MPLS/SDN 2013 International Conference: Path Computation and Instantiation in Software Defined Networks Using Stateful PCE


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Slides presented by Cisco's Siva Sivabalan and Santiago Alvarez at the MPLS/SDN 2013 International Conference. The 2013 event is the 16th Annual International Conference on Next Generation Internet and Related Technologies. Read more:

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MPLS/SDN 2013 International Conference: Path Computation and Instantiation in Software Defined Networks Using Stateful PCE

  1. 1. Path Computation and Instantiation in Software Defined Networks Using Stateful PCE Siva Sivabalan Santiago Alvarez Cisco Systems {, }
  2. 2. Why PCE as an SDN Component? •  •  •  •  •  SDN premise: programmatic, centralized control can contribute to greater network agility, optimization, customization and automation PCE architecture already enables centralized path computation for large, multi-domain and multi-layer networks PCE provides a good starting point for implementing an SDN model in WAN Commercially available implementation of base functionality available for at least 5 years Recent extensions (SDN driven): stateful PCE, PCEinitiated LSPs, Segment Routing support 2
  3. 3. PCE: One Piece of the SDN WAN Puzzle Workflow Orchestration/Apps Customer SDN APPS APPS DC SDN APIs SDN WAN Customers Viz & Analytics Application Engine Collector Programming IP/MPLS NGN WAN Multi-Layer 3 Segment Routing DC/Cloud Providers
  4. 4. Stateless and Stateful PCE Stateful PCE Stateless PCE LSP DB TED TED PCEP PCEP Stateless PCC Stateful PCC •  More optimal centralized path computation •  Limited ability to optimize network resources (e.g. LSP state, resource usage, policy, network analytics, etc.) •  Enables centralized path initiation and update control •  No knowledge of previously established paths •  Not well suited for SDN deployments •  Still useful for inter-domain MPLS-TE in non-SDN deployments •  Requires LSP state synchronization 4 (LSP database)
  5. 5. Active and Passive Stateful PCE Passive Stateful PCE Active Stateful PCE LSP DB PCE has update control over delegated paths TED PCC maintains update control over paths PCEP LSP DB TED PCEP Stateful PCC Stateful PCC •  PCC initiates path setup •  PCC or PCE may initiate path setup •  PCC retains control on path updates •  PCC may delegate update control to PCE •  PCE learns LSP state to optimize path •  PCC may revoke delegation computation •  PCE may return delegation 5
  6. 6. Active Stateful PCE PCE-Initiated and PCC-Initiated LSPs PCE-Initiated (Active Stateful PCE) Application initiates LSP via PCE PCC-Initiated (Active Stateful PCE) LSP DB LSP DB TED TED PCC initiates LSP based on local policy PCEP Stateful PCC PCEP Stateful PCC •  PCC may initiate path setup based on •  Tighter integration with application demands distributed network state •  Can be used in conjunction with PCEinitiated paths •  PCE can be part of controller architecture determining what paths to set up and when 6
  7. 7. PCE Path Profiles PCE-Initiated (Active Stateful PCE) Path Comp PCEP Create / Initiate Path computation parameters, path profile 10 PCC-Initiated (Active Stateful PCE) LSP DB Path Path profile 10 Comp TED LSP DB TED PCEP Request Destination, path profile 10 Stateful PCC Stateful PCC Path Path Usage Comp Path Path Usage Comp Path profile 10 Path profile 10 •  Path usage profiles preconfigured on PCC •  Path computation profile centralized on •  PCE initiates LSP and references usage PCE •  PCC initiates LSP and only specifies destination and profile id profile id to apply 7
  8. 8. PCE Extensions for Segment Routing (SR) •  Segment routing enables source routing based on segment ids distributed by IGP •  PCE specifies path as list of segment ids •  PCC forwards traffic by pushing segment id list on packets •  No path signaling required •  Minimal forwarding state •  Maximum network forwarding virtualization •  The state is no longer in the network but in the packet Stateful PCE Application LSP DB Path Request TED PCEP Stateful PCC In Node SID Adjacency SID Out Int L1 … L7 L8 … L9 L1 … L7 Pop … Pop Intf1 … Int3 Intf3 … Intf5 Forwarding table remains constant
  9. 9. Summary •  •  •  Stateful PCE is an important SDN enabler providing centralized path computation optimization Different degrees of centralization (computation, updates, initiation, configuration) PCE and SR provide a very compelling SDN solution •  •  PCE Stateless Stateful Passive Tight application integration Maximum network forwarding virtualization 9 Active PCE Initiated paths PCC Initiated paths
  10. 10. References •  •  •  •  •  •  A Path Computation Element (PCE)-Based Architecture RFC 4655 Applicability of Stateful Path Computation Element (PCE) draft-zhang-pce-stateful-pce-app PCEP Extensions for Stateful PCE draft-ietf-pce-stateful-pce PCEP Extensions for PCE-initiated LSP Setup in a Stateful PCE Model draft-crabbe-pce-pce-initiated-lsp PCE Path Profiles draft-alvarez-pce-path-profiles PCEP Extensions for Segment Routing draft-sivabalan-pce-segment-routing 10
  11. 11. Thank you!