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Computers on the Internet are connected by various networks. The complexity of
networking is addressed by dividing the Internet into many layers. The International
Organization for Standardization (ISO) developed a 7 layer network model (Application,
Presentation, Session, Transport,Network, Data Link and Physical layers) long before
the Internet has gained popularity. The 7 layer model has been revised to a 5 layer
TCP/IP based Internet Model (Application, Transport, Internet, Network, and
Physical layers).
Application Layer
Application layer defines generic available network applications or services the Internet
can support. See the table below for widely used network applications and
the corresponding network protocols.
| Application | Protocol |
|---|
| Web | HTTP |
| Email | SMTP |
| File Transfer | FTP |
Transmission Control Protocol (TCP) Layer
This layer concerns how data can be reliably transferred over the network. UDP
(User Datagram Protocol) is used when speed of data transmission is more important
than reliability.
Internet Protocol (IP) Layer
This layer handles address and routing of the network.
Local Network Access Protocol (NAP) Layer
This is the part of your system that is concerned with how you communicate with your
local network, whether is Ethernet or token ring.
Physical Layer
This is the physical connection whether using a Network Interface Card (NIC) or with
a modem to connect to the local network.
Related Topics
Network Management - five major functional areas
Classification of Computer network
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