Understand the transfer of information, how the Data Communications deals with the technology, tools, products and equipment. Data communications are the transfer of data from one device to another via some form of transmission medium. A data communications system must transmit data to the correct destination in an accurate and timely manner. The five components that make up data communication system are the messages, sender, receiver, medium, and protocol. The seven layer OSI model provides guidelines for the development of universally compatible networking protocols.
The physical, data link, and network layers are the network support layers. Data can be analog or digital. Analog data are continuous and take continuous values. Digital data have discrete status and take discrete values.
Bandwidth utilization is the use of available bandwidth to achieve specific goals; Efficiency can be achieved by using multiplexing. Multiplexing is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link. In a multiplexed system, n lines share the bandwidth of one link. The word link refers to the physical path.
A guided medium provides a physical conduit from one device to another. Twisted pair cable, coaxial cable, and optical fiber are the most popular types of guided media. Unguided media transport electromagnetic waves without the use of a physical conductor. A switched network consists of a series of inter linked nodes, called switches.
Network must be able to transfer data from one device to another with acceptable accuracy. For most applications, a system must guarantee that the data received are identical to the data transmitted. Describe how the Error Detection and Correction can work; data can be corrupted during transmission.
Data can be corrupted during transmission some applications require that errors be detected and corrected, In a single bit errors, need to send extra bits with data. Data link control deals with the design and procedures for communication between two adjacent nodes. The data link layer has two sub layers. The upper sub layer is responsible for data link control, and the lower sub layer is responsible for resolving access to the shared media.
Networks:
Understand the Connecting LANs, Backbone Networks, and Virtual LANs, Connecting Devices, Backbone Networks, Virtual LANs, Cellular Telephony, Satellite Networks, Frame Relay and ATM. A repeater is a connecting device that operates in the physical layer of the Internet model. A repeater regenerates a signal, connects segments of a LAN. Abridge is a connecting device that operates in the physical and data link layers of the internet model. Cellular telephony provides communication between two devices. One or both may be mobile. A cellular service area is divided into cells SONET has defined a hierarchy of signals called synchronous transport signals. SDH has defined a similar hierarchy of signals called synchronous transfer modules. Virtual circuit switching is a data link layer technology in which links are shared.
Understand the how the network layer deals with end-to-end transmission. At the network layer, a global identification system that uniquely identifies every host and router is necessary for delivery of a packet from host to host. An IP4 address is 32 bit long and uniquely and universally defines a host or router on the internet. IP4 is an unreliable connectionless protocol responsible for source to destination delivery. Packets in ipv4 layer are called data grams. Delivery of packet to a host or router requires two levels of addresses: Logical and physical. Mapping of a logical address to a physical address can be static or dynamic. The delivery of a packet is called direct if the deliverer and the destination are on the same network. The delivery of a packet is called indirect if the deliverer and the destination are on different networks.
working of Transport layer
Describe the working of Transport layer and its protocol hierarchy. In the client/server paradigm, an application program on the local host, called the client, needs services from an application program on the remote host, called a server. Each application program has a port number that distinguishes it from other programs running at the same time on the same machine. UDP is connectionless, unreliable transport layer protocol with no embedded flow or error control mechanism except the checksum for error detection. A data flow can have a constant bit rate, a variable bit rate, or traffic that is busy. Congestion control refers to the mechanisms and techniques to control congestion and keep the load below capacity.
Explain the usage of application layer; how it provides the domain name service, sending and receiving electronic mails. The domain name system (DNS) is client/server application that identifies each host on the internet with a unique user-friendly name.DNS organises the name space in a hierarchical structure to decentralize the responsibilities involved in naming. The name space information is distributed among DNS servers. Each server has jurisdiction over its zone. Each country domain specifies a country. The inverse domain finds a domain name for a given address. This is called address-to-name resolution. TELNET is a client/server application that allows a user to log on to a remote machine, giving the user access to the remote system.
Understand the World Wide Web and its architecture, how it works in user side and also In server side. The World Wide Web (www) is a repository of information linked together from points all over the world. Hypertexts are documents linked to one another through the concept of pointers. Browsers interpret and display a web document. The five areas comprising network management are configuration management, and security management. Simple network management protocol (SNMP) is a framework for managing devices in an internet using TCP/IP protocol suite. The audio/video files can be downloaded for future use or broadcast to clients over the internet .The internet can also be used for live audio/video interaction.