What is Coaxial cable ? What is application of Coaxial cable? What are advantages of Coaxial cable ?

COAXIAL CABLE :-

coaxial cable

* Definition of coaxial cable :- 

- A coaxial cable is a type of shielded and insulated copper cable that is used in to deliver TV services and computer networkto end users devices .                 
   - Coaxial cable is a type of copper cable specially built with a metal shield and other components engineered to block signal interference.

It was  implemented in the early 1940s for commercial purpose .

 It is used for both baseband and broadband data communication. services.

LAYER of coaxial cable :-

The ‘centre core’ is what carries the signal. The core can be a single solid wire, or stranded, or in high power/current applications it can be hollow (because of the skin effect means you don’t need to bother with conductor in the middle).

The ‘dielectric insulator’ not only separates the core from the shield, but provides the core with a consistent impedance (mostly capacitance) between core and shield. This in turn governs how high a frequency can be carried, and for what length of a coaxial cable (before being attenuated too much). The higher the dielectric constant of the insulator, the higher the frequency that can be carried by the core, &/or for a longer length.

The ‘metallic shield’ serves multiple purposes: one already mentioned above (known & consistent capacitance between core & shield), as well as preventing signal from escaping from the core conductor (ie. preventing radio broadcasts off the coax cable), and also preventing unwanted external noise or signals from impinging on the signal carried by the core conductor. So the shield works bi-directionally.

Finally the ‘plastic jacket’ protects the overall coaxial cable from its environment. In simple low-end applications this is just a single layer of plastic. But it can range all the way up to multiple layers of both insulating as well as metallic materials, to help make it more robust to water ingress, chemical corrosion, attack by wildlife, and physical strength for when men with axes and backhoe’s accidentally try to break it while digging for something else.

Application of coaxial cable :-

1. Wireless and antenna application(connecting from dish to television through co-axial cable. example: Dish TV,etc.)

2.RF and Microwave transmission

3.Video distribution

4.Cable television and cable internet

Advantages:-

- they are cheap to make 

- cheap to install 
- easy to modify 
- good bandwith 
- great channel capacity 
- noise immunity due to low error rate 

what are types of transmission Media ?, what is characteristic of transmission Media ?, what is Transmission Media ?

Transmission Media :-

*# What is Transmission Media ?
- The transmission Media can be defined as a pathway that can transmit information from a sender to a receiver. Transmission Media are located below the physical layer and are controlled by the physical layer. Transmission Media are also called communication channels.

*# What are types of transmission Media ?
- transmission Media has divided into following types :-
*Bounded/Guided Media
- twisted pair cable
- Coaxial cable
- Fibre optic cable
*Unbounded/ Unguided Media
- Radio transmission
- Microwave transmission
- Infrared

*# What are characteristic of  transmission Media ?
- Segment Length
- Attention/Power loss over distance
- Transmission Rate / Bandwidth
- Cost
- Interference Susceptibility
- Resistance to Environmental Conditions 
- Ease of Installation

What is Topology ? What are types of topology ? What is advantages and disadvantages of various Topology ?

                               Topology refers to the way in which the network of computers is connected. Each topology is suited to specific tasks and has its own advantages and disadvantages. The choice of topology is dependent upon type and number of equipment being used, planned
applications and rate of data transfer required, response time, and cost. Topology can also be defined as the geometrically interconnection pattern by which the stations (nodes/computers) are connected using suitable transmission media (which can be point-to-point and broadcast).
 Various commonly used topologies are as follows:

1.Mesh Topology :-

In this topology each node or station is connected to every other station .

The key characteristics of this topology are as follows:
o Fully connected
o Robust – Highly reliable
o Not flexible
o Poor expandability
In MeshTopology two nodes are connected by dedicated point-point links between them. So the total number of links to connect n nodes = n(n-1)/2; which is proportional to n2 .

Media used :-
for the connection (links) can be twisted pair, co-axial cable or optical fiber.

With this topology there is no need to provide any additional information, that is from where the packet is coming, along with the packet because two nodes have a point-point dedicated link between them. And each node knows which link is connected to which node on the
other end.
Mesh Topology is not flexible and has a
poor expandability as to add a new node n
links have to be laid because that new node
has to be connected to each of the existing
nodes .

Advantages:-
- if any device failed in network not affecting network.
- A fault is diagnosed easily.
- Good in privacy and security.
- it is relatively power.

 Disadvantages :-
 - it is costlier.
- it is complex.

2.BUS Topology :-

            A bus topology is a topology for a Local Area Network in which all the nodes are connected to a single cable. The cable to which the nodes connect is called a "backbone". 

* Advantages :-

- easy to connect.

- low cost

- require less cable

- best in small organisation.

*Disadvantages :-

- if backbone cable fail then entire network will shut down.

- difficult to identify failure problem

- can't used in large network.


3. STAR  Topology :-

Star topology is a network topology where each individual piece of a network is attached to a central node (often called a hub or switch). The attachment of these network pieces to the central component is visually represented in a form similar to a star. Star topology is also known as a star network.

Advantages :-

- If one node or its connection breaks, it doesn’t  affect the other computers nor their connections

- Devices can be added or removed without disturbing the network

- They work well under heavy loading

- It is possible to create very large network.

Disadvantages :-

- An expensive network layout to install because of the number and length of cables needed to wire each host to the central hub


- The central hub is a single point of failure or the network

4. Ring Topolology :-

     ln ring topology all  devices are connected in a ring and pass information to or from each other according to their adjacent proximity in the ring structure. This type of topology is highly efficient and handles heavier loads better than bus topology.

Advantages :-
-Very orderly network where every device has access to the token and the opportunity to transmit

-Performs better than a bus topology under heavy network load

-Does not require a central node to manage the connectivity between the computers

-Due to the point to point line configuration of devices with a device on either side (each device is connected to its immediate neighbor), it is quite easy to install and reconfigure since adding or removing a device requires moving just two connections.

-Point to point line configuration makes it easy to identify and isolate faults.


-Reconfiguration for line faults of bidirectional rings can be very fast, as switching happens at a high level, and thus the traffic does not require individual rerouting.

Disadvantages :- 

-One malfunctioning workstation can create problems for the entire network. This can be solved by using a dual ring or a switch that closes off the break.

-Moving, adding and changing the devices can affect the network

-Communication delay is directly proportional to number of nodes in the network

-Bandwidth is shared on all links between devices


-More difficult to configure than a Star: node adjunction = Ring shutdown and reconfiguration

5. Hybrid Topology :-

Hybrid topology is an interconnection of two or more basic network topologies, each of which contains its own nodes.

The resulting interconnection allows the nodes in a given basic topology to communicate with other nodes in the same basic topology as well as those in other basic topologies within the hybrid topology.

https://youtu.be/lZvILl4rY2o

What is OSI model and how it works?

The Open Systems Interconnection model(OSI model) is a conceptual model that characterizes and standardizes the communication functions ofa telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard protocols. The model partitions a communication system into abstraction layer.

 The original version of the model defined seven layers.

1. PHYSICAL LAYER  :-

       The physical layer of the OSI model refers to the actual hardware specifications. The Physical Layer defines characteristics such as timing and voltage. The physical layer defines the hardware specifications used by network adapters and by the network cables (assuming that the connection is not wireless). To put it simply, the physical layer defines what it means to transmit and to receive data.

*Transmission Media:- 
- Wired:- coaxial cable, twisted pair cable and fibre optic cable etc.
- Wireless :- bluetooth, wi-fi,wi-max,infra red etc.

- Transmission mode :- simplex, half duplex and full duplex .
- Central device :- Hub

2.The Data Link Layer:-
                           The data link layer can be sub divided into two other layers:-
-  the Media Access Control (MAC) layer and the Logical Link Control (LLC) layer.

The MAC layer basically establishes the computer’s identity on the network, via its MAC address. A MAC address is the address that is assigned to a network adapter at the hardware level. This is the address that is ultimately used when sending and receiving packets.

The LLC layer controls frame synchronization and provides a degree of error checked.

 - Functions of Data Link Layer

1. Framing
2. Physical Addressing
3. Flow Control
4. Error Control
5. Access Control 

- Central device :- Switch, Bridge etc.

*3. Network layer :-

In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers.

Function :-

The network layer provides the means of transferring variable-length network packetsfrom a source to a destination host via one or more networks. Within the service layering semantics of the OSI network architecture, the network layer responds to service requests from the transport layer and issues service requests to the data link layer.

4.Transport layer :-

The Transport layer is responsible for maintaining flow control. As you are no doubt aware, the Windows operating system allows users to run multiple applications simultaneously. It is therefore possible that multiple applications, and the operating system itself, may need to communicate over the network simultaneously. The Transport Layer takes the data from each application, and integrates it all into a single stream. This layer is also responsible for providing error checking and performing data recovery when necessary. In essence, the Transport Layer is responsible for ensuring that all of the data makes it from the sending host to the receiving host.

5. Session layer :-

In the Open Systems Interconnection (OSI) model, the session layer is the fifth layer, which controls the connections between multiple computers. The session layer tracks the dialogs between computers, which are also called sessions. This layer establishes, controls and ends the sessions between local and remote applications.

6.Presentation layer :-



The presentation layer does some rather complex things, but everything that the presentation layer does can be summed up in one sentence. The presentation layer takes the data that is provided by the application layer, and converts it into a standard format that the other layers can understand. Likewise, this layer converts the inbound data that is received from the session layer into something that the application layer can understand. The reason why this layer is necessary is because applications handle data differently from one another. In order for network communications to function properly, the data needs to be structured in a standard way.

7 . Application layer :-

 is the top most layer of OSI Model. Manipulation of data(information) in various ways is done in this layer which enables user or software to get access to the network. Some services provided by this layer includes: E-Mail, transferring files, distributing the results to user, directory services, network resources, etc.

The Application Layer contains a variety of protocols that are commonly needed by users. One widely-used application protocol is HTTP(HyperText Transfer Protocol), which is the basis for the World Wide Web. When a browser wants a web page, it sends the name of the page it wants to the server using HTTP. The server then sends the page back.

Other Application protocols that are used are: File Transfer Protocol(FTP), Trivial File Transfer Protocol(TFTP), Simple Mail Transfer Protocol(SMTP), TELNET, Domain Name System(DNS) etc.

What is metropolitan area network?

3.Metropolitan area network :-
A metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network(WAN). The term MAN is applied to the interconnection of networks in a city into a single larger network which may then also offer efficient connection to a wide area network. The term is also used to describe the interconnection of several local area networks in a metropolitan area through the use of point-to-point connections between them.^[1][2]It has a range of 5 to 50 kilometers.

MAN

What are network types ? What is LAN ? What is WAN ?

* Types of network :-

 1. LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a  LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.
In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring.

LAN

2.WIDE AREA NETWORK :-
A wide area network (WAN) is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LANs) and metro area networks (MANs). This ensures that computers and users in one location can communicate with computers and users in other locations. WAN implementation can be done either with the help of the public transmission system or a private network.

WAN

Networking definition and advantages

* what is network?
- network, in computing, is a group of two or more devices that can communicate. In practice, a network is comprised of a number of different computer systems connected by physical and/or wireless connections.

*What is networking ?

_Networking, also known as computer networking, is the practice of transporting and exchanging data between nodes(pc or laptops etc.) over a shared medium in an information system. 

Advantages :-

- connectivity and communication

- Data sharing

- Hardware sharing

- Internet access

- Internet access sharing

- Data security and management

- performance enhancement and balancing

- entertainment