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FINAL EXAM

FINAL EXAM. TUE 5/16 MRST 132 10:30 - 12.30 - open book/open notes - 25% of final grade - off campus students will receive exam by postal mail. A FLEXIBLE MODEL FOR RESOURCE MANAGEMENT IN VIRTAL PRIVATE NETWORKS N.Duffield, P.Goyal …. Proc. of ACM SIGCOMM’99. A. B.

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FINAL EXAM

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  1. FINAL EXAM TUE 5/16 MRST 132 10:30 - 12.30 - open book/open notes - 25% of final grade - off campus students will receive exam by postal mail

  2. A FLEXIBLE MODEL FOR RESOURCE MANAGEMENT IN VIRTAL PRIVATE NETWORKS N.Duffield, P.Goyal …. Proc. of ACM SIGCOMM’99

  3. A B What are Virtual Private Networks? • Virtual network that allows secure association between end points • Features-security -performance isolation -guaranteed bandwidth, loss, delay =>logically similar to a private leased line.

  4. VPNs for Multiple Endpoints - Large customers => multiple end points - Users are unwilling to specify point-to-point bandwidth matrix. - No multiplexing gains.

  5. Branch C Branch A service provider’s IP Branch B VPNs with Multiple Endpoints • Organizations with multiple branch offices need VPNs with multiple end points • Customer Pipe Model

  6. C in/out A in/out Branch C Branch A B in/out Branch B VPNs with the Hose Model - customer-pipes - endpoints

  7. Hose Model Advantages -Ease of specification -Flexibility -Multiplexing gain -Characterization -Statistical Multiplexing gains -Resizing

  8. B 2 1 C A F E D G 3 Implementation scenarios -Provisioned VPNs -Dynamically Resized VPNs -study workload -resize

  9. AN EXPERIMENTAL STUDY OF INTERNET ROUTING CONVERGENCE C.Labovitz, A Ahuja, A.Bose, F.Jahanian Proc. Of SIGCOM 2000, Stockholm, Sweden

  10. Motivation -Study impact of path failures, failovers and repairs on inter-domain routing convergence -Telephone network: failover takes milliseconds -Internet: failover takes several minutes -Why does convergence take this long?

  11. Upstream ISP BGP fault BGP ISP3 AS AS BGP fault BGP ISP4 Internet BGP ISP6 Upstream ISP Methodology -Fault injection at probe points -Monitor (passively) major exchange points FI server Collect data Fault = routing failures, repairs, multihome failures

  12. Key Results -BGP uses path vectors => eliminate count to infinite problem. BUT increases possibility of oscillations -Avg failover time 3 mm(15 min in some cases) -theoretical upper bound on convergence # of states explored O(e(n-1)!); n = #AS -Lower bound ((n-3)*30)sec,O(n) states. -Reason interactions of protocol timers -Impact: loss rate increases by factor of 30, latency by factor of 4 -Minor implementation changes can reduce bounds

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