Networking & the Internet

Networking & the Internet

1. Internet

   • Many computers (including networking equipment) connected together.

2. Network Topologies

   • Star Networks
     • Computers connected to a single computer (typically a switch or a router).
       • Pros
         • Easier to manage all the devices
       • Cons
         • More cables required to connect to a single computer
         • Single point of failure (router/switch fails, all connected computers fail.
   • Bus Networks
     • Computers connected to a single cable
       • Cons
         • Single point of failure
           • (if the cable which all computers are connected fails, all fails)
         • Decreased bandwidth per computer
       • Pros
         • Simple
   • Ring Topology
     • Computers connected to each other, if one breaks or is shut down, all connections stops.
       • P2P?
       • Cons
         • All computers become single point of failure of the network
       • Pros
         • Reliable and efficient
   • Mesh Topology
     • All computers connected to all other computers.
       • Cons
         • Complex
         • Expensive (single RJ45 cable for amount of other computers)
       • Pros
         • Reliable
           • Always redundancy if any of the other computers breaks
   • Hybrid
     • Mixture of different topologies

3. Connectivity

   • History of connectivity
     • The First Oceanic Cable
       • 25000 m cable in the Atlantic made in 2858
         • 1tn/mi
   • Bandwidth
     • Amount of data that can be carried at a time
     • latest oceanic cable can carry theoretically up to 250 Tbps
   • Connection Speeds
     • Mbps (Mega bits / sec)

4. Encryption

   • Caesar Cipher
     • Shifting set amounts of the alphabet to "encrypt" and "decrypt"
   • Vigenère cipher
   • Modern Encryptions
     • RSA, AES
     • Public-private

5. Types of networks

   • LAN
   • WAN
   • MAN
   • PAN