1. Requirements for PCE Discovery draft-leroux-pce-discovery-reqs-00.txt Jean-Louis Le Roux (France Telecom) Paul Mabey (Qwest) Eiji Oki (NTT) Ting Wo Chung (Bell Canada) Raymond Zhang (BT Infonet) IETF 62, Minneapolis 03/07/2005

2. Where this ID fits in with the PCE Charter l This draft lists a set of functional requirements for an automatic discovery of PCEs è No assumption on the protocol(s) that could be used l From PCE Charter and milestones : "Specification of techniques in support of PCE discovery within and across domains. -Feb 05 Submit first draft of PCE discovery requirements and protocol extensions documents"

3. Problem Statement l A PCC may have to be aware of a potentially large number of PCEs è PCEs with distinct capabilities, PCE load balancing, redundancy, PCEs in adjacent domains l Manual PCE configuration may have some limitations è A Potentially huge configuration overhead on each PCC è No discovery of a change in PCE capabilities or that a PCE is no longer alive l Hence a mechanism allowing for Automatic and Dynamic PCE discovery is highly required l Note: No distinction between PCE discovery by PCC or by PCE è A PCE that has to request a path of another PCE can be considered as a PCC

4. Requirements overview l The PCE Discovery Mechanism MUST allow a PCC è To automatically discover a set of PCEs in its domain è To automatically discover PCEs of other domains that are relevant for inter-domain path computation purpose l MUST allow learning information about a set of PCE capabilities l MUST allow detecting a new PCE or when a PCE capability has changed

5. Application Example l Potentially a large number of PCEs in the backbone area l Manual config would lead to the configuration of N PCEs per PCC… è (N can be > 50 in operational networks) l Automatically PCE Discovery => Each PCC discovers all PCEs l Multi-area network with 1 backbone area and N areas l Multi-area TE-LSP placement with inter-PCE communication l PCE function distributed on several ABRs Area 1 Area 0 Area 2 Area 3 Area 4 Area 5 Area N * * * * * * * * * * * ABR ABR acting as PCE R1 R2

6. Detailed requirements1/3 l Discovery of PCE location è IP address (v4 or V6) to be used to reach the PCE => Typically a loopback address always reachable l Discovery of PCE capabilities: è Path related capabilities –Capability to compute MPLS-TE, GMPLS paths –Link/Path constraints that can be handled –Supported optimization criteria –Support for backup path computation –… è Path Computation Scope: intra-area, inter-area, inter-AS è Domain IDs : Area IDs, AS Numbers… è Path computation power è …

7. Detailed requirements2/3 l Discovery of backup PCEs è A PCE may indicate a backup PCE to be used in case of failure è This would ease the backup selection procedure l Control of the Scope of Discovery, on a per PCE basis è MUST allow controlling to which PCC or group of PCCs the information related to a PCE will be advertised –All PCCs in a single IGP area, –All PCCs in a single AS –A set of one or more PCCs in a set of one or more ASs –… è MUST support discovery across areas and AS boundaries

8. Detailed requirements3/3 l PCE Discovery Information Synchronization è Detect any change in PCE capabilities è Detect a new PCE è Time scale for such detection : Within 60s l A specific PCE selection algorithm should be defined è Ensure consistency in computation load balancing behavior è Detailed requirements are beyond the scope of this doc l Scalability with an increase of : è Number of PCCs è Number of PCEs è Number of IGP areas in the discovery scope è Number of ASs in the discovery scope

9. Remaining issues l Address received comments l Need to improve the security section, particularly for inter-AS PCE discovery è Secured PCE discovery è Identity of any PCE can only be learnt by authorized PCC l Discovery of dynamic parameters such as the PCE CPU state ? è Would improve PCE selection and load balancing è Need to control the frequency of such advertisements l What about PCE aliveness detection ? è Should belong to the PCE discovery procedure? è Should belong to the PCC-PCE communication? è Both?

10. Next Steps l Interest for this work ? l Consensus for a WG doc ? l Please send your comments to the PCE mailing list