1.3.2 Wired and Wireless networks, protocols, layers.

1.3.2 Wired and Wireless networks, protocols, layers.

1. Modes of connection

   • Wired connection - Needs a wire or cables to transmit data.
   • Wireless Connection - Connection that does not need wires and transmits data through radio signals.

2. Encryption

   • Encryption does not prevent someone from intercepting a message - instead it prevents them from being able to understand it.
     • Unencrypted messages are referred as plaintext messages. Encrypted messages are known as ciphertext.

3. IP and MAC Addressing

   • IP address = Unique address for each computer device on a network.
   • MAC address is a unique serial number assigned to each NIC.

4. Common protocols.

   • TCP/IP = Transmission Control Protocol / Internet Protocol - Enables communications over the internet.
   • HTTP and HTTPS = Hypertext Transfer Protocol - Governs communication between a webserver and a client. HTTPS (secure) includes secure encryption to allow transactions to be made over the internet.
   • FTP - File Transfer Protocol - Governs the transmission of files across a network and the internet.
   • SMTP - Simple Mail Transfer Protocol - Governs the sending of email over a network to a mail server.
   • POP and IMAP - Post Office Protocol and Internet Message Access Protocol - govern retrieving emails from email servers. POP is an older implementation, largely replaced by IMAP

5. Network Layering

   • Application layer - encodes/decodes the message in a form that is understood by the sender and the recipient.
   • Transport layer - breaks down the message into small chunks (packets). Each packet is given a packet number and the total number of packets. The recipient uses this information to assemble the packets together in the correct order. It also allows the recipient to see if there are any missing packets.
   • Network layer - adds the sender’s IP address and that of the recipient. The network then knows where to send the message, and where it came from.
   • Data link layer - enables the transfer of packets between nodes on a network, and between one network and another.
   • Layering allows standards to be put in place and simply adapted as new hardware and software is developed.