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  1. Network Research at CTI James Yu, Ph.D. Assistant Professor School of CTI jyu@cs.depaul.edu DePaul University

  2. James Yu, Ph.D. • Ph.D. in Computer Science from Purdue University, 1985 • [Distinguished] Member of Technical Staff, Bell Labs, Lucent Technologies, 1985 – 2000 • Director of Network Technologies, ARBROS Communications, 2000 – 2001 • Assistant Professor, DePaul University, 2002 - now DePaul University

  3. Research Interests • Network Performance Evaluation • Wireless Security • VoIP Traffic Engineering • Fault Tolerant Network Design • Network education: hands-on exercises for distance learning students DePaul University

  4. Framework of Network Research Problem Statement Empirical Framework Theoretical Model References Solutions to The problem Revision Data Analysis Comparative Study Conclusion DePaul University

  5. Network: the BIG Picture PSTN NNI Network Services and Management Internet Switched Network Access Network Security Layer Transport Network ISP Network UNI carrier network Security Layer Security Layer Data LAN Voice Network 2G/3G Network Data Center Call Center cellular network converged enterprise network DePaul University

  6. Project I: Performance Analysis Key measurement: throughput (bps) and delay (ms or s) Ethernet Switch IP Router Linux Bridge/Router Windows Bridge/Router DePaul University

  7. One-way Delay (in s) on 100baseTX Link (Linux Bridge vs. Linux Router) Throughput (bps) on 100BaseTX Link (Linux Bridge vs. Linux Router) DePaul University

  8. Switch Performance Comparisonon Gigabit Ethernet Question: could you develop a problem statement from this chart? DePaul University

  9. Wireless Performance Question: why is TCP performance is only 50% of the line rate for wireless communications? DePaul University

  10. Project II: Wireless Denial of Service (DoS) Research DePaul University

  11. TCP performance under DoS Stop Start DePaul University

  12. SS7 SS7 IP (internal) IP (public) IP (private) Project III: VoIP Research PSTN Switch PSTN Switch SoftSwitch SoftSwitch Carrier VoIP Network Trunk MG Trunk MG Call Manager (SIP Proxy) Q.931 Access MG Call Manager (Enterprise) MG: Media Gateway DePaul University

  13. VoIP: Traffic Engineering • Design the network with sufficient capacity to meet the traffic demand with satisfactory performance • Requirement: assurance of Voice Quality. • If call quality cannot be assured, reject the call request. • Demand (A) - Traffic Intensity number of calls × duration of average calls Erlang • Resources (N) – Network bandwidth (bps) and capacity (pps) • Grade of Service (GoS) – blocking probability DePaul University

  14. Research Areas of VoIP • IP Multimedia Subsystem (IMS) • How is a VoIP call from one service provider to another service provider today? • VoIP Security • Voice Quality • Quality of Service (QoS) over internet and intranet • Supplemental and Intelligent Network (IN) services • API and VoXML DePaul University

  15. Project IV: Fault Tolerant Network RSL RSTP (802.1w) VRRP Dual Homing ISP-01 ISP-02 • Network Design Goal: • No single point of failure • Failover time << 1 sec DePaul University

  16. Project V: Remote Lab Access Linux Gateway Public Internet Private Networking Labs Windows Terminal Server Devices w/ Console interface Devices w/ IP interface Telecom Terminal Server Console interface Problem Statement: supporting distance learning students to perform hands-on network exercises from any place with 24×7 access to the network lab DePaul University

  17. Conclusions • Evolution of the telecom networks and network technologies • Convergence of PSTN and Internet • Growing demand for wireless networks (bandwidth utilization, more bandwidth, new applications, etc.) • Increasing threat and concerns of network security • Higher requirements for network reliability and service availability • New generation of devices and services • Needs: more research work DePaul University