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

Foundations of Networking
Networking
CS 3470, Section 1
Sarah Diesburg
The Gist of it all
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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
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Most people know about the Internet (a
computer network) through applications
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World Wide Web
Email
Online Social Network
Streaming Audio Video
File Sharing
Instant Messaging
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Take Facebook….
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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
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Post updates
Get updates
Chat instantaneously
Watch embedded videos
…
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Motivation Example
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What happens when I click on
http://www.cs.uni.edu in my browser?
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A (Simple) WWW Example
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URL
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HTTP
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Uniform resource locater
http://www.cs.uni.edu
Hyper Text Transfer
Protocol
TCP
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17 messages for one
URL request
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Transmission Control
Protocol
6 to find the IP (Internet
Protocol) address
3 for connection
establishment of TCP
4 for HTTP request and
acknowledgement
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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
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Fundamentally, our quest begins with the
study of this little guy.
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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
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Conduits through which packets pass
through are called links.
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The components (typically computers or
routers) connected by these links are called
nodes.
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Dedicated links connecting pairs of nodes
are said to be point-to-point connections.
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Shared links that carry packets originating
and destined for nodes beyond are referred
to as multiple-access.
Switched Networks
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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.
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Circuit-switched networks (dedicated)
Packet-switched networks (contentious)
Circuit Switching
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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
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The core quantity is a packet (what else?)
which consists of a predefined organization
of information.
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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
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Nodes on the inside of the cloud implement
the network [switches]
Nodes on the outside of the cloud use the
network [hosts]
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The Big Picture
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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
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Please turn in your experience surveys
Explore website resources
Brush-up on C programming
Start reading Chapter 1
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