COMMUNICATIONS

COMMUNICATIONS

1. Networks

   • Topologies
     • Star
     • Bus
     • Mesh
       • Sending data
         • Circuit network
           • Single fixed route
           • Little delay as all information is already in order but route can slow down with traffic so not as reliable
         • Packet switching
           • When sending large amounts of data it is faster to have each packet find an optimal route separately so if the current route slows down due to high traffic, it will find a faster one
           • There is a delay to ensure that all packets are received in correct order
             • This makes it not ideal for live video such as calls but fine for streaming videos or movies.
         • Pathfinding
           • Sending multiple signals across different paths through a mesh network to find the fastest route
     • Ring
   • Types
     • LAN
       • Local Area Network
       • Confined to a single organisation.
     • WAN
       • Wide area network
       • Multiple organisations (i.e. the internet)
   • Protocols
     • HTTP
       • HTTPS
         • HTTP-Secure
         • Slightly slower
         • Encrypted
         • Certificatated
         • Sensitive information
           • Passwords
           • Bank info
       • Hyper-Text-Transfer-Protocol
       • Send information for web-pages etc.
       • Non-sensitive data
     • FTP
       • File-Transfer-Protocol
       • Give one computer access to another's file system to send and receive files
     • Email
       • POP3
         • Post-Office-Protocol-3
         • Old system of receiving emails
         • Removed from email server and sent to be stored on computer
       • SMTP
         • Simple-Mail-Transfer-Protocol
         • Used for sending emails to servers
       • IMAP
         • Internet-Message-Access-Protocol
         • Send message copy
         • Stays on server as well as client
   • • Pros
       • You can send data between machines without transferring physical storage mediums between them
       • Fast
     • Cons
       • Susceptible to viruses
       • Expensive to set up and maintain
       • Not 100% reliable
   • Connections
     • TCP/IP
       • Application layer
         • Transport layer
           • Network layer
             • Data link layer
               • Physical layer
                 • Sends and recieves bits
               • Hardware address (MAC)
               • Frames
             • Packets
             • Network address & routing
           • Data-consistency (Error checking)
         • Provies apps and services
     • IP Addresses
     • DNS

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