1.5 Network Topologies, Protocols and Layers

1.5 Network Topologies, Protocols and Layers

1. Networks

   • A computer network is a number of computers linked together to allow them to share resources. Networked computers can share hardware, software and data
   • Mesh Network
     • Where some or all of the workstations or other devices are connected directly to eachother.
     • Most are usually connected to the one that they exchange the most data with.
   • Star Network
     • Each device is connected by an individual cable directly to the server.
     • Usually the layout of choice in schools and offices because they tend to be the most reliable of topologies

2. WiFi

   • WiFi is Wireless Frequency
     • Radio waves are used to transmit data packets without the need for wires
   • This method is slower and more vulnerable to attack but it removes the need for cabling and networks
     • This means it can be set up in remote locations such as cars and planes

3. Encryption

   • Encryption is a method of scrambling data with a key code which makes no sense
   • On an open or public wifi network anyone can join and sniff out packets of data from other users
     • Therefore encryption is used. If intercepted the data will have no meaning
   • In order to read the data the user is required to decrypt the data using the key

4. IP Address

   • A unique string of numbers separated by full stops that identifies each computer using the Internet Protocol to communicate over a network
   • They are similar to a postcode
   • 192.168.1.23
   • Data travelling on a network are sent in packets
   • Each device on the network has a unique IP address which is sent with the packets to identify which computer to send it to
   • It is broken down into four numbers which can represent a number between 0 and 255 separated by a full stop

5. IP Classes

   • IP addresses also have different classes which identify the class of network that the user is on
   • This indicates the number of total possible users and the purpose of the network

6. MAC Address

   • Media Access Controlled Address
   • Uniquely identify a device on a network by identifying the network adapter that the device is using
   • Embedded into the device when it is manufactured and the owner cannot change it
   • A unique code which is built into the NIC
   • Each address is individual and is made up of 48 bits, usually written in hexadecimal for ease
     • AA-34-G4-44-23-F1

7. KEY PROTOCOLS

   • TCP/IP- Transmission Control Protocol/Internet Protocol
     • HTTP-Hyper Text Transfer Protocol
       • HTTPS-Hyper Text Transfer Protocol Secure
         • FTP-File Transfer Protocol
           • POP- Post Office Protocol
             • IMAC-Internet Message Access Protocol
               • SMTP-Simple Mail Transfer Protocol

8. PACKET SWITCHING

   • Emailing a photo
     • The photo is broken down into small packets of data
       • Each packet is given a header which contains the IP address of the network and device it is being sent to. It also contains the IP address of the device it was sent from
         • The header also contains the packet number as well as the total number of packets, eg. 4 of 60
           • When the packets arrive at the destination this information is used to reassemble the data
             • Packets can be lost so sometimes the computer requests for it to be sent again, if a packet never arrives then it is deleted by the router

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