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COMPLEXITY IN NETWORK ARCHITECTURE

COMPLEXITY IN NETWORK ARCHITECTURE. Gunnar Karlsson Laboratory for Communication Networks KTH, Royal Institute of Technology Stockholm, Sweden. Thoughts on architecture. Modernist view Less is more. Ludwig Mies van der Rohe Post-modernist view Less is a bore. Robert Venturi.

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COMPLEXITY IN NETWORK ARCHITECTURE

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  1. COMPLEXITY IN NETWORK ARCHITECTURE Gunnar Karlsson Laboratory for Communication Networks KTH, Royal Institute of Technology Stockholm, Sweden NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  2. Thoughts on architecture Modernist view Less is more.Ludwig Mies van der Rohe Post-modernist view Less is a bore. Robert Venturi NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  3. Form follows function • New functions add to the form • More users represent larger span of tastes, needs and interests • Technical capabilities open new service options • New business models require system support • The architecture of the evolving system is increasingly complex NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  4. Complexity a challenge • Cannot be avoided, must be managed • Research phase • System design • Standardization • Operation • Evolution • Tradoff with performance and functionality NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  5. Design paradigms Commodity components and decentralized systems • Simple systems in large numbers • Self-organizing with synchronized states • Predictable and controllable aggregate system behavior Reduced set of network services • Coordinated by service-specific signaling • Enhanced by functions at the edges NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  6. A reduced-service set architecture A controlled-load service • Packet-scale buffering for low delay • Probe-based admission control • Low priority for probes • High priority for data • Tuneable FEC for quality enhancement QoS PDQ – Transport-level differentiation • TCP for batch data • Free admission, rate-controlled flows • PBAC controlled UDP for streams • Inelastic flows, load-controlled aggregate NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  7. The simplified guaranteed service • Shaping in all nodes • Delay bounds for any number of hops and loads • Makes the reservation state additive • Service specific signaling • Messages carried lossfree in service • Reservation state is a shared variable per link • Fast path processing • Reservation: add rate to shared state variable; subtract to deallocate • Admission control when reservation state reaches max, request is dropped • Garbage collection after lost messages in the background • Short time-scale for dropped reservation messages • Long time-scale for loss of other messages due to transmission errors and link failures • Combined with stateful routing for traffic engineering • Circuit-switched backbones and VPNs NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

  8. Research agenda • Complexity metrics for distributed systems • Allow quantitative comparisons • Computable and applicable • Link to performance metrics for tradeoff analysis • Design methodologies • Modularization, patterns • The role of aesthetics • Standardization process • What should be standardized? • System evolution and ability to upgrade • Interoperability and feature interactions NeXtworking’03 June 23-25, 2003, Chania, Crete, Greece The First COST-IST(EU)-NSF(USA) Workshop on EXCHANGES & TRENDS IN NETWORKING

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