Computer networks
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This document provides information about various computer networking concepts and components. It discusses networking faceplates, cables, connectors, routers, switches, wireless access points and controllers. It also covers networking protocols like IP addressing and topics like file downloading, uploading and network troubleshooting. The document is meant as a guide for a practical computer networking lab session.
Computer networks
- 1. COMPUTER NETWORKS PRACTICAL 1 TG/2017/233 W. W. M. S. KARUNASENA
- 2. Also known as wall plates or outlet covers, networking faceplates are plastic, or metal plates used for Cat5 cable, Cat5e or Cat6 ethernet cable installation. They organize and keep network cables out of reach, so are ideal for use in residential or commercial settings. Exercise 1 • Part 1 network diagram of computer lab o Face plate (outlet) o Network cable Networking cables are networking hardware used to connect one network device to other network devices or to connect two or more computers to share printers, scanners etc. Different types of network cables, such as coaxial cable, optical fiber cable, and twisted pair cables, are used depending on the network's physical layer, topology, and size.
- 3. A simple device that physically links, couples, or connects, two things together. A male connector has pins that fit into the sockets, or receptacles, of a female connector, as the connectors mate. A male connector sometimes is referred to as a plug, and a female connector as a jack. A router is a device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP's network. Routers are located at gateways, the places where two or more networks connect. o Connector • Part 2 network diagram of server room o Router
- 4. Unshielded twisted pair (UTP) is a ubiquitous type of copper cabling used in telephone wiring and local area networks (LANs). There are five types of UTP cables -- identified with the prefix CAT, as in category -- each supporting a different amount of bandwidth. Shielded twisted pair (STP) cable was originally designed by IBM for token ring networks that include two individual wires covered with a foil shielding, which prevents electromagnetic interference, thereby transporting data faster. Fiber optic cable is a high-speed data transmission medium. It contains tiny glass or plastic filaments that carry light beams. Digital data is transmitted through the cable via rapid pulses of light. The receiving end of a fiber optic transmission translates the light pulses into binary values, which can be read by a computer. o Switch o UTP - Unshielded Twisted Pair o STP - Shielded Twisted Pair o Fiber cable A network switch is a hardware device that channels incoming data from multiple input ports to a specific output port that will take it toward its intended destination. It is a small device that transfers data packets between multiple network devices such as computers, routers, servers or other switches.
- 5. • Part 3 o IP address An Internet Protocol address (IP address) is a logical numeric address that is assigned to every single computer, printer, switch, router or any other device that is part of a TCP/IP-based network. The IP address is the core component on which the networking architecture is built; no network exists without it. An IP address is a logical address that is used to uniquely identify every node in the network. Because IP addresses are logical, they can change. They are like addresses in a town or city because the IP address gives the network node an address so that it can communicate with other nodes or networks, just like mail is sent to friends and relatives. The numerals in an IP address are divided into 2 parts: ▪ The network part specifies which networks this address belongs to and ▪ The host part further pinpoints the exact location.
- 6. o default gateway A default gateway is a hardware node that facilitates smooth connections between networks. Its primary use is to serve as an access point for outbound connections to other networks, essentially allowing one computer to communicate with another computer on a different network. 'Default' gateway simply refers to the fact that this node will be used by default unless a different route is specified in a request. Perhaps the most common request is when a computer seeks to access a webpage, which is sent through the default gateway before being sent to the internet. However, it can also be used to connect devices on one subnet with devices on another - the gateway acting as an intermediary. o DNS server A DNS server is a type of name server that manages, maintains and processes Internet domain names and their associated records. In other words, a DNS server is the primary component that implements the DNS (Domain Name System) protocol and provisions domain name resolution services to Web hosts and clients on an IP-based network. o Ping A ping is a signal sent to a host that requests a response. It serves two primary purposes: 1. to check if the host is available and 2. to measure how long the response takes. A ping request can be performed using a ping command, which is a standard command in most command line interfaces. Several network utilities provide a ping feature, which allows you to ping a server by simply entering the IP address or domain name. Most ping programs send multiple pings and provide and average of the pings at the end. o Download Downloading is the transmission of a file from one computer system to another, usually smaller computer system. From the Internet user's point-of-view, to download a file is to request it from another computer (or from a Web page on another computer) and to receive it. o Upload Uploading is the process of moving digital files such as photographs or documents from your computer and placing them on to a central server so that someone else can retrieve them or to a website so others can see them. For example, you might save photographs from your digital camera on to your computer and upload them on to a social network such as Facebook, where you can allow friends and family to see them.
- 7. A crimping tool is a device used to conjoin two pieces of metal by deforming one or both in a way that causes them to hold each other. The result of the tool's work is called a crimp. A good example of crimping is the process of affixing a connector to the end of a cable. For instance, network cables and phone cables are created using a crimping tool (shown below) to join the RJ-45 and RJ-11 connectors to both ends of either phone or Cat 5 cable. Exercise 2 o 5 port switches o RJ45 connector o UTP cable o Crimping tool A switch used to connect only five devices to a computer network. RJ45 is the most common type of connector for Ethernet networking. It's like a phone jack, but slightly wider. Ethernet cables are also sometimes referred to as RJ45 cables because each end of the Ethernet cable has an RJ45 connector. Switch, hub, PC, router, firewall etc. are used to interconnect different types of devices. RJ 45 is the most well-known and popular connectivity type in the IT world. UTP cables are widely used in the computer and telecommunications industry as Ethernet cables and telephone wires. In an UTP cable, conductors which form a single circuit are twisted around each other in order to cancel out electromagnetic interference (EMI) from external sources. Unshielded means no additional shielding like meshes or aluminum foil, which add bulk, are used. UTP cables are often groups of twisted pairs grouped together with color coded insulators, the number of which depends on the purpose.
- 8. o Toolkit Exercise 3 o Dial-up Advantages Disadvantages Security Slow connection speed (max of 56Kbps) Include inexpensive hardware Inconvenience Ease of setup and use Telephone line will be tied up while accessing the Internet Widespread availability Can’t use phone and internet at same time unless have multiple lines o ADSL - Asymmetric Digital Subscriber Line A single utility program, a set of software routines or a complete integrated set of software utilities that are used to develop and maintain applications and databases. There are toolkits for developing almost anything. See tool, developer's toolkit, library, class library and CASE. Dial-up refers to an Internet connection that is established using a modem. The modem connects the computer to standard phone lines, which serve as the data transfer medium. When a user initiates a dial-up connection, the modem dials a phone number of an Internet Service Provider (ISP) that is designated to receive dial-up calls. The ISP then establishes the connection, which usually takes about ten seconds and is accompanied by several beeping a buzzing sound. The ADSL (Asymmetric Digital Subscriber Line) is a type of technology of digital data transmission and Internet access, which consists of the transmission through symmetrical pairs of telephone line copper. This is, a method of accessing the Internet through the telephone line (Telephone Network Switched, PSTN) that does not prevent the regular use of the line for calls.
- 9. Advantages Disadvantages This represents an advantage when installing the service in homes and companies, since it allows the autonomy of both services, something impossible with the dialing method. It is not enough to have a copper wire telephone connection to use the ADSL, since this technology has a limit of 3km of line length from the emission center. It does not require new and extensive investments or large works, because it takes advantage of traditional copper wiring. In countries where this material is expensive or scarce, the service may not be as economical as in others. It offers much better speed / price ratio than the dialing methods, which in addition to occupying the telephone line are usually at 56 kps, while the ADSL can reach 4mbps (70 times faster). The quality of the service is subject to the quality of the cables, the distance from the power station and fluctuations in the service flow. Since it uses telephone cables, each subscriber receives an independent and non- transferable service directly to his home or office. The fiber optic connections far exceed the ADSL stability and speed. o Dongle Advantages Disadvantages Data is more secured Access Speed Limits It is handy Users are limited to a single interface Dongles are universal There are no greater options Easy Installation No Traffic Maintenance o Leased line A dongle is a USB device which allows users to access the internet remotely via a 3G broadband connection. This plug-in is also referred to as Internet Stick, USB modem, USB, USB network adapter, and mobile broadband stick in different countries. People who are looking for a device which they can use to access the Internet from any location, a dongle come in handy. leased line is a dedicated internet line that handles both data and voice. A leased line is a symmetric circuit, meaning you can send or receive data quickly from one location to another (this can include multiple locations). With a leased line, there is a dedicated connection which results in not having to share the bandwidth with anyone else. Essentially, your connection is not shared so speeds will not be impacted during peak times when others are using the same ISP (Internet Service Provider) to full capacity.
- 10. Advantages Disadvantages Leased Lines are Available at Higher Speeds Limited range of services - Only Plain Leased Line Service, Data cards support only up to 64 kbps, no support for N x 64 Kbps. No Slow-Down at Peak Times From Operator point of view in case of Leased Line Circuit different boxes from different vendors so difficult to manage & control. Faster Uploads No Centralized Monitoring or alarm or performance monitoring. The solution to this is MLLN. More Reliable o Wi-Fi router Usage ▪ Can use for LAN connections which means you can communicate to other devices which are connected to the same router. ▪ You can run Webserver in router and use that Web Server as centralized memory to share files. No need of USB to share files between devices. ▪ Can connect smoke USB censor to your router and get the information about your Air pollution in your deployed area daily. o Wireless access point Usage ▪ To extend the coverage area, multiple access points are used together under a Wireless LAN Controller. ▪ In WLC-LWAPs setup, the WLC controls and manages all LWAPs. A wireless router is a device that performs the functions of a router and includes the functions of a wireless access point. It is used to provide access to the Internet or a private computer network. Depending on the manufacturer and model, it can function in a wired local area network, in a wireless-only LAN, or in a mixed wired and wireless network. A wireless access point (WAP) is a hardware device or configured node on a local area network (LAN) that allows wireless capable devices and wired networks to connect through a wireless standard, including Wi-Fi or Bluetooth. WAPs feature radio transmitters and antennae, which facilitate connectivity between devices and the Internet or a network.
- 11. ▪ A LWAP works as the bridge between the WLC and the end device. ▪ A standalone access point works in the wireless network exactly as the switch works in the wired network. ▪ To control the unauthorized access, Access point uses authorization. ▪ Access point connects multiple wireless devices together in a single wireless network. o Wireless controller Usage ▪ Load balancing: Disabled by default, high-speed load balancing can be used to connect a user to multiple access points for better coverage and data rates. Discussion • Improvements in ICT Lab design o Since cable costs a lot of money, I expect cable-free technology to be more convenient. Troubleshooting is also easier. o Can upgrade to a mesh-based system for faster connectivity. • Improvements in Server Room design o A remote-control server room needs to be set up. because If the server down, it can be repaired very quickly from anywhere. • Extend wireless connectivity to hostels o Difficulties ▪ The hostel has many Internet users. Therefore, the speed of the connection is slightly reduced. ▪ Given that the hostel is located a short distance away, it is not easy to provide the connection. o How to overcome ▪ can increase the range of the wireless connectivity using repeaters or range extenders. ▪ A series of individual nodes can be installed around the hostel. Then can access the internet without interruption throughout the hostel. A wireless LAN (or WLAN) controller is used in combination with the Lightweight Access Point Protocol (LWAPP) to manage light-weight access points in large quantities by the network administrator or network operations center. The wireless LAN controller is part of the Data Plane within the Cisco Wireless Model. The WLAN controller automatically handles the configuration of wireless access-points.