Post on 29-Dec-2015
Aims
HNC COMPUTING - Network Concepts
2Gain a knowledge about network topologies
Discuss the advantages and disadvantages of different network topologies
Draw a network topology in Visio
What is a network topology
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In computer terms, topology means the structure or layout of the communications network…logical
Each workstation on a network is known as a node.
What is a network topology
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Types of Networks ring, star, bus, mesh Combined
Ring Networks
HNC COMPUTING - Network Concepts
6An example of a Ring network is a token
ring network
Each node connects to two other nodes creating a circular effect.
Data travels from one node to another until the correct destination has been reached.
Ring Networks
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A node handles every packet that is sent through the network.
Access is achieved either by means of a token, passed from one node to the other, or by polling
The two main logical topologies which use this physical topology are Token ring and FDDI.
Ring Networks
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Some advantages Orderly network because every device has to access
the token in order to transmit data.
Degrades gracefully. Network traffic gradually slows down when busy opposed to Ethernet which grounds to a halt.
Ring Networks
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Some disadvantages A failure in any cable or device breaks the loop and
can take down the entire network.
Any movement of devices on the network can cause it to fail.
Star Networks
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A star network consists of one central switch, hub or computer, which acts as a channel to transmit messages.
Server dependent - often a mainframe
Star Networks
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Some advantages A Star Network Topology is very easy to manage
because of its simplicity in functionality.
The problems can be easily located logically in a Star Topology and therefore is easy to troubleshoot.
The star topology reduces the chance of network failure by connecting all of the systems to a central node
It is easier to add additional nodes
Star Networks
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Some disadvantages
if the central hub fails, all computers connected to that hub would be disconnected.
The performance and scalability of the network depends on the capabilities of the hub.
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Bus NetworksA bus network topology is a network
architecture in which a set of clients/nodes are connected via a shared communications line, called a bus.
A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
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Bus Networks
A media access method called CSMA (Carrier Sense Multiple Access) is used to handle the collision that occur when two signals placed on the wire at the same time.
The bus topology is passive. In other words, the computers on the bus simply 'listen' for a signal; they are not responsible for moving the signal along.
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Bus Networks
Some advantages Easy to implement and extend Requires less cable length than a star topology Cost effective as only a single cable is used.
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Bus Networks
Some disadvantages If there is a problem with the cable, the entire
network goes down. Performance degrades as additional computers are
added or on heavy traffic. It works best with limited number of nodes. It is slower than the other topologies.
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Mesh NetworksIt allows for continuous connections and
reconfiguration around broken or blocked paths by “hopping” from node to node until the destination is reached.
A netlike communications network in which there are at least two pathways to each node. A fully meshed network means that every node has a direct connection to every other node.
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Mesh Networks
Some advantages
Self-healing: the network can still operate even when a node breaks down or a connection goes bad. As a result, a very reliable network is formed.
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Mesh Networks
Some disadvantages
Setup time can be quite time consuming. Expensive
Tasks
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Write notes and/or store web links regarding token ring networks.
Find out about physical topologies and logical topologies. – make notes.
Research into different topologies, including combined topologies.
Select one topology and draw it in Visio