Chapter 1

1. IEG4020 Telecommunication Switching and Network Systems Chapter 1 Introduction and Overview

2. Outline 1. Introduction and Overview • Switching and Transmission • Multiplexing and Concentration • Timescales of Information Transfer 2. Circuit Switch Design Principles • Space-domain Circuit Switching • Nonblocking Properties, Complexity • Clos, Benes and Cantor Switches • Time-domain Switching 3. Fundamental Principles of Packet Switch Design • Packet Contention • Interconnection Networks (Banyan Networks) • Sorting Networks • Nonblocking and Self-Routing Properties of Clos Networks

3. Outline 4. Advanced Packet Switching Principles • Performances of Simple Switches • Look-Ahead Contention Resolution • Speedup Principle • Channel-Grouping Principle • Knockout Principle • Replication Principle • Dilation Principle 5. Advanced Switch Design Principles • Switch Design Principles Based on Deflection Routing • Tandem-Banyan Network • Shuffle-Exchange Network • Feedback Shuffle-Exchange Network • Feedback Bidirectional Shuffle-Exchange Network • Dual Shuffle-Exchange Network • Switching by Memory I/O

4. Outline 6. Switching Principles for Multicast, Multirate, and Multimedia Services • Multicast Switching • Multicasting Based on Nonblocking Copy Networks • Performance Improvement of Copy Networks • Multicasting Algorithm for Arbitrary Network Topologies • Nonblocking Copy Networks Based on Broadcast Clos Networks • Path Switching • Basic Concept of Path Switching • Capacity and Route Assignments for Multirate Traffic • Trade-Off Between Performance and Complexity • Multicasting in Path Switching

5. Outline 7. Packet Switching and Information Transmission • Duality of Switching and Transmission • Parallel Characteristics of Contention and Noise • Pseudo Signal-to-Noise Ratio of Packet Switch • Clos Network with Random Routing as a Noisy Channel • Clos Network with Deflection Routing • Cascaded Clos Network • Analysis of Deflection Clos Network • Route Assignments and Error-Correcting Codes • Complete Matching in Bipartite Graphs • Graphical Codes • Route Assignments of Benes Network • Clos Network as Noiseless Channel-Path Switch • Capacity Allocation • Capacity Matrix Decomposition • Scheduling and Source Coding • Smoothness of Scheduling • Comparison of Scheduling Algorithms • Two-Dimensional Scheduling

6. Roles of Switching and Transmission • Merging of computer and communications technologies • Traditional Computer Networks • Services non real time • data rate not too high • service quality not guaranteed • Telephone Networks • Real time • low data rate (64 kbps) • Service quality guaranteed

7. Roles of Switching and Transmission • Computer Networks on Telephone Networks • Modems • leased line • Multimedia services • Integrated Communications Networks • Broadband • Integration • Support of unforeseen services

8. Transmission Facilites Control Functions Switching Facilites Switching center A Transmission Line B Roles of Switching and Transmission

9. Fig. 1.1. A two-user network; switching is not required Roles of Switching and Transmission Transmission Medium A B When there are only two users, information from A is by default destined for B, and vice versa For a two-user network, switching is not required

10. Roles of Switching and Transmission Fig. 1.2. A three-user network; switching is required C Switching A B Information from A may be destined for B or C For a three-user network, switching is required

11. . N 1 . . 2 3 . N 1 . Central Switch . 2 3 Roles of Switching and Transmission Fig. 1.3. N-user networks with switching performed (a) at users' location (b) by a central switch Switching is performed at user’s location by selecting one of the links for reception # of bi-directional links = N(N-1)/2 Switching is performed by a central switch

12. user user Switching center user Long Transmission Lines . . . . . . Roles of Switching and Transmission An example in which totally centralized switching is not attractive In case the totally centralized switch is not attractive, no communication can be processed between any users

13. Higher Level Hierarchy Primary Office Toll Office D . . . . . . . . . . . . LocalOffice(End Office) A B C Subscribe Loop Transmission Hierarchy Fig. 1.4. Telephone network hierarchy i.) Decrease of Traffic volume as going up in hierarchy ii.) Resources at upper hierarchy shared by larger population iii.) Hierarchical routing

14. S1 Frequency Modulator Filter for S1 Receiver 1 Source 1 S1,S2,…,SN Frequency Modulator Filter for SN SN Receiver N Source N Transmission Medium . . . . 1 1 1 1 0 0 0 0 . . Multiplexing and Concentration Fig. 1.5. Frequency-division multiplexing

15. B bps Frame Time Slot Source 1 Receiver 1 D E M U X M U X . . . . . . Source 2 Receiver 2 NB bps Source N Receiver N Multiplexing and Concentration Fig. 1.6. Time-division multiplexing

16. I bits/s O bits/s Inputs Outputs 1 1 . . . . . . . . . . . . 2 2 N N Multiplexing and Concentration Difference between Multiplexing and Switching : Difference between Multiplexing and concentration : I = O in mux. system I > O in concentrator Connectivity is static in mux, system but dynamic in switching system

17. N x M Concentrator (N > M) Output 1 Input 1 Output 2 Input 2 . . . . Output M Input N . . Multiplexing and Concentration Fig. 1.7. An N x M concentrator An active input is assigned to one of the outputs. It does not matter which output is assigned.

18. Arriving packets B bps Input 1 2 1 Less than NB bps Statistical Multiplexer Input 2 3 3 2 1 Transmission capacity is shared dynamically among the input according to packet arrivals . . . Input N Multiplexing and Concentration Fig. 1.8. A Statistical multiplexer • Combines multiplexing and concentration • Packet header indicating destination • Switching involved • Connectivity changes with time

19. TASI : . . N x M Satellite Links assigned based on talkspurts . . . . N > M Multiplexing and Concentration Sessions, circuits (concentration) : • Session needs to be set up before communication • Exclusive and non-exclusive dedication of resources during connection • Virtual circuits (not connection oriented) Messages (Statistical multiplexing) : • variable packets • talk spurts

20. Timescales of Information Transfer Packets and Cells : • Transport Entities • Variable versus fixed length • Long versus short packets Messages are broken into smaller packets in network since: • Network does not support large packet size • Most networks are store-and-forward network, less delay under light load • Prevent a long packet from hogging a communication channel

21. Switch Concentrator . . . . . . . . . . . . . . . Concentration used to reduce switching cost

22. Broadband Integrated Services Network • Capable of supporting many different kinds of services • Same resources can be assigned to different services at different times • Better resources sharing (different services have different peak times) • Support unforeseen future services Challenge: How to support and control traffic of diverse characteristics in one single network?

23. Duration of Session (second) 107 High-quality Entertainment Video 106 Conference Video 105 104 Voice 103 Low-speed Data 102 High-speed Data Information Retrieval Telemetry 10 1 Bit Rate (bps) 0 1010 106 107 108 109 1 10 102 103 104 105 Broadband Integrated Services Network Fig. 1.9. Holding times and bit rates of various services

24. Fig. 1.10. Traffic characteristics of sources of different burstiness Bursty Traffic Bit Rate Time Less-bursty Traffic Bit Rate Time Continuous Traffic Bit Rate Time ~END~