Packet vs. Circuit Switching Summary

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Del curso dictado por Princeton University

Networks Illustrated: Principles without Calculus

43 calificaciones

Princeton University

Networks Illustrated: Principles without Calculus

43 calificaciones

What makes WiFi faster at home than at a coffee shop? How does Google order its search results from the trillions of webpages on the Internet? Why does Verizon charge $15 for every GB of data we use? Is it really true that we are connected in six social steps or less? These are just a few of the many intriguing questions we can ask about the social and technical networks that form integral parts of our daily lives. This course is about exploring the answers, using a language that anyone can understand. We will focus on fundamental principles like “sharing is hard”, “crowds are wise”, and “network of networks” that have guided the design and sustainability of today’s networks, and summarize the theories behind everything from the social connections we make on platforms like Facebook to the technology upon which these websites run. Unlike other networking courses, the mathematics included here are no more complicated than adding and multiplying numbers. While mathematical details are necessary to fully specify the algorithms and systems we investigate, they are not required to understand the main ideas. We use illustrations, analogies, and anecdotes about networks as pedagogical tools in lieu of detailed equations. All the features of this course are available for free. It does not offer a certificate upon completion.

De la lección

Routing Traffic through the Internet

It is hard to overstate the impact that the Internet has had on society. In this lesson, we will overview the fundamental concepts behind the way the Internet is designed. We will also take a look at routing, which is the process of determining how packets of information are transported.

Conoce a los instructores

Christopher Brinton
Lecturer
Electrical Engineering
Mung Chiang
Professor
Electrical Engineering

So just to summarize this discussion we've had on packet switching versus

circuit switching, here's the main properties and what they each of them has.

A guarantee of quality is a property of circuit switching.

You can guess.

You can guarantee and say you're going to be able to

get this amount of service, because we're dedicating the resources.

Under packet switching, you can't dedicate a

quality, because packets get lost they get

reordered or dropped or, and things of

those sort of depending on the congestion conditions,

so you can't, you can't guarantee

quality because you're sharing the network resources.

but packet switching has two main advantages it.

First there's ease of connectivity, you don't have to tear down any sessions.

You just kind of send and the network will Direct the traffic as it needs to go.

under circuit switching that's not the case, right because you have to setup

and tear down all the sessions each time you make a communication establishment.

scalability, circuit switching is not having

a property of scalability.

We talked about where you can just add more and more devices and really.

>> have a lot of that.

and scalability ties in: you need to

be highly efficient in order to achieve scalability.

And we talked about packet switching, the properties of statistical

multiplexing and resource pooling, help it to be very efficient, right?

Because there's never any wasted resources as long as there is demand.

but scale, the scalability property is part of circuit switching.

But in the end, packet switching won the day

for the Internet, and this wasn't really clear until the

early 2000s, and there was active research going on

in the realm of circuit switching up until the 2000s.

And people still look at circuit switching, it's

just much of it's switched, at least in

terms of the Internet, so you're looking at

packet switching as being the the dominant sharing.

That's how the Internet works today, that it's on packet switching.

The idea is, you know, guar-, quality is important, right?

So you can't, you can't go without having any

sort of quality of service, but the idea, the

paradigm became, what's the cheapest scalability first, so we

can get to a large number of devices, right?

And we're going to do that by having packet switching,

and then we'll search for other methods of quality control.

Right, so we leave it to certain protocols to be able

to say, well okay there's too much congestion on the Internet

right now, or okay, once it gets, once the message gets

to the receiver, the packets have to be reordered, and things

along those sorts.

So we can have scalability first just by using

packet switching, and we have east of connectivity as

well and then we can just have other means

of, not guaranteeing quality but achieving high quality of service.

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