The Transport Layer

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Google의 강좌에서

The Bits and Bytes of Computer Networking

6576개의 평가

Google

The Bits and Bytes of Computer Networking

6576개의 평가

Specialization Google IT Support Professional Certificate에서 5의 강좌 2

This course is designed to provide a full overview of computer networking. We’ll cover everything from the fundamentals of modern networking technologies and protocols to an overview of the cloud to practical applications and network troubleshooting. We’ll wrap up by covering how this information might show up in a job interview and giving you a few tips for troubleshooting on the spot. 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. ● understand cloud computing, everything as a service, and cloud storage.

수업에서

The Transport and Application Layers

In the third week of this course, we'll explore the transport and application layers. By the end of this module, you'll be able to describe TCP ports and sockets, identify the different components of a TCP header, show the difference between connection-oriented and connectionless protocols, and explain how TCP is used to ensure data integrity.

The Transport Layer3:31

Dissection of a TCP Segment5:22

TCP Control Flags and the Three-way Handshake5:51

TCP Socket States3:03

Connection-oriented and Connectionless Protocols4:24

강사 만나기

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The transport layer is responsible for

lots of important functions of reliable computer networking.

These include multiplexing and

demultiplexing traffic, establishing long running connections and

ensuring data integrity through error checking and data verification.

By the end of this lesson you should be able to describe what multiplexing and

demultiplexing are, and how they work.

You'll be able to identify the differences between TCP and UDP, explain

the three way handshake, and understand how TCP flags are used in this process.

Finally, you'll be able to describe the basics of how firewalls keep

networks safe.

The transport layer has the ability to multiplex and demultiplex,

which sets this layer apart from all others.

Multiplexing in the transport layer means that nodes on the network have the ability

to direct traffic toward many different receiving services.

Demultiplexing is the same concept, just at the receiving end,

it's taking traffic that's all aimed at the same node and

delivering it to the proper receiving service.

The transport layer handles multiplexing and demultiplexing through ports.

A port is a 16-bit number

that's used to direct traffic to specific services running on a networked computer.

Remember the concept of server and clients?

A server or

service is a program running on a computer waiting to be asked for data.

A client is another program that is requesting this data.

Different network services run while listening on specific ports for

incoming requests.

For example, the traditional port for HTTP or unencrypted web traffic is port 80.

If we want tor request the webpage from a web server running on a computer listening

on IP 10.1.1.100, the traffic would be directed to port 80 on that computer.

Ports are normally denoted with a colon after the IP address.

So the full IP and port in this scenario could be described as 10.1.1.100:80.

When written this way, it's known as a socket address or socket number.

The same device might also be running an FTP or file transfer protocol server.

FTP is an older method used for transferring files from one computer

to another, but you still see it in use today.

FTP traditionally listens on port 21, so if you wanted to establish a connection to

an FTP server running on the same IP that our example web server was running on,

you direct traffic to 10.1.1.100 port 21.

You might find yourself working in IT support at a small business.

In these environments,

a single server could host almost all of the applications needed to run a business.

The same computer might host an internal website, the mail server for

the company, file server for sharing files, a print server for

sharing network printers, pretty much anything.

This is all possible because of multiplexing and demultiplexing, and

the addition of ports to our addressing scheme.

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