Data Communication and Networking: Components, Representation, Flow, Networks, Criteria, Lecture notes of Computer Systems Networking and Telecommunications

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Department of Communication and Operating Systems

Lecturer : M.Younis Popal Contact : [email protected] Lec01 ( Data Communication) 28 - Feb- 19

Computer Network

Brain Storming

 Networks  Internet  Bluetooth technology  Zapya application  Point-to-point connection between TV and remote TV

But!

 How physically today networks are setup?  How logically networks are operate?  Which flow network follow to reach to destination?

Data Communication  Data Communications , Are the exchange of data between two parties via some form of transmission media such as a wire cable.  Communicating devices must be part of communication system (hardware and software) to communication occur.  The effectiveness of data communications system depends on four following fundamental characteristics.  Delivery : The system must deliver data to the correct destination.  Accuracy : The system must deliver the data accurately  Timeline : The system must deliver data in a timely manner  Jitter : Jitter refers to the variation in the packet arrival time

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Data Communication: Components  A data communications system has five components  Message  Sender  Receiver  Transmission media  Protocol

For more: B.Frozan. Data Communication and Networking

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Data Representation  Text  Text is represents as bit patterns  Coding system (ASCII, Unicode)  In ASCII each symbol is 1 byte but in Unicode each symbol is 4 bytes  Number  A code such as ASCII is not used to represent a number  Directly converted to binary

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Data Representation  Image  Images are also represents by bit patterns  An image is composed of matrix of pixels each pixel is a small dot.  Size of dot depends on resolution of image more dots result in better resolution.  Each pixel is assigned to a bit patterns. For black and white 1 bit is enough but for other more bits are required.  Methods: RGB(red, green,blue), YCM(yellow, cyan, magenta)  Audio  Analog or digital  Video  Continuous images .

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Data Flow (Transmission mode)  Communication between two devices can be  Simplex  Communication is unidirectional, as one way street  Example

• Keyboard, monitor  Half-duplex  Each station can send and receive but not at same time.  The entire capacity is used by sender  Full duplex  Both station can send and receive data simultaneously, as two street  Capacity is shared between two devices  Example: telephone network

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Network  A network is a set of devices (nodes) connected by communication links.  A node can be a computer, printer or any other device that capable of sending and receiving data.  Network criteria  Performance  Reliability  Recovery  Security

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Network  Reliability  The time it takes to recover a link from a failure  Recovery  Recovery is the Network's ability to return to a prescribed level of operation after a network failure.  Recovery is based on having Back-up Files.  Security  Security is the protection of Hardware, Software and Data from unauthorized access.  Restricted physical access to computers, password protection, limiting user privileges and data encryption are common security methods.

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Type of Connection  There are two type of connections in networking  Point to point  Provide a dedicated connection between two devices.  Entire capacity is reserved between those devices  Example: remote TV and TV  Multiple point  A link is shared among devices  The entire capacity is shared among devices if simultaneously transferring is allowed

Physical Topology: Mesh  Every device has a dedicated point to point connection to every other device.  To find number of physical links based each device in fully connected mesh network with n nodes  n (n - 1 )  But if the links are duplex  n (n - 1 )/ 2  Number of ports for each device  n - 1

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Physical Topology: Mesh  Advantages  Dedicated links, Robust ,Security, fault identification  Disadvantages  Amount of cabling and ports  More physical env  cost  Example : telephone original offices

For more: B.Frozan. Data Communication and Networking

(p.3-25)

Physical Topology: Bus  A bus topology is a multiple point example, one long cable act as backbone to link all devices in the network.  Advantages  Ease of installation, less cables,  Disadvantages  Fault isolation, break in backbone down whole network

Physical Topology: Ring  Each device has a dedicated point to point connection to only two devices on either side of it.  Advantages  All data flows in one direction, reducing the chance of packet collisions.  Data can transfer between workstations at high speeds.  Disadvantages  All data being transferred over the network must pass through each workstation on the network, which can make it slower  The entire network will be impacted if one workstation shuts down.

For more: B.Frozan. Data Communication and Networking

(p.3-25)