Dan, Many thanks for your fast reply. Are you familiar with any "real-time" implementation of few of the PCE ideas? Anyone that implements the distributed approach? Warm regards, David Amzallag, BT
________________________________ From: Daniel King [mailto:[EMAIL PROTECTED] Sent: 19 June 2008 12:50 To: [email protected] Subject: RE: [Pce] Concurrent Optimization and More Hi David, A few quick responses: >>1. How does the protocol for computing a single path works in a hierarchical network (more than one level of PCE's)? So far this requirement has been out of scope for the current work. There is growing momentum in the application of PCE to multi-layer networks, ASON, and "domain-paths." So this topic will require further thought and discussion. >>2. What the draft for the concurrent optimization referred to: only inside of a sub-domain or also an inter-domain optimization which requires communication between the PCE's? As above. The pce-global-concurrent-optimization draft focuses on single domain optimisation, specifically the PCC-PCE communication needs and protocol extensions to support the concurrent optimisation. Although, the authors do mention that a Global Concurrent Optimization (GCO) is applicable to a Virtual Network Topology (VNT) and multi-layer traffic engineering for new deployments. >>3. Can we assume that the node's demands are splittable (i.e., can be simultaneously satisfied by more than one path)? I may need some further clarity on this question. Do you mean that there may be more than one possible solution to a path computation, or that the solution to the computation may be a set of "parallel" paths with some assumption of load sharing (e.g. inverse multiplexing)? The answer to the first question is yes and is already done, although some work might be required to allow the PCE to supply a choice of paths to the PCC. The answer to the second question is also yes, but (very simple) protocol extensions will be needed to handle this case. Other relevant drafts you may find interesting for this topic include: A Path Computation Element (PCE)-Based Architecture http://www.ietf.org/rfc/rfc4655.txt A Framework for Inter-Domain Multiprotocol Label Switching Traffic Engineering http://www.ietf.org/rfc/rfc4726.txt A Per-Domain Path Computation Method for Establishing Inter-Domain Traffic Engineering (TE) Label Switched Paths (LSPs) http://www.ietf.org/rfc/rfc5152.txt Evaluation of existing GMPLS Protocols against Multi Layer and Multi Region Networks (MLN/MRN) http://www.ietf.org/internet-drafts/draft-ietf-ccamp-gmpls-mln-eval-05.t xt A Backward Recursive PCE-based Computation (BRPC) Procedure To Compute Shortest Constrained Inter-domain Traffic Engineering Label Switched Paths http://www.ietf.org/internet-drafts/draft-ietf-pce-brpc-09.txt Br, Dan From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: 19 June 2008 07:25 To: [email protected] Subject: [Pce] Concurrent Optimization and More Hi, I have three basic questions (but I might the correct place in RFCs or drafts for that...); 1. How does the protocol for computing a single path works in a hierarchical network (more than one level of PCE's)? 2. What the draft for the concurrent optimization referred to: only inside of a sub-domain or also an inter-domain optimization which requires communication between the PCE's? 3. Can we assume that the node's demands are splittable (i.e., can be simultaneously satisfied by more than one path)? Many thanks, David Amzallag BT
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