wired and wireless networks

wired and wireless networks

1. TCP/IP

   • layers
     • Application
       • Network applications operate on this level
     • Link
       • Hardware operates on this level
     • Transport
       • Links hosts together
     • Network
       • Routers operate on this layer

2. Protocols

   • Hyper Text Transfer Protocol (HTTP)
     • HTTP is used to access and recieve web pages in the form of Hyper Text Markup Language
     • HTTPS is the same yet the data is encrypted
       • It is used for bank websites
   • File Transfer Protocol (FTP)
     • Used to send and recieve files to and from a remote server
   • POP and IMAP
     • POP downloads the entire message to your computer and deletes them from the server
     • IMAP will only download the header and will download the rest of the message when opened however it will leave the file on the server
   • SMTP (Simple Mail Transfer Protocol)
     • Protocol used for transferring e-mails between servers
   • TCP/IP (see left)

3. The Internet

   • The Internet is an interconnected web of Wide Area Networks (WAN)
     • A WAN is any network that uses third party carriers (eg. Britsh Telecom)
     • WANs usually spread over a large geographical area
   • To avoid confusion between the 2.5 billion connected devices the internet has adopted a system called the IP address
     • IP addresses act as home addresses for devices
   • Packet Switching
     • A file being sent is divided into 512 byte packets
       • Each packet contains...
         • Destination IP
         • Origin IP
         • Seqence number
         • Number of Packets
         • Error checking data
   • Domain Name Server (DNS)
     • DNS links a URL to an IP address

4. Local Area Networks (LAN)

   • LANs operate on a small geographical area such as a single site
     • LANs can be wired or wireless
     • All networks allow computers to share files

5. Wireless transmission

   • Radio waves are used to transfer data wirelessly usually 2.4 Ghz to 5.9Ghz
   • Network Interface Cards (NICs) are needed to access wireless networks