GCSE Computing - Network Topologies
- Created by: MrSwalbert
- Created on: 25-01-18 12:36
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- Network Topologies
- Star Network
- This is the most common layout for a network.
- All nodes are connected to a central device.
- They are very fast and reliable.
- There is a low chance of packet collision.
- Mesh Network
- All nodes are involved in the transmission of a message.
- There is no central router needed.
- They are very fault tolerant.
- All nodes are connected to each other.
- If a route is blocked, the routing algorithm can find a new route for the packets.
- WiFi
- WiFi uses wireless radio frequencies.
- These are normally 2.4GHz and 5GHz wavebands.
- The waveband is split into many channels.
- Has a range of about 20 meters.
- Security is an issue.
- Encryption
- Due to the vulnerability of many networks, we need to protect the messages we send.
- Encryption is the transmission of a message so that it can only be understood by who we want to read it.
- Two keys called the public key and private key are used to encrypt messages.
- The public key can be used by anyone and the private key is kept secret and is used to decode.
- Protocols
- Almost everything on the internet uses protocols.
- Network addressing is getting a message from one computer to another.
- The main one uses MAC and IP addressing.
- IPv4 uses 4 groups of numbers. There can be just over 4 billion combinations.
- Because we are running out of IPv4 addresses, we now use IPv6 which has more combinations.
- IP addresses can be static or temporary. Static addresses never change.
- The MAC address is unique to the network card and can be used to track any device on the internet.
- Protocols and Standards
- HTML - Hypertext mark-up language - writing web pages for display.
- XML - Extensible mark-up language - A text-based means of describing data.
- HTTP - Hypertext transfer protocol - for requesting and receiving HTML files.
- HTTPS - Hypertext transfer protocol secure - for requesting and receiving HTML files over a secure encrypted connection.
- CSS - Cascading office protocol - define how HTML elements are to be displayed.
- POP - Post office protocol - for retrieving emails from a remote server.
- IMAP - Internet message access protocol - allows complete management of a remote mailbox.
- SMTP - Simple mail transfer protocol - This is the old standard for the transmission of email.
- FTP - File transfer protocol - This is used to send computer files from one host to another.
- Layering
- Layering is used to split up tasks of a program which makes it easier to find an error had there happen to be one.
- TCP/IP is used to define how to transfer data through a network.
- TCP/IP stack: Layer 1: Application Layer 2: Transport Layer 3: Internet Layer 4: Network
- Packet Switching
- The sending computer splits data into equal packets and each packet is given an address. Each packet gets error checking data and are then sent across the network.
- The receiving computer checks to see if all the packets have been received. Packets are checked for errors.
- Star Network
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