The Internet is a globally interconnected system of computer networks (a network of networks). The World Wide Web (WWW) is the interconnected system of documents and pages.
Connections between machines can be two-way. Digital subscriber lines (DSL), which make use of complicated DSP circuits, allow data to be transmitted on the same cables as phone lines.
The Internet protocol suite (TCP/IP) is a set of communication protocols used in computer networking and the Internet. They define common/consistent ways for each machine to communicate with each other.
The Internet is physically broken into two main components.
- The network edge consists of hosts (personal devices, IoT devices, servers), access networks (home Wi-Fi, Local Area Networks).
- The network core consists of a mesh of interconnected links. These links are routers, which transport packets from source to destination with a mechanism called packet switching.
- Another less popular mechanism for the links are circuit switching.
consists of:
- many billions of connected computing devices
- hosts: end systems
- running networked apps at the “edge” Edge computing
- packet switches — routers, switches: hardware that forwards packets (chunks of data)
- communication links (fibre optics, copper, radio, satellite) — transmission rate == Bandwidth
- networks — collection of devices, routers, links managed by an organisation
- internet: interconnected ISPs
- protocols
large number of switches, small num routers switches: used to transmit info inside network — each switch has large number of output ports to computers routers: transmits outside network
slide 19: , roughly speed of light, basically speed one bit gets propagated packet switching slides slide 14: forwarding table in practice refreshed periodically (say every 10 seconds)
The Internet protocol layered network model has the following layers:
- Application
- Transport
- Network
- Data link
- Physical