by Dinesh Thakur Category: Computer Network

Modem word came from the combination of two words modulator and demodulator.A modem is a hardware device that enables the computers to transmit data over cable or satellite connection.A modem converts signals between modulator and demodulator vice versa. The outgoing digital signals from a computer a modem can modulates to an analog signals and in the demodulation in reverse analog signal are converts back to a digital signal.The modems can be classified according to their characteristics as below:



 
by Dinesh Thakur Category: Computer Network

In "frequency shift keying (FSK)", the frequency of a sinusoidal carrier is shifted between two discrete values. One of these frequencies (f1) represents a binary "1" and the other value (f0) represents a binary "0". The representation of digital data using FSK is as shown in Fig. Note that there is no change in the amplitude of the carrier.

 
by Dinesh Thakur Category: Computer Network

Amplitude Shift Keying (ASK) is the simplest type of digital CW modulation. Here the carrier is a sinewave of frequency fc. We can represent the carrier signal mathematically as follows:

 
by Dinesh Thakur Category: Computer Network

• The SMDS is designed to connect the multiple LANs together. This is the first high speed broadband service offered to the public.

• Fig.(a) shows the interconnection of four LANs using six high speed leased lines. But this interconnection is expensive.

 
by Dinesh Thakur Category: Computer Network

WAN is the acronym for, Wide Area Network and refers to a network used to connect different equipments from remote areas. This technology connects sites that are in diverse locations. Wide Area Networks (WANs) connect larger geographic area, such as New York, Canada, or the world. The geographical limit of WAN is unlimited. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of network. Hence, a WAN may be defined as a data communications network that covers a relatively broad geographic area to connect LANs together between different cities with the help of transmission facilities provided by common carriers, such as telephone companies. WAN technologies function at the lower three layers.            

 
by Dinesh Thakur Category: Computer Network

what is lan: It is a privately-owned network and stands for local area network. A network is a group of computers and other devices connected so they can pass information back and forth. The local area network (LAN) is a network which is designed to operate over a small physical area such as an office, factory or a group of buildings up to a few kilometers in size. LANs very widely used in a variety of computers to share resources (e.g., printers) and exchange information.



 
by Dinesh Thakur Category: Computer Network

The transmission means, is that sending a signal from one location to another. Transmission technologies refer to the physical layer protocol such as modulation, demodulation, line coding, error control etc. The transmission technology can be categorized broadly into two types:

Broadcast networks

• Broadcast networks have a single communication channel that is shared or used by all the machines on the network. Short messages called packets sent by any machine are received by all the others.



 
by Dinesh Thakur Category: Computer Network

Connectionless service is a self-contained action and does not include establishment, maintenance and releasing a connection.

• Each message carries the full destination address and is treated and routed independently of all other messages.

 
by Dinesh Thakur Category: Computer Network

• Hybrid networks are the networks that are based on both peer-to-peer & client-server relationship.
• Hybrid networks incorporate the best features of workgroups in peer-to-peer networks with the performance, security and reliability of server-based networks.
• Hybrid networks still provide all of the centralized services of servers, but they also allow users to share and manage their own resources within the workgroup.

 
by Dinesh Thakur Category: Computer Network

What is router: Router is a network layer (Layer 3) of the OSI reference model device that means it can connect multiple computer networks via wired or wireless connections. Network router can receive, analyze, perform the traffic directing functions and forwards data packet from one network to its destination node. A router is a device that forwards packets between networks by processing the routing information included in the packet.



 
by Dinesh Thakur Category: Computer Network

Switching is the most valuable asset of computer networking. Every time in computer network you access the internet or another computer network outside your immediate location, or your messages are sent through a maze of transmission media and connection devices. The mechanism for exchange of information between different computer networks and network segments is called switching in Networking. On the other words we can say that any type signal or data element directing or Switching toward a particular hardware address or hardware pieces.



 
by Dinesh Thakur Category: Computer Network

In computer networking Switches (also called switching hub, bridging hub,and more correctly called a network switch) and Bridges are the layer 2 computer networking devices. Once the number of users began to push the limits of a single computer network segment, there was a need to create a new segment to link two computer networks together a device called bridges accomplished this. basically the bridges have 2 ports, one for each computer networks, bridges actually inspect the data that passes through them and make decisions about whether to send it to the other computer network or not. Switch takes data from one network device and forwards it to the destination node based on MAC address.



 
by Dinesh Thakur Category: Computer Network

To access Internet Through a Cable TV. Computer Network requires a cable Modem. It has two interfaces on it one for computer  and other for Cable Network The Computer side interface is usually is a USB Interface or 10Mbps Ethernet And The Cable Network is common cable wire interface.

 
by Dinesh Thakur Category: Computer Network

Modem is abbreviation for Modulator – Demodulator. Modems are used for data transfer from one computer network to another computer network through telephone lines. The computer network works in digital mode, while analog technology is used for carrying massages across phone lines.



 
by Dinesh Thakur Category: Computer Network

A packet is the unit of data that is routed between an origin of computer or device to another on the Internet or any other packet-switched network. When any file (e-mail message, HTML file, Graphics Interchange Format file, Uniform Resource Locator request, and so forth) is sent from one place of network to another place of network on the Internet, the Transmission Control Protocol (TCP) layer of TCP/IP of network.



 
by Dinesh Thakur Category: Computer Network

Client Computer: A personal computer in networking that connects to the server and uses the network services to perform user's tasks is a client computer.



 
by Dinesh Thakur Category: Computer Network

The IEEE 802.3 standard is popularly called as Ethernet. It is a bus based broadcast network with decentralized control. It can operate at 10 Mbps or 100 Mbps or above. Computers on an Ethernet can transmit whenever they want to do so. If two or more machines transmit simultaneously, then their packets collide. Then the transmitting computers just wait for an arbitrary time and retransmit their signal. There are various technologies available in the LAN market but the most popular one of them is Ethernet.

 
by Dinesh Thakur Category: Computer Network

IEEE 802.4 Token Bus: In token bus Computer network station must have possession of a token before it can transmit on the computer network. The IEEE 802.4 Committee has defined token bus standards as broadband computer networks, as opposed to Ethernet's baseband transmission technique. Physically, the token bus is a linear or tree-shape cable to which the stations are attached.



 
by Dinesh Thakur Category: Computer Network

Ethernet : IEEE 802.3 Local Area Network (LAN) Protocols : Ethernet protocols refer to the family of local-area network (LAN) technology covered by the IEEE 802.3. It is working examplc of the more general carrier sense multiple access with collision detect (CSMA/CD). In the Ethernet Computer Network standard, there are two modes of operation: half-duplex and full-duplex modes. In the half duplex mode, data are transmitted using the popular Carrier-SenseMultiple Access/Collision Detection (CSMA/CD) protocol on as hared medium.



 
by Dinesh Thakur Category: Computer Network

The term Network Topology defines the geographic Physical or logical arrangement of computer networking devices . The term Topology refers to the way in which the various nodes or computers of a network are linked together. It describes the actual layout of the computer network hardware. Two or more devices connect to a link; two or more links form a topology. Topology determines the data paths that may be used between any pair of devices of the network.



 

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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.