What is the Internet

Question 1

Internet fundamentals (Black box view)

Answer 1

• The internet is an infrastructure that supports applications such as:
  – Web, VoIP, email, games, e commerce, social networks, …
• There’s a programming interface that offers
  access to this infrastructure to such applications
  – “Hooks” that allow sending/receiving applications to “connect” to the Internet
  – Provides various service options

Question 2

Internet fundamentals

Answer 2

• The Internet comprises three main types of basic component:
• Hosts
  
  • Billions of connected computing devices/ “end-systems”
  • Each runs one or more network applications

▪ Communication links
* Fibre, copper, radio, satellite
* Key notion of transmission rate: cf. bandwidth

▪ Packet switches
* Used to forward packets (chunks of data) down links
* Routers and switches

Question 3

Internet infrastructure (An Overview)

Answer 3

Question 4

Internet infrastructure (A more detailed view)

Answer 4

Internet: “networkof networks”
- Interconnected ISPs

Protocols control the sending and receiving of data messages
- e.g., TCP, IP, HTTP, Skype, 802.11

Internet standards
- IETF: Internet Engineering Task Force
- RFC: Request for comments

Question 5

What’s a Protocol? (Definition)

Answer 5

Protocols define the format and ordering of messages sent and received among network entities, and actions to be taken on message transmission/receipt

Question 6

What’s a Protocol? (Human vs Network)

Answer 6

Human protocols:
* “what’s the time?”
* “I have a question”
* Introductions
… specific messages sent
… specific actions taken when messages (or other events) are received

Network protocols:
* Analogous, but mediated by machines rather than humans (obviously)
* All communication activity in the Internet is governed by protocols

Question 7

What’s a Protocol? (Comparison)

Answer 7

A human protocol and a computer network protocol:

Question 8

Why is the Internet so important?

Answer 8

Question 9

Global Submarine Cable Map

Answer 9

Question 10

AS Core Visualisation (CAIDA)

Answer 10

Depicts the Internet’s Autonomous Systems (ASes)
- Each AS approximately corresponds to an Internet Service Provider
* British Telecom
* Vodafone
* Many others!
* More on this later…
* Includes their geographic locations, numbers of customers, and interconnections

Question 11

What if we didn’t have the Internet?

Answer 11

• It is the unseen infrastructure behind much of our daily lives
• Imagine if it went away tomorrow…
• What would you miss?
  – Education
  – Banking
  – Communication
• In the future, maybe:
  – Transport
  – Home

Question 12

What does it mean for your future career??

Answer 12

• Thinking about your job prospects in a few years…
  – You might not become a network engineer
  – You might however become a software developer
• It is easy to ignore the network, and treat it as a given commodity that is always there and always perfect
• But it can easily:
  – Break the best engineered application
  – Ruin the smoothest user interaction
• Don’t underestimate the impact of the network in all of this!