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Thus, a PCE is an entity capable of computing paths for a single or set of services. A PCE might be a [[Computer network|network]] node, network management station, or dedicated computational platform that is resource-aware and has the ability to consider multiple constraints for sophisticated path computation. PCE applications compute label switched paths for MPLS and GMPLS traffic engineering. The various components of the PCE architecture are in the process of being standardized by the [[IETF]]'s ''PCE Working Group''.<ref name=pce>IETF's Working Group, [http://www.ietf.org/html.charters/pce-charter.html "Path Computation Element (pce)"]</ref>
PCE represents a vision of networks that separates route computations from the signaling of end-to-end connections and from actual [[packet forwarding]]. There is a basic tutorial on PCE as presented at ISOCORE's MPLS2008 conference.<ref name=tutorial>Basic PCE tutorial [http://www.olddog.co.uk/Farrel_PCE_Tutorial.ppt "PCE Tutorial]</ref>
Since the early days, the PCE architecture has evolved considerably to encompass more sophisticated concepts and allow application to more complicated network scenarios. This evolution includes Hierarchical PCE (H-PCE)<ref name=H-PCE>RFC 6805 [http://www.rfc-editor.org/rfc/rfc6805.txt] "Hierarchical PCE"</ref> and both Stateful and Active PCE.<ref name=Stateful>draft-ietf-pce-questions[http://datatracker.ietf.org/doc/draft-ietf-pce-questions/] "Unanswered Questions in the Path Computation Element Architecture"</ref>
A potential deployment of PCE separates the computation element from the client (the PCC) that request computation services. communications between the PCE and PCC are achieved using the Path Computation Element Communication Protocol (PCEP)<ref name=PCEP>RFC 5440 [http://www.rfc-editor.org/rfc/rfc5440.txt] "Path Computation Element Communications Protocol"</ref> which runs over [[TCP]].
As the architecture has evolved, new protocol extensions have been developed to add functionality to support new applications and the new architectural elements. These developments are tracked by the PACE project<ref name=PACE>PACE [http://www.ict-pace.net/] "PACE: Next Steps in PAth Computation Element (PCE) Architectures"</ref> which is funded by the [[European Union]]'s Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 619712.
The PACE project has developed a primer for those interested in PCE. It can be downloaded without charge from the PACE website.<ref name=primer>PCE Primer [http://www.ict-pace.net/files/3313/8929/2782/PCE_Primer.pdf] "PACE project PCE Primer"</ref>
== PCE extensions ==
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