In TCP/IP, the application layer contains all protocols and methods that fall into the realm of process-to-process communications across an Internet Protocol (IP) network. Application layer methods use the underlying transport layer protocols to establish host-to-host connections.
The Internet protocol suite (TCP/IP) and the Open Systems Interconnection model (OSI model) of computer networking each specify a group of protocols and methods identified by the name application layer.
In the OSI model, the definition of its application layer is narrower in scope, explicitly distinguishing additional functionality above the transport layer at two additional levels, the session layer and the presentation layer. OSI specifies strict modular separation of functionality at these layers and provides protocol implementations for each layer.
| Internet protocols |
|---|
| Application layer |
|
| Transport layer |
|
| Routing protocols * |
|
| Internet layer |
|
| Link layer |
|
| * Not a layer. A routing protocol belongs either to application or network layer. |
| The OSI model |
|---|
| 7 Application layer |
| 6 Presentation layer |
| 5 Session layer |
| 4 Transport layer |
| 3 Network layer |
| 2 Data link layer |
|
| 1 Physical layer |
Read more about Application Layer: TCP/IP Protocols, Other Protocol Examples
Famous quotes containing the words application and/or layer:
“The human mind is capable of excitement without the application of gross and violent stimulants; and he must have a very faint perception of its beauty and dignity who does not know this.”
—William Wordsworth (1770–1850)
“This world is run by people who know how to do things. They know how things work. They are equipped. Up there, there’s a layer of people who run everything. But we—we’re just peasants. We don’t understand what’s going on, and we can’t do anything.”
—Doris Lessing (b. 1919)