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Networks - Coggle Diagram
Networks
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Buses
The computers are connected to a single cable on which data can be sent, called the bus.
The bus has terminators on each end, which are needed to close each end of the cable.
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As the packets arrive at each computer system, it checks the destination address contained in the packet to see if it matches its own.
If the address does not match, the computer system ignores the packet. If the address of the computer system matches that contained in the packet, it processes the data.
For image, look on powerpoint
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Disadvantages
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Limited cable length and number of stations – performance degrades as additional computers are added
If there is a problem with the main cable or connection, the entire network goes down
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Data collisions are more likely, which causes the network to slow down. A collision is when two computers try to send a packet at the same time
Packet switching
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Packet switching is less susceptible to interception and is more reliable because if a route fails then the packet can use an alternate route. Missing packets are resent when needed.
Contents of a packet
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Packet ID is needed so that, afterwards, data from multiple packets can be arranged into the correct order
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Protocol is an indication of which protocol (HTTP, FTP, SMTP, etc.) has been used to form the packet.
Data is the reason a packet is being sent in the first place, Eventually, all packet components are discarded except for the data itself.
Checksum is a technique that verifies that the data that was sent matches the data that was received
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Disadvantages
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Sever is down, all workstations are affected
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Hardware
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Routers a router stores the addresses of computers on the network and transfers data between devices.
Gateways a gateway joins together two networks that use different base protocols, e.g. links a LAN to WAN.
Bridge a bridge joins together two networks that use the same base protocols, e.g. links LAN to LAN.
Star
Where one or more central switch, hub or computer acts as a central conduit to transmit messages
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Sending data, computer A sends data with address on, to hub, hub sends it to computer D
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Ring
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Each node connects to exactly two other nodes, providing a single pathway for signals through each node.
Advantages
The transmission of data is simple as packets travel in one direction only, so no collisions.
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Disadvantages
If any of the computer systems fail, the ring is broken and data cannot be transmitted efficiently
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Because nodes are wired together, to add another you must shut down the network
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Mesh
Each node relays data for the mesh network. All mesh nodes cooperate in the distribution of data in the network.
This is very reliable as it can 'self-heal' by reconfiguring around broken paths. This network is complex, expensive and difficult to set up. A large part of the network may be redundant
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