Chapter 1: Overview of Networks PDF

CHAPTER 1: Overview of Networks  Chapter Objectives ► 1- Definition of a Network. ► 2-Types of networks based on the communication media: ► a. Wired. ► b. Wireless. ► 3-Types of network topologies. a. Wired topology. i. Bus topology....

CHAPTER 1: Overview of Networks  Chapter Objectives ► 1- Definition of a Network. ► 2-Types of networks based on the communication media: ► a. Wired. ► b. Wireless. ► 3-Types of network topologies. a. Wired topology. i. Bus topology. ii. Ring topology. iii. Star topology. iv. Mesh topology. b. Wireless topology. i. Infrastructure wireless topology. ii. Ad Hoc wireless topology. iii. Wireless Mesh topology. iv. Hybrid topology. 2  Chapter Objectives ► 4. Types of networks based on the geographical areas. ► a. LANs. ► b. WLANs. ► c. WANs. ► d. MANs. ► e. CANs. ► f. SANs. ► g. PANs. ► 5. Router Device. ► 6. Switch Device. 3  Chapter Objectives ► 7.Routing: ► a. Static routing ► b. Dynamic routing ► 8. Switching methods: ► a. Packet switching ► b. Circuit switching ► c. Comparing between packet switching and circuit switching. ► d. Virtual Circuits. 4  Definition of a Network  A network is nothing more than two or more computers connected by a cable or by a wireless radio connection so that they can exchange information.  Of course, computers can exchange information in ways other than networks. Like you copy a file to a flash drive or other portable storage device and then walk the data over to someone else’s computer. However, connecting computers with cables was cheaper and faster.  On the network: Every computer connected to the network is said to be a node. 5 Definition of a Network 6  Types of Networks based on the Communication Media  Wire  You can create a wired computer network by hooking together all the computers in your office with cables and using the computer’s network interface (an electronic circuit that resides inside your computer and has a special jack on the computer’s backside).  Wireless  In a wireless network, the computers use wireless network adapters that communicate via radio signals. All modern laptop computers have built-in wireless network adapters, as do most desktop computers. (If yours doesn’t, you can purchase a separate wireless network adapter that plugs into one of the computer’s USB ports.) 7  Types of Network Topologies  The term network topology refers to the shape of how the computers and other network components are connected to each other. A topology refers to a network’s physical and logical layout.  A network’s physical topology refers to the actual layout of the computer cables and other network devices.  A network’s logical topology refers to the way in which the network appears to the devices that use it.  There are several different types of network topologies, each with advantages and disadvantages. 8  Types of Network Topologies Wired topology  Bus Topology  A bus topology uses a trunk or backbone to connect all the computers on the network in a line, The key to understanding how a bus topology works is to think of the entire network as a single cable, with each node “tapping” into the cable so it can listen in on the packets being sent over that cable. To avoid signal reflection, a physical bus topology requires that each end of the physical bus be terminated , with one end “Terminator” also being grounded.  It is very old technology and not used that much.  Note that a hub or switch is not needed in this installation. 9 Types of Network Topologies Bus 10 Types of Network Topologies Bus 11  Types of Network Topologies Wired topology  Ring Topology  It is old and rarely used today.  In a ring topology, each computer is connected to each other in shape of a ring. Packets are sent around the circle from computer to computer. Each computer looks at each packet to decide whether the packet was intended for it. If not, the packet is passed on to the next computer in the ring.  Note that a hub or switch is not needed in this installation either.  In a true ring topology, if a single computer or section of cable fails, the signal is interrupted. The entire network becomes inaccessible. Network disruption can also occur when computers are added to or removed from the network, making it an impractical network design in environments where the network changes often. 12 Types of Network Topologies Ring 13 Types of Network Topologies Ring 14  Types of Network Topologies Wired topology  Star Topology  In the star topology, all computers and other network devices connect to a central device called a hub or switch. Each connected device requires a single cable to be connected to the hub or switch, creating a point-to-point connection between the device and the hub or switch.  Using a separate cable to connect to the hub or switch allows the network to be expanded without disruption. A break in any single cable does not cause the entire network to fail. 15 Types of Network Topologies Star 16 Types of Network Topologies Star 17  Types of Network Topologies Wired topology  Mesh Topology  It has a unique network design in which each computer on the network connects to every other, creating a point-to-point connection between every device on the network. The purpose of the mesh design is to provide a high level of redundancy. If one network cable fails, the data always has an alternative path to get to its destination; each node can act as a relay.  The wiring for a mesh network can be complicated. Furthermore, the cabling costs associated with the mesh topology can be high, and troubleshooting a failed cable can be tricky. Because of this, the mesh topology is not the first choice for many wired networks but is more popular with 18 servers/routers.  Types of Network Topologies Wired topology  Mesh Topology  Mesh networks aren’t very practical in a LAN setting. However, Mesh networks are common for metropolitan or wide area networks. These networks use routers to route packets from network to network. For reliability and performance reasons, routers are usually arranged in a way that provides multiple paths between any two nodes on the network in a mesh-like arrangement 19 Types of Network Topologies Mesh 20 Types of Network Topologies Mesh 21 Types of Network Topologies 22  Types of Network Topologies Wireless topology  Wireless topology refers to the arrangement of interconnected nodes or devices in a wireless network. It defines how these devices communicate with each other and how data is transmitted within the network. There are several common wireless topologies, each with its own advantages and disadvantages. 23  Types of Network Topologies Wireless topology i. Infrastructure wireless topology. In infrastructure topology, devices communicate through a central infrastructure, such as a wireless router or access point. This is a common topology in home and office networks where devices connect to a central hub for internet access. 24 Types of Network Topologies Wireless topology 25  Types of Network Topologies Wireless topology ii. Ad Hoc wireless topology. In an ad-hoc network, devices communicate with each other directly without the need for a central access point. This type of topology is often seen in mobile and temporary networks, such as those created by smartphones or laptops. 26 Types of Network Topologies Wireless topology 27  Types of Network Topologies Wireless topology iii. Wireless Mesh topology. In a mesh topology, each device in the network is connected to every other device, forming a mesh-like structure. Mesh topologies are highly reliable because if one node fails, the communication path can be rerouted through other nodes. 28 Types of Network Topologies Wireless topology 29  Types of Network Topologies Wireless topology iv. Hybrid topology. Hybrid topologies combine two or more different types of wireless topologies to form a more complex and adaptable network. For example, a combination of point-to-point links and a mesh network can provide both dedicated connections and redundancy. 30 Types of Network Topologies Wireless topology 31  Types of Networks based on the Geographical Areas  Network types depend on how large they are and how much of an area they cover geographically.  LAN A local-area network (LAN) is a data network that is restricted to a single geographic location and typically encompasses a relatively small area, such as an office building or school.  WLAN (wireless local area network) is a LAN but uses wireless communication instead of wired communication.  WANs A wide-area network (WAN) is a network that spans more than one geographic location, often connecting separated LANs. WANs are slower than LANs and often require additional and costly hardware, such as routers, dedicated leased lines, and complicated implementation procedures. 32  Types of Networks based on the Geographical Areas  MAN  a MAN will be called a metropolitan-area network (MAN) when it is confined to a certain geographic area, such as a town or city. technically, a MAN is a WAN. Perhaps for this reason, the term MAN is used less often than WAN. If any distinction exists, it is that a MAN is smaller than a WAN. A MAN is almost always bigger than a LAN and usually is smaller than or equal to a WAN. MANs utilize an internet service provider (ISP) or telecommunications (telco) provider.  CAN  It is a computer network in a defined area that links buildings and consists of multiple LANs within that limited geographical area is usually called a Campus-Area Network (CAN). The CAN may encompass the whole college campus, or a portion of it. It may also have nothing to do with a college but consists of office buildings in an enterprise “campus,” industrial complex, military base, or anywhere else. 33  Types of Networks based on the Geographical Areas  SAN A storage-area network (SAN) consists of just what the name implies: networked/shared storage devices. With clustered storage, you can use multiple devices to increase performance. SANs are subsets of LANs and offer block-level data storage that appears within the operating systems of the connected devices as locally attached devices. File systems built on top of SANs can provide file-level access, but the SAN itself does not provide file abstraction, only block-level operations. 34  Types of Networks based on the Geographical Areas  PAN  A personal-area network (PAN) is essentially a LAN created to share data among devices associated with you(personal level) such as smartphones, tablets, and laptops. Wireless technologies have taken PAN further and introduced a new term—wireless personal-area network (WPAN). WPAN refers to the technologies involved in connecting devices in very close proximity to exchange data or resources, usually through the use of Bluetooth, infrared, or near-field communication (NFC). An example is connecting a laptop with a smartphone to synchronize an address book. 35 Generally, used to transfer small files such as photos, music and so on. Types of Networks based on the Geographical Areas 36  Router & Switch Devices ► Connectivity Devices: are network devices that interconnect networks.  Router: It creates larger networks by joining two network segments. It can route data it receives from one network to another.  Example: A small office/home office router connects a user to the Internet.  Switch  It is a box with a bunch of cable connectors. Each computer on the network is connected by cable to the switch. The switch, in turn, connects all the computers to each other.  a switch forwards it to only the port that connects to the destination device. It does this by the MAC address of the devices attached to it. 37 Network Components 38 Network Components 39 Network Components 40  Routing ► Routing is a crucial concept in networking that involves the process of directing data packets between different networks or devices to help them reach their intended destinations. The device responsible for making routing decisions is called a router. Routing occurs at the network layer of the OSI model and involves determining the most efficient path for data to travel from the source to the destination. 41  Routing Static routing ► In static routing, network administrators manually configure the routing table on a router. This method is suitable for small networks with a predictable and unchanging topology. ► Static routing is a networking technique in which a network administrator manually configures the routing table of routers within a network. Unlike dynamic routing, where routers exchange information with each other to automatically update their routing tables, static routing requires explicit and fixed routing entries. ► While static routing has its advantages in simplicity and lower overhead, it may not be the best choice for large, dynamic networks where 42 frequent changes occur. In such cases, dynamic routing protocols are  Routing Static routing 43  Routing Dynamic routing ► Dynamic routing protocols enable routers to exchange information and dynamically adjust their routing tables based on network changes. This allows for more adaptability in larger, more complex networks. ► Dynamic routing is a networking technique in which routers communicate with each other using routing protocols to dynamically update and adjust their routing tables. Unlike static routing, where administrators manually configure routes, dynamic routing allows routers to automatically learn about the network's topology and make real-time decisions about the best paths for data packets. ► Dynamic routing is commonly used in enterprise networks and the internet backbone, where networks are large, complex, and subject to frequent changes. It allows for efficient utilization of network resources and faster response to network modifications. 44  Routing Dynamic routing 45  Switching methods ► Switching methods in networking refer to the techniques used to forward data frames from the source to the destination within a network.  Packet Switching: In packet switching, data is broken into small packets before transmission. These packets are individually routed from the source to the destination through the network, and they may take different paths. Each packet is treated independently and may arrive out of order at the destination, where they are reassembled. The internet primarily relies on packet switching, and the most common protocols used are TCP/IP. 46  Switching methods Packet Switching 1. Advantages: 1. Efficient use of network resources, as bandwidth is shared among multiple users. 2. Scalable for a large number of users and variable traffic patterns. 3. Flexibility in routing packets, allowing for dynamic adaptation to network conditions. 2. Disadvantages: 1. Variable and potentially unpredictable delays due to the shared nature of the network. 2. Possibility of packet loss or out-of-order delivery, which requires additional protocols for error handling and 47 correction. Switching methods Packet Switching 48  Switching methods  Circuit Switching: In circuit switching, a dedicated communication path is established between two devices for the duration of their conversation or data transfer. The path remains reserved for the exclusive use of the communicating devices until the session is complete. Traditional telephone networks use circuit switching, 49 where a physical circuit is established for the duration of  Switching methods Circuit Switching  Advantages: Predictable and constant delay. Guaranteed bandwidth during the connection.  Disadvantages: Inefficient use of resources, as the circuit is dedicated even if there is no active communication. Scalability challenges in managing a large 50 number of simultaneous connections. Switching methods Circuit Switching 51  Switching methods Comparing between packet switching and circuit switching.  In contemporary networking, packet switching is the dominant method due to its efficiency, scalability, and adaptability to variable network conditions.  Circuit switching is still used in specific scenarios, such as voice calls over the Public Switched Telephone Network (PSTN).  The choice between these switching methods depends on the nature of the communication and the requirements of 52 the application or service.  Switching methods  Virtual Circuits  Virtual Circuits refer to a communication paradigm used in networking, particularly in the context of packet-switched networks. This concept is closely associated with a networking technique called  Virtual Circuit Switching, which is a type of communication setup that provides a connection-oriented service in contrast to the connectionless service offered by packet switching. 53  Switching methods Virtual Circuits  It's important to note that while virtual circuits provide a dedicated and predictable path for communication, they do introduce additional complexity and overhead. In contrast, packet switching, with its connectionless approach, is more scalable and adaptable to variable network conditions. The choice between virtual circuits and other communication models depends on the specific requirements of the 54 application and the characteristics of the network.  References  CompTIA Network+ Certification All-in-One Exam Guide, By Scott Jernigan, 6th Edition.  Essential References Materials Computer Networking: A Top-Down Approach, By James F. Kurose, 6th Edition.  Networking All-in-One For Dummies, By Doug Lowe, 8th Edition.  Networking Fundamentals by Crystal Panek.  PowerCertAnimatedVideos. “Network Types: LAN, WAN, PAN, CAN, MAN, SAN, WLAN” YouTube, 21 November, 2018. Youtube/4_zSIXb7tLQ.  PowerCertAnimatedVideos. “Network Topologies (Star, Bus, Ring, Mesh, Ad hoc, Infrastructure, & Wireless Mesh Topology)” YouTube, 21 November, 2018. Youtube/zbqrNg4C98U. 55