Friday, July 20, 2007

Difference Between LAN and WAN


LAN

Up to now we've been talking about Ethernet and I've made reference to the fact that Ethernet is a LAN.

A LAN is a Local Area Network. Local is generally referred to a network contained within a building or an office or a campus.

Examples:

  1. You might have a LAN for example on a University campus or between office blocks in an office park.

  2. A big corporate perhaps like Anglo American, would generally have a LAN that might span several buildings.

To set up a LAN -relatively speaking- is cheap. If you want to put an extra couple of network points or an extra couple of devices on the network, it 's not very expensive to do that.




WAN

Using a similar example, a Wide Area Network is a network that connects campuses.

What I'm going to do is write down some short descriptions of what a WAN is:

1. A WAN is generally slow. If we compare that to a LAN, we said that Ethernet could run up to 1000 Mbs, currently, certainly in South Africa, the fastest WAN is 155 Mbs, so you can see in a LAN we can talk up to 1000 Mbs whereas in a WAN, at the moment, currently, today in South Africa, we can only take, literally a 10th of the speed.

2. WAN's are expensive. If we look at the path of telecommunications, we need to connect two offices, one in Pretoria and one in Johannesburg together - it 's an expensive operation even for a slow line.

One of the differences between a WAN (Wide Area Network) and a LAN (Local Area Network) is the set-up cost. WAN generally are to connect remote offices and when we talk about remote offices we generally refer to the remote offices as those that are outside the campus. For example, if we have an office in Pretoria and we have an office in Cape Town, these are remote offices. There is no chance that we can connect the LAN between Cape Town and Pretoria. In a LAN we connect local offices whereas in a WAN we can connect remote offices.









Example establishment of LAN and WAN



WAN Technologies CCNA 4 Companion Guide is the official supplemental textbook for the CCNA 4 course of the Cisco Networking Academy Program. Completely revised from the previous edition with new examples and explanations, this textbook includes original material developed by the author, yet it fully aligns with the CCNA 4 curriculum. Written by an experienced author who present material in a comprehensive manner--using his own voice and own examples--this new edition augments student understanding of course material. The new edition incorporates improved features to aid instructors and enhance student comprehension. For example, chapters align with course modules in both name and number, and chapter objectives are stated as questions to encourage students to think about and find answers as they read chapters. End-of-chapter questions and summaries align with chapter objectives to emphasize key topics, while key terms are listed in each chapter opener in the order of occurrence to alert students to upcoming vocabulary words. In addition, new features include "How To" quick references for step-by-step tasks; real-world examples and all-new illustrations; concise explanations with a focus on word usage and sentence structure for improved readability; and correlations to the CCNA exam in Chapter Objectives, Check Your Understanding questions, and new Challenge Activities.




Tuesday, July 17, 2007

Audio

Computer networking is a process of sharing data and shared resources between two or more connected computers. The shared resources can include printer, Fax modem, Hard disk, CD - DVD Rom, Database and the data files. A computer network can be divided into a small or local area network, a networking between computers in a building of a office (LAN), medium sized network (MAN), a network between two offices in a city and Wide network (WAN) a network between the computers, one is locally and the other can be thousands of miles away in any other country of the world.
WAN connectivity is achieved by a network device known as “Router”. The internet is the world’s largest WAN network, where millions of computers from all over the globe and connected with each other.
Networking is the practice of linking two or more computers or devices with each other. The connectivity can be wired or wireless. A computer network can be categorized in different ways, depends on the geographical area as mentioned above.
There are two main types of the computer network client-server and peer to peer. In the client server computing, a computer plays a major role known as server, where the files, data in the form of web pages, docs or spread sheet files, video, database & resources are placed.
All the other computers in the client/server network are called clients and they get the data from the server. In the peer to peer network all the computers play the same role and no computer act as a centralized server. In the major businesses around the world client-server network model is in major use.
A network topology defines the structure, design or layout of a network. There are different topologies like bus, ring, star, mesh, hybrid etc. The star topology is most commonly used network topology. In the star topology, all the computers in the network are connected with a centralized device such as hub or switch. Thus forms a star like structure. If the hubs/switch fails to work for any reason then all the connectivity and communication between the computers of a network will be halted.
In the network, a common communication language is used by the computers and the network devices and this language is known as protocols. The most commonly used and popular protocols on the internet and in the home and other networks is called TCP/IP. TCP/IP is not a singleprotocol but it is a suite of several protocols.
A network can be a wired or wireless and TCP/IP protocol can work both in types of network.
A data flow in a computer network can be divided into seven logical layers called OSI layersmodel that was developed by Intel and Xerox Corporation and was standardized by ISO.
1. Application layer 2. Presentation layer 3. Session layer 4. Transport layer 5. Network layer 6. Data Link layer
2. a. Media access control sub-layer
b. Logical link control sub-layer 7. Physical layer.
A network can be divided into different scales and ranges and it depends on the requirement of the network and the geographical location. Computer Network can be divided into Local Area Network, Personal Area Network, Campus Area Network, Wireless Local Area Network,Metropolitan Area Network and Wide Area Network.
There are several network connection methods like HomePNA, Power line communication, Ethernet and Wifi connection method.A network can also be categorized into several different types based on the services it provides like Server farms, Storage area networks, Value control networks, Value-Added networks,SOHO network, Wireless network and Jungle networks.
B. Bashir manages this website
Networking Tutorials and regularly writes articles on various topics such as Computer Networking Network Troubleshooting Tips Wireless Networking, Computer Hardware, Certifications, How Tos, Network Security Guide and computer tips.