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Traffic Engineering and Routing

Traffic Engineering and Routing . Hansen Bow. Topics. Traffic Engineering with MPLS Issues Concerning Voice over IP Features of Netscope QoS Routing for High-Speed Networks QoS Routing for Multimedia. Traffic Engineering with MPLS: Methods. MPLS – multiprotocol label switching

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Traffic Engineering and Routing

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  1. Traffic Engineering and Routing Hansen Bow

  2. Topics • Traffic Engineering with MPLS • Issues Concerning Voice over IP • Features of Netscope • QoS Routing for High-Speed Networks • QoS Routing for Multimedia

  3. Traffic Engineering with MPLS:Methods • MPLS – multiprotocol label switching • Constraint-based routing • Enhanced link state IGP

  4. MPLS-multiprotocol label switching • forwarding scheme • at ingress of MPLS network, IP packets are classified, tagged, and routed • at next router, tag is used to determine destination • before leaving, tag is removed

  5. Constraint-Based Routing • computes bounded routes • reservable bandwidth of a link is an approximation • can be done online or offline

  6. Enhanced Link State IGP (interior gateway protocol) • distribute link information • flood network to obtain information

  7. Deploying MPLS System (GlobeCenter) • Statistics Collection • Deploy LSP (label-switched path) with bandwidth constraint • Periodic update of LSP Bandwidth • Offline Constraint-Based Routing

  8. Voice over IP Issues • modify capacity management and routing methods in IP to support IP telephony • delay less than 300ms • loss rate <1% • First Model: RSVP • Second Model: voice service uses Virtual Private Network

  9. RSVP Routing • Shortest Path First • Shortest Available Path First • Widest Available Path First

  10. Virtual Private Networks • interconnects telephony switches • Direct Path Only • Success to the Top • State-Dependent Routing • Approximate State-Dependent Routing

  11. Direct and Alternate Routing Policies

  12. Differently Routed Calls with Trunk Reservation

  13. Routing Policies with Integrated Services Model • not much difference between SPF, SAPF, WAPF • fewer blocked calls for a given network capacity because of better sharing of network capacity

  14. Features of Netscope • traffic measurement and network modeling • provide global views of configuration and useage data

  15. Utility of Netscope • realizing customer SLAs • tuning parameters of network components • unite configuration • experiment with possible solutions to variable complex traffic

  16. Data • Network components • Modeling Traffic • Routing • multiple shortest paths

  17. Visualization • Objects • Statistics • Traffic and Links • Changing Routes

  18. QoS Routing Issues for High Speed Networks • Goals • satisfy QoS requirements for admitted connection • global efficiency • Classes • Source routing • Distributed routing • Hierarchical routing

  19. Routing • Collection of State Information • local and global state • aggregated global state

  20. Routing • Finding Feasible Path • Unicast • link optimization • link constrained • path optimization • path constrained • Dijkstra’s algorithm • http://www.cs.uwa.edu.au/undergraduate/courses/230.300/readings/graphapplet/graph.html • Multicast • Steiner Tree

  21. Routing Strategies • Source routing • centralized problem, loop-free • need global state, computation overhead • Distributed routing • routing response faster, scalable • need global state, more messages, loops • Hierarchical routing • scales well, computation shared • imprecision because aggregate state, complicated with constraints,

  22. Future Directions • Efficient Routing Algorithms • Routing with imprecise state information • Multipath Routing • Rerouting

  23. QoS Routing for Multimedia • Metric Selection • Efficient algorithms must exist for path computation • Reflect basic information of network • orthogonal • Multiple Metrics • additive, multiplicative, concave

  24. Bandwidth and Delay as Metrics • finding path subject to two or more additive and multiplicative metrics is NP-complete • only feasible combination is bandwidth and, for example, delay

  25. Path Computation Algorithms • Source Routing • Hop-by-hop • compute best path to every destination • shortest-widest path is free of loops

  26. References • “NetScope: Traffic Engineering for IP Networks,” A. Feldmann, A. Greenberg, C. Lund, N. Reingold, and J. Rexford, IEEE Network, Mar./Apr. 2000, pp. 11-19 • “Traffic Engineering with MPLS in the Internet,” X. Xiao, A. Hannan, B. Bailey, and L.M. Ni, Ibid., pp. 28-33 • “Capacity Management and Routing Policies for Voice over IP Traffic,” P.P. Mishra, and H. Saran, Ibid, pp. 20-27 • “Quality-of-Service Routing for Supporting Multimedia Applications,” Z. Wang, and J. Crowcroft, IEEE Journal on Selected Areas in Communications, Vol. 14, No. 7, Sept. 1996 • “An Overview of Quality of Service Routhing for Next-Generation High-Speed Networks: Problems and Solutions,” S. Chen and K. Nahrstedt, IEEE Network, Nov./Dec. 1998, pp. 64-79

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