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Selective Flooding for Improved Quality-of-Service Routing

Selective Flooding for Improved Quality-of-Service Routing. Mark Claypool and Gangadharan Kannan. Presented by Hariharan Kannan. Worcester Polytechnic Institute Worcester, MA-01609, USA . Selective Flooding for Improved Quality-of-Service Routing . Introduction Our Approach

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Selective Flooding for Improved Quality-of-Service Routing

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  1. Selective Flooding for Improved Quality-of-Service Routing Mark Claypool and Gangadharan Kannan Presented by Hariharan Kannan Worcester Polytechnic Institute Worcester, MA-01609, USA

  2. Selective Flooding for Improved Quality-of-Service Routing • Introduction • Our Approach • Implementation • Evaluation • Conclusions

  3. Introduction • The Internet : Connection-less, best effort, shared resources. • QoS Routing : Connection oriented, Guarantees on QoS. • Feasible path search that satisfies QoS constraints of a connection. • Network Topology : Available Paths. • Link State Information : Available Bandwidth. • Call Blocking Rate.

  4. Flooding, Source Routing • Flooding. (K.J.Shin et.al., Sep 1995). • No expensive LSAs, latest and hence, most accurate. • High network bandwidth overhead. • Source routing. ( Z.Zhang et.al., Sep 1997 ). • Expensive LSAs. • Stale information, hence high call blocking rate. • High computing cost at switches per call. • Goals. • Low call blocking rate. • Reduced network overhead.

  5. Our Approach: Selective Flooding • Store network topology as a graph at every source. (static). • Multiple routes are computed and stored at the source. • Bellman-Ford algorithm for computation of path. (Bellman, 1958, Ford et.al., 1962). • On QoS request "selectively" flood control packets. • Packets collect QoS info on the path. • Destination/Source then chooses optimal/feasible path. • Advantages. • Reduced Network overhead : On demand, selective. • Reduced CBR : Recent LS information.

  6. A B C D E QoS Routing Illustration Nodes Links Goal: A-E Feasible Path search. Illustration : Topology

  7. B C A E E D C B A D QoS Routing Illustration: Source Routing X - Routing failure 1 1 2 X

  8. C A B C D E E D B A QoS Routing Illustration: Selective Flooding X - Routing failure 1 1 1 1 1 1 2 X 2 2 X

  9. Implementation • Routesim. (A.Shaikh, Jun 1999) (A.Shaikh et.al., Oct 1998). • ( http://www.eecs.umich.edu/~ashaikh/research/ ). • Event driven simulator. • Topology, Traffic generation, Routing algorithm, Link-state updates. • Enhancing Routesim. • Finding multiple paths. • Selective flooding algorithm.

  10. Calls: • 6% bandwidth/call • Poisson inter-arrivals. • Heavily tailed . Evaluation • Selective Flooding vs. Source Routing • Performance Measures: • Call Blocking Rate • Network Overhead

  11. Source Routing SF

  12. Conclusions • Source Routing : • Call Blocking Rate vs. Network Overhead tradeoff. • Selective Flooding : • Reduced call blocking rate, latest LSAs. • Low switch computation overhead at marginal bandwidth overhead. • Reduced call setup time.

  13. Future Work • Hierarchical Routing for Scalability. • Periodic link-state updates to provide fresh topology “snapshots”. • Combine with source routing for volatile networks. • Busy switches can block probing packets.

  14. Selective Flooding for Improved Quality-of-Service Routing Mark Claypool and Gangadharan Kannan Presented by Hariharan Kannan Worcester Polytechnic Institute Worcester, MA-01609, USA

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