2000/10/02Chin-Kai Wu, CS, NTHU1 Capacity Management and Routing Policies for Voice over IP Traffic Partho P. Mishra, Gigabit Wireless Huzur Saran, Indian Institute of Technology Delhi

2000/10/02Chin-Kai Wu, CS, NTHU2 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.

2000/10/02Chin-Kai Wu, CS, NTHU3 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)

2000/10/02Chin-Kai Wu, CS, NTHU4 Routing Polices Used in Existing Circuit-Switched Network OriginatingIntermediateTerminating Predetermined N-Clique Search each switch From 1 to N Search each switch From Random Switch Randomize Start Search Switch STT Maintain a stack For success switch Is the top one

2000/10/02Chin-Kai Wu, CS, NTHU5 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) Routing Polices Used in Existing Circuit-Switched Network K = MAX(min(Avail(I, L), Avail(L, J))) 10 1

2000/10/02Chin-Kai Wu, CS, NTHU6 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.

2000/10/02Chin-Kai Wu, CS, NTHU7 Routing Polices Used in Existing IP 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.

2000/10/02Chin-Kai Wu, CS, NTHU8 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. IP Network PSTN RSVP Message

2000/10/02Chin-Kai Wu, CS, NTHU9 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.

2000/10/02Chin-Kai Wu, CS, NTHU10 The VPN Model for Capacity Management 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 VPN ISP’s network router VLL

2000/10/02Chin-Kai Wu, CS, NTHU11 Experiment Environment 168 PSTN Gateway 12 core routers 42 links

2000/10/02Chin-Kai Wu, CS, NTHU12 Results (trunk reservation)

2000/10/02Chin-Kai Wu, CS, NTHU13 Results (Greater Traffic Aggregation)

2000/10/02Chin-Kai Wu, CS, NTHU14 Results (Integrated Service Model)