NCERT Computer: Chapter 6 – Fundamentals of Internet and Java Programming Part 4
Gateway Access is also known as Level-One connection.
The gateway allows the two different types of networks to "talk" to each other.
The local Internet Service Provider (ISP) normally defines this limitation.
Good example of network with Level One Connectivity within India is that of VSNL (Videsh Sanchar Nigam Limited).
‘Dial-up’ connection is also known as Level Two connection. This provides connection to Internet through a dial-up terminal connection.
The computer, which provides Internet access, is known as 'Host' and the computer that receives the access, is ‘Client’ or ‘Terminal’.
In dial-up connection to Internet, Host carries all the command that are types on a client machine and forwards them to Internet.
It also receives the data or information from the Internet on behalf of the 'Client' and passes it to them.
The client computer acted as a 'dumb' terminal connected to remote host.
This type of connection can further be divided into two categories.
(1) Shell Connection
In this type of Internet connection, the user will get only textual matter of a Web Page.
This connection does not support Graphics display. However the user will be able to surf the Internet, do FTP, receive mail.
(2) TCP/IP Connection
Today's graphical World Wide Web browser provides easier access with multimedia sound and pictures. The major difference between Shell and TCP/ IP account is that shell can only display text and does not support graphics display, whereas TCP/IP can display both.
Hence TCP/IP is more popular Internet connection. Shell accounts are slowly phasing out from the Internet scenario.
To access any of these dial-up accounts you need the followings;
Shell or TCP/IP account from the ISP
Internet client software such as Internet browser
Leased connection is also known as direct Internet access or Level Three connection. It is the secured, dedicated and most expensive, level of Internet connection.
Leased Internet connections are limited to large corporations and universities who could afford the cost.