Evolution of Computer Networks - Networking Fundamentals - PDF

LESSON 1 OBJECTIVES: At the end of the lesson, the student will be able to: Recall the evolution of computer networks and the Internet. Understand the fundamental characteristics and components of data communication. Describe the network’s criteria, connection types, topology, types of t...

LESSON 1 OBJECTIVES: At the end of the lesson, the student will be able to: Recall the evolution of computer networks and the Internet. Understand the fundamental characteristics and components of data communication. Describe the network’s criteria, connection types, topology, types of transmission, categories, and switching types. Understand the importance of protocols in a network. Presentation Outline: Evolution of Computer Networks Data Communications Network Components Topology and Categories Switching Internet Evolution of Computer Networks  Computer networks, also known as Datacom, or Data- transmission networks, represent a logical result of the evolution of two of the most important scientific and technical branches of modern civilization… - Computing and - Telecommunication technologies. Data Communications Data Communications – exchange of data between two devices via some form of transmission media. Five Components of Data Communication Message/Information Sender Receiver Transmission Medium Protocol  Information can be in a form of text, numbers, images, audio, and video Communication can be simplex, half-duplex, or full duplex. (Data flow types) Networks A network is the interconnection of a set of devices capable of communication. A device can be a host such as a large computer, desktop, laptop, workstation, cellular phone, or security system. A device can also be a connecting device such as a router, switch or modem that changes the form of data. Network Criteria Performance Depends on network elements Measured in terms of delay and throughput Reliability Failure rate of network components Measured in terms of availability/robustness Security Data protection against corruption/loss of data due to error or malicious users. Types of Connection Point to point – single transmitter and receiver Multipoint – multiple recipients of single transmission Physical Topology Connection of devices Mesh Star Topology Topology Bus Topology Ring Topology Types of Transmission Unicast – packet is sent from a single source to a specific destination. Broadcast – information is sent from one point to all other points. Multicast – information is sent from one or more points to a set of other points. Categories of Networks Local Area Network (LAN) Short distances Designed to provide local interconnectivity Wide Area Network (WAN) Long distances Provide connectivity over large areas Metropolitan Area Network (MAN) Provide connectivity over areas such as a city or a campus. LAN WAN MAN Switching An internet is a switched network in which a switch connects at least two links together. A switch needs to forward data from a network to another network when required. Two Common types of Switched Network 1. Circuit-switched Network 2. Packet-switched Network Circuit-switched Network Packet-switched Network  The Internet is a global system of interconnected computer networks that use the standard Internet Protocol suite. (TCP/IP) The history of Internet began with the development of computers in the 1950s with point-to-point communication between mainframe computers and terminals. In 1972, Vint Cert and Bob Kahn (part of ARPANET group) collaborated in the Internetting Project. They use Gateway as an intermediary hardware to communicate dissimilar networks. Protocols Set of rules that governs data communications. Elements of Protocol 1. Syntax Structure or format of the data Indicates how to read the bits 2. Semantics Interprets the meaning of the bits Knows which fields define the actions 3. Timing When data should be sent Speed at which data should be sent or received Key Thing to Remember: Loving yourself underlies all motivation to becoming a better person, so don’t withhold your self-love. You matter. LESSON 2 OBJECTIVES: At the end of the lesson, the student will be able to: Describe the characteristics of a layered architecture. Explain the network architecture requirements. Learn the roles and importance of protocols in network. Understand the details of the OSI Layer Model. Understand the details of the TCP/IP Model. Differentiate between OSI and TCP/IP models. Presentation Outline: Characteristics of a Layered Architecture Network Architecture Requirements Layering and Protocols OSI Layer Model TCP/IP Model OSI Layer vs. TCP/IP Model Characteristics of a Layered Architecture Allows complex problems to decomposed into small manageable units. Implementation details of the layer are abstracted. Separation of implementation and specification. Layers work as one by sharing the services provided by each other. Provide framework to implement multiple specific protocols per layer.  Layer architecture simplifies the network design. It is easy to debug network applications. The network management is easier due to the layered architecture. Network layers follow a set of rules, called protocol. Network Architecture Requirements Requirements of computer network: ✓Connectivity ✓Cost effective resource sharing ✓Support for common services ✓Reliability Network Architecture Network Architecture – framework that guide the design and implementation of networks. The most widely used architectures: ✓OSI Model ✓TCP/IP Model Layering and Protocol Services offered by the underlying hardware, added with a sequence of layers – each provides a higher level of services. These services are implemented in terms of services provided by the lower layers. Features of Layering Decomposes the problem of building a network into more manageable components. Modular design  The above layered system having two layers of abstraction sandwiched between the underlying hardware and the application program.  The above layered system having multiple abstractions provided at any level of the system Two types of channel. - Request/reply channel - Message stream channel Protocol The protocol defines the format of the data being exchanged and the control and timing for the handshake between layers. It defines the interfaces between the layers in the same system and with the layers of peer system. Protocol defines two interfaces: 1. Service interfaces - Interface between objects in the same machine. 2. Peer interfaces – messages exchanged with peer. Protocol Specification Combination of prose, pseudo code, state transition diagrams, packet formats and abstract notations. Encapsulation Defined as the wrapping up of data under a single unit. (adding information to the data). Header A small piece of information used among peers to communicate each other. Payload Data being transmitted by the application. Functions of the 7 OSI Layers 1. Physical Layer Characteristics of the interface between the devices. Type of transmission medium Representation of bits (1’s or 0’s) Transmission rate (bps) Clock Synchronization (sender and receiver sync) 2. Data Link Layer Framing (frames) Physical Addressing (MAC Address) Flow Control (avoid overwhelming the receiver) Error Control (detect and retransmit damaged or lost frames, trailer added to the end of the frame) Access Control (control over the same link when two or more devices are connected) 3. Network Layer Source to destination delivery of the packets. Logical Addressing (IP) Routing (router, internetworks) 4. Transport Layer Process-to-process delivery (process – running program) Service point Addressing (port address) Segmentation and Reassembly (segments) Connection Control (TCP – connection-oriented, UDP-connectionless – oriented) Flow Control (end-to-end flow control) Error Control (assures no damage or loss – retransmission) 5. Session Layer Opening, closing and managing session between end-user application processes Inter-host communication Controlling ports and sessions 6. Presentation Layer Syntax (formats) and semantics Encryption and compression 7. Application Layer User interface services (e-mail, file transfer) TCP/IP Model (Internet Architecture) Functions of the TCP/IP Layers 1. Application Layer Application protocols FTP, TFTP, SMTP, Telnet, HTTP 2. Transport Layer TCP-reliable/connection-oriented , UDP- unreliable/connectionless- oriented 3. Internet Layer IP (supports interconnection of multiple networking technologies) Supporting protocols (ARP, RARP, ICMP-querying and error reporting protocol) 4. Network Interface Layer (Host to Network Layer) Protocols denoted with Network Interface 1 (NET1), NET2,..NETn Hardware –ex. network adapter Software – ex. network device driver Key Thing to Remember: Focus on the beauty and blessings of each day. LESSON 3 OBJECTIVES: At the end of the lesson, the student will be able to: Describe the different networking devices. Identify the role and contribution of some governing bodies in computer networking. Understand the multiple access techniques used in a network. Describe the various LAN technologies. Presentation Outline: Different Networking Devices Standard Organizations Multiple Access Schemes LAN technologies Networking Devices What are different networking devices? includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communications within the network Different Networking Devices Network Interface Card (NIC) Hubs Switches Repeaters Bridge Router Modem Network Interface card (NIC) Provides the physical connection between the network and the computer workstation. Also referred to as Ethernet adapters, network adapters, LAN cards, or LAN adapters. Hub Sometimes referred to as a concentrator Acts as a convergence point of a network, allowing the transfer of data packets Works by duplicating the data packets received via one port, and making it available to all ports, therefore allowing data sharing between all devices connected to the hub. Works at physical layer of the OSI model. Switch Joins multiple computers together within one local area network. Capable of inspecting data packets as they are received, determining the source and destination device of each packet, and forwarding them appropriately. Works at data link layer and network layer (for multi-layer switch). Hub works by sending the data to all ports on the device whereas a switch transfers it only to that port which is connected to the destination device. Repeater Electrically amplifies the signal it receives and rebroadcasts it. Can be separate devices or they can be incorporated into a concentrator. Used when the total length of your network cable exceeds the standards set for the type of cable being used. Works in the physical layer of the OSI model. Bridge Used to create a connection between two separate computer networks or to divide one network into two. Works in the data link layer of OSI model. Difference between Bridge and Switch in Networking Bridge Switch Works in data link layer of OSI works in data link layer and model network layer of OSI model. Has only two ports Has multiple numbers of ports. Used to connect two LAN Used to connect devices to the segment using the same network. same topology. Can operate only in half- Can operate in both half duplex duplex mode and full duplex mode. Performance of bridge is slower Performance of Switch is faster then switch than a bridge. Router Connects at least two networks. Forwards and routes data packets along networks. The router makes sure that information does make it to the intended destination. Operate in the network layer of the OSI model. Modem A communication device that is used to provide the connectivity with the internet. Works in the physical and data link layers of the OSI model.  Modem vs. Router Modem Router Device which performs both modulation and Networking device which associates various demodulation of signals. networks with each other for LAN and WAN networks. It works on the data-link layer of the OSI It works on the physical, data-link and network model and doesn’t have any inbuilt layer of the OSI model and maintains the intelligence. routing table to forward and route the data packet to the desired destination path. It is an essential part of the networking It routes the data packets among the system for connecting any device to the ISP. networking devices and the different networking systems. Limited to only LAN connectivity Used for LAN as well as WAN communication networking. Gateway A device which connects multiple networks. Acts as an entrance to another network. It allows the computer programs, either on the same computer or different computers to share information across the network through protocols. A router is also a gateway. Operate in all seven layers of the OSI model. Firewall A firewall is a system designed to prevent unauthorized access to or from a private network. A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules. You can implement a firewall in either hardware or software form, or a combination of both. Network Standards Standards Allow different computers to communicate. Increase the market for products adhering to the standard, resulting in mass production and cheaper prices. Two Categories of Standards De facto (Latin for “from the fact”) – those standards that have just happened, without any formal plan - Ex. IBM, PC, Unix, QWERTY) De jure (Latin for “by law”) – formal, legal standards adopted by some organization body. - Ex. ASCII, TCP/IP Standard Organizations 1. ITU-T (International Telecommunication Union-Telecommunication) promote the development of telecommunication networks and access to telecommunication services 2. ISO (International Organization for Standardization) OSI Layer 3. IETF (Internet Engineering Task Force) Responsible for publishing RFCs (Request For Comments) 4. IEEE (Institute of Electrical and Electronic Engineers) The world’s largest technical professional organization dedicated to advancing technology for the benefit of humanity. Communication Protocols A communication protocol is the set of rules that determines how and when stations are allowed to transmit or receive data, how the data is formatted, and how error checking is performed, etc. MAC (Media Access Control) protocol is a set of rules to control access to a shared communication medium among various users. One station transmit at a time Multiple Access Schemes Multiple access schemes can be classified into three main categories: 1. Fixed Assignment Example: FDMA (Frequency Division Multiple Access ) TDMA (Time Division Multiple Access) 2. Random Assignment Example: CSMA/CD (Carrier Sensed Multiple Access with Collision Detection) 3. Demand Assignment Example: DAMA (Demand Assignment Multiple Access) Poll and Select Primary (supervisor) station – ask each secondary station in a sequence if it has data to send (Polling) Secondary station can send only if the primary station permits. This method may be used in a star topology. Polling list can be modified in case of higher priority stations. ALOHA Protocols Developed for packet radio networks in 1970. Frequency band: 30kHz – 300 GHz PURE ALOHA Whenever a station has a frame to send, station listens for a round- trip propagation time, if no acknowledgment, then retransmits. Collision occurs if two frames interfere each other during increased of load/data. CSMA A station wishing to transmit first listens to the medium if another transmission is in progress (carrier sense). - If the medium is in use – station waits. - If the medium is idle – station may transmit. Collisions can occur only when more than one user begins transmitting within the period of propagation delay. Fast Ethernet a low-cost, Ethernet compatible LAN operating at 100 Mbps Token Bus Physically, the token bus is a linear cable onto which stations are attached. Logically, stations are organized into a ring. A special control frame called token is transmitted from one station to the next, with each station knowing the address of the station to its ``left’’ and ``right’’. Token Ring IEEE 802.5 Medium Access Protocol The token ring technique is based on the use of a small frame, called a token that circulates. FDDI (Fiber Distributed Data Interface) The FDDI standard specifies a ring topology operating at 100 Mbps. Optical fiber or twisted pair are used for medium. Key Thing to Remember: Don’t define success based on what you accomplish; base it on who you become. - Dr. Josh Axe