3Com 3C888 User Guide - Page 139

Simple Mail Transfer Protocol SMTP and Post Office Protocol POP 3, which, What is a POTS, connection?

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What is a network? 139 What is a POTS connection? POTS stands for "Plain Old Telephone Service" and refers to a basic, analog telephone connection without any added features or functions. A POTS line is used to connect analog devices, such as a telephone, fax machine, or your Dual 56K LAN Modem, to the public telephone network. How do different devices communicate with each other? Once communications devices are physically connected together in a network, they must run some type of standard communications software that allows different types of devices to communicate with one another according to common, or shared, protocols. One of the most popular protocols in use within networks today for this purpose is the Transmission Control Protocol/Internet Protocol (TCP/IP). What is TCP/IP? TCP/IP is a group of standardized communications protocols which has become an industry standard for allowing devices of differing technologies and vendor origin to communicate across both LAN and WAN environments. The history of TCP/IP's use and increased popularity over the years is tied to its use in the original Internet and to the Internet's subsequent growth and expansion. As its name indicates, TCP/IP has two main components: TCP, which is classified as a "connection" protocol, and IP, which is known as a "routing" protocol. The two protocols work in conjunction with one another to transport data across networks. IP defines a set of rules for routing data from one location to another, including, for instance, that data is segmented into specific sized packets (called "IP packets"); that each packet contains source and destination information; and that the form of this source and destination information is a 32-bit value-an IP address-which uniquely identifies each location within the network. (See also IP Address, below.) While IP provides rules for routing data, the reliability of the data's delivery to its destination is not automatically ensured. This is where TCP plays a role; it works on an entirely different level to ensure delivery by defining rules for error detection and correction during transmission, and by initiating the retransmission of IP packets until their receipt by the other end is confirmed. To use an analogy, in an overnight delivery service, in which many rules and procedures are followed to ensure swift and reliable delivery of packages, IP might cover the rules involving addressing (for example, that a street address, telephone number, and sender's information must be included) and packaging (that materials be sorted into envelopes and boxes of set sizes and weight restriction). TCP, by contrast, might cover the rules having to do with actual delivery (obtaining a signature from the recipient, leaving a note if the package is not delivered, etc.) In actuality, TCP/IP encompasses more than the two protocols which define its name. Among the software applications which also form part of the suite are the file transfer protocol (FTP), which allows for the transfer of files between remote devices, Telnet, which allows for login to a device from a remote location, and the Simple Mail Transfer Protocol (SMTP) and Post Office Protocol (POP) 3, which establish rules for e-mail transmission.

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What is a network?
139
What is a POTS
connection?
POTS stands for “Plain Old Telephone Service” and refers to a basic, analog
telephone connection without any added features or functions. A POTS line is
used to connect analog devices, such as a telephone, fax machine, or your Dual
56K LAN Modem, to the public telephone network.
How do different
devices communicate
with each other?
Once communications devices are physically connected together in a network,
they must run some type of standard communications software that allows
different types of devices to communicate with one another according to
common, or shared, protocols. One of the most popular protocols in use within
networks today for this purpose is the Transmission Control Protocol/Internet
Protocol (TCP/IP).
What is TCP/IP?
TCP/IP is a group of standardized communications protocols which has become an
industry standard for allowing devices of differing technologies and vendor origin
to communicate across both LAN and WAN environments. The history of TCP/IP’s
use and increased popularity over the years is tied to its use in the original Internet
and to the Internet’s subsequent growth and expansion.
As its name indicates, TCP/IP has two main components: TCP, which is classified as
a “connection” protocol, and IP, which is known as a “routing” protocol. The two
protocols work in conjunction with one another to transport data across
networks.
IP defines a set of rules for routing data from one location to another, including,
for instance, that data is segmented into specific sized packets (called “IP
packets”); that each packet contains source and destination information; and that
the form of this source and destination information is a 32-bit value—an
IP
address—
which uniquely identifies each location within the network. (See also
IP
Address,
below.)
While IP provides rules for routing data, the reliability of the data’s delivery to its
destination is not automatically ensured. This is where TCP plays a role; it works on
an entirely different level to ensure delivery by defining rules for error detection
and correction during transmission, and by initiating the retransmission of IP
packets until their receipt by the other end is confirmed.
To use an analogy, in an overnight delivery service, in which many rules and
procedures are followed to ensure swift and reliable delivery of packages, IP might
cover the rules involving addressing (for example, that a street address, telephone
number, and sender’s information must be included) and packaging (that materials
be sorted into envelopes and boxes of set sizes and weight restriction). TCP, by
contrast, might cover the rules having to do with actual delivery (obtaining a
signature from the recipient, leaving a note if the package is not delivered, etc.)
In actuality, TCP/IP encompasses more than the two protocols which define its
name. Among the software applications which also form part of the suite are the
file transfer protocol (FTP), which allows for the transfer of files between remote
devices, Telnet, which allows for login to a device from a remote location, and the
Simple Mail Transfer Protocol (SMTP) and Post Office Protocol (POP) 3, which
establish rules for e-mail transmission.