by Dinesh Thakur

This uses traditional thick baseband coaxial cable in bus topology to connect multiple computers as shown. This single transmission line is called a segment. A coaxial cable 10 mm in diameter, known as a thick coaxial cable is used as a transmission line. A terminator is connected at each end of the cable. Note that proper data communication cannot be assured even if one of these terminators is missing or not properly connected.

 
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Data link layer is the second layer in OSI reference model and lies above the physical layer. The physical layer provides only a raw bitstream service between computers. The data link layer provides data reliability and provides tools to establish, maintain, and release data link connections among the network nodes.

 
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The function of the network layer is to provide an end-to-end communication capability to the transport layer, which lies above it as shown in Figure. The OSI reference model specifies that the transport layer need not know the method by which the network layer performs communications.

 
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A computer network can be classified into different categories. Different criteria are used to classify computer networks. Following are the criteria widely used.



 
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The access point (abbreviated AP or WAP (for wireless access point)), is a networking hardware device, such as a wireless router, that transmits and receives data (sometimes referred to as a transceiver) and also can serve as the bridge between the WAP device and a wired LAN (Local Area Network), which facilitates connectivity between nearby wireless clients. A WAP (also known as a hotspot) acts as a central transmitter and receiver of wireless radio signals.

 
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Definition: Ethernet (pronounced "eether net") is a computer network technology which is used in different area networks like LAN, MAN, WAN. Ethernet connecting computers together with cable so the computers can share information. Within each main branch of the network, "Ethernet" can connect up to 1,024 personal computers and workstations.



 
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What is Hub: Another name of Hub is Ethernet Hub, Repeater Hub, Active Hub and Network Hub. Basically, it is a similar to switch but are not as "smart", 

Hub Definition and Meaning

hub in computer network is used for connecting multiple computers or segments of a LAN. Normally, it is used for Peer to Peer small Home Network. LAN Hub receive data packets (frames) through one port and broadcasts them through all other ports, so that all other computers or other network devices can see all packets.



 
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UnGuided or also called wireless or wireless communication, transport electromagnetic waves without using a physical conductor. Instead, signals are radiated through the air (or, in a few cases, water) and therefore, are available to anyone with a device capable of accepting them.

The electromagnetic spectrum

 
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The word network protocol designates a set of rules or conventions to carry out a particular task. In data transmission, the network protocol is used in a less broad sense to indicate the set of rules or specifications that are used to implement one or more levels of the OSI model.

A network protocol defines that it communicates, how it communicates, and when it communicates. The critical elements of a network protocol are its syntax, its semantics and its timing.



 
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SONET (Synchronous Optical Network) is a physical level standard, proposal by Bellcore (Bell Communications Research) in the mid-80s for transmission through an optical fiber. SONET is a technique of transport between two nodes, which defines the interface adopted for the NNI (Network Node Interface). Standardized by the ANSI and recommended worldwide by the CCITT, SONET can be thought of as a physical network for a global communication system in the same way that a twisted pair LAN can see as the communication system of a corporate network. It is a potentially global network, built on fiber optic cable, with standardized data transmission speeds and recognized worldwide. SONET eliminates limits between telephone companies worldwide.

 
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Definition: Asynchronous Transfer Mode (ATM) also called cell relay (transferring data in cells of a fixed size) that is operates at the data link layer (Layer 2) of OSI Model over fiber or twisted-pair cable, a high-speed switched network technology based on ITU-T Broadband Integrated Services Digital Network (B-ISDN) standard, developed by the telecommunications industry to implement the next generation network. ATM was designed for use in WANs such as the public telephone system and corporate data networks, though it has also been applied to create super-fast LANs.

 
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Definition: Storage area network is abbreviated as SAN. SAN is a network which is designed to attach computer storage devices such as disk array controllers and tape libraries to servers. SAN network can be accessed by multiple computers. It is a secure and high-speed data network. It is also known as SAN storage, SAN network, etc.



 
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Guided means are those that provide a conductor from one device to the other and include twisted-pair cables, coaxial cables, and fiber optic cables. A signal traveling by any of these means is directed and contained by the physical limits of the medium. Twisted pair and coaxial cable use metallic (copper) conductors that accept and carry electrical current signals. Fiber optic is a glass or plastic cable that accepts and transports signals in the form of light.

 
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Server: A server is a computer program or device in the network that provides resources, data, services, or programs to the client computer such as login requests processing, files access and storage, internet access, printing access and many other types of services. This architecture is called the client-server model. Servers are often referred to as dedicated.



 
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FDDI stands for Fiber Distributed Data Interface. It is a high-speed, high-bandwidth network based on optical transmissions. It is most often used as a network backbone, for connecting high-end computers (mainframes, minicomputers, and peripherals), and for LANs connecting high-performance engineering, graphics, and other workstations that demand a rapid transfer of large amounts of data. It can transport data at a rate of 100 Megabits per second and can support up to 500 stations on a single network. FDDI was designed to run through fiber cables, transmitting light pulses to convey information between stations, but it can also run on copper using electrical signals. It is relatively expensive to implement, although the mixing of fiber-optic with copper cabling can hold down the cost.



 
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Digital Equipment Corporation (DEC) has given support to network connectivity for networks of its own and networks of other vendors also. DEC has its own architecture known as Digital Network Architecture (DNA) the product that implements the architecture is known as DEC net. The DNA was developed during 1974, to provide communication facility between various DEC systems.

 
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The Systems Network Architecture (SNA) from IBM uses a 7 layer architecture similar to the OSI model.

 
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Definition:  General Packet Radio Service is a packet-based wireless communication service. It promises data rate up to 114 kbps. It is a standard technology which extends the Global system. It abbreviated as GPRS. It is designed to replace the current circuit-switched services.

General Packet Radio Service is a non-voice and high-speed technology which is useful for the GSM networks. We make use of GPRS so that we can enable connections which depend on the internet protocol. As we know, IP supports a wide variety of applications. We can send and receive the compressed data and large volume data over the mobile network by using GPRS as the packet switching system used. So, before sending the data, it breaks the whole data into packets and then shifts them through the network. Now the data again assembled at the recipient side.



 
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Cluster computing or High-Performance computing frameworks is a form of computing in which bunch of computers (often called nodes) that are connected through a LAN (local area network) so that, they behave like a single machine. A computer cluster help to solve complex operations more efficiently with much faster processing speed, better data integrity than a single computer and they only used for mission-critical applications.



 
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The TCP / IP layer set corresponds to the OSI reference model levels as follows:

This correspondence is theoretical because, as the TCP / IP protocols developed before the OSI reference model, there are substantial differences, such as:



 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.