Hubs and Switches

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来自 Google 的课程

The Bits and Bytes of Computer Networking

2774 个评分

Google

The Bits and Bytes of Computer Networking

2774 个评分

课程 2（共 5 门，Specialization Google IT Support Professional Certificate）

This course is designed to provide a full overview of computer networking. In this course, we’ll cover everything from the fundamentals of modern networking technologies and protocols to practical applications and network troubleshooting. By the end of this course, you’ll be able to: - describe computer networks in terms of a five-layer model. - understand all of the standard protocols involved with TCP/IP communications. - grasp powerful network troubleshooting tools and techniques. - learn network services like DNS and DHCP that help make computer networks run. Except as otherwise noted, the contents on this site are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

从本节课中

Introduction to Networking

Welcome to the Networking course of the IT Support Professional Certificate! In the first week of this course, we will cover the basics of computer networking. We will learn about the TCP/IP and OSI networking models and how the network layers work together. We'll also cover the basics of networking devices such as cables, hubs and switches, routers, servers and clients. We'll also explore the physical layer and data link layer of our networking model in more detail. By the end of this module, you will know how all the different layers of the network model fit together to create a network.

Hubs and Switches2:28

Servers and Clients2:00

Sergio Being A Network Engineer1:26

与讲师见面

Google

We're going to do a rundown of network devices in this video and the next one.

Almost every IT specialist will have to interact with these sorts of devices on

a regular basis.

Cables allow you to form point-to-point networking connections.

These are networks where only a single device at each end of the link exists.

Not to knock point-to-point networking connections, but

they're not super useful in a world with billions of computers.

Luckily, there are network devices that allow for

many computers to communicate with each other.

The most simple of these devices is a hub.

A hub is a physical layer device that allows for

connections from many computers at once.

All the devices connected to a hub will end up talking to

all other devices at the same time.

It's up to each system connected to the hub to determine

if the incoming data was meant for them, or to ignore it if it isn't.

This causes a lot of noise on the network and

creates what's called a collision domain.

A collision domain is a network segment

where only one device can communicate at a time.

If multiple systems try sending data at the same time,

the electrical pulses sent across the cable can interfere with each other.

This causes these systems to have to wait for

a quiet period before they try sending their data again.

It really slows down network communications, and

is the primary reason hubs are fairly rare.

They're mostly a historical artifact today.

A much more common way of connecting many computers is with a more sophisticated

device, known as a network switch, originally known as a switching hub.

A switch is very similar to a hub, since you can connect many devices to it so

they can communicate.

The difference is that while a hub is a layer 1 or

physical layer device, a switch is a level 2 or data link device.

This means that a switch can actually inspect the contents of the Ethernet

protocol data being sent around the network, determine which system

the data is intended for and then only send that data to that one system.

This reduces or

even completely eliminates the size of collision domains on a network.

If you guessed that this will lead to fewer retransmissions and

a higher overall throughput, you're right.

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