A group of interconnected devices that communicate and share resources with each other.
Network Scale
- Personal Area Network (PAN)
Spans a few meters. Connects personal devices. Examples: Bluetooth, USB. - Local-Area Network (LAN)
Spans < 1 km. Run by individual organizations. - Metropolitan Area Network (MAN)
Spans up to ~50 km. Covers a city region. Operated by telecom providers. - Wide-Area Network (WAN)
Spans > 30 km. Operated by telecom providers. - Internet
Global network of interconnected networks. No single owner or operator.
They were traditionally used distinct technologies. Now the differences between them is diminishing.
Network Topologies
Physical or logical arrangement of nodes and links.
- Bus
All nodes share a single cable. Simple, but a fault on the cable disables the whole network. - Ring
Nodes connected in a closed loop. Each node forwards traffic to the next. - Star
All nodes connect to a central switch or hub. Fault in 1 node does not affect others. - Mesh
Nodes connect to multiple others directly. High redundancy. Used in WANs and the internet.