Networking

Networking

A computer network allows sharing of resources and information among interconnected devices. Network exist for one major reason: to share information and resources.

Types of network

• ARCNET
• Token ring
• Ethernet

ARCNET: attached resource computer network is a star (LAN) topology network. ARCNET was the first widely available network system for microcomputer and became popular in the 1980s for office automation task. ARCNET was developed by John Murphy of data point cooperation in 1976.

Token ring: token ring (LAN) technology is a ring topology network. It uses a specific three-byte frame called a “Token” that travels around the ring. Physically, when connected through cable to a “HUB” it is the hub that manages the network in a ring topology manner. An example of a token ring network is IBM Token Ring System.

Ethernet: it is a bus topology “LAN” network system “LAN” use coaxial or twisted pair cables to connect computer system.

Network topology

In computer network topology refers to the layout of connected devices. There are two types of network topology.  Physical topology and a logical topology.

The physical topology of a network refers to the layout of the cables and network devices. Logical topology refers to the method of communication of the network devices. Network topologies are of communication of the network devices. Network topologies are categorized into the following basic types.

• Star topology
• Bus topology
• Ring topology

STAR TOPOLOGY: in star topology network, the network devices are connected to the central point like a star. The central point may be a hub, a switch or a router. All the individual network devices communicate with the central point.

Thus once the hub fails, the network is grounded but if any other network devices fail, the network will still be operating without the failed device. Also, the star topology requires more cable because cables are laid form all the network devices to the hub. Data on a star network pass through the hub, switch or concentrator before continuing to its destination. The hub, switch or concentration manages and controls all functions of the network.

Advantages of star network

• Easy to install and wire
• No distruption to the network when connecting or removing devices.
• More expensive than linear bus because of the cost of the hubs etc\

Disadvantages

• Requires more cable length than a linear topology
• If the hub/switch or concentrator fails, nodes attached are disabled
• More expensive than linear bus because of the cost of hubs, cable etc.

Bus topology

Bus network topology uses a common beackbone (a cable) to connect all devices. The backbone is a shared communication medium that all devices are attached or connected.

A device wanting to communicate with another device in the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and process the message. Bus network work best with a limited number of devices but if the backbone cable fails, the entire network fails. Also if any of the devices are down, the network fails. An example of bus network is the Ethernet.

Advantage of bus topology

• Easy to connect a computer or peripheral to a linear bus.
• Require less cable length than a star topology.

Disadvantages of a bus topology

• Entire network shuts down if there is a break in the main cables
• Terminators are required at both end of the backbone cable
• Difficult to identify the problem if the entire network shutdown

Ring topology

In a ring topology, all network devices are connected together in a ring form. That is, every device has exactly two neighbor for communication purpose. All messages travel through a ring in the same direction (Either clock wise or anti-clock wise).

A failure in any cable or device breaks the loop and can shutdown the entire network. An example of a ring topology is IBM Token Ring network and it's hub is the multi-access unit(MAU).

Network devices

The network devices are the  nodes of the network . They are device that aif connection and communication. The common network device are:

1. The Hub: it is a device that connect all other devices in a star network together. Every device in the network connect directly to the hub through a single cable. The Hub receives messages from a device and broadcast it to all other devices. Due to the fact that the hub broadcast messages, one message sent by the hub is not able to identify the device that owns the message. This is the reason why people say that the hub is not intelligent.

2. Modem: it's an an acronym for Modulator and Demodulator. It's is a device that can connect a digital data to an analogue data and vice versa.

3. Switches:  A switch is a device that channel incoming data from any of the network device to the specific device that is the destination of the data. Unlike that hub, the switch is intelligent because it does not broadcast but channel the data to the specific destination.

4. Bridge: It is a device that connect two similar network together. A bridge will connect or join 2 ring network together or 2 star network. It could connect many similar networks together.

5. Router: it is a network device that connect 2 or more dissimilar network together, for example, a router can connect a ring network with a star network. A wireless network and cable network a LAN with a WAN and so on.

6. Network interface card: NIC: A network interface card/ controller or network adapter, LAN adapter and by similar terms is a computer hardware components that connects a computer to a network.

Benefits of computer networking

1. It helps to enhance connectivity: network connect and link unlimited numbers of computers. This in turn connect the people using this computer.

2. Networking helps in sharing of hardware resources. Network helps in sharing of different hardware devices. E.g a single printer can be shared by Many staff in an office. This saves a lot of cost.

3. Eases out management of data: network provide the advantage of centralization of data from all the users system to one system where it can be managed in an easy wnd better way

4. Internet: Internet is a network that connects different people in different parts of the world.

5. Data sharing

Assignment

Which of the network topology do you consider the best and why?