Multiplexing and types of Multiplexing

Multiplexing 

Multiplexing is a process in which multiple Data Streams coming from different sources are combined and transmitted over a single channel or Data Stream. In electronic communications the two basic forms of Multiplexing.

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Types of Multiplexing  

1: Time Division Multiplexing
2: Frequency Division Multiplexing.

Time Division Multiplexing 

 In Time Division Multiplexing transmission time on a single channel is divided into overlapped time slots.Data Streams from different sources are divided into units with same size and interleaved successively into the time slots.

Frequency Division Multiplexing  

In Frequency Division Multiplexing, Data Streams are carried simultaneously on the same transmission medium by allocating to each of them a different Frequency Band within the bandwidth of the single channel.

What is Virtual Private Network , when to choose Virtual Private Network and Advantages?

What is Virtual Private Network 

•  Virtual Private Network enable enterprises to build secure private communications over public network infrastructures. 
• Virtual Private Network essentially takes two systems or networks connected to the Internet and creates a secure. 
• Virtual Private Network that is private but virtual. 
• It is private because it guarantees privacy inside an organization.
• It is virtual because it does not use real private WAN the network is physically public but virtually private. https://maliksajid5675.blogspot.com/

When to choose Virtual Private Network

• Secure communications required. 
• More locations. 
• Longer distances. 
• Less bandwidth/site. 
• Quality of service less critical. 

Advantages 

• Extend geographic connectivity. 

• Improve security. 

• Reduce operational costs versus traditional WAN. 

• Reduce transit time and transportation costs for remote users. 

• Improve productivity. 

• Simplify network topology. 

• Private global networking opportunities.

Twisted Pair Cable, Straight -Through, Cross-over and Roll-over Cable

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Twisted Pair Cable 

Twisted pair cable is a type of wiring in which two conductors of a single circuit are twisted together for the purpose of canceling out Electromagnetic Interference (E M I) from external sources ; for instance, electromagnetic radiation from UN-shielded twisted pair (U T P) cables and cross talk between neighboring pairs.

Straight-Through Wired Cables

Straight-Through refers to cables that have pin assignments on each end of cable. In other words Pin 1 connector A goes to Pin 1 on connected B, Pin 2 to Pin 2 etc.Straight-Through wired cables are most commonly used to connect host to client.Straight-Through wired cat 5_e patch cable is used to connect computers,printers and other network client devices.

Cross_over Wired Cable 

Cross-Over wired cable are very much like Straight-Through cable with the exception that TX and RX line are crossed. Cross-Over cable are most used to connect two hosts directly. Example would be connecting a computer directly to another computer. Connecting a switch directly to another switch. Connecting a router to a router.

Roll-Over Wired Cable

Roll-Over wired cable most commonly called Roll-Over cable, have opposite Pin assignments on each end of cable or in another word it is "Roll-Over" Pin 1 of connector A would be connected to Pin 8 of connector B.Pin 2 of connector A would be connected to Pin 7 of connector B and so on.

Network and Categories

Network = A network can be defined as two or more computers connected together in such a way that they can share resources is called Network.

Categories =  1: LAN  2:  MAN 3: WAN 4: PAN.

1: LAN =  LAN stands for Local Area Network. Network of computers located in a single location. like a home, school, or office building.Can share connection with other LAN and with Internet. Characteristics of  LAN = 1: Local area network. 2: Relatively limited in size. 3: Computers connected in small area. 4: Same office. 5: Can support limited number of nodes.

2: MAN =  MAN stands for Metropolitan Area Network. A Metropolitan area network is a network that is utilized across multiple buildings.Commonly used in school campuses or large companies with multiple buildings. Is larger then a LAN, bit smaller then a WAN. Is also used to mean the interconnection of several LAN's by bridging them together.This sort of network is also referred to as a campus.
3:WAN =  WAN is stands for Wide Area Network. Network over a large area like a city, a country or multiple countries connect multiple LAN together.Generally utilized different and much more expensive networking equipment then LAN. The Internet is most popular WAN.

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4: PAN = PAN is stands for Personal Area Network. A PAN is a network that is used for communicating among computers and computer devices in close proximity of around few meters within a room. It can be used for communicating between devices themselves or for connecting to a larger network such as the internet.

Firewalls and types of Firewalls

A firewalls is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.

 There are several types of Firewall that works on different layers of the OSI models. The following are list of seven different types of Firewall that are widely used for Network Security.
1: Screened Host Firewall.
2: Screened Sub net Firewall.
3: Pocket Filter Firewall.
4: State full Inspection Firewall.
5:Hybrid Firewall.
6: Proxy Server Firewall.
7: Application Level Firewall.

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Electricity Magnetism

Electricity Magnetism:
Demonstrate that like poles repel each other while un-like poles attract each other 7 " Investigate that a freely suspended magnet always points in the North south ' Identify the various uses of magnets and magnetic materials in daily life.

Uses:
 Demonstrate how magnetism can be formed and stored. Differentiate between temporary and permanent magnets. n Where we use Electricity? You know that machines make our work easier. Every work to be done requites energy. The machines decrease the requirement of energy but they do use energy. The main energy used in machines is the electrical energy or power When we supply electrical power to a machine or instrument, the electrical power flows in it. The flow of the electrical power is called electricity You have seen many instruments or devices and machines in your home that work on electricity . Your mother uses iron, washing machine, sewing machine etc.

Advantages:
1:You use energy saver bulbs to get light and run fans for air.
2:, A number of other home appliances like TV, computer, radio, air conditioners refrigerators use electricity.
3:Similarly, electricity is used in offices and markets for many purposes. Factories use electricity to run machines for making some products.

Did  you ever think about the electricity supply to any of your home appliance?
What your mother does when she clothes in washing machine?

1:She plugs the power wire of machine in the socket.
2: The socket in the wall has electricity connection, from where electricity passes wire and reaches the  machinery of the washing.
3:The wheel at the base of washing chamber of machine starts rotations.It mixes the water and washing powder.The mixturespreads over the clothes.