Definition - What does Layer 7 mean?
Layer 7 refers to the seventh and topmost layer of the Open Systems Interconnect (OSI) Model known as the application layer. This is the highest layer which supports end-user processes and applications. Layer 7 identifies the communicating parties and the quality of service between them, considers privacy and user authentication, as well as identifies any constraints on the data syntax. This layer is wholly application-specific.
Techopedia explains Layer 7
In the OSI model’s application layer, as opposed to the Internet model, is narrow in scope and defines it as interacting directly with the application which is responsible for displaying images and data to the user as a human-recognizable format in order to allow the user to interface with the layer below it, which is the presentation layer. This layer interacts with software applications which implement a communication component.
Application layer functions include the identification of communication partners, determining resource availability and quality and then synchronizing the communication between the partners. In determining partners the layer identifies the identities and availability of the communicators and then it determines whether there are sufficient resources or if the selected communication method exists. When the communication has been established, the layer synchronizes this through cooperation of the communicating partners.
Application layer implementations on OSI stack:
- Common Management Information Protocol (CMIP)
- X.400 Mail
- File Transfer and Access Management Protocol (FTAM)
Application layer implementation on TCP/IP stack:
- Hypertext Transfer Protocol (HTTP)
- File Transfer Protocol (FTP)
- Simple Network Management Protocol (SNMP)
- Simple Mail Transfer Protocol (SMTP)