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1.5: Network topologies, protocols and layers - Coggle Diagram
1.5: Network topologies, protocols and layers
Network topologies
Mesh networks
In a mesh topology there is no central connection point. Instead, each node is connected to at least one other node and usually to more than one.
Full mesh: Each node is connected to every other node. This enables a message to be sent along many individual routes.
Partial mesh: Not all nodes are connected directly to each other. A partial mesh, therefore, has fewer routes for a message to travel along than a full mesh but are cheaper and easier to implement.
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Any device connected to a network is referred to as a node. A network's topology is the arrangement in which all nodes on a network are connected together.
Star networks
In a star topology all nodes indirectly connect to each other through one or more switches. The switch acts as a central point through which all communications are passed.
Large networks using a star topology are usually controlled by one or more servers. Hence, the client-server model usually uses a star topology. However, some P2P models also use the star topology.
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Tend to be found in organisations like schools or offices where high performance is essential. Also found in homes, especially with wireless connections.
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Encryption
Encryption is the disguising of a message so that it cannot be understood but anyone but the intended recipient. The intended recipient will have a key, which can be used to understand the message.
Asymmetric encryption
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However, public keys can't decrypt a message, only the private key can do that. As long as the private key is not given out, messages will stay safely encrypted.
Encryption is of little use if unauthorised personnel know the key, which they can then use to unscramble any message with the key.
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Addressing and protocols
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The two types of protocols that control addressing are known as Internet Protocol (IP) addressing and Media Access Control (MAC) addressing.
IP Addressing
IP addresses can be static or dynamic. Static addresses stay the same each time you connect to a network whereas dynamic addresses change every time you connect to a network.
The method of addressing using four sets of digits is called IPv4, however due to a rise in the number of devices, IPv6 has been introduced.
When connecting to a network, each device has a unique IP address consisting of four sets of up to three numbers, with dots between the sets. E.g. 192.168.0.254
MAC addressing
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A MAC address is a unique serial number assigned to each NIC, which allows a network to identify any device, even when a dynamic IP address is assigned to the device.
Other protocols
Hypertext Transfer Protocol (HTTP) governs communication between a web server and a client. Hypertext Transfer Protocol Secure (HTTPS) includes encryption to allow transactions to be made over the internet.
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Network layering
Types of layers
Transport layer: breaks down the message into packets. This information is used to assemble the packets in the correct order and to see if there are any missing packets.
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Network layering is the sending of messages in separate components. This is known as the Transmission Control Protocol/Internet Protocol (TC/IP) model.
Packet switching
With packet switching, messages are broken up into small pieces, called packets. These consist of two parts: the header and the payload.
Header: Includes metadata i.e. the IP addresses, the packet number, the total number of packets, plus the details of any protocols used...
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Packets are sent along the route of quickest transmission. Due to this, they may arrive out of sequence. The recipient takes each packet, makes a note of its number and puts them into the correct order. If packets are missing, the recipient can request that those packets are re-sent.