Communication Systems and Computer Networks (1404703) PDF

Communication Systems and Computer Networks (1404703) Prepared by: Prof. Shawkat K. Guirguis Professor of Computer Science & Informatics 2024-10-15 (c) Prof.Shawkat K...

Communication Systems and Computer Networks (1404703) Prepared by: Prof. Shawkat K. Guirguis Professor of Computer Science & Informatics 2024-10-15 (c) Prof.Shawkat K. Guirguis 1  INTRODUCTION Classification of a computer network Is it: Centralized computing? Decentralized computing? Distributed computing? Network is classified as: ?! (c) Prof. Shawkat K. Guirguis` 2024-10-15 2  USES OF COMPUTER NETWORKS 1. Business applications 2. Home applications 3. Mobile applications 4. Social issues 2024-10-15 (c) Prof. Shawkat K. Guirguis 3  1. Business Applications Integrating Business components: Inventory, Accounting, Payroll Resource sharing Replication of databases and important data Standby machines in case of failures Client-Server model (message / reply) (Query / response) Communication medium (e.g. e-mail) File sharing and Instant view and access of remote activities Videoconferencing Electronic Business systems e-commerce 2024-10-15 (c) Prof. Shawkat K. Guirguis 4  2. Home Applications Access to the Internet for serious or funny matters Person-to-person communication Interactive entertainment Electronic Commerce (Internet shopping) Newspapers (Personalized) Research papers (ACM, IEEE... etc.) Instant messaging Chat rooms 2024-10-15 (c) Prof. Shawkat K. Guirguis 5  2. Home Applications (cont.) peer-to-peer communication (file sharing) Gaming & Gambling VOIP Entertainment (VOD) Online consultations Paying bills Managing bank accounts Handle investment (Stock Market) On line auctions See Next Figure for e-commerce configuration and examples 2024-10-15 (c) Prof. Shawkat K. Guirguis 6  2. Home Network Applications (cont.) Some forms of e-commerce. 2024-10-15 (c) Prof. Shawkat K. Guirguis 7  3. Mobile Users Notebooks and PDAs, why? portable office Wireless internet in conferences, Hotels, universities... etc. People on the move, e.g. Taxi drivers, repair-men.. etc. Military purposes Car rental and payment in remote destinations Wireless utility meter readings, e.g. gas, electricity, water,..etc. WAP (Wireless Application Protocol) Mobile maps Wearable computers 2024-10-15 (c) Prof. Shawkat K. Guirguis 8  4. Social Issues Different chatting habits (Newsgroups and Bulletin Boards) Spying & snooping Hacking Spam Tapping 2024-10-15 (c) Prof. Shawkat K. Guirguis 9  NETWORK HARDWARE Two types of transmission technology known as: A. Broadcast links B. Point-to-point links 2024-10-15 (c) Prof. Shawkat K. Guirguis 10  NETWORK HARDWARE (cont.) Broadcast networks have single communication channel shared by all An address in the packet identifies the recipient It could address a packet to ALL destinations (broadcasting) Or to a SUBSET (multicasting) Point-to-point links Connections between individual pairs. The packet may visit intermediate machines first 2024-10-15 (c) Prof. Shawkat K. Guirguis 11  Network classification by scale 2024-10-15 (c) Prof. Shawkat K. Guirguis 12  Local Area Networks (LANs) Restricted in size i.e. worst case transmission time is bounded and known in advance Speed of 10-100-1000 Mbps Now 10Gbps Topologies: Bus, Ring.. etc. (see next figure) Most popular is IEEE 802.3 standard (ETHERNET), It is a kind of broadcast NW and resolves collision by waiting a random time In ring IEEE 802.5 standard is the token ring Broadcast NW can be divided into: 1. Static channel allocation:. Using time slots and a round-robin algorithm. It wastes channel capacity 2. Dynamic allocation (centralized/decentralized) but with a preset order 2024-10-15 (c) Prof. Shawkat K. Guirguis 13  Local Area Network Topologies (a) Bus (b) Ring 2024-10-15 (c) Prof. Shawkat K. Guirguis 14  Popular LAN network topologies Bus Star Ring Token-ring Tree Mesh Fully connected 2024-10-15 (c) Prof. Shawkat K. Guirguis 15 2024-10-15 (c) Prof. Shawkat K. Guirguis 16  Local Area Networks Comparison Architecture/Organization Delay/Response time Complexity Security Congestion control Routing methodology Reliability Cost 2024-10-15 (c) Prof. Shawkat K. Guirguis 17  Assignment The following network topologies: Bus, Star, Ring, Token-ring, Tree, Mesh, and Fully connected are to be compared according to (at least) the following: Architecture/Organization, Delay/Response time, Complexity, Security, Congestion control, Routing methodology, Reliability and Cost 2024-10-15 (c) Prof. Shawkat K. Guirguis 18  Metropolitan Area Networks (MAN) e.g. Cable TV See next figure 2024-10-15 (c) Prof. Shawkat K. Guirguis 19  Metropolitan Area Networks example 2024-10-15 (c) Prof. Shawkat K. Guirguis 20  Wide Area Networks (WAN) Spans along continents Consists of Hosts, communication lines, switching elements (routers) (connect >=3 lines) Works on store-and-forward (or packet switched) subnet. (N.B. Satellite linked WANs cannot be packet switched) Packets are transmitted individually and assembled at the destination. Routing is due to a routing algorithm 2024-10-15 (c) Prof. Shawkat K. Guirguis 21  Stream of packets 2024-10-15 (c) Prof. Shawkat K. Guirguis 22  Wireless Networks Back to 1901 used Ship-to-shore Morse code Can be divided into three main categories: A. System interconnection using short-range radio B. Wireless LAN (IEEE 802.11) Above 50 Mbps C. Wireless WAN (e.g. Mobiles) below 1Mbps 2024-10-15 (c) Prof. Shawkat K. Guirguis 23  A.System interconnection using short- range radio e.g. Bluetooth: short-range wireless network It allows other devices to be connected Simplest is the Master-Slave 2024-10-15 (c) Prof. Shawkat K. Guirguis 24  B. Wireless LAN (IEEE 802.11) Above 50 Mbps Standard is IEEE 802.11 Every computer has a Radio modem and an antenna Wireless LAN becoming more common in small offices, conference rooms, hotels, airports … etc. 2024-10-15 (c) Prof. Shawkat K. Guirguis 25  C. Wireless WAN (e.g. Mobiles) below 1Mbps Best example is Mobile networks: low-bandwidth wireless communication Mobile Generations: 1. Analog voice 2. Digital voice 3. Digital voice + data 4. Long Term Evolution (LTE) 5. (Please read) High speed standard of wireless WAN is IEEE 802.16 Must hook up to the wired network at some stage to provide access to files, databases, and the Internet. 2024-10-15 (c) Prof. Shawkat K. Guirguis 26  Actual speeds of GPRS, EDGE, UMTS, HSPA Theoretical maximum speeds of 4G Long Term Evolution (LTE) reach 100Mbps or a bit more. However, actual performance of mobile data is much lower, considering signal strength, frequencies used, congestion, etc. Here are the real-life speed ranges of the various mobile wireless standards commonly used GSM (Global System for Mobile Communications) 2G -- 9.6Kbps GPRS (General packet radio services) 2.5G -- 35Kbps to 171kbps EDGE (Enhanced Data rates for GSM Evolution) 2.75G -- 120Kbps to 384Kbps UMTS (Universal Mobile Telecommunications System) 3G -- 384Kbps to 2Mbps HSPA (High Speed Packet Access) is a software upgrade to UMTS (theoretical 42Mbps) 3.5G -- 600Kbps to 10Mbps, averages 1-3Mbps WiMAX/LTE "4G" (theoretical 100Mbps) -- 3Mbps to 10Mbps average, 20Mbps+ peak download speeds. 2024-10-15 (c) Prof. Shawkat K. Guirguis 27  Home Networks (visionary concepts) Entertainment: TV, camera, Home theaters,.. etc. Communication: Telephone, mobile, intercom, … etc. Appliances (Microwave, refrigerator, clock, furnace, air- condition, light, …etc. Telemetry (Utility meters, smoke/burglar alarm, thermostat, baby-cam) Problems are that user manuals are getting bigger (How to deal with that?) Also, a rather big problem is SECURITY. 2024-10-15 (c) Prof. Shawkat K. Guirguis 28  Internetworks (Connection of different networks) Gateways connect different and maybe incompatible networks Subnet, networks and internetworks are often confused 1. Subnet: Collection of routers and communication lines owned by the network operator 2. Combination of Subnet+Hosts  Network 3. Internetwork is formed when distinct networks are connected (e.g. different owners or different technology) Best Internetwork example  INTERNET 2024-10-15 (c) Prof. Shawkat K. Guirguis 29