1. Foundations of Networking
CS 3470, Section 1
Sarah Diesburg

2. The Gist of it all Networking is all about communication.
Communication is all about protocols.
Protocols are all about standards
Standards are all about interoperability
We can implement pieces of the full network stack which will fit together!

3. The University of Adelaide, School of Computer Science
19 November 2018
Applications
Most people know about the Internet (a computer network) through applications
World Wide Web
Online Social Network
Streaming Audio Video
File Sharing
Instant Messaging …
Chapter 2 — Instructions: Language of the Computer

4. Take Facebook…. Can run in a web browser or a stand-alone application
Think of all the network magic that must happen behind the scenes to allows us to
Post updates
Get updates
Chat instantaneously
Watch embedded videos …

5. Motivation Example
What happens when I click on in my browser?

6. The University of Adelaide, School of Computer Science
19 November 2018
A (Simple) WWW Example
URL
Uniform resource locater
HTTP
Hyper Text Transfer Protocol
TCP
Transmission Control Protocol
17 messages for one URL request
6 to find the IP (Internet Protocol) address
3 for connection establishment of TCP
4 for HTTP request and acknowledgement
Client: Send me the web page
Sever: Ok (ACK)
Sever: Here is your data
Client: Ok (ACK)
4 messages for tearing down TCP connection
Chapter 2 — Instructions: Language of the Computer

7. Packets
Fundamentally, our quest begins with the study of this little guy.
What all happens to it?
Macro view: How does this packet relate to others?
Micro view: What's inside the packet? How's it laid out?

8. Links, nodes, and the abyss
Conduits through which packets pass through are called links.
The components (typically computers or routers) connected by these links are called nodes.
Dedicated links connecting pairs of nodes are said to be point-to-point connections.
Shared links that carry packets originating and destined for nodes beyond are referred to as multiple-access.

9. Switched Networks
Like characteristics of hardware you may have studied in the System Architecture Course.
Analogous to the way that peripherals (many) need to communicate: shared and dedicated pathways.
Circuit-switched networks (dedicated)
Packet-switched networks (contentious)

10. Circuit Switching
Circuit switching refers to scenarios with dedicated, guaranteed — either logical or physical — commitments to link usage.
Used mainly by telecoms, where the fundamentals of “networks” are rooted.

11. Packet Switching
The core quantity is a packet (what else?) which consists of a predefined organization of information.
Commonly have multiple input and output links that logically support multiple communication paths between external nodes
Typically use store-and-forward strategy: data is received on a channel, validated, then queued for output.

12. Switched Network
Nodes on the inside of the cloud implement the network [switches]
Nodes on the outside of the cloud use the network [hosts]

13. The Big Picture
A communication pathway is a link between two or more nodes
A network is a collection of path-connected communication pathways
Book's definition: A network is a construction of nesting networks, where at the bottom level, the network is implemented by some physical medium.

14. For Next Time Please turn in your experience surveys
Explore website resources
Brush-up on C programming
Start reading Chapter 1