Computer Home Network » Network Topology http://www.msefsaudi.org Tue, 30 Mar 2010 22:00:40 +0000 http://wordpress.org/?v=2.8.6 en hourly 1 Computer Networking http://www.msefsaudi.org/computer-networking.html http://www.msefsaudi.org/computer-networking.html#comments Sun, 21 Mar 2010 17:35:48 +0000 admin http://msefsaudi.org/computer-networking.html

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


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.

By: Bushra Bashir

]]> http://www.msefsaudi.org/computer-networking.html/feed 0 Network Basics http://www.msefsaudi.org/network-basics.html http://www.msefsaudi.org/network-basics.html#comments Sat, 30 Jan 2010 12:01:53 +0000 admin http://msefsaudi.org/network-basics.html

When dealing with networks one has to understand the different types and how they are used along with the advantages and disadvantages of each.

A mesh network allows for redundancy in that if one node goes down all terminals are able to still communicate with
other terminals and networks by taking several possible paths. The mesh network will be more complex and time consuming
to install, but is also the more reliable than other topologies. If each terminal having reliable connectivity is mission
critical, the knowledge is available and cost is not really a factor then a mesh would be the preferred network.

Bus topology is probably the least preferred topology to implement. If one node is removed or non-operational on the bus
then all terminals will not be able to utilize the network. According to Annabel Dodd (2005) “Prior to hubs, each device
in a LAN was wired to another device in a “bus” arrangement.”(p. 26)
Circumstances that may play a factor in this use of this particular topology would be cost savings in regards to cable and
the importance of that particular network to the department’s mission, as well as the network’s size as well as security.
Required speed, number of attachments, cable length, and use play a factor in determining the use of the bus topology.
Bates & Gregory (2000) tell us that bus speed is limited to “10Mbits/s with effective throughput of 3.3-4 Mbits/s” and that
attachments cannot exceed “1024 addressable nodes” and are “limited to cable lengths of 1500 meters.” They continue on to
say that “collisions when the network gets 40% busy, resulting in less throughput.” It seems that the bus topology is also
the least secure in respect to the fact that all transmissions are a broadcast to the entire network.

The star topology is another network architecture. Circumstances to install this type of network would be similar to those of the bus topology. The star topology would be
primarily used with hubs and switches. This topology allows for all terminals to continually communicate on the network
when a terminal is dropped or goes down. This type of topology is important when connectivity of each terminal in the
network is important and is mission critical to operations.

Combinations of all the various topologies will be seen in MAN, WAN, and even some larger LANs. An example would be a
college campus in which each department uses a star topology internally, but meshes with all the other outlying departments.
So in the case of a college campus all departments would still be able to access records from other departments on campus
when one or more departments lose connectivity.

By: Joseph Brochin

]]> http://www.msefsaudi.org/network-basics.html/feed 0 Network Topology Basics http://www.msefsaudi.org/network-topology-basics.html http://www.msefsaudi.org/network-topology-basics.html#comments Thu, 24 Dec 2009 10:40:10 +0000 admin http://msefsaudi.org/network-topology-basics.html

Hierarchical Model

A hierarchical model is a modular design for an enterprise network that defines three specific layers that each has network services associated with those layers. The layers are access, distribution and core. The access layer is associated with branch offices that usually run lower speed circuits. These branch offices are aggregated at a distribution office and several distribution offices are aggregated at a core office. Modular designs are more scalable and utilize bandwidth more effectively than flat networks.

]]> http://www.msefsaudi.org/network-topology-basics.html/feed 0 Types of Network Topology http://www.msefsaudi.org/types-of-network-topology.html http://www.msefsaudi.org/types-of-network-topology.html#comments Tue, 17 Nov 2009 16:09:08 +0000 admin http://msefsaudi.org/types-of-network-topology.html

Network topology refers to the physical layout of the network i.e. the locations of the computers and how the cable is run between them. To select the right topology for how the network will be used is very important. Each topology has its own strength and weaknesses.

The choice of a topology for installing a computer network depends upon a combination of factors such as, reliability, performance of the system, number of nodes and geographical distribution of the system.

The main 2 types are

Bus Topology & Peer to Peer Topology

Peer to Peer topology consists of Star topology and Ring topology.

Bus Topology

It is often used when network installation is small, simple or temporary. On a typical bus network the cable is just 1 or more wires with no active electronics to amplify the signal or pass it along from computer to computer. This makes the bus a passive topology. When 1 computer send a signal up the wire all the computers receive the information but only one with the address that matches accepts the information, the rest disregard the message.

Advantages:

1) Easy to use and to understand.

2) Requires least amount of cable to connect the computers together. It is therefore less expensive than other cabling arrangements.

3) It is easy to extend a bus; two cables can be joined into 1 longer cable with a BNC, Barrel connector making a longer cable and allowing more computers to join the network.

Disadvantages:

1) Heavy network traffic can slow a bus considerably as only 1 computer can send a message at a time.

2) It is difficult to troubleshoot the bus. A cable break or loose connector causes reflection and stops all the activity.

Star Topology

In this kind of topology all the cables run from the computers to the central location where they are all connected by a device called hub or switch. Each computer on a star network communicates with a central device that resends the message either to each computer or only to the destination computer, e.g. if it is a hub then it will send to all and if it is a switch then it will send to only destination computer.When network expansion is expected and when the greater reliability is needed, star topology is the best.

Advantages:

1) It is easy to modify and add new computers without disturbing the rest of the network.

2) The center of the star network is a good place to diagnose the faults.

3) Single computer failure does not necessarily bring down the whole star network.

Disadvantages:

1) If the central device fails the whole network fails to operate.

2) Star networking is expensive because all network cables must be pulled to one central point, requires more cable than other network topologies.

Ring Topology

In this type each computer is connected to the next computer with the last one connected to the first. Each retransmits what it receives from the previous computer. The message flows around the ring in one direction. The ring network does not subject to signal loss problem as a bus network experiences. There is no termination because there is no end to the ring.

Advantages:

1) Each node has equal access.

2) Capable of high speed data transfer.

Disadvantages:

1) Failure of one computer on the ring can affect the whole network.

2) Difficult to troubleshoot the network.

Topologies remain an essential part of network design speculation. But understanding these can help you to get the deeper knowledge of the elements like hub, switch etc.

By: Deepti Pawar

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