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Foundations of Networking

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

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Foundations of Networking

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  1. Foundations of Networking 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 • By adhering to specifications, we are able to implement pieces of the full network stack, which will fit together to provide for robust communication.

  3. Applications • Most people know about the Internet (a computer network) through applications • World Wide Web • Email • Online Social Network • Streaming Audio Video • File Sharing • Instant Messaging • …

  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 (push out) • Get updates (pull in) • Chat instantaneously • Watch embedded videos • …

  5. Motivation Example • What happens when I click on http://www.cs.uni.edu in my browser?

  6. A (Simple) WWW Example • URL • Uniform resource locater • http://www.cs.uni.edu • 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

  7. Packets • Fundamentally, our quest begins with the study of this little guy. • How does it get from source todestination? • If it's too big, how is it broken up? • When there's competition between packets, how do you determine resolution? • 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 • In many ways, networks will embody many of the characteristics of the 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. A bit awkward, but motivates “the cloud.”

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

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