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Capacity Management and Routing Policies for Voice over IP Traffic

Capacity Management and Routing Policies for Voice over IP Traffic. Partho P. Mishra, Gigabit Wireless Huzur Saran, Indian Institute of Technology Delhi. Outline. Review the routing algorithm used in voice(circuit-switching) and data(IP) network

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Capacity Management and Routing Policies for Voice over IP Traffic

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  1. Capacity Management andRouting Policiesfor Voice over IP Traffic Partho P. Mishra, Gigabit Wireless Huzur Saran, Indian Institute of Technology Delhi Chin-Kai Wu, CS, NTHU

  2. Outline • Review the routing algorithm used in voice(circuit-switching) and data(IP) network • Evaluate the performance of two distinct models for capacity management (on IP-based network) • Integrated Services Model (SPF, SAPF, WAPF) • VPN Model (DPO, STT, ASDR) • Experiment results. Chin-Kai Wu, CS, NTHU

  3. Routing Polices Used in Existing Circuit-Switched Network • DPO – accept only when adequate capacity on direct path between originating and terminating switches • Always possible exceed capacity due to transient overload • Alternative routing policy - A two-hop route • Predetermined order • Randomize the start point of search • According to historical load information • STT (Success To the Top) Chin-Kai Wu, CS, NTHU

  4. N-Clique N-Clique N-Clique Search each switch From 1 to N Search each switch From Random Switch Routing Polices Used in Existing Circuit-Switched Network Originating Intermediate Terminating Randomize Start Search Switch Predetermined STT Maintain a stack For success switch Is the top one Chin-Kai Wu, CS, NTHU

  5. Routing Polices Used in Existing Circuit-Switched Network • SDR – State Dependent Routing • Consider the existing state of a link • Determine intermediate switch: • Ex. • ASDR – Approximate SDR • Based on predicted link loads (periodic link state updates) K = MAX(min(Avail(I, L), Avail(L, J))) 10 10 1 10 Chin-Kai Wu, CS, NTHU

  6. Routing Polices Used in Existing Circuit-Switched Network • Alternate path routing can demonstrate instability under heavy load. “trunk reservation” always used to address this potential problem. • Trunk Reservation • When available capacity is below trunk reservation parameter, alternate path routing will be refused. Chin-Kai Wu, CS, NTHU

  7. Routing Polices Used in ExistingIP Network • Traditionally employ only a single forwarding path at a time between a pair of IP routers (OSPF). • Certain extension to OSPF offer multipath routing capability. • More recently, multiprotocol label switching (MPLS) offers another mechanism through which multiple logical paths or links may be configured. Chin-Kai Wu, CS, NTHU

  8. The Integrated Services Model for Capacity Management • The routing of the RSVP signaling messages follows the path determined by the IP layer routing protocol. • Sophisticated QoS-sensitive routing policies may be viewed as analogous to STT/SDR-like policies in IP world. PSTN IP Network RSVP Message Chin-Kai Wu, CS, NTHU

  9. The Integrated Services Model for Capacity Management • Two extremes policies for choosing alternative path: • SAPF – Shortest Available Path First, explored in the order of hop count. • WAPF – Widest Available Path First, maximum (current) available capacity. • Not been deployed very widely. • Because of scalability problem resulting from the need to implement per-flow signaling and retain per-flow state at every router on the end-to-end path of a flow. Chin-Kai Wu, CS, NTHU

  10. The VPN Model for Capacity Management router • The VLL(Virtual leased lines) requires the customer to request capacity to accommodate the worst case traffic requirements for each VLL. • The use of alternate routing policies can be viewed as a way to compensate for traffic burstiness and improve the efficiency ISP’s network VPN VLL Chin-Kai Wu, CS, NTHU

  11. Experiment Environment 12 core routers 42 links 168 PSTN Gateway Chin-Kai Wu, CS, NTHU

  12. Results (trunk reservation) Chin-Kai Wu, CS, NTHU

  13. Results (Greater Traffic Aggregation) Chin-Kai Wu, CS, NTHU

  14. Results (Integrated Service Model) Chin-Kai Wu, CS, NTHU

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