3.4~3.7 Internet Routing & Functions

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Do curso por Yonsei University

Introduction to TCP/IP

219 ratings

Yonsei University

Introduction to TCP/IP

219 ratings

You use the Internet through your PC (Personal Computer), laptop, tablet, smartpad, and smartphone every day in everything you do. Through your own PC/laptop, you can easily learn everything about the Internet, and that is what this course is focused on. In this course ‘Introduction to TCP/IP,’ you will learn the operational functions of Internet technologies (which include IPv4, IPv6, TCP, UDP, addressing, routing, domain names, etc.) and your PC/laptop's security and gateway Internet setup and basic principles. In addition, through a simple Wireshark experiment, you will see the TCP/IP packets and security systems in action that are serving your PC/laptop, that serves you.

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Internet Routing & Functions

The third module ‘Internet Routing & Functions’ focuses on the main protocols and functions used in the Internet that you have been using every day to make network connections. The lecture ‘IGP vs. EGP’ is focused on the types and functions of IGPs (Interior Gateway Protocols) and EGPs (Exterior Gateway Protocols). The lecture ‘OSPF’ describes how OSPF (Open Shortest Path First) sets up SPT (Shortest Path Tree) routing paths, which makes your Internet connections more reliable and fast. The lectures ‘ARP’ and ‘NAT’ explains how you have used ARP (Address Resolution Protocol) and NAT (Network Address Translation) to inter-changing IP addresses for access to private networks and how your PC/laptop/smartphone had been finding IP addresses from web host names. The lectures ‘RPC’ and ‘FTP’ describes how RPC (Remote Procedure Call) had been enabling you to make connections to remote computers/servers, and how FTP (File Transfer Protocol) helped you move files from a remote computer/server to your PC/laptop so quickly. The last lecture ‘E-mail’ compares the characteristics of IMAP (Internet Message Access Protocol) and POP3 (Post Office Protocol version 3) and how they operate in serving your all your e-mails.

3.4~3.7 Internet Routing & Functions6:01

Conheça os instrutores

Jong-Moon Chung
Professor, School of Electrical & Electronic Engineering
Director, Communications & Networking Laboratory

Network address translation (NAT).

There are two types of NAT,

one-to-one NAT and one-to-many NAT.

One-to-one NAT is known as basic NAT.

And it enables interconnection of two incompatibly addressed assigned IP networks.

For example, if there's an address structure within

a company that is used in an address structure outside, well,

typically, the address structure outside may have a problem when connecting to address,

an IP address, within the company network.

And therefore, this is when basic NAT,

one-to-one NAT, can be very effective.

One-too-many NAT is also known as IP masquerading.

An address space that includes many private IP addresses

can be hidden under a single public IP address that is used externally.

For example, these private IP addresses may be using

one representative IP address when they connect to the Internet.

Some of the advantages of one-too-many NAT include,

it provides enhanced security,

and also it was made such that we could save

public IPv4 addresses which we are running out very quickly.

RPC which is Remote Procedure Call.

In RPC, this is a program that enables

a function/procedure to be executed on a remote computer.

It enables easy programming as if the function is

to run on a local computer that is currently being used.

Recovery procedures from unpredictable network problems are needed.

RPC request and response procedures include,

a client initiates RPC by sending a request message with a set of

parameters to a remote server and the server replies with a response to the client.

FTP, file transfer protocol.

FTP is used to transfer files from a server to a client computer.

It is used over TCP/IP based upon the internet standard RFC 959.

FTP sign-in protocol commonly requires a username and a password.

An FTP with TLS (Transport Layer Security) protection,

which we call FTPS, is commonly used.

FTP must include active mode and passive mode.

In FTP active mode,

a client sends a FTP command port M to the server to inform which port to use.

Server sends data from its FTP server data port to the client's port.

FTP passive mode is used when the client is behind

a firewall and cannot accept incoming TCP connections from the server.

The client uses the control connection to send a passive command to the server.

The server sends its IP address and server port number.

The client opens data connection to the server IP address and port number.

FTP active and passive modes were updated to support

IPv6 and enhanced passive mode in our RFC 2428.

FTP data transfer modes include stream mode,

block mode, and compressed mode.

Stream mode is, TCP is used to send data in

a continuous stream and FTP does minimum processing.

In block mode, FTP divides data into blocks and uses TCP to transfer.

In compressed mode, data compression,

for example, run-length encoding is applied.

Enhanced data transfer techniques exist.

Email.

Now we are going to compare POP3 and IMAP.

They are both email retrieval applications that use TCP and IP.

POP3 stands for Post Office Protocol version 3.

IMAP stands for Internet Message Access Protocol version 4.

Encryption through TLS and STARTTLS or SSL can be used.

POP3 has a very simple operation.

It moves emails from the server onto your device.

POP3 can be set to leave emails on the server after being retrieved.

In IMAP, IMAP enables complete management of

a user mailbox on the server from multiple e-mail devices such as your PC,

your smartphone, and your notebook computer,

your laptop computer, and other devices.

IMAP is more popular due to multiple device support.

IMAP uses more complex queries because it needs to support multiple devices.

It leaves emails on the server after retrieval

and it's left there until the email is deleted by the user.

SMTP stands for Simple Mail Transfer Protocol.

It is an Internet e-mail protocol.

It is text-based and it uses TCP/IP.

It is commonly used to send and receive emails between servers.

These are the references that I use and I recommend them to you. Thank you.

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