Packet, routers, and reliability | Internet 101 | Computer Science | Khan Academy
Summary
TLDRIn this video, Lynn Root, a Software Engineer at Spotify, discusses the Internet's reliability and the complex process behind data delivery. The script explains how the Internet Protocol (IP) and Transmission Control Protocol (TCP) work together to ensure data packets are sent, received, and reassembled correctly, even if they travel different routes or arrive out of order. The video highlights the Internet's fault tolerance and scalability, emphasizing its ability to grow without interrupting service.
Takeaways
- ๐ The Internet's reliability is often taken for granted, yet it handles an astonishing amount of data efficiently.
- ๐ Data on the Internet doesn't travel on direct, dedicated lines but through a less direct, packet-based system.
- ๐ฃ๏ธ Information travels in packets, which can change paths dynamically, similar to how one might choose different routes in a car based on traffic.
- ๐ฆ Large files, like images, are broken down into smaller packets for transmission, which are then reassembled at the destination.
- ๐ Routers act as traffic managers on the Internet, directing packets through the most efficient routes based on various factors.
- ๐ Packets may take different routes and arrive out of order, but the system is designed to handle this and maintain data integrity.
- ๐ก๏ธ The Internet Protocol (IP) ensures that routers keep track of multiple paths, enhancing the network's fault tolerance.
- ๐ต TCP (Transmission Control Protocol) acts as a reliable mail service, ensuring all packets of a data request are delivered correctly.
- ๐ If packets are missing or incomplete, TCP will request retransmission until all parts are successfully received.
- ๐ The scalability of TCP and routers allows the Internet to function smoothly even as the number of devices grows exponentially.
- ๐ The Internet's interconnectedness is facilitated by agreed-upon standards, allowing diverse systems to communicate effectively.
Q & A
What does Lynn Root admit to taking for granted about the Internet?
-Lynn Root admits to often taking for granted the reliability of the Internet.
How does the Internet typically deliver data to users?
-Data travels on the Internet in a less direct fashion, not through direct, dedicated connections, but rather through a system of packets that can take various routes to reach their destination.
Who is Bob Kahn and what was his contribution to the Internet?
-Bob Kahn is Lynn Root's partner, and together they began working on the design of what we now call the Internet in the early 1970s, focusing on the Internet's protocols and architecture.
What is a packet in the context of the Internet?
-A packet is a unit of data that travels from one computer to another on the Internet, similar to how a car travels from one place to another depending on traffic or road conditions.
How does the Internet handle large amounts of data, such as a large image?
-Large amounts of data, like an image, are broken down into smaller parts called packets. These packets can take different routes and be reassembled at the destination.
What are routers and what role do they play in the Internet?
-Routers are special computers on the Internet that act like traffic managers, keeping packets moving through the networks smoothly and choosing the best available path for each packet based on various factors.
What does 'cheapest' mean in the context of choosing a path for data packets?
-'Cheapest' in this context refers to the most efficient path in terms of time and non-technical factors such as politics and relationships between companies, rather than monetary cost.
What is the Transmission Control Protocol (TCP) and how does it ensure data delivery?
-TCP is a protocol that manages the sending and receiving of data packets. It ensures all packets are delivered by doing a full inventory upon arrival and sending back acknowledgements for each packet received. Missing packets are resent until all are accounted for.
How does the TCP protocol handle missing or incomplete packets?
-If TCP detects missing or incomplete packets, it will request the sender, such as Spotify, to resend them. Only after TCP verifies the delivery of all packets will the data, like a song, start to play.
Why is the Internet considered scalable and reliable?
-The Internet is scalable and reliable due to its principles of fault tolerance and redundancy. The system can work with a small or large number of devices, and adding more routers increases the network's reliability.
How do the different systems that make up the Internet communicate and work together?
-The different systems on the Internet communicate and work together based on agreed-upon standards for how data is sent around, allowing for seamless data transfer across various networks and devices.
Outlines
๐ Internet's Indirect Data Delivery
This paragraph introduces the concept of how the Internet delivers data in an indirect manner, contrary to the common misconception of direct connections. It explains that data travels in packets, similar to how one might choose different routes in a car based on traffic or road conditions. The paragraph also highlights the early development of the Internet by Bob Kahn and the narrator, emphasizing the importance of protocols and architecture in the Internet's design. It uses the analogy of transporting a space shuttle in pieces to illustrate how large data sets are broken down into smaller packets for transmission.
๐ The Role of TCP in Internet Data Reliability
The second paragraph delves into the role of the Transmission Control Protocol (TCP) in ensuring the reliable delivery of data over the Internet. It describes TCP as a system that manages packet transmission, akin to a guaranteed mail service, where packets are sent, received, and acknowledged. The paragraph explains how TCP ensures all data packets are delivered correctly by requesting retransmission of any missing or incomplete packets. It also touches on the scalability and fault tolerance of the Internet, highlighting how the addition of routers enhances network reliability without disrupting service. The paragraph concludes by emphasizing the agreed-upon standards that allow diverse systems to communicate and function cohesively on the Internet.
Mindmap
Keywords
๐กInternet
๐กPacket
๐กRouters
๐กTCP (Transmission Control Protocol)
๐กReliability
๐กIP Address
๐กBob Kahn
๐กCongestion
๐กFault Tolerance
๐กRedundancy
๐กProtocols
Highlights
The Internet's reliability is often taken for granted despite the vast amount of information being transmitted.
The Internet does not operate on direct, dedicated connections but uses a less direct method for data transmission.
In the 1970s, the design of the Internet's protocols and architecture was initiated by Bob Kahn and Vint Cerf.
Data on the Internet travels in packets, which can change paths dynamically during transmission.
Packets of information on the Internet are similar to transporting goods in vehicles, adapting to traffic and road conditions.
Large files like images are broken down into smaller packets for transmission.
Routers on the Internet act as traffic managers, directing packets based on the destination IP address.
Packets may take different routes and arrive out of order, but are reassembled at the destination.
The 'cheapest' path for data is determined by factors like time and non-technical aspects, not cost.
The Internet's fault tolerance allows continuous packet transmission even when some components fail.
TCP (Transmission Control Protocol) ensures reliable data delivery by managing packet sending and receiving.
TCP verifies the delivery of all packets, requesting retransmission of any missing or incomplete packets.
The scalability of TCP and router systems allows the Internet to handle billions of devices without service interruption.
The Internet's growth and scaling can occur without disrupting service due to its principles of fault tolerance and redundancy.
Hundreds of thousands of networks and billions of devices connect and communicate through agreed-upon Internet standards.
Computing devices and routers help packets reach their destinations, where they are reassembled in the correct order.
The Internet facilitates billions of data transmissions daily for various activities like emails, web browsing, video chats, and IoT communications.
Transcripts
- [Voiceover] Seven, six, five, four, three, two, one.
(funky music)
- Hi, my name is Lynn Root. I am the Software Engineer
here at Spotify, and I will be the first to admit that I
often take for granted the reliability of the Internet.
The sheer amount of information zooming around the
Internet is astonishing. But how's it possible for every
piece of data to be delivered to you reliably?
Say you want to play a song from Spotify.
It seems like your computer connects directly to
Spotify's servers, and Spotify sends you a song
on a direct, dedicated line. But actually, that's not
how the Internet works.
If the Internet were made of direct, dedicated connections,
it would be impossible to keep things working as
millions of users join, especially since there is no
guarantee that every wire and computer is
working all the time.
Instead, data travels on the Internet in a much less
direct fashion.
- Many, many years ago, in the early 1970s,
my partner, Bob Kahn, and I began working on
the design of what we now call the Internet.
Bob and I had the responsibility and the opportunity
to design the Internet's protocols and its architecture.
So, we persisted in participating in the Internet's growth
and evolution for all of this time,
up to, and including, the present.
The way information gets transferred from one computer
to another is pretty interesting.
It need not follow a fixed path.
In fact, your path may change in the midst of a
computer-to-computer conversation.
Information on the Internet goes from one computer
to another in what we call a packet of information,
and a packet travels from one place to another on
the Internet a lot like how you might get from one place
to another in a car, depending on traffic congestion or
road conditions, you might choose or be forced to take
a different route to get to the same place each time
you travel.
And just as you can transport all sorts of stuff
inside a car, many kinds of digital information can be
sent with IP packets, but there are some limits.
What if, for example, you need to move a space shuttle
from where it was built to where it will be launched?
A shuttle won't fit in one truck, so it needs to be broken
down into pieces, transported using a fleet of trucks.
They could all take different routes, and might get to
the destination at different times, but once all the pieces
are there, you can reassemble the pieces into the
complete shuttle, and it'll be ready for launch.
On the Internet, the details work similarly.
If you have a very large image that you want to send
to a friend or upload to a website, that image might
be made up of tens of billions of bits of ones and zeroes,
too many to send along in one packet.
Since it's data on a computer, the computer sending
the image can quickly break it into hundreds or even
thousands of smaller parts called packets.
Unlike cars or trucks, these packets don't have drivers,
and they don't choose their route. Each packet has
the internet address of where it came from and where
it's going. Special computers on the Internet,
called routers, act like traffic managers to keep the
packets moving through the networks smoothly.
If one route is congested, individual packets may
travel different routes through the Internet,
and they may arrive at the destination at slightly
different times, or even out of order.
- So, let's talk about how this works.
As part of the Internet Protocol, every router
keeps track of multiple paths for sending packets,
and it chooses the cheapest available path for
each piece of data, based on destination
IP address for the packet.
"Cheapest," in this case, doesn't mean cost,
but time and non-technical factors such as politics
and relationships between companies.
Often the best route for data to travel isn't necessarily
the most direct. Having options for paths makes the
network fault tolerant, which means the network can
keep sending packets, even if something goes horribly,
horribly wrong. This is the basis for a key principle of
the Internet, reliability.
Now, what if you want to request some data
and not everything is delivered?
Say you want to listen to a song.
How can you bee 100% sure all the data will be
delivered so the song plays perfectly?
Introducing your new best friend, TCP,
Transmission Control Protocol.
TCP manages the sending and receiving of all your data
as packets. Think of it like a guaranteed mail service.
When you request a song on your device,
Spotify sends the song broken up into many packets.
When your packets arrive, TCP does a full inventory
and sends back acknowledgements of each packet received.
If all packets are there, TCP signs for your delivery,
and you're done.
(upbeat music)
If TCP finds some packets are missing,
it won't sign. Otherwise, your song wouldn't sound as good,
or portions of the song could be missing.
For each missing or incomplete packet,
Spotify will resend them. Once TCP verifies the delivery
of many packets for that one song request,
your song will start to play.
(upbeat music)
What's great about the TCP and router systems is
they're scalable. They can work with eight devices or
8,000,000,000 devices. In fact, because of these principles
of fault tolerance and redundancy, the more routers we add,
the more reliable the Internet becomes.
What's also great is we can grow and scale the
Internet without interrupting service for anybody using it.
- The Internet is made of hundreds of thousands of
networks and billions of computers and devices
connected physically. These different systems that make up
the Internet connect to each other, communicate with
each other, and work together because of agreed upon
standards for how data is sent around on the Internet.
Computing devices, or routers along the Internet,
help all the packets make their way to the destination
where they're reassembled, if necessary, in order.
This happens billions of times a day, whether you and
others are sending an email, visiting a webpage,
doing a video chat, using a mobile app, or when sensors
or devices on the Internet talk to each other.
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