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NETWORK TOPOLOGIES HNC COMPUTING - Network Concepts 1 Network Concepts Topologies

NETWORK TOPOLOGIES HNC COMPUTING - Network Concepts 1 Network Concepts Topologies

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NETWORK TOPOLOGIES

HNC COMPUTING - Network Concepts

1

Network ConceptsTopologies

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

HNC COMPUTING - Network Concepts

3

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

HNC COMPUTING - Network Concepts

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Types of Networks ring, star, bus, mesh Combined

Ring Networks

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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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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 Networks

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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 Networks

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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

Conclusion

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Gained knowledge about network topologies.

Discussed the advantages and disadvantages of different network topologies.

Created a drawing in Visio to represent a network topology