication and discovery protocols • 16 bit code point registry to be managed by IANA • PCE Discovery Extension: A new sub-TLV, OF-List, carried in the PCED TLV • Carries the list of supported objective functions • PCEP Extension: A new PCEP OF object • Carried in a PCReq message to indicate the desired OF • Carried in a PCRep message to indicate the OF applied by the PCE • New error type/value

  4. Changes since last version • As agreed in Prague, we defined in this document the six mandatory objective functions listed in RFC4657

  5. Definition of Objective Functions 1/2 • Notation: • A network comprises a set of N links {Li, (i=1..N)} • A path P is a list of K links {Lpi,(i=1..K)} • Metric of link L is noted M(L) • The cost of a path P is noted C(P), C(P) = sum {M(Lpi), (i=1...K)}. • Residual bandwidth on link L is noted R(L) • Speed of link L is noted B(L)

  6. Definition of Objective Functions 2/2 • Objective functions that apply to the computation of a single path • OF 1: Minimum Cost Path (MCP) • Find a path P such that C(P) is minimized • OF2: Minimum Load Path (MLP) • Find a path P such that ( Max {(B(Lpi) - R(Lpi)) / B(Lpi), i=1..K } ) is minimized • OF3: Maximum residual Bandwidth Path (MBP) • Find a path P such that ( Min { R(Lpi)), i=1..K } ) is maximized • Objective functions that apply to a set of path requests • OF4: Minimize aggregate Bandwidth Consumption (MBC) • Find a set of paths such that ( Sum {B(Li) - R(Li), i=..N} ) is minimized • OF5: Minimize the Load of the most loaded Link (MLL) • Find a set of paths such that ( Max { B(Li) - R(Li)) / B(Li), i=1..N}) is minimized. • OF6: Minimize the Cumulative Cost of a set of paths (MCC) • Find a set of paths {P1..Pm} such that (Sum { C(Pi), i=1..m}) is minimized

  7. Next Steps • Straightforward PCED and PCEP extensions • We covered the major point raised in Prague, i.e. the definition of the six mandatory objective functions • Stable specification • Only one expected change in next revision: Factorization of the OF in the reply message with synchronized path requests • Running code • Adoption as WG doc?

  8. ThanksQuestions?

More Related