The TCP/IP Internet protocols, a common example, consist
of: Transmission Control Protocol (TCP), which uses a set of
rules to exchange messages with other Internet points at the information
packet level. Internet Protocol (IP), which uses a set of rules
to send and receive messages at the Internet address level.
A 'protocol' is a rather technical word. But it simply means an
agreed method of doing something. A 'network protocol' is the agreed method of
communication to be used within the network. For example the network protocol
for the internet is TCP/IP.
Computer
Protocols- TCP/IP, POP, SMTP, HTTP, FTP and More
In
order for computers to communicate with one another, standard methods of
information transfer and processing have been devised. These are referred to as
"protocols" and some of the more common ones such as TCP, IP, UDP,
POP, SMTP, HTTP, and FTP are discussed here.
What are protocols?
When
two humans converse, they may have to use the same language but they generally
understand each other without having to adhere to rigid rules of grammar or
formal language frameworks. Computers, on the other hand, have to have
everything explicitly defined and structured. If computers wish to communicate
with one another, they have to know in advance exactly how information is to be
exchanged and precisely what the format will be. Therefore, standard methods of
transmitting and processing various kinds of information are used and these
methods are called "protocols". Protocols are established by
international agreement and ensure that computers everywhere can talk to one another.
There are a variety of protocols for different kinds of information and
functions. This article will discuss some of the common protocols that the
average PC user is likely to encounter.
TCP/IP
TCP (Transmission Control Protocol) and IP (Internet
Protocol) are two different procedures that are often linked together. The
linking of several protocols is common since the functions of different
protocols can be complementary so that together they carry out some complete
task. The combination of several protocols to carry out a particular task is
often called a "stack" because it has layers of operations. In fact,
the term "TCP/IP" is normally used to refer to a whole suite of
protocols, each with different functions. This suite of protocols is what
carries out the basic operations of the Web. TCP/IP is also used on many local
area networks. The details of how the Web works are beyond the scope of this
article but I will briefly describe some of the basics of this very important
group of protocols. More details can be found in the references in the last
section.
When information is sent over the Internet, it is generally
broken up into smaller pieces or "packets". The use of packets facilitates
speedy transmission since different parts of a message can be sent by different
routes and then reassembled at the destination. It is also a safety measure to
minimize the chances of losing information in the transmission process. TCP is
the means for creating the packets, putting them back together in the correct
order at the end, and checking to make sure that no packets got lost in
transmission. If necessary, TCP will request that a packet be resent.
Internet Protocol (IP) is the method used to route
information to the proper address. Every computer on the Internet has to have
its own unique address known as the IP
address. Every packet sent will contain an IP address showing where it
is supposed to go. A packet may go through a number of computer routers before
arriving at its final destination and IP controls the process of getting
everything to the designated computer. Note that IP does not make physical
connections between computers but relies on TCP for this function. IP is also
used in conjunction with other protocols that create connections.
UDP and ICMP
Another member of the TCP/IP suite is User Datagram Protocol
(UDP). (A datagram is almost the same as a packet except that sometimes a
packet will contain more than one datagram.) This protocol is used together
with IP when small amounts of information are involved. It is simpler than TCP
and lacks the flow-control and error-recovery functions of TCP. Thus, it uses
fewer system resources.
A different type of protocol is Internet Control Message
Protocol (ICMP) . It defines a small number of messages used for diagnostic and
management purposes. It is also used by Ping
and Traceroute.
Mail
Protocols POP3 and SMTP
Email requires its own set of protocols and there are a
variety, both for sending and for receiving mail. The most common protocol for
sending mail is Simple Mail Transfer Protocol (SMTP). When configuring email
clients, an Internet address for an SMTP server must be entered. The most
common protocol used by PCs for receiving mail is Post Office Protocol(POP). It
is now in version 3 so it is called POP3. Email clients require an address for
a POP3 server before they can read mail. The SMTP and POP3 servers may or may
not be the same address. Both SMTP and POP3 use TCP for managing the
transmission and delivery of mail across the Internet.
A more powerful protocol for reading mail is Interactive Mail
Access Protocol (IMAP). This protocol allows for the reading of individual
mailboxes at a single account and is more common in business environments. IMAP
also uses TCP to manage the actual transmission of mail.
Hypertext
Transfer Protocol
Web pages are constructed according to a standard method
called Hypertext Markup Language (HTML). An HTML page is transmitted over the
Web in a standard way and format known as Hypertext Transfer Protocol (HTTP).
This protocol uses TCP/IP to manage the Web transmission.
A related protocol is "Hypertext Transfer Protocol over
Secure Socket Layer" (HTTPS), first introduced by Netscape. It provides
for the transmission in encrypted form to provide security for sensitive data.
A Web page using this protocol will have https: at the front of its URL.
File
Transfer Protocol
File Transfer Protocol (FTP) lives up to its name and
provides a method for copying files over a network from one computer to another.
More generally, it provides for some simple file management on the contents of
a remote computer. It is an old protocol and is used less than it was before
the World Wide Web came along. Today, Its primary use is uploading files to a
Web site. It can also be used for downloading from the Web but, more often than
not, downloading is done via HTTP. Sites that have a lot of downloading
(software sites, for example) will often have an FTP server to handle the
traffic. If FTP is involved, the URL will have ftp: at the front.
References
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