Computer Networks Study Guide PDF

FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 STUDY GUIDE FOR MODULE NO. 5 COMPUTER NETWORKS MODULE O...

FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 STUDY GUIDE FOR MODULE NO. 5 COMPUTER NETWORKS MODULE OVERVIEW Data communications and networking are shifting the world scenario. Today, enterprise and day-to-day affairs depend upon computer networks and internet mechanisms. A network is a set of devices frequently called nodes associated via means of media links. A node can be a computer, printer, or extra device able to sending or receiving information generated with the aid of using distinctive nodes at the network. Also, the links connecting the devices are referred to as communication channels. There has been a great development in the computer industry. The development of the computer carried approximately high-quality modifications for business, industry, science, and education. A comparable revolution is taking place in data communications and networking. Further, technological advances are making it feasible for communication links to hold extra and faster signals. Because of this, services are evolving to permit the use of the increased capacity, such as the extension to established telephone services which include call waiting, voice mail, and caller id, etc. The primary intention of data communications and networking is with a purpose to exchange data for example text, audio, and video from one point to another point in the world. This module aims to understand the definition and classifications of computer networks, the network components and topology and the network cables. MODULE LEARNING OBJECTIVES At the end of this, students are expected to: 1. Explain the types/classification, components, topology, standards, channel organization and the different network protocols. 2. Discuss the different networking technologies. 3. Create a straight through cabling using UTP cable. LEARNING CONTENTS (DEFINITION OF COMPUTER NETWORK) DEFINITION OF COMPUTER NETWORKS Computer communications is the technique of sharing data, programs, and information among one or more computers. Connectivity is an idea associated with the use of computer networks to link human beings and resources. A computer network is a set of devices associated through links. A node may be computer, printer, or additional device capable of sending or receiving the data. The links connecting the devices are referred as communication channels. Computer Network makes use of distributed processing wherein job is allocated with several computers. Instead, a single computer handles a complete task; every separate computer holds a subset. Network is a big term which can be very much alike to system. Network is a communication system which facilitates many users. A computer network is a system which allows communication among the numerous computers related within the network. A network must be able to meet certain criteria: performance, reliability and security. Performance may be measured in lots of ways. We can measure it in relations of transit time and response time. A. Transit time is described as the quantity of time required for a message to travel from one device to the other. B. Response time elapsed among inquiry and response. The other factors deciding the performance are as follows:  Number of users  Type of transmission medium  Capability of connected hardware  Efficiency of software PANGASINAN STATE UNIVERSITY 1  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 Reliability is vital as it makes a decision the frequency at which community failure takes place. It also decides the time taken by the network to recover and its robustness in the catastrophe. Security refers to safety of data from the unauthorized user/client or access. DATA COMMUNICATION MODEL  Source - this device generates the data to be transmitted.  Transmitter - a transmitter transforms and encodes the information in such a manner to produce electromagnetic waves or signals. These electromagnetic waves may be transmitted throughout a few types of transmission systems.  Transmission System - may be a single transmission line or a compound network connecting source and destination.  Receiver - accepts the signal from the transmission device and converts it into a form which may be controlled through the destination device.  Destination - takes the incoming data from the receiver. LEARNING CONTENTS (CLASSIFICATIONS OF NETWORK) CLASSIFICATIONS OF NETWORK 1. Peer-to-Peer Networks – is characterized through its simplicity in implementation and operation. All computer systems are linked to the network have the same relationships to each other and having access to resources are free for all. 2. Client/Server Networks – is a server-based network. Each client PCs on the network share the processing and storage workload with the main computer known as server. One of the most common application of client/server setting is in the operation of relational database management system (RDBMS) which is commonly installed on the main computer for centralized access of its resources. 3. Server – it serves as warehouse for software program and data information which might be shared by various users who are connected to it thru cables or antenna. 4. Workstation – usually used by the users. It is a term used for a computer connected to the main computer called server. LOCAL AREA NETWORK (LAN) Local Area Network, typically referred to as LANs, is privately-owned networks inside a building or campus of up to a limited KM in size. They are extensively used to connect personal computers and workstation in offices and factories to share resources (e.g., printers) and exchange information. LANs are well-known from different kinds of networks with three characteristics: size, transmission technology and topology. LANs are limited in size, because of this means the worst-case transmission time is bounded and identified in advance. Knowing these certain makes it feasible to apply certain varieties of designs that might not otherwise be feasible. It additionally simplifies network management. METROPOLITAN AREA NETWORK (MAN) A Metropolitan Area network, or MAN (plural: MANs, not MEN) is mainly a larger version of a LAN and commonly makes use of comparable technology. It might cover a crowd of close offices or a town and probably both private or public. A MAN PANGASINAN STATE UNIVERSITY 2  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 can sustain both data and voice, and may also be associated with the local cable television network. A MAN simply has one or two cables and does not cover switching elements, which shunt packets over one of more than a few output lines. WIDE AREA NETWORK (WAN) A Wide Area Network, or WAN, spans a huge geographical area, regularly a country or continent. It carries of machines meant for running user (i.e., application/software) programs. We will observe conventional utilization and call these machines hosts. The term end system occasionally used in the literature. The hosts are connected via way of communication subnet. The task of the subnet is to hold messages from host to host, simply because the telephone system includes words from speaker to listener. By setting apart the natural communication aspects of the network (the subnet) from the application aspects (the hosts), the comprehensive network design is substantially simplified. In maximum huge area networks, the subnet includes of two components: transmission lines and switching elements. Transmission traces (additionally known as circuits, channels or trunks) move bits among machines. The switching elements are specialized computer systems used to attach two or greater transmission lines. When data arrives on an incoming line, the switching detail ought to pick an outgoing line to ahead them on. In most WANs, the network consists of several cables or telephone lines, every one connecting a pair of routers. If two routers that don't share a cable however desire to communicate, they need to do this indirectly, through different routers. When a packet is send from one router to another through one or more intermediate routers, the packet is received at every intermediate router in every entirety, stored there until the specified output line is free, and the forwarded. A subnet using this principle is called a point-to-point, store and forward or packet switched subnet. Nearly all wide area networks (except those using satellite) have store and forward subnet. When the packet are small and all the same size, they regularly referred to as cells. WIRELESS NETWORK (WLAN, WWAN, WMAN) Mobile computers, which as notebook computers and personal digital assistants (PDA) are the quickest developing sector of the computer industries. Many of the owners of these computers have desktop machines on LANs and WANs back at the workplace and want to be connected to their home base even when away from home or in route. Since having a wired connection is difficult in cars and airplanes, there is a lot of interest in wireless network. Wireless networks come in many forms. Another option is using a cellular (i.e. Portable) telephone with a conventional analog modem. Direct digital cellular service, called CDPD (Cellular Digital Packet Data) is becoming accessible in many cities. ORGANIZATIONAL INTERNETS: INTRANETS AND EXTRANETS INTRANETS are private networks within an organization that resemble the Internet. Like the Internet, they use browsers, Web sites, and Web pages. Unlike the Internet, intranets are available only to those within the organization. EXTRANETS are similar to intranets, excepts that extranets connect more than one organization. Extranets are often used to connect suppliers and producers to increase efficeincy. FIREWALL is a security system to protect against external threats. It consist of both hardware and software. All communications into and out of an organization pass through a special security computer called a proxy server. LEARNING CONTENTS (TRANSMISSION MEDIA) TRANSMISSION MEDIA o Transmission media is a communication channel that transmits the information from the sender to the receiver. Data is transmitted via the electromagnetic signals. o The major functionality of the transmission media is to hold the information in the form of bits via LAN(Local Area Network). o It is a physical path between transmitter and receiver in data communication. o In a copper-based network, the bits in the form of electrical signals. o In a fibre based network, the bits in the form of light pulses. o In OSI (Open System Interconnection) phase, transmission media helps the Layer 1. Therefore, it is considered to be as a Layer 1 component. o The electrical signals can be sent through the copper wire, fibre optics, atmosphere, water, and vacuum. o The quality and traits of data transmission are determined by the characteristics of medium and signal. o Transmission media is of two types are wired media and wireless media. In wired media, medium characteristics are more vital whereas, in wireless media, signal characteristics are more essential. PANGASINAN STATE UNIVERSITY 3  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 o Different transmission media have various properties such as bandwidth, delay, cost and ease of installation and maintenance. o The transmission media is accessible in the lowest layer of the OSI reference model, i.e., Physical layer. In data communication terminology, a transmission medium is a physical path among the transmitter and the receiver i.e it is the channel through which data is sent from one location to another. Transmission Media is widely categorized into the following types: GUIDED MEDIA It is also known as Wired or Bounded transmission media. Signals being transmitted are directed and restricted in a narrow pathway by using physical links. Features:  High Speed  Secure  Used for comparatively shorter distances There are 3 major types of Guided Media 1. TWISTED PAIR CABLE It consists of two separately insulated conductor wires wound about each other. Generally, several such pairs are bundled collectively in a protective cover. They are the most broadly used Transmission Media. Two Types of Twisted Pair A. Unshielded Twisted Pair (UTP) - This kind of cable has the capability to block interference and does not depend on a physical shield for this purpose. It is used for telephonic applications. Advantages:  Least expensive  Easy to install  High speed capacity  Susceptible to external interference  Lower capacity and performance in comparison to STP  Short distance transmission due to attenuation B. Shielded Twisted Pair (STP) - This kind of cable contains of a special jacket to block external interference. It is used in fast-data-rate Ethernet and in voice and data channels of telephone lines. Advantages:  Better performance at a higher data rate in comparison to UTP  Eliminates crosstalk  Comparatively faster  Comparatively difficult to install and manufacture  More expensive  Bulky 2. COAXIAL CABLE It has an outer plastic covering containing 2 parallel conductors each having a separate insulated shield cover. Coaxial cable conveys information in two modes: Baseband mode (dedicated cable bandwidth) and Broadband mode (cable bandwidth is divided into separate ranges). Cable TVs and analog television networks broadly use Coaxial cables. Advantages:  High Bandwidth PANGASINAN STATE UNIVERSITY 4  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5  Better noise Immunity  Easy to install and expand  Inexpensive Disadvantages:  Single cable failure can disrupt the entire network 3. OPTICAL FIBRE CABLE It makes use of the idea of reflection of light through a core made up of glass or plastic. The core is surrounded by a less dense glass or plastic covering called the cladding. It is used for transmission of huge volumes of data. Advantages:  Increased capacity and bandwidth  Light weight  Less signal attenuation  Immunity to electromagnetic interference  Resistance to corrosive materials Disadvantages:  Difficult to install and maintain  High cost  Fragile UNGUIDED MEDIA It is also known as Wireless or Unbounded transmission media. No physical medium is needed for the transmission of electromagnetic signals. Features:  Signal is broadcast through air  Less Secure  Used for larger distances There are 3 major types of Unguided Media 1. RADIOWAVES These are easy to generate and might penetrate via buildings. The sending and receiving antennas need not be aligned. Frequency Range:3KHz – 1GHz. AM and FM radios and cordless phones with Radiowaves for transmission. 2. MICROWAVES It is a line of sight transmission i.e. the sending and receiving antennas need to be well aligned with each other. The distance enclosed by the signal is directly proportional to the height of the antenna. Frequency Range: 1GHz – 300GHz. These are mainly used for mobile phone communication and television distribution. 3. INFRARED Infrared waves are used for quick short distance communication. They can’t penetrate via obstacles. This prevents interference among systems with a frequency Range: 300GHz – 400THz. It is utilized in TV remotes, wireless mouse, keyboard, printer, etc. LEARNING CONTENTS (CHANNEL ORGANIZATION) CHANNEL ORGANIZATION A network is two or more devices connected to each other through connecting links. There are two possible methods to connect the devices. They are as under:  Point-to-Point Connection  Multipoint Connection POINT-TO-POINT CONNECTION A point-to-point connection provides a committed link between two devices. Entire capacity of the link is reserved for transmission among these two devices only. It is possible to connect the two devices by means of a pair of wires or with a microwave or satellite link. PANGASINAN STATE UNIVERSITY 5  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 Simplex: Channel passes data in one direction. Half-Duplex: Transmits data one direction at a time Full-Duplex: Transmits data in both directions simultaneously MULTIPOINT CONNECTION A multipoint connection is also referred to a multiplier connection. In such a connection, more than two devices share a single link. In the multipoint connection, the channel capacity is shared. If lot of devices share the link concurrently, it is called spatially shared connection. But, if users share it turn then it is time sharing connection. Broadcasts messages to all connected receivers. LEARNING CONTENTS (NETWORKING COMPONENTS) NETWORKING COMPONENTS Computer network components are the major components which are required to install the software. Some significant network components are NIC, switch, cable, hub, router, and modem. Depending on the type of network that we want to install, a few network components also can be removed. For example, the wireless network does not require a cable. The following are the major components required to install a network: NIC (NETWORK INTERFACE CARD) NIC is a hardware component used to connect a computer with another computer onto a network. It can support a transfer rate of 10,100 to 1000 Mb/s. The MAC address or physical address is encoded on the network card chip which is assigned by the IEEE to identify a network card uniquely. The MAC address is stored in the PROM (Programmable read-only memory). There are two types of NIC: 1. Wired NIC - The Wired NIC is current within the motherboard. Cables and connectors are used with wired NIC to transfer data. 2. Wireless NIC - The wireless NIC covers the antenna to acquire the connection over the wireless network. For example, laptop computer contains the wireless NIC. HUB A Hub is a hardware device that divides the network connection among many devices. When computer requests for certain information from a network, it first sends the request to the Hub via cable. Hub will broadcast this request to the whole network. All the devices will verify whether the request belongs to them or not. If not, the request can be dropped. PANGASINAN STATE UNIVERSITY 6  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 The process utilized by the Hub consumes extra bandwidth and limits the amount of communication. Nowadays, the use of hub is obsolete, and it is substituted by more advanced computer network components such as Switches, Routers. SWITCH A switch is a hardware device that connects many devices on a computer network. A Switch covers extra advanced features than Hub. The Switch covers the updated table that decides where the data is transmitted or not. Switch carries the message to the right destination based on the physical address present in the incoming message. A Switch does not longer broadcast the message to the entire network like the Hub. It regulates the device to whom the message is to be transmitted. Therefore, we can say that switch delivers a direct connection between the source and destination. It increases the speed of the network. ROUTER A router is a hardware device which is used to connect a LAN with an internet connection. It is used to receive, analyze and forward the incoming packets to other network. A router works in a Layer 3 (Network layer) of the OSI Reference model. A router forwards the packet based on the information accessible in the routing table. It determines the best path from the existing paths for the transmission of the packet. Advantages of Router:  Security: The information which is conveyed to the network will traverse the entire cable, but the only identified device which has been addressed can read the data.  Reliability: If the server has stopped functioning, the network is going down, however no different networks are affected that are served by the router.  Performance: Router improves the overall performance of the network. Suppose there are 24 workstations in a network generates an equal quantity of traffic. This increases the traffic load on the network. Router splits the single network into two networks of 12 workstations each, decreases the traffic load by half. MODEM A modem (Modulator/Demodulator) is a hardware device that permits on the computer to connect to the internet over the current telephone line. A modem is not incorporated with the motherboard rather than it is installed on the PCI slot found on the motherboard. It converts the digital data into an analog signal over the telephone lines. Based on the differences in speed and transmission rate, a modem can be classified in the following categories:  Standard PC modem or Dial-up modem  Cellular Modem  Cable modem  Cables and Connectors CABLE Cable is a transmission media tool that is used for transmitting a signal. There are three types of cables used in transmission:  Twisted pair cable  Coaxial cable  Fiber-optic cable. LEARNING CONTENTS (NETWOK TOPOLOGY AND PROTOCOLS) NETWORK TOPOLOGY AND PROTOCOLS Network topology describes the format or appearance of a network that is how the computers, cables, and other components within a data communication network are interconnected, both physically and logically. The physical topology describes the way wherein a network is physically laid out, and the logical topology describes how data surely flow via network. In a data communication, two or more devices are connected to form a link whereas two or more links form a topology. The topology of a network is the geometric representation of the relationship of all the links connecting the devices (or nodes). The network topology are: 1. Bus Topology 2. Ring Topology 3. Star Topology 4. Mesh Topology 5. Tree Topology 6. Hybrid Topology PANGASINAN STATE UNIVERSITY 7  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 BUS TOPOLOGY A bus topology is a multipoint data communication circuit that makes it quite simple to control data flow between and among the computers because this configuration permits all stations to acquire each transmission over the network. On an ordinary bus network, the cable is simply one or more wires, with no active electronics to increase the signal or pass it along from computer to computer. This makes the bus a passive technology. When one computer sends a signal up to the cable, all the computers on the network receive the information, but the one with the address that matches the one encoded in the message accepts the information while all the others reject the message. The speed of the bus topology is slow because only one computer can send a message at a time. Computers have to wait until the bus is free before it can transmit. The bus topology needs a right termination at both the ends of the cable. Advantages of Bus Topology  Low-cost cable: In bus topology, nodes are directly connected to the cable without passing via hub. Therefore, the preliminary fee of set up is low.  Moderate data speeds: Coaxial or twisted pair cables are mostly used in bus-based networks that support up to 10 Mbps.  Familiar technology: Bus topology is a familiar technology as the installation and troubleshooting procedures are nicely known, and hardware components are easily available.  Limited failure: A failure in one node will not have any effect on other nodes. Disadvantages of Bus Topology  Extensive cabling: A bus topology is rather simpler; however it requires a lot of cabling.  Difficult troubleshooting: It requires specialized test equipment to regulate the cable faults. If any fault takes place within the cable, then it might disrupt the communication for all the nodes.  Signal interference: If two nodes send the messages at the same time, then the signals of both the nodes collide with each other.  Reconfiguration difficult: Adding new devices to the network might slow down the network.  Attenuation: Attenuation is a loss of signal leads to communication issues. Repeaters are used to regenerate the signal. RING TOPOLOGY In a ring topology, every computer is connected to the next computer, with the last one connected to the first computer. Rings are used in high-performance networks where large bandwidth is vital, time attractive features such as video and audio. A ring topology is a multipoint data communication network where all stations are interconnected in series to form a closed loop or circle. A ring topology is sometimes called a loop. Each station within the loop is joined by point-to-point links to two other stations, (the transmitter of one and the receiver of the other). The messages run around the ring in one direction. There is no termination because there is no end to the ring. Some ring networks do token passing. A short message called a token, is handed across the ring till a computer desires to send information to other computer. That computer modifies the token, provides an electronic address and data and sends it around the ring. Each computer in order receives the token and the information and passes them to the next computer until both the electronic address matches the address of a computer or the token returns to its origin. The receiving computer returns a message to the originator indicating that the message has been received. The sending computer then creates another token and places it on its network, permitting every station to capture the token and start transmitting. The token circulates until a station is ready to send and capture the token. Faster networks circulate numerous tokens at once. A ring can perform as a communication network if it executes the following three functions: Data Insertion, Data Reception and Data Removal. Advantages of Ring Topology  Network Management: Faulty devices can be eliminated from the network without bringing the network down.  Product availability: Many hardware and software tools for network operation and monitoring are available.  Cost: Twisted pair cabling is cheap and simply available. Therefore, the installation cost is very low.  Reliable: It is a more consistent network because the communication system is not dependent on the single host computer. Disadvantages of Bus Topology  Difficult troubleshooting: It requires specialized test equipment to regulate the cable faults. If any fault takes place within the cable, then it might disrupt the communication for all the nodes.  Failure: The breakdown in one station results to the failure of the overall network.  Reconfiguration difficult: Adding new devices to the network might slow down the network.  Delay: Communication delay is directly proportional to the number of nodes. Adding new devices increases the communication delay. PANGASINAN STATE UNIVERSITY 8  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 STAR TOPOLOGY In a star topology, the entire cables run from the computers to a central location where they are all connected by a device called a hub. Stars are used in concentrated networks, where the end points are directly accessible from a central location when network expansion is conveyed and when the greater reliability of a star topology is required. Each computer on a star network communicates with a central hub that re-sends the message either to all the computers in a broadcast star network or only to the destination computer in a switched star network. The hub in a broadcast star network can be active or passive. An active hub generates the electrical signal and sends it to all the computers connected to it. This type of hub is typically called a multipoint repeater. Active hubs need external power supply. A passive hub is a wiring panel or punch down block which acts as a connection point. It does not longer extend or regenerate the signal. Passive hubs do not require electrical power supply. Advantages of Star Topology  Efficient troubleshooting: Troubleshooting is quite effective in a star topology as compared to bus topology. In a bus topology, the manager has to check the kilometers of cable. In a star topology, all the stations are connected to the centralized network. Therefore, the network administrator has to go to the single station to troubleshoot the problem.  Network control: Complex network control features can be easily executed in the star topology. Any adjustments made within the star topology are automatically accommodated.  Limited failure: As each station is connected to the central hub with its own cable, therefore failure in one cable will no longer affect the entire network.  Familiar technology: Star topology is a familiar technology as its tools are cost-effective.  Easily expandable: It is easily expandable as new stations can be added to the open ports on the hub.  Cost effective: Star topology networks are cost-effective as it uses less expensive coaxial cable.  High data speeds: It supports a bandwidth of approx. 100Mbps. Ethernet 100BaseT is one of the most common Star topology networks. Disadvantages of Star Topology  A Central point of failure: If the central hub or switch is going down, then all the connected nodes will not be able to communicate with each other.  Cable: Sometimes cable routing becomes difficult when a widespread quantity of routing is required. MESH TOPOLOGY In a mesh topology, every device has a dedicated point-to-point link to each different device. The term dedicated means that the link conveys traffic only among two devices it connects. A completely connected mesh network therefore has n(n  1) / 2 physical channels to link hn devices. To accommodate those links, every device on the network must have n  1 input/output ports. Advantages of Mesh Topology  Reliable: The mesh topology networks are very consistent as though any link breakdown will not affect the communication among connected computers.  Fast Communication: Communication is very fast between the nodes.  Easier Reconfiguration: Adding new devices would not disrupt the communication among different devices. Disadvantages of Mesh Topology  Cost: A mesh topology covers a huge number of connected devices such as a router and more transmission media than different topology.  Management: Mesh topology networks are very huge and very hard to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.  Efficiency: In this topology, redundant connections are excessive that reduces the performance of the network. TREE TOPOLOGY A tree topology is the variant of a star. As in a star, nodes in a tree are connected to a central hub that holds the traffic to the network. However, not every computer plugs into the central hub, mostly of them are connected to a secondary hub which, in turn, is connected to the central hub. The central hub in the tree is an active hub which includes repeater. The repeater strengthens the signal and increases the distance a signal can travel. The secondary hubs may be active or passive. A passive hub delivers a simple physical connection among the attached devices. PANGASINAN STATE UNIVERSITY 9  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 Advantages of Tree Topology  Support for broadband transmission: Tree topology is particularly used to provide broadband transmission, i.e., signals are sent over long distances without being reduced.  Easily expandable: We can add the new device to the current network. Therefore, we can say that tree topology is easily expandable.  Easily manageable: In tree topology, the entire network is distributed into segments known as star networks which can be easily managed and maintained.  Error detection: Error detection and error correction are very easy in a tree topology.  Limited failure: The breakdown in one station does not affect the whole network.  Point-to-point wiring: It has point-to-point wiring for individual segments. Disadvantages of Tree Topology  Difficult troubleshooting: If any fault happens within the node, then it turns difficult to troubleshoot the problem.  High cost: Devices required for broadband transmission are very expensive.  Failure: A tree topology mainly depends on main bus cable and failure in main bus cable will harm the whole network.  Reconfiguration difficult: If new devices are added, then it becomes difficult to reconfigure. HYBRID TOPOLOGY The combination of many different topology is known as Hybrid topology. A Hybrid topology is a connection among different links and nodes to transfer the data. When two or more different topology are mixed together is called as Hybrid topology and if related topology are connected with each other will not result in Hybrid topology. For example, if there exist a ring topology in one branch of ICICI bank and bus topology in another branch of ICICI bank, connecting these two topology will result in Hybrid topology. Advantages of Hybrid Topology  Reliable: If a fault happens in any part of the network will not affect the operation of the rest of the network.  Scalable: Size of the network can be certainly expanded through adding new devices without affecting the capability of the existing network.  Flexible: This topology is very flexible as it can be designed consistent with the requirements of the organization.  Effective: Hybrid topology is very effective as it can be designed in this kind of manner that the strength of the network is maximized and weakness of the network is minimized. Disadvantages of Hybrid topology  Complex design: The main disadvantage of the Hybrid topology is the design of the Hybrid network. It is very hard to design the architecture of the Hybrid network.  Costly Hub: The Hubs used within the Hybrid topology are very costly as these hubs are not the same from typical Hubs used in different topology.  Costly infrastructure: The infrastructure rate is very high as a hybrid network needs a lot of cabling, network devices, etc. LEARNING CONTENTS (STRAIGHT-THROUGH vs CROSSOVER CABLES) STRAIGHT THROUGH VS CROSSOVER CABLE STRAIGHT THROUGH CABLE A straight through cable is a type of twisted pair cable that is used in local area networks to connect a computer to a network hub such as a router. This type of cable is also occasionally known as patch cable and is a substitute to wireless connections where one or more computers access a router through a wireless signal. On a straight through cable, the wired pins match. Straight through cable use one wiring standard: both ends use T568A wiring standard or both ends use T568B wiring standard. PANGASINAN STATE UNIVERSITY 10  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 CROSSOVER CABLE A crossover Ethernet cable is a type of Ethernet cable used to connect computing devices collected directly. Unlike straight through cable, the RJ45 crossover cable uses two different wiring standards: one end uses the T568A wiring standard and the other end uses the T568B wiring standard. The internal wiring of Ethernet crossover cables reverses the transmit and receive signals. It is most often used to connect two devices of the same type: e.g. two computers (via network interface controller) or two switches to each other. Usually, straight through cables are primarily used for connecting different devices. And crossover cables are used for connecting similar devices. Use straight through Ethernet cable for the following cabling:  Switch to router  Switch to PC or server  Hub to PC or server Use crossover cables for the following cabling:  Switch to switch  Switch to hub  Hub to hub  Router to router  Router Ethernet port to PC NIC  PC to PC LEARNING ACTIVITY Self-check Questions Name:_____________________________________ Course/Year:_________ Date:________ Score:_______ IDENTIFICATION: Read the following statements. Write your answers on the blank space provided before each number. _______________ 1. It is privately-owned networks inside a building or campus of up to a limited KM in size. _______________ 2. An idea associated with the use of computer networks to link human beings and resources. _______________ 3. A type of twisted pair cable that is used in local area networks to connect a computer to a network hub such as a router. _______________ 4. The combination of many different topology. _______________ 5. A security system to protect against external threats. It consists of both hardware and software. _______________ 6. A hardware device that permits on the computer to connect to the internet over the current telephone line. _______________ 7. It serves as warehouse for software program and data information which might be shared by various users who are connected to it through cables or antenna. _______________ 8. This kind of cable has the capability to block interference and does not depend on a physical shield for this purpose. _______________ 9. A private networks within an organization that resemble the Internet. _______________ 10. It provides a committed link between two devices. _______________ 11. A hardware device which is used to connect a LAN with an internet connection. PANGASINAN STATE UNIVERSITY 11  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 _______________ 12. A type of Ethernet cable used to connect computing devices collected directly. _______________ 13. The format or appearance of a network that is how the computers, cables, and other components within a data communication network are interconnected, both physically and logically. _______________ 14. These are used for quick short distance communication. _______________ 15. It has an outer plastic covering containing 2 parallel conductors each having a separate insulated shield cover. _______________ 16. It makes use of the idea of reflection of light through a core made up of glass or plastic _______________ 17. A hardware component used to connect a computer with another computer onto a network _______________ 18. It is mainly a larger version of a LAN and commonly makes use of comparable technology. _______________ 19. A multipoint data communication circuit that makes it quite simple to control data flow between and among the computers because this configuration permits all stations to acquire each transmission over the network. _______________ 20. This kind of cable contains of a special jacket to block external interference. LEARNING ACTIVITY 1 ESSAY: Give your idea about the given statements. 1. Define and discuss connectivity, the wireless revolution and communications. 2. What is the primary difference between LAN, MAN and WAN? 3. Compare the types of guided media and unguided media. SUMMARY  A Network is set of devices often referred to a odes connected by media links.  Classifications of networks are LAN, MAN, WAN, Wireless Network Peer-to-Peer Networks, Client/Server Networks, Server, Workstation.  The types of transmission media are Guided media (Twisted Pair Cable, Coaxial Cable, Optical Cable) and Unguided Media (Radiowaves, Microwaves, Infrared)  Networking components are network interface card, hub switch, router, modem, cable.  The network topology are Bus Topology, Ring Topology, Star Topology, Mesh Topology, Tree Topology, Hybrid Topology  Network Cables are straight-through, and crossover. REFERENCES Book and E-book (2014)Computing Essentials, McGraw-Hill Companies Inc. Sanjay Sharma (2014), Elements of Computer Networks, S.K. KATARIA & SONS Volante, Tam (2014). Fundamentals of Information Technology, Unlimited Books Library Services & Publishing Inc. Web-links https://en.wikibooks.org/wiki/Introduction_to_Computer_Information_Systems https://www.geeksforgeeks.org/types-transmission-media/ https://www.javatpoint.com/computer-network-transmission-modes http://www.cables-solutions.com/difference-between-straight-through-and-crossover-cable.html PANGASINAN STATE UNIVERSITY 12  FM-AA-CIA-15 Rev. 0 10-July-2020 Study Guide in CC 101 - Introduction to Computing Module No. 5 PANGASINAN STATE UNIVERSITY 13