Lecture 1 (11.2 in text)
What is the Internet?
The Internet is a global system of interconnected computer networks that use the standard
Internet protocol suite (TCP/IP) to serve billions of users worldwide. It is a network of networks
that consists of millions of private, public, academic, business, and government networks, of
local to global scope, that are linked by a broad array of electronic, wireless and optical
What are the three dimensions of the internet / a network?
What is a system?
Computing devices connected by communication links (fiber, copper, radio, satellite), these
communication links have a transmission rate (bandwidth) and packet switches which forward
packets (chunks of data)
What is a packet switch?
A packet switch takes a packet arriving on one of its incoming communication links and forwards
that packet on one of its outgoing communication links. The two most prominent types are
routers and linklayer switches.
Difference between linklayer switch and router?
Linklayer typically used in access networks while routers are used in the network core.
What is a rule?
The internet follows rules (protocols) like a software library or interface. This allows
programmers to separate concerns and builds expectations of how things are encoded.
Protocols control the sending and receiving of messages. Protocols can be public (http) or
The Internet Engineering Task Force (IETF) is the primary group responsible for standardizing
protocols used on the internet through RFC’s. If a standard gains enough momentum it forces
vendors to use it (market driven economics).
What is a service?
The internet can be described as an Infrastructure that provides services to applications (web,
VoIP, email, games. soc