Protocols

Protocols

1. Application

   • HTTP(S)
     • Web pages sent and recieved with this.
     • "S" on end of https means secure.
       • Works like http, but encrypts web page data before sent out.
         • So no one can intercept and read data.
   • FTP
     • Transfer files between a client and server on computer network.
   • IMAP
     • More complex commands
       • Set flags on emails if viewed etc.
       • Access
   • POP
     • Allows emails to be downladed/deleted from mail server
       • Only handle one mailbox
       • doesn't support complex searches of emails on the server.
       • After messages downloaded, removed from the email server, cannot be viewed by other devices
   • SMTP
     • Used by email server to send and recieve emails across internet

2. Transport

   • TCP
     • Prepares messages for transmission and reassembles any recieved messages.
       • Sending
         • Divides messages into packets.
         • Adding sequence number to each packet, so message can be reassembled.
         • Adding error-correction info, so errors can be detencted and fixed.
       • Recieving
         • Examining each packet for errors, uses extra info added to it .
         • Fixing any errors, request that the packet be re-sent.
         • Spotting missing packets, request that the packet be re-sent.
         • If all packets present, uses sequence number of each packet to re-assemble message.

3. Network

   • IP

4. Link

   • Bluetooth
   • Ethernet