Paragraph Styles Editing Answer each of the following: Q1. Electromagnetic Spect

Question

Paragraph Styles Editing Answer each of the following: Q1. Electromagnetic Spectrum and bandwidth. Define the following 1 (?) frequency, (iiLuavelength; (iii) amplitude; (iv) bandwidth; (v) attenuation; (vi) latency 2. Name the devices that boost weak signals (analo? /digital) 3. Show the derivation of the bandwidth for 64kbps. Q2 G) Switches and Routers operate at what layer of the OSI model? What does a router do when it receives a packet? Describe the characteristics and function of a router Explain G) Static Router, (n) Dynamic Router Q3?a) Define passive and active topology 1. Describe the basic physical and logical topologies and their uses, advantages and disadvantages. State if it's passive or active topology

Explanation / Answer

Answer1)

i)Frequency:

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Frequency is defined as the number of waves that pass a given point in a specified unit of time. The unit commonly used is Hertz which is the number of wave cycles pass a point in one second. So one cycle per second equals one Hertz.Minimum frequency for electro magnetic spectrum is of Radio Waves and maximum frequesncy is of Gamma Rays.

ii)Wavelength:

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Wavelength defines the distance between adjacent points of the electromagnetic wave that are in equal phase (e.g., wavecrests).The wavelength can be measured as the distance from crest to crest or from trough to trough. In fact, the wavelength of a wave can be measured as the distance from a point on a wave to the corresponding point on the next cycle of the wave. Wavelength is inversely proportional to frequency i.e. higher the wavelength lower is the frequency.

Maximum wavelength is of Radio Waves and minimum wavelength is of Gamma Rays.

iii)Amplitude:

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Amplitude is the maximum displacement of points on a wave, which you can think of as the degree or intensity of change. This maximum displacement is measured from the equilibrium position.

iv)Bandwidth:

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Bandwidth is the range of frequencies -- the difference between the highest-frequency signal component and the lowest-frequency signal component -- an electronic signal uses on a given transmission medium. Like the frequency of a signal, bandwidth is measured in hertz (cycles per second).

v)Attenuation:

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When sound travels through a medium, its intensity diminishes with distance. In idealized materials, sound pressure (signal amplitude) is only reduced by the spreading of the wave.Scattering is the reflection of the sound in directions other than its original direction of propagation. Absorption is the conversion of the sound energy to other forms of energy. The combined effect of scattering and absorption is called attenuation.

vi)Latency:

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Latency is the amount of time a message takes to traverse a system.It is sometimes measured as the time required for a packet to be returned to its sender.

Latency depends on the speed of the transmission medium (e.g.optical fiber or radio waves) and the delays in the transmission by devices along the way (e.g., routers and modems). A low latency indicates a high network efficiency.

Answer2)

Apmlifier:

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An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current). An amplifier uses electric power from a power supply to increase the amplitude of a signal.

Answer3)

Bandwith is calculate mostly into Bytes per sec. To convert bits (bps) to Byte(Bps) we devide bps by 8.

ifSpeed=64kbps

Bandwidth=64kbps/8

=8kBps

Answer2)

i) Router belongs to Layer 3 i.e. Network Layer of the OSI model

Switche belongs to Layer 2 i.e. Datalink layer

A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another router through the networks that constitute an internetwork until it reaches its destination node.

ii)

Static Router-

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A router with manually configured routing tables is known as a static router. A network administrator, with knowledge of the internetwork topology, manually builds and updates the routing table, programming all routes in the routing table. Static routers can work well for small internetworks but do not scale well to large or dynamically changing internetworks due to their manual administration.

Dynamic Router:

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A router with dynamically configured routing tables is known as a dynamic router. Dynamic routing consists of routing tables that are built and maintained automatically through an ongoing communication between routers. This communication is facilitated by a routing protocol, a series of periodic or on-demand messages containing routing information that is exchanged between routers

Answer3)

Passive Topology:

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When the computers on the network simply listen and receive the signal, they are referred to as passive because they don't amplify the signal in any way. Example for passive topology - linear bus.

Active Topology:

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The term active topology describes a network topology in which the signal is amplified at each step as it passes from one computer to the next.

Examplefor active topology -CSMA CD.

Logical Topology:

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A logical topology is how devices appear connected to the user. It refers how the data flow in the network .For example, in a shared Ethernet network that uses hubs rather than switches, the logical topology appears as if every node is connected to a common bus that runs from node to node.

Types of logical topologies

1.Bus topology: Ethernet uses the logical bus topology to transfer data. Under a bus topology a node broadcasts the data to the entire network. All other nodes on the network hear the data and check if the data is intended for them.

Used with: 10BaseT, 100BaseTX

Pros: Manageable , Inexpensive, most commonly used.

Cons: Less Efficient, number of systems connected is limited , low security.

2.Ring topology: In this topology, only one node can be allowed to transfer the data in a network at a given time. This mechanism is achieved by token (the node having token only can transmit the data in a network) and hence the collision can be avoided in a network.

Used with: Token Ring

Pros: Cheap, easy setup and maintenance.

Cons: If central node is down all other nodes gets disconnected.

Physical Topology:

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A physical topology describes how network devices are physically connected - in other words, how devices are actually plugged into each other. It includes cables, wireless connectivity, and more. For example, in a shared Ethernet network that uses hubs rather than switches, its physical topology is a star, in which every node on the network connects to a central hub.

Type of physical topology-

1.Star Topology:Network where all nodes are connected to a centralized point (Hub or switch).

Used with: FDDI (Fiber Distributed Data Interface) and Token Ring

Pros: Low signal degeneration. Since only one node can pass the token at any one time, it inherently reduces collisions significantly.

Cons: Expensive. Difficult to find a problem segment. If one node fails, whole network goes down. Dual-ring implementations provide redundancy and makes failures less likely.

2.Line Topology: Network in straight, linear sequence of nodes, terminated on both ends

Used with: 10BaseT, 100BaseTX

Pros: Cheap, easy setup and maintenance, reliable, and fault tolerant. Common wired standards of today.

Cons: In a given collision domain (a hub-based network segment), all nodes receive the same signal, giving rise to collisions and security concerns.

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