by Dinesh Thakur Category: Communication Networks

AppleTalk: A proprietary LAN protocol that is built into Apple's MACINTOSH computers. AppleTalk is independent of the underlying network transport, and is currently able to run over serial cable (LocalTalk) or over an ETHERNET network (EtherTalk).  An AppleTalk port is built in to all Macs.



 
by Dinesh Thakur Category: Communication Networks

The purpose of error control is to ensure that the information received by the receiver is exactly the information transmitted by the sender. As the communication channel is highly unreliable, the receiver must be able to deal with the received data, if it contains error. The term error control is defined as the process of identification or correction of error occurred in the transmitted data. There are two types of error control mechanisms. They are:



 
by Dinesh Thakur Category: Communication Networks

Data is transmitted between communication devices in multiples of fixed-length units, typically 8-bits. For example, if the computer is transferring a source program, the data will be made up of a block of 8-bit binary-encoded characters. On the other hand, if the data is in the form of a compiled object code of the program, the data will be made up of a block of 8-bit bytes. At the receiving end, the following parameters are determined to decode and interpret the message correctly.



 
by Dinesh Thakur Category: Communication Networks

This is very simple optical fiber communication system. In this particular scenario, the optical fiber requires one connection to the transmitter side and another connection at the receiver side. In another scenario when it is required to communicate over long distances where more than one length of fiber cable and other supporting equipment are placed in the system.

 
by Dinesh Thakur Category: Communication Networks

Like other communication system, fiber optic communication has also a transmitter at one end of the system, which injects information on to the fiber cables. The transmitter processes and translates coded electronic pulse information coming from copper wire into equivalently coded light pulses. The basic concept behind the optical transmitter is that it converts electrical input signals into modulated light for transmission over an optical fiber. The input signal determines the characteristics of the resulting modulated light, which may be turned on and off or may be linearly varied in intensity between two predetermined levels.



 
by Dinesh Thakur Category: Communication Networks

In case of coaxial cables and twisted cable the maximum signal frequency, and hence the information rate that can be transmitted using a solid conductor is limited. Optical fiber differs from both these transmission media in that it carries the transmitted information in the' form of a fluctuating beam of light in a glass fiber rather than as an electrical signal on a wire. This type of transmission has become strong support for digital network owing to its high capacity and other factors favorable for digital communication.



 
by Dinesh Thakur Category: Communication Networks

Open Systems Interconnection (OSI) was set up as an international standard for network architecture. The International Organization for Standardization (ISO) took the initiative in setting up OSI. OSI has two meanings. It 'refers to:

 
by Dinesh Thakur Category: Communication Networks

Network Architecture defines the communications products and services, which ensure that the various components can work together. In the early days of data communication systems, the majority of communications were between the DTE and the host computer. Therefore, transmission control procedures were alone enough as communication protocols. However, recent computer systems link with other systems to form a network which result in a situation where different protocols serving different purposes are required. Hence, the network architecture represents a systemization of the various kinds of protocols needed to build a network.



 
by Dinesh Thakur Category: Communication Networks

VLANs have the primary role to enable easier configuration and management of large corporate networks built around many bridges. There are several implementation strategies for these virtual networks.

 
by Dinesh Thakur Category: Communication Networks

A switch, which resembles a hub, is known as switching hub. But there is stark difference between hub and switching hub or a switch. Hub acts as a LAN concentrator, and repeater. It consists of a single box with multiple ports. Each port is connected with a separate computer. A signal transmitted by a computer travels to all ports like a bus topology.



 
by Dinesh Thakur Category: Communication Networks

This advises the routers are used to connect dissimilar LANs and perform all the functions of bridges and routers. It operates at all seven layers of the OSI Reference Model. These are actually predecessors of router nowadays and are technology wise more expensive and highly functional. They in general consist of software which resides in a host computer, such as mid-range or mainframe.



 
by Dinesh Thakur Category: Communication Networks

Routers are used to connect both similar and dissimilar LANs. Router operates on the network layer of OSI model using the physical layer, data link layer and network layer to provide connectivity, addressing and switching. These are highly intelligent devices. In case of TCP/IP network, Internet Protocol (IP) is used as addresses for network; this is the router which interprets the IP address and delivers the packet reliably.

 
by Dinesh Thakur Category: Communication Networks

Like repeaters, bridges are used to connect similar LANs together, for example, Ethernet-to-Ethernet and operate at the bottom two layers of the OSI model, i.e. physical layer and data link layer. As it operates on second layer of the OSI model,' it relays only necessary data to other signals. MAC addresses (physical addresses) are used to determine whether data is necessary or not.

 
by Dinesh Thakur Category: Communication Networks

When an electrical signal travels along a medium it gets attenuated depending upon the medium characteristics. That is why a LAN cannot send signal beyond a certain limit imposed by the different types of LAN technologies. To increase the length of the LAN, repeaters are frequently used. Repeaters in its simplest form relay analog electric signal. It means that they transmit the physical layer signals or data and therefore correspond to the bottom layer of OSI model.                        

 
by Dinesh Thakur Category: Communication Networks

100VG-AnyLan (VG =Voice Grade) is a joint development of AT&T Microelectronics, Hewlett-Packard, and IBM and is standardized by the newly created IEEE 802.12 committee. 100VG-AnyLAN supports Ethernet, Token Ring, and other LAN standards, incorporating a collision less polling technique. It is not that simple as it appears. A router upgrade is required to connect 100VG Ethernet and 100VG Token Ring.

 
by Dinesh Thakur Category: Communication Networks

With the advancement of time and intensive use of LAN, more workstations and more active users have resulted in more LAN traffic. Increased use of graphics and other bandwidth-intensive applications have increased LAN traffic. Other applications like video conferencing and multimedia have created a demand for fast LANs. Bandwidth of 10 Mbps, 16 Mbps and even 20 Mbps are becoming bottleneck. In response to this, Fast LANs have been developed, offering bandwidth of 100 Mbps and soon to 1 Gbps. Fast LAN options currently include:

 
by Dinesh Thakur Category: Communication Networks

Wireless LANs offer the obvious advantage of avoidance of cabling costs, which can be especially important in a dynamic environment where there is frequent reconfiguration of the workplace. Additionally, wireless LANs provides LAN capabilities in temporary quarters where costly cabling would have to be abandoned. Each workstation is fitted with a low power radio antenna.

 
by Dinesh Thakur Category: Communication Networks

Due its outstanding performance characteristics, fiber-optic cable is also used in LAN s. FDD I (Fiber Distributed Data Interface) is the current LAN standard (IEEE and ANSI) for such a network. FDDI can be extended to the desktop, either directly or through the use of twisted pair in a CDDI application.

 
by Dinesh Thakur Category: Communication Networks

The maximum allowable length of a segment for the 10Base5 is 500 meters. Up to 100 nodes can be connected to a segment. That is up to 100 transceivers can be connected. Repeaters are used to connect terminals that are separated from one another beyond the distance specified above, or to connect more than a limited number of nodes. Each repeater has two ports so that it receives signals through one of these ports and sends them through the other port after amplification. An example of the 10Base5 LAN, Up to 1024 nodes can be connected to a LAN expanded by using repeaters.

 
by Dinesh Thakur Category: Communication Networks

CDDI is also known as TPDDI (Twisted-pair Distributed Data Interface). CDDI employs Cat 5 UTP as an inexpensive means of connecting workstations and peripherals to FDDI fiber optic backbone LANs. A transmission rates up to 100 Mbps may be achieved in this scheme.

 

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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.