Networks

Networks

1. LAN

   • used for a specific companies or area

2. WAN

   • used for world wide

3. Topology

   • Bus
     • all devices connected to one cable (terminator)
     • the terminators are attached to each end
     • cheap, easy to install
     • no extra equipment needed
     • high chance of collision (more comp means more)
     • catastrophic failure damages wires
   • Ring
     • connected with two other comps to form ring formation
     • passes data in a direction until reaches intended recipement
     • no collision
     • no. of comps does not affect speed
     • one faulty cable or faulty comp will result catstrophic failure
     • more difficult to add comps
   • Star
     • all comps are connected to hub or switch making a star formation
     • hub sends each message to all comps
     • switch checks address and send it to only rhe right comps
     • no collision and easy to add comps
     • failure of cable does not affect
     • expensive
     • failure of hub/switch is catastrophic and expensive/difficult to fix
   • Mesh
     • circuit swithing
       • path across net is established
       • path is locked , remains open during communication
       • data arrives in order
       • data arrives at constant speed
       • clogs the network with constant one way
       • blocks other data
     • packet switching
       • packets are re-assembled at the other siade
       • data are split to small packets, sent independantly using different paths
       • don't clog
       • multiple transmissions can happen simultaneously
       • lag needed
       • doesn't arrive in order
     • pathfinding
       • can be used for weighted graphs
       • needs to run once and finds the shortest path
       • finds shortest route between two points
       • usually used ofr heavy weight graphs
       • can't be used for negative graphs
       • time consuming becuase it flows to every direction
     • full = all comps coneected each other
     • partial = some are connected
     • mulitle transmission at the time
     • zero catastophics
     • redundacy
     • expensive

4. wired

   • connected with physical wires
   • used to transmit data

5. wireless

   • radio waves are used to transmit data
   • no physical connection needed

6. protocols

   • HTTP / HTTPS
     • standard protocol used for requesting an HTML file from a webserver
     • HTTPS is a secure version of HTTP
   • POP3
     • a protocol for downloading email from email server
     • only delivers email - doesn't support leaving it on the sever
   • FTP
     • a protocol for transferring files between two computers
     • commonly used by web developers for uploading their HTML files to their webservers
   • SMTP
     • the protocol for uploading email to a email server
     • email are sent with stmp and received with pop3
   • IMAP