Methods of Accessing the Internet

by Gary Cleveland

Network News #2
ISSN 1201-4338
Information Technology Services
National Library of Canada
October 1994

There are a number of ways to connect to the Internet, ranging from full dedicated connections to dial-up services. This backgrounder describes three of the most common methods of gaining access to the Internet---the dedicated connection, SLIP or PPP connections, and dial-up terminal access.

The dedicated connection

The dedicated connection is the traditional and most common method of accessing the Internet. It involves establishing a permanent link between a local network and the rest of the TCP/IP Internet. In a dedicated connection, all mainframes, minicomputers and microcomputers on the local network are part of the Internet with their own individual Internet addresses.

Technically, a dedicated connection is most commonly comprised of three basic elements:

a leased line, which is a permanently open switched circuit that provides point-to-point-or machine to machine-telecommunications
a router, which is a computer that is responsible for directing data, or "packets", to their proper destination-essentially a "gateway" between two networks
and TCP/IP software. TCP/IP, of course, is the set of protocols that underlie communications on the Internet.

To create a dedicated connection, a router is placed on a local network and TCP/IP software is loaded on LAN-connected computers. The router is then connected via a leased line to another site's router that is already part of the Internet. Thus, data can travel from a workstation on the local network, through the local router, to other routers in the network, from network to network throughout the Internet, until it reaches its final destination.

The dedicated connection has the greatest functionality and flexibility of all connectivity options. A dedicated Internet connection provides:

the ability to connect a large number of users and subnetworks
unrestricted 24 hour, seven day a week access
unlimited use of Internet information resources and network services (e.g., email, discussion lists, TELNET, FTP, WAIS, gopher, IRC, USENET news, and WWW/Mosaic) without additional time- or volume-sensitive charges
the ability to set up local information services, such as online databases, anonymous FTP, WWW, WAIS and Gopher servers. These services can be made continuously available to the Internet community.

The enhanced functionality and flexibility of a dedicated connection, however, comes at a cost. This method requires the largest commitments in time, equipment, funding, and technical support. The exact cost of a dedicated connection for a particular institution is dependent upon a number of factors, such as the service provider, line speeds, distance from the nearest network point of presence, equipment, and membership or connection fees. These costs can easily add up to thousands of dollars per year.

SLIP/PPP

A step down from a dedicated leased lined connection-both monetarily and technically-is an SLIP/PPP connection. SLIP (Serial Line Internet Protocol), and the newer PPP (Point- to-Point Protocol) are protocols that support TCP/IP connections over standard telephone lines. Like a dedicated connection, SLIP/PPP allows the user's computer to be part of the Internet-but only for the duration of the telephone call. Generally, there are two uses of SLIP/PPP connections. One is "individual" SLIP/PPP where an individual shares access to a limited bank of modems with many other people. This form of connection is low-cost, and is designed to allow individual users to connect directly to the Internet on an causal, intermittent basis. The other is a form of "dedicated" connection, where a modem at a service provider is reserved for the exclusive use of one client, and where the telephone connection is up all, or most of, the time. This form of "dedicated" SLIP/PPP provides some of the benefits of a leased line connection, but at a lower cost. Note, however, that SLIP/PPP is considerably slower than a connection based on leased line. While a SLIP/PPP connection is not as complex as setting up and maintaining a dedicated connection, it still requires some technical proficiency. This is changing, at least for individual SLIP/PPP, with the introduction of software packages that do the setup automatically (e.g., Internet in a Box).

Because SLIP/PPP makes a computer actually part of the Internet, all Internet services can be used. As with a lease line dedicated connection, users must mount the software to support Internet services on their machines themselves, such as software for TELNET, FTP, Gopher, and WWW clients like Mosaic. Also like leased line, "dedicated" connections based on SLIP/PPP can be used to support inhouse information services (e.g., a WWW server). This is not true of individual SLIP/PPP connections because the user's machine would only be part of the Internet for short, intermittent periods.

SLIP/PPP connections require a computer, a telephone line, a high-speed modem, SLIP or PPP software, and TCP/IP software. Also needed is an account with a service provider who provides SLIP or PPP connections.

Dial-up terminal access

The least technical and most economical method of obtaining access to the Internet is to login as a terminal to a computer that is a dedicated Internet node. Users dial-up an Internet host, login with a password, and use the TCP/IP software on that remote machine. The user's local machine is not part of the Internet, but simply acts as a terminal of the remote host. For this method of access, all that is required is a computer, modem, a standard communications package (e.g., ProComm), and an account on an Internet- connected host.

While this method has the advantages of simplicity and low- cost, there are limitations. First of all, only a sub-set of all Internet services may be available, depending on those the particular service provider chooses to mount on its Internet host machine. Second, users will likely be limited in the amount of disk space they can use to store email and FTPed files (excess files, of course, can be subsequently downloaded to the user's own machine using a standard telecommunications package). Finally, it will not support inhouse information services-since the local machine is not part of the Internet, it is impossible for other people on the Internet to access it.

A version of this paper entitled "Methods of Accessing the Internet" was first published in Liaison, March/April 1994, Number 83, p. 5-6.