Hi Yongli, Thanks for reviewing the draft. In response to your questions:
1. The Parent PCE will determine the likely domain paths from the source to the destination. The Parent PCE will then send an edge-to-edge request to a Child PCE in the ingress domain (ingress-to-edge), and requests to a Child PCE in each candidate transmit domain (edge-to-edge) and finally a Child PCE in the egress domain (edge-to-egress). Once the responses are collated a suitable path can be identified and selected by Parent PCE. The Parent PCE will then send a response back to the Child PCE in the ingress domain. The Child PCE will then send an ERO response to the PCC that requested the inter-domain path. 2. H-PCE has been designed so the Parent PCE will not have the same detailed internal domain topology information of the Child PCE's it services. However the Parent PCE does know capabilities of the links that connect the domains together. The inter-domain link information would be reported by the Child PCE during the initial Child and Parent PCE information exchange. The Child PCE can learn about its inter-domain links via its domain IGP. During "step 9" of the example procedure the Parent PCE has the opportunity to apply network or policy constraints based on its knowledge of the inter-domain links selected for the candidate path. So in summary, one aim of H-PCE is to avoid the need for anyone one entity to have a detailed topology view of each transit domain. A Child PCE per domain, is used to compute a segment of the end-to-end path. The Child PCE can also replace its path segment information with a path-key [RFC5520] to further maintain confidentiality. On review of the step 9 procedure, we will update the text so the process and actual network topology view is clearer. Br, Dan. From: 赵永利 [mailto:[email protected]] Sent: 03 January 2010 09:45 To: [email protected] Cc: [email protected] Subject: question on draft-king-hierarchy-fwk-03.txt Hi Dan, I have two questions on the document "draft-king-hierarchy-fwk-03.txt". (1) In the procedure of section 5.6.2, three domain paths have been gained, and PCEs 1 to 4 have received the path compuation requests from the parent PCE. Does it mean that the parent PCE will send edge-to-edge path computation requests to all the PCEs along all the domain paths? (2) In step 9 of the same section, it seems not very clear about the compuation responses in the sentence of "PCE 5 correlates all the computation responses from each child PCE". Does it mean the detailed constraint-based path segments in the local domain? Thank you very much. Best regards. Yongli Zhao Beijing University of Posts and Telecommunications Beijing, China _______________________________________________ Pce mailing list [email protected] https://www.ietf.org/mailman/listinfo/pce
