Computer Networks: A Systems Approach, 5e
Larry L. Peterson and Bruce S. Davie
Chapter 9
Applications
Copyright © 2010, Elsevier Inc. All rights Reserved
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Chapter 9
Problem
Applications need their own protocols.
These applications are part network protocol (in
the sense that they exchange messages with
their peers on other machines) and part
traditional application program (in the sense that
they interact with the windowing system, the file
system, and ultimately, the user).
This chapter explores some of the most popular
network applications available today.
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Chapter 9
Chapter Outline
Remote login to hosts: Telnet
File transfer: File Transfer Protocol (FTP), Trivial File
Transfer Protocol (TFTP)
Electronic mail transport: Simple Mail Transfer
Protocol (SMTP)
Networking support: Domain Name System (DNS)
HTTP: Hyper Text Transfer Protocol
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Remote login to hosts
Telnet is a client-server protocol, based on
a reliable connection-oriented transport.
Typically, this protocol is used to establish
a connection to Transmission Control
Protocol(TCP) port number )23(, where a
Telnet server application is listening.
Telnet, however, predates TCP/IP and was
originally run over Network Control
Program (NCP) protocols.
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Chapter 9
File transfer
The File Transfer Protocol (FTP) is a
standard network protocol used to
transfer computer files between a client and
server on a computer network.
FTP is built on a client-server model architecture
and uses separate control and data connections
between the client and the server. FTP users
may authenticate themselves with a cleartext sign-in protocol, normally in the form of a
username and password, but can connect
anonymously if the server is configured to allow
it.
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File transfer
Trivial File Transfer Protocol (TFTP) is a
simple, lockstep, File Transfer
Protocol which allows a client to get from
or put a file onto a remote host. One of its
primary uses is in the early stages of
nodes booting from a local area network.
TFTP has been used for this application
because it is very simple to implement.
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Electronic mail transport
Simple Mail Transfer Protocol (SMTP) is
an Internet standard for electronic
mail (email) transmission.
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Chapter 9
Networking support
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The Domain Name System (DNS) is
a hierarchical decentralized naming system for
computers, services, or any resource connected to
the Internet or a private network. It associates various
information with domain names assigned to each of the
participating entities. Most prominently, it translates more
readily memorized domain names to the numerical IP
addresses needed for the purpose of locating and
identifying computer services and devices with the
underlying network protocols. By providing a worldwide,
distributed directory service, the Domain Name System
is an essential component of the functionality of the
Internet.
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Chapter 9
Hypertext Transfer Protocol
The Hypertext Transfer Protocol (HTTP)
is an application protocol for distributed,
collaborative, hypermedia information
systems. HTTP is the foundation of data
communication for the World Wide Web.
Hypertext is structured text that uses
logical links (hyperlinks)
between nodes containing text. HTTP is
the protocol to exchange or transfer
hypertext.
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