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Learn about the basics of networking, including communication, protocols, standards, and interoperability. Discover how applications like the Internet work and delve into the magic that happens behind the scenes. Study circuit-switched and packet-switched networks, and understand the key components and pathways involved in networking.
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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 • We can implement pieces of the full network stack which will fit together!
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 • …
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 • …
Motivation Example • What happens when I click on http://www.cs.uni.edu in my browser?
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
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?
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.
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)
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.
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.
Switched Network • Nodes on the inside of the cloud implement the network [switches] • Nodes on the outside of the cloud use the network [hosts]
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.
For Next Time • Explore website resources • Brush-up on C programming • Start reading Chapter 1