Faital, On Nov 9, 2012, at 12:20 AM, Fatai Zhang wrote:
>The delegation of LSP control to a PCE is *implicit* in RFC4655. When a PCC >sends a PCReq message to a PCE requesting path computation (and parameter >setting) for an LSP, it effectively > delegates control over that LSP to the PCE. The delegation is valid for one > request (and one path computation) only. [Fatai] I don't think that RFC4655 can support delegation of LSP *control* (even implicitly). A PCC sends a PCReq to a PCE, it does not mean that this LSP is delegated to the PCE. By requesting a path computation from a PCE, the PCC gives the PCE authority to determine the ERO, LSP Bandwidth, protection, LSP setup and hold priorities, etc. The PCE is the entity that determines these parameters - would you agree? Now, whether we use "control", "authority", "power", "mandate", whatever - that does not change the fact that the PCC asks the PCC to determine what the LSP parameters are, and the PCE determines what the LSP parameters are. That's what we call delegation - the PCC "delegates" the computation of LSP path and determination of LSP parameters to the PCE. My email states a little later: "the PCC may or may not use the LSP path/parameters that it got from the PCE". We all agree that the PCC has the ultimate control over the LSP - it may take the directions from the PCE, it may not. draft-ietf-pce-stateful-pce does not change any of this. The PCC gives the PCE the control/authority/mandate/power to determine the LSP's parameter. But, rather than doing this implicitly by requesting the PCE to determine those parameters (in a PCReq message), it does it explicitly. Delegation does not change the paradigm set by RFC4655 and RFC5440 - but in addition to LSP parameters, it allows the PCE to determine the timing of the LSP setup. If you don't like the term "delegation", please suggest another one. I don't particularly care what we call the mechanism. Thanks, Jan
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