"Encoding of Objective Functions in Path Computation Element (PCE) communication and discovery protocols", Jean-Louis Le Roux
http://www.ietf.org/internet-drafts/draft-leroux-pce-of-01.txt
The computation of one or a series of Traffic Engineering Label Switched Paths (TE LSP) in MultiProtocol Label Switching (MPLS) and Generalized MPLS (GMPLS) networks, is subject to a set of one or more specific optimization criteria(s), referred to as an objective function (e.g. minimum cost path, widest path, etc.). A Path Computation Element (PCE) may support one or multiple objective functions, and it is desired for a Path Computation Client (PCC) to automatically discover the set of objective functions supported by a PCE. Furthermore, it may be useful for a PCC to specify in a path computation request the required objective function used by the PCE to compute a TE LSP or a set of TE LSPs. Thus the aim of this document is to define extensions to the PCE Discovery (PCED) TLV carried within the IS-IS Router Capability TLV and the OSPF Router Information LSA so as to allow a PCC to discover the set of objective functions supported by a PCE. Extensions to the PCE communication Protocol (PCEP) are also specified allowing a PCC to indicate in a path computation request the required objective function and a PCE to indicate in a path computation reply the objective function actually applied.2007-07-10T22:00:00-00:00