You are working in the IT department in an organization and responsible to design a network system for the organization. Do a research on the types of network topology available and identify the network topology that you would recommend to the management. Give the reasons to support your recommendation.
The transmission media that are used to convey information can be classified as guided or unguided. Guided media provide a physical path along which signal is propagated; unguided media employ an antenna for transmitting through air, vacuum, or water. Discuss the both transmission media in detail with examples.
Introduction
Question 1 was discussed about the types of network topology and the suitable network topology for the company which I was worked in. There are some example and also the definition for the network topology being declared below.
Question 2 was discussed about the transmission media that are used to convey information which can be classified as guided or unguided. There are also example and definition for the both transmission media in detail with examples.
Question 1
Network topology is the plan of the variety of elements (links, nodes, etc.) of a computer or biological network. Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network's various components, including device location and cable installation, while logical topology shows how data surges within a network, despite of its physical design. Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two networks, yet their topologies may be identical.
There are two basic categories of network topologies:
Physical topologies
Logical topologies
The physical topology of a network is resolute by the capabilities of the network access devices and media, the level of control or fault tolerance needed, and the cost allied with cabling or telecommunications circuits.
The logical topology, in disparity, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without stare to the physical interconnection of the devices. A network's logical topology is not necessarily the same as its physical topology. For example, the original twisted pair Ethernet using repeater hubs was a logical bus topology with a physical star topology outline. Token Ring is a logical ring topology, but is strung out a physical star from the Media Access Unit.
The logical classification of network topologies usually follows the same classifications as those in the physical classifications of network topologies but describes the path that the data takes between nodes being used as disparate to the actual physical connections between nodes. The logical topologies are generally determined by network protocols as opposed to being determined by the physical design of cables, wires, and network devices or by the surge of the electrical signals, although in many cases the paths that the electrical signals take between nodes may directly match the logical flow of data, therefore the convention of using the terms logical topology and signal topology interchangeably.
Network topologies are categorized into the following basic types:
Bus
Ring
Star
Tree
Mesh
Hybrid
Daisy Chain
Bus Topology
Bus networks use a common backbone to connect all devices. A single cable, the backbone functions as a mutual communication medium that devices connect or tap into with an interface connector. A device deficient to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the planned recipient actually accepts and processes the message.
Ring Topology
In a ring network, every device has accurately two neighbours for communication purposes. All messages travel through a ring in the same direction. A failure in any cable or device breaks the loop and can take down the entire network. The ring topology is a computer network construction where each network computer and device is connected to each other forming a large circle. Each packet is sent around the ring until it achieves its final destination. Today, the ring topology is seldom used.
Star Topology
Many home networks use the star topology. A star network description a central connection point called a "hub node" that may be a network hub, switch or router. Devices classically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network usually involves more cable, but a failure in any star network cable will only transcribe one computer's network access and not the entire LAN.
Tree Topology
Tree topologies incorporate multiple star topologies together onto a bus. In its simplest form, only hub devices connect nonstop to the tree bus and each hub functions as the root of a tree of devices. This bus/star hybrid approach wires future expandability of the network much better than a bus (limited in the number of devices appropriate to the broadcast traffic it generates) or a star (connection points limited by the number of hub) alone.
Mesh Topology
Mesh topologies involve the idea of routes. Dissimilar each of the preceding topologies, messages sent on a mesh network can take any of several possible paths from source to destination. Some WANs, most particularly the Internet, employ mesh routing.
Hybrid
Hybrid networks use an arrangement of any two or more topologies in such a way that the resulting network does not reveal one of the standard topologies (e.g., bus, star, ring, etc.). For example a tree network connected to a tree network is still a tree network topology. A hybrid topology is always formed when two different basic network topologies are connected. Two common examples for Hybrid network are: starring network and star bus network
A Starring network consists of two or more star topologies connected using a multi-station access unit (MAU) as a centralized hub.
A Star Bus network consists of two or more star topologies connected using a bus trunk (the bus trunk serves as the network's backbone).
While grid and torus networks have found reputation in high-performance computing applications, some systems have used genetic algorithms to design custom networks that have the smallest possible hops in between different nodes. Some of the consequential layouts are nearly unintelligible, although they function quite well.
A Snowflake topology is really a "Star of Stars" network, so it displays characteristics of a hybrid network topology but is not unruffled of two different basic network topologies being connected.
Daisy chain
Except for star-based networks, the simplest way to add more computers into a network is by daisy-chaining, or connecting each computer in series to the next. If a message is planned for a computer partway down the line, each system spring ups it along in series until it reaches the destination. A daisy-chained network can take two basic forms: linear and ring.
A linear topology puts a two-way relation between one computer and the next. However, this was high-priced in the early days of computing, since each computer (except for the ones at each end) necessary two receivers and two transmitters.
By connecting the computers at each end, a ring topology can be formed. An advantage of the ring is that the number of receives and recipients can be cut in half, since a message will ultimately loop all of the way around. When a node sends a message, the message is progression by each computer in the ring. If the ring smashes at a particular link then the transmission can be sent through the reverse path in that way ensuring that all nodes are always connected in the case of a single failure.
The Type of Topology I suggest for company is the ring topology. Instead referred to as a ring network, the ring topology is a computer network construction where each network computer and device is associated to each other forming a large circle (or similar shape). Each packet is sent around the ring until it arrive its final destination. Today, the ring topology is rarely used. This type of network topology is very structured. Each node gets to send the data when it receives a blank token. This helps to trim downs chances of crash. Also in ring topology all the traffic streams in only one direction at very high speed. Even when the load on the network increases, its performance is better than that of Bus topology. There is no need for network server to control the connectivity between workstations. Additional components do not influence the performance of network. Each computer has equal access to property. Other that, the ring topology is very orderly network where every device has access to the token and the opportunity to convey. Due to the point to point line configuration of devices with a device on either side, it is moderately easy to install and reconfigure since adding or removing a device necessitates moving just two connections. Point to point line configuration makes it easy to identify and isolate faults. It is easy to set-up and active topology implementation strengthens signal as it passes around ring.
There are also some deficiencies for the ring network topologies which are moving, adding and shifting the devices have an effect on the network. One malfunctioning workstation can create problems for the entire network. This can be resolved by using a dual ring or a switch that closes off the break. Bandwidth is mutual on all links between devices and the ring network topology is more complicated to configure than a Star network topology. There are also some communication stoppage is straight proportional to number of nodes in the network. Lack of fault tolerance and is not easy to add and remove devices once the network has been set up.
Question 2
Transmission media is communication guides in the animal world include touch, sound, sight, and scent. Electric eels even utilize electric pulses. Ravens also are very meaningful. By a grouping voice, patterns of feather erection and body posture ravens communicate so clearly that an qualified observer can recognize anger, affection, hunger, curiosity, playfulness, fright, boldness, and misery.
The transmission media that are used to express information can be classified as guided or unguided. Guided media supply a physical path along which the signals are propagated; these include twisted pair, coaxial cable, and optical fiber. Unguided media utilize an antenna for transmitting through air, vacuum, or water.
The individuality and quality of a data transmission are determined both by the characteristics of the medium and the individuality of the signal. In the case of guided media, the medium itself is more significant in determining the limitations of transmission.
Table 4.1(shown above) indicates the characteristics typical for the common guided media for long-distance point-to-point applications. The three guided media commonly used for data transmission are twisted pair, coaxial cable, and optical fiber. We examine each of these in turn.
Twisted Pair
By far the most general guided transmission medium for both analog and digital signals is twisted pair. It is the most frequently used medium in the telephone network, and for transportation within buildings. Twisted pair is much less luxurious than the other usually used guided transmission media and is easier to work with.
A twisted pair consists of two insulated copper wires approved in a regular spiral pattern. A wire matches up as a single communication link. Classically, a number of these pairs are bunched together into a cable by covering them in a tough protective sheath. The twisting has a propensity to decrease the crosstalk interference between contiguous pairs in a cable. Neighboring pairs in a fortune classically have somewhat different twist lengths to decrease the crosstalk interference.
Compared to other generally used guided transmission media, twisted pair is restricted in distance, bandwidth, and data rate. The reduction for twisted pair is a very strong function of frequency. Other impairments are also harsh for twisted pair. The medium is quite vulnerable to interference and noise because of its simple coupling with electromagnetic fields. Several measures are taken to trim down impairments. Shielding the wire with metallic braid or sheathing reduces intrusion. The twisting of the wire reduces low-frequency interference, and the use of different twist lengths in contiguous pairs reduces crosstalk.
Unshielded Twisted Pair
Twisted pair comes in two varieties: unshielded and shielded.
Unshielded twisted pair (UTP) is usual telephone wire. Office buildings, by universal practice, are prewired with excess unshielded twisted pair, more than is needed for simple telephone support. This is the smallest amount expensive of all the transmission media normally used for local area networks and is uncomplicated to work with and easy to install. However UTP is subject to peripheral electromagnetic interference, including interference from nearby twisted pair and from noise generated in the environment.
A way to improve the individuality of this medium is to shield the twisted pair with a tinny braid or sheathing that reduces interference. This shielded twisted pair (STP) provides better performance at higher data rates. However, it is more luxurious and more difficult to work with than unshielded twisted pair.
Coaxial Cable
Coaxial cable, like twisted pair, consists of two conductors, but is constructed another way to authorize it to operate over a wider range of frequencies. It consists of an unfilled outer cylindrical composer that surrounds a single inner wire. The inner conductor is held in place by either regularly spaced insulating rings or a solid dielectric material. The outer conductor is roofed with a jacket or shield. A single coaxial cable has a diameter of from 1 to 2.5 cm. Coaxial cable can be worn over longer distances and support more stations on a shared line than twisted pair.
Coaxial cable is a adaptable transmission medium, used in a wide variety of applications, including:
Television distribution - aerial to TV & CATV systems
Long-distance telephone transmission - traditionally used for inter-exchange links, now being replaced by optical fiber/microwave/satellite
Short-run computer system links
Local area networks
Optical Fiber
An optical fiber is a thin, flexible medium capable of guiding an optical ray. A choice of glasses and plastics can be used to make optical fibers. An optical fiber cable has a cylindrical shape and consists of three concentric sections: the core, the cladding, and the jacket. The hub is the innermost section and consists of one or more very thin strands, or fibers, made of glass or plastic. Each fiber is bounded by its own cladding, a glass or plastic coating that has visual properties different from those of the hub. The boundary between the hub and cladding acts as a reflector to confine light that would otherwise escape the core. The jacket is calm of plastic and other material covered to protect against moisture, abrasion, crushing, and other environmental dangers.
Optical fiber already likes considerable use in long-distance telecommunications, and its use in military applications is growing. The continuing improvements in performance and decline in prices, together with the intrinsic advantages of optical fiber, have made it more and more attractive for local area networking. Five basic categories of application have become important for optical fiber: Long-haul trunks, Metropolitan trunks, Rural exchange trunks, Subscriber loops & Local area networks.
Propagation
Propagation methods Ground propagation in ground propagation, radio waves pass through the lowest segment of the atmosphere. These low frequency signals originate in all directions from the transmitting antenna and follow the twist of the planet. Sky propagation in sky propagation, higher frequency radio waves glow with upward in to the ionosphere where they are reflected back to the earth. Line of sight propagation Very high incidence signals are transmitted in straight lines unswervingly from antenna to antenna. Antennas must be directional, facing each other.
Unguided Media
For unguided media, the bandwidth of the signal formed by the transmitting antenna is more imperative than the medium in determining transmission characteristics. One key belonging of signals transmitted by antenna is directionality. In general, signals at lower frequencies are unidirectional; that is, the signal propagates in all instructions from the antenna. At higher frequencies, it is possible to focus the signal into a directional beam. In considering the aim of data transmission systems, key concerns are data rate and distance: the greater the data rate and distance the better.
A number of design factors involving to the transmission medium and the signal decide the data rate and distance:
Bandwidth: All other factors remaining constant, the greater the bandwidth of a signal, the higher the data rate that can be achieved.
Transmission impairments: Impairments, such as attenuation, limit the distance. For guided media, twisted pair generally suffers more impairment than coaxial cable, which in turn suffers more than optical fiber.
Interference: Interference from competing signals in overlapping frequency bands can distort or wipe out a signal. Interference is of particular concern for unguided media, but is also a problem with guided media. For guided media, interference can be caused by emanations from nearby cables. For example, twisted pairs are frequently bundled together and conduits often carry multiple cables. Interference can also be qualified from unguided transmissions. Proper shielding of a guided medium can reduce this problem.
Number of receivers: A guided medium can be used to assemble a point-to-point link or a shared link with multiple attachments. In the latter case, each attachment introduces some shrinking and distortion on the line, limiting distance and/or data rate.
Type of Unguided media:
Radio wave
Microwave
Infrared
Radio wave
Radio Waves Advantages not line of sight can go through most solids and through walls longer range not light sensitive. Disadvantages Interference Lack of security higher cost than infrared Federal Communications Commission (FCC) licenses required for some products lower speed (lower than wired and infrared transmission).
Microwave
Microwaves are worn for uncast communication such as cellular telephones, dependency networks, and wireless LANs. Terrestrial Microwave Terrestrial Microwave transmission systems broadcast firmly focused beams of radio frequencies from one ground-based microwave antenna to another. Antennas are typically located at substantial heights above the ground level. Terrestrial Microwave Parabolic dish (typically 3m in diameter) Focused beam Line of sight Long drag telecommunications higher frequencies give higher data rates Transmission Distance is limited by: Height of Antennas Intervening Obstacles in the path of signals
Infrared
Infrared communications is achieved using transmitters/receivers (transceivers) that adapt no coherent infrared light. Transceivers must be surrounded by the line of sight of each other either straight or by reflection from a light-colored surface such as the maximum of a room.
One important difference between infrared and microwave transmission is that the former does not go through walls. Thus the security and interference problems encountered in microwave systems are not present. Furthermore, there is no frequency allocation concern with infrared, because no licensing is required.
Conclusion
Question 1 was discussed about the network topology. The Type of Topology I suggest for company is the ring topology. Although, the ring topology is rarely used, this type of network topology is very structured. Each node gets to send the data when it receives a blank token. This helps to trim downs chances of crash. Also in ring topology all the traffic streams in only one direction at very high speed. Even when the load on the network increases, its performance is better than that of Bus topology.
Question 2 was discussed about the transmission media. The transmission media that are used to express information can be classified as guided or unguided. Guided media supply a physical path along which the signals are propagated; these include twisted pair, coaxial cable, and optical fiber. Unguided media utilize an antenna for transmitting through air, vacuum, or water.
