COLOUR THEME
Network types from PAN to WAN, bus, star, ring and mesh topologies, simplex, half-duplex and full-duplex modes, transmission media, and the layered models.
6 sub-topics, in the order to study them. Tap one to jump to it.
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In brief
A computer network is two or more connected devices that share data and resources.
A computer network is two or more connected devices that share data and resources. Benefits: resource sharing (printers, files), communication, centralised data, cost savings and reliability.
In brief
Type Area Example PAN A few metres Bluetooth between phone and earphones LAN Building or campus College computer lab CAN Campus University network MAN City Cable TV network…
| Type | Area | Example |
|---|---|---|
| PAN | A few metres | Bluetooth between phone and earphones |
| LAN | Building or campus | College computer lab |
| CAN | Campus | University network |
| MAN | City | Cable TV network, city Wi-Fi |
| WAN | Country or world | The Internet |
By size: PAN \< LAN \< CAN \< MAN \< WAN. VPN (Virtual Private Network) builds a secure private tunnel over a public network.
In brief
Covers Bus, Star, Ring, Mesh, Tree and more.
Bus: one common cable, cheap, a break stops the network, collisions.
Star: all devices connect to a central hub or switch. Most common in LANs, easy to add devices, central failure stops all.
Ring: circular, data moves in one direction, token passing.
Mesh: every node connected to every other, very reliable, costly. Number of links in full mesh = n(n-1)/2.
Tree: hierarchical, combination of star and bus.
Hybrid: combination of topologies.
In brief
Covers Simplex, Half-duplex, Full-duplex.
Simplex: one direction only (keyboard to computer, TV broadcast).
Half-duplex: both directions, but one at a time (walkie-talkie).
Full-duplex: both directions simultaneously (telephone, mobile call).
In brief
Covers Guided (wired), Unguided (wireless).
Guided (wired): twisted pair (UTP and STP, used in LAN cables), coaxial cable (cable TV), optical fibre (light, highest speed, no electromagnetic interference, most secure).
Unguided (wireless): radio waves, microwave, infrared, satellite, Bluetooth, Wi-Fi.
Bandwidth is the data-carrying capacity, in bits per second. Latency is delay.
In brief
OSI model (7 layers, top to bottom): Application → Presentation → Session → Transport → Network → Data Link → Physical.
OSI model (7 layers, top to bottom): Application → Presentation → Session → Transport → Network → Data Link → Physical. Mnemonic from the bottom: Please Do Not Throw Sausage Pizza Away. TCP/IP model (4 layers): Application, Transport, Internet, Network Access.
Client-server: central server provides services to clients (web, e-mail). Peer-to-peer (P2P): all nodes are equal and share resources directly (torrent).
Switching: circuit switching (dedicated path, telephone) versus packet switching (data split into packets, internet).
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Last updated: . Notes are a revision aid; check official UGC sources for any rule or scheme that changes over time. Spotted a mistake? Write to netlawverse@gmail.com.