AI Introduction to Computer Networks Fall 2024-2025 Lecture Notes PDF

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 Small Office Home Phone STB Small Business Server Ethernet 802.11 Internet Internet PLC xDSL Residential Ethernet Communication is almost as Cable Phone T1, T3, … Bluetooth Gateway important to us as our reliance on air, GPRS water, food, and shelter GPRS IrDA Phone Bluetooth Public Space Enterprise GPRS GPRS IrDA Bluetooth Web Server Internet Internet T1, T3, … 802.11 802.11 Proxy Web Server Server T1, T3, … Ethernet Ethernet Proxy Server 2 2100 2100 2100 2100 2100 2100 2100 2100 3 4 A data communication system consists of anumber of independent Computrizied devices within moderate size geographic area communicated directly with each other over shared physical channel plus s.w NOS to provide services of communications. A system in which a number of independent computes are linked together to share data and peripheral. Sharing is the purpose of computer networking. 5  Network: Group of components or devices which are connected together to give the user a certain service (application). 6 Data network is a result of business need. Easy access and sharing of information ◦Sharing of expensive devices and network resources ◦Modern Technologies (IP telephony, Video Conferencing, ….e 7  What is meant by computer network ?  Give some examples (applications) for the using of the Network in our daily life?  Name two technologies by which you would connect two offices in remote locations  Explain the advantages and disadvantages of networking computers  List the most Modern Technologies and trends For each give a brief discussion Due date 1 week 8 1- Elements of Communication  The Elements of Network  Human beings often seek to send and  receive a variety of messages using computer applications; these applications require services to be provided by the network  Network Components H /W S/W Shared channel N IC Devices Application NOS Wireles Services ; Rules Wired End Network s Message Devices Devices Network Internetworking Access Router Repeater Hub Bridge Switch 12  Establishing the Rules  Quality of Communication Internal Factors External Factors The size of the message The quality of the pathway No of message has to change The complexity of the No of message has to be message redirected The importance of the Amount successful communication message 13  Rules or agreements to govern how the messages are sent.  The messages or units of information that travel between devices  A means of interconnecting these devices - a medium  The standardization of the various elements of the network 14  The Elements of Network  Human beings often seek to send and receive a variety of messages using computer applications; these applications require services to be provided by the network 15 16  State the main components of the communication systems and computer network (give an example for each components)  What is meant by converged network?  Draw Commonly icons that are used to represent networking devices  What is meant by a link and node? 17  Network architecture refers to both the technologies that support the infrastructure and the programmed services and protocols that move the messages across that infrastructure. Fault Tolerance Impact of a HW or SW failure and can recover quickly when such a failure occurs. redundant links, or paths Scalability Network can expand quickly to support new users and applications without impacting the performance Quality of Service (QoS) Security 18 (1) Circuit Switched Connection-oriented Networks connection-oriented network, the circuit remains connected and resources reserved until one of the parties disconnects the call.  Disadvantage The cost to create many alternate paths with enough capacity to support a large number of simultaneous circuits, and the technologies necessary to dynamically recreate dropped circuits in the event of a failure Idle circuits 19 (2) Packet Switched Connectionless Networks a single message can be broken into multiple message blocks. Individual blocks containing addressing information indicate both their origination point and their final destination. Using this embedded information, these message blocks, called packets, can be sent through the network along various paths, and can be reassembled into the original message upon reaching their destination. No reserved circuit is built between sender and receiver. packets that may be lost in the advent of a failure can be retransmitted to the destination along a different path 20 21  Internet is able to expand at the rate that it is, without seriously impacting the performance experienced by individual users, is a function of the design of the protocols and underlying technologies on which it is built  New protocols and addressing structures are under development to meet the increasing rate at which Internet applications and services are being added. 22  QoS mechanisms enable the establishment of queue management strategies that enforce priorities for different classifications of application data. Priority might include:  Time-sensitive communication - increase priority for services like telephony or video distribution.  Non time-sensitive communication - decrease priority for web page retrieval or e-mail.  High importance to organization - increase priority for production control or business transaction data.  Undesirable communication - decrease priority or block unwanted activity, like peer-to-peer file sharing or live entertainment. 23  Major trends that are contributing to the future shape of complex information networks:  Increasing number of mobile users  Increase of network capable devices (PDA, VoIP , gaming systems )  Expanding range of services 24  State the main components of the communication systems and computer network (give an example for each components)  What is meant by converged network?  Write a short note about the Characteristics of the Network architectures Due date 1 week 25  Networks can classified according to  1- Area (LAN-MAN-WAN)  2- Sharing Information (P2P – Server based)  3- Data Transfer mode (Packet switch – Circuit Switch)  4- Topology (Star – Bus- Ring – Tree) 26  Classifications of Networks  According to covered area: –LAN. –MAN. –WAN.  According to Sharing of Information: –Client/Server. –P2P.  According to network topology: –Bus, Star, Ring, Extended Star, Mesh etc.  According to Switching: ITE PC v4.0 –Circuit switch and Packet switch Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 27  Classifications of Networks According to covered area:  Local Area Networks [LAN]: –A LAN is a group of computers connected in small geographical area. –Allow users to share files and services.  Metropolitan Area Networks [MAN]: –A MAN connects an area larger than a LAN but smaller than a WAN, such as a city.  Wide Area Networks [WAN] –A WAN is a group of computers connected in Large geographical area such as country. ITE PC v4.0 Chapter 1 –A WAN often connects two LANs (WAN Link). © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 28  Classifications of Networks According Sharing of Information: 1) Peer – too – Peer Networks (P2P):  In a peer-to-peer network, all computers are considered equal; they all have the same abilities to use the resources available on the network.  Example : Windows Workgroup. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 29  Classifications of Networks According Sharing of Info. (cont.): 2) Client / Server Networks(C/S):  Some nodes (SERVER) are dedicated to present services to other nodes (CLIENTS).  Examples: –Mail Server. –Web Server. –FTP Server. –DNS Server. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 30  Client Server Model ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 31  Classifications of Networks According to Network Topology:  Topology refers to the shape of a network, or the network's layout.  How different nodes in a network are connected to each other and how they communicate are determined by the network's topology.  The choice of topology is dependent upon –Type and number of equipment being used ITE PC v4.0 Chapter 1 –Cost © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 32  Classifications of Networks According to Network Topology (Cont.):  According to topology computer networks can be (Types of network Topologies): –Bus. –Star. –Ring. –Mesh. –Hybrid. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 33  BusTopology  All devices are connected to a central cable, called the bus or backbone. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 34  Bus Topology (cont.)  Both ends of the network must be terminated with a terminator.  A barrel connector can be used to extend the network. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 35  Bus Topology (cont.)  The backbone functions as a shared communication medium  Device wanting to communicate with another device on the network sends a message onto the backbone  The message is heard by all stations, but only the intended recipient actually accepts and processes the message.  Terminator absorbs frames at end of medium ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 36  Bus Topology (cont.) Frame Transmission - Bus LAN  ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 37  Bus Topology (cont.) Advantages & Disadvantages Advantages: Simple, easy to use and construct Requires least amount of cable (less expensive) Disadvantages: A faulty cable will take the entire LAN down Difficult to troubleshoot Heavy network traffic can slow bus considerably ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 38  Star Topology  A physical Star topology connects the devices via a centralized unit such as a Hub or Switch.  Nodes communicate across the network by passing data through the central device. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 39  Star Topology (cont.) Star Types  Broadcasted Star Topology (Hubbed Star)  Switched Star Topology (Switched Star) ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 40  Star Topology (cont.) Advantages  Single computer failure doesn’t bring down whole network.  Adding new devices to a Star network is very simple compared to any of the other topologies.  No disruptions to the network when connecting or removing devices.  Centralized control.  Centralized network/hub monitoring.  Easy to troubleshoot. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 41  Report 4  List the Elements of Communication Over the Network ?  State The Elements of Network (for each give a brief discussions and some examples)  Compare between Packet Switched Connectionless Networks and circuit Switched Networks (for each specify the suitable applications)  Network can be classified according may parameters (state these parameters and the types belongs under this types of classifications)  Give the disadvantage of the peer-peer network. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 42  Computer network Sharing Data Area Information Topology Transfer Circui Server Packet Star LAN MAN WAN P2P t Based Switch Ring switch Bus Tree 43  Topology: How devices are connected together  Physical Topology: It describes how devices are physically cabled  Logical Topology: It describes how devices communicate across physical topology The term physical topology refers to the way in which a network is laid out physically. There are four basic topologies possible: mesh, star, bus and ring. 45 A mesh topology is implemented to provide as much protection as possible from interruption of service. Each host has its own connections to all other hosts. Although the Internet has multiple paths to any one location, it does not adopt the full mesh topology. Networks infrastructures can vary greatly in terms of: The size of the area covered The number of users connected The number and types of services available LAN (Local Area Network):  It is a group of network components that work within small area.  It characterized by high data speeds (up to 10Gbps) using: MAN (Metropolitan Area Network):  It is a group of LANs that are interconnected within small area.  It characterized by very high data speeds (up to 40Gbps) WAN (Wide Area Network):  It is a group of LANs that are interconnected within large area  It characterized by slow data speeds (up to 155Mbps & 622Mbps using: analog dial-up, digital dial-up (ISDN), leased lines, X.25, DSL, Frame-Relay & ATM.  Personal Area Network ( PAN ) A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person..  Campus Area Network CAN A network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, or a military base. Global Area Network GAN  The internet is defined as a  A global mesh of interconnected networks (internetworks) meets these human communication needs The Internet is created by the interconnection of networks belonging to Internet Service Providers (ISPs)  end systems (hosts): run application programs e.g. Web, email at “edge of network” peer-peer  client/server model  client host requests, receives service from always-on server  e.g. Web browser/server; client/server email client/server  peer-peer model:  minimal (or no) use of dedicated servers  e.g. Skype, BitTorrent 50  Consideration Peer-to-Peer Network Server-Based Network Good for 10 or fewer Limited only by server and Size computers network hardware Security established by the Extensive and consistent Security user of each computer resource and user security Administration Individual users responsible Centrally located for network for their own administration; control; requires at least one no full-time administrator knowledgeable administrator necessary  A B Source Destination  circuit switched = telephone  A call has three phases: 1. Establish circuit from end-to-end (“dialing”), 2. Communicate, 3. Close circuit (“tear down”).  Originally, a circuit was an end-to-end physical wire.  Nowadays, a circuit is like a virtual private wire: each call has its own private, guaranteed data rate from end-to-end. 52  Each phone call is allocated 64kb/s. So, a 2.5Gb/s trunk line can carry about 39,000 calls. Destination Source “Callee” “Caller” Central Office Central “C.O.” Office “C.O.” Trunk Exchange 53  A B R2 Source R1 Destination R3 R4  It’s the method used by the Internet.  Each packet is individually routed packet-by-packet, using the router’s local routing table.  The routers maintain no per-flow state.  Different packets may take different paths.  Several packets may arrive for the same output link at the same time, therefore a packet switch has buffers. 54  Define the main characteristics of the following network types (LAN-MAN-WAN- Internet)  Specify why the portioning of the message within the network is bad solution?  Network can be classified based on may parameters; State these parameters, for each specify the different types based on such parameter Due date 1 week 55  Network Reference Models  A framework (guideline) for network implementation and troubleshooting.  Divides complex functions into simpler components.  Importance of reference model: –Vendor interoperability “standardization”. –Better understanding of data transfer  Reference model types : OSI (Open System Interconnection ). TCP/IP (DOD Model) ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 56  Network Reference Models (cont.) Advantages of R.M  It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.  It allows multiple-vendor development through standardization of network components.  It encourages industry standardization by defining what functions occur at each layer of the model.  It allows various types of network hardware and software to communicate. ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 57  OSI Reference Model  OSI: Open Systems Interconnection  The OSI model is the primary architectural model for networks.  It describes how data and network information are communicated from an application on one computer, through the network media, to an application on another computer.  The model was defined by the International ITE PC v4.0 Organization for Standardization (ISO) Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 58  OSI Reference Model (cont.) ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 59 Layer 7 - The Application Layer 7 Application It’s the S\w on our pcs that is used to represent a user 6 Presentation interface to the network & 5 Session so aids the user to make applications. 4 Transport 3 Network Examples: Email (SMTP,POP3) 2 Data Link Web browsers (HTTP) FTP 1 Physical Telnet ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 60 Layer 6 - The Presentation Layer 7 Application This layer is responsible 6 Presentation for presenting the data in the proper format. 5 Session Examples: 4 Transport ASCII, AVI,JPG,…. 3 Network 2 Data Link 1 Physical ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 61 Layer 5 - The Session Layer 7 Application Ensure that all information required for opening a 6 Presentation session is available. 5 Session Give orders for: establishment, management, 4 Transport and termination of the 3 Network session. 2 Data Link 1 Physical ITE PC v4.0 Chapter 1 © 2007 Cisco Systems, Inc. All rights reserved. Cisco Public 62