What is a network? 139
What is a POTS POTS stands for “Plain Old Telephone Service” and refers to a basic, analog connection? 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 Once communications devices are physically connected together in a network, devices communicate they must run some type of standard communications software that allows
with each other? 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
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
