NETWORKING
Computer Science ICT SSS3 FIRST Term
WEEK 1
NETWORKING
Content
DEFINITION OF NETWORK
A computer network often simply referred to as a network, is a collection of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources.
A computer network allows sharing of resources and information among interconnected devices.
The network exists for one major reason: to share information and resources.
TYPES OF NETWORKS
- Ethernet
- Token ring
- ARCNET
ARCNET
An acronym from Attached Resource Computer Network is a star LAN network. It was the first widely available networking system for microcomputers and became popular in the 1980s for office automation tasks. ARCNET was developed by John Murphy at Data-point Corporation in 1976.
TOKEN RING
Token ring local area network (LAN) technology is a ring topology network.
It uses a special three-byte frame called a token that travels around the ring. Physically, when implemented, the computers are connected through cables to a “HUB”.
It is the hub that manages the network in a ring-topology manner. An example of a token ring network is the IBM Token Ring.
ETHERNET
Ethernet is a bus topology LAN network system. Ethernet LANs use coaxial or twisted pair cables to connect computer systems
NETWORK TOPOLOGY
In computer networking, topology refers to the layout of connected devices. There are two types of network topology, a physical topology and a logical topology.
The physical topology of a network refers to the layout of the cables and network devices, and logical topology refers to the method of communication of the network devices.
Network topologies are categorized into the following basic types:
- Star topology
- Bus topology
- Ring topology
STAR TOPOLOGY
In a star topology network, the network devices are connected to a central 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 whole network is grounded but if any other network device fails, the network will be operating without the failed device.
Also, the star topology requires more cables because cables are laid from all the network devices to the hub.
A star topology is designed with each node (file server, workstations, and peripheral(s) connected directly to a central network hub, switch, or concentrator.
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network.
It also acts as a repeater for the data flow. This configuration is common with twisted pair cable, coaxial cable or fibre optic cable. An example of a star network is the ARCNET.
ADVANTAGES OF A STAR TOPOLOGY
- Easy to install and wire
- No disruptions to the network when connecting or removing devices.
- Easy to detect faults and remove parts.
DISADVANTAGES OF A STAR TOPOLOGY
- Requires more cable length than a linear topology
- If the hub, switch or concentrator fails, the nodes attached are disabled.
- More expensive than linear bus topologies because of the cost of the hubs, switches or concentrators.
BUS TOPOLOGY
Bust network topology uses a common backbone (a cable) to connect all devices. The backbone is a shared communication medium that all devices that are attached or connected.
A device wanting to communicate with another device on the network sends a broadcasting message onto the wire that all other devices see, but only the intended recipient actually accepts and processed the message.
Bus networks 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.
ADVANTAGES OF A BUS TOPOLOGY
- Easy to connect a computer or peripherals to a linear bus
- Requires less cable length than a star topology
DISADVANTAGES OF A BUST TOPOLOGY
- The entire network shuts down if there is a break in the main cable.
- Terminators are required at both ends of the backbone cable.
- Difficult to identify the problem if the entire network shuts down
RING TOPOLOGY
In a ring network, all the network devices are connected together in a ring form. That is, every device has exactly two neighbours for communication purposes.
All messages travel through a ring in the same direction (either clockwise or counter-clockwise). A failure in any cable or device breaks the loop and can shut down the entire network. An example of a ring topology is the IBM token Ring network and its hub is the Multi-Access Unit (MAU).
Reading Assignment: Reading Assignment:
Hiit @ School, Computer Studies for Senior Secondary Education. Pgs 122 - 126.
WEEK ONE (1) WEEKEND ASSIGNMENT
OBJECTIVE
1. The following are types of Networks EXCEPT one.
(a) Bus (b) Ethernet (c) Token Ring (d) ARCNET
2. One of the following is not an advantage of star topology.
(a) No disruptions to the network when connecting or removing devices.
(b) Easy to detect faults and remove parts.
(c) Entire network shuts down if there is a break in the main cable.
(d) No disruptions to the network when connecting or removing devices.
3. The following are categories of Network topology EXCEPT one
(a) Ethernet topology (b) Star topology (c) Bus topology (d) Ring topology
4. A ________ allows sharing of resources and information among interconnected devices.
(a) Bus topology (b) Computer Network (c) Ethernet (d) ARCNET
5. One of the following is not a disadvantage of bus topology.
(a) Entire network shuts down if there is a break in the main cable.
- Terminators are required at both ends of the backbone cable.
(c) Difficult to identify the problem if the entire network shuts down.
(d) Requires more cable length than a linear topology
THEORY
- List and explain the types of Network topology.
- Define Network and Network topology.