What is Layer 7 of the OSI Model?

Layer 7 of the OSI Model Allows Application-Layer Load Balancing

Layer 7 of the OSI model, or the application layer, supports communications for end-user processes and applications, and the presentation of data for user-facing software applications. As the highest layer of the OSI model, and the closest to the end user, layer 7 provides application-specific functions such as identifying communication partners and the quality of service between them, determining resource availability, considering privacy and user authentication, and synchronizing communication, as well as connecting the application to the lower levels of the OSI model.

Layer 7 provides application services for network software services based on level 7 protocols such as HTTP and SMTP, including file transfers, email, web browsing, and top-level API calls and responses.

Interacting directly with software applications, layer 7 has full visibility into network data, allowing an intelligent approach to level 7 load balancing. A layer 7 load balancer terminates network traffic, performs TLS/SSL decryption as needed, inspects messages, makes routing decisions based on its content, initiates a new TCP connection to the appropriate upstream server, and writes the request to the server.

As a result, layer 7 load balancing can consider the actual content of each message to ensure the best experience for any user, device, and location, while meeting requirements for compliance, content localization, and efficiency. For example, a layer 7 load balancer can use the language indicated in a browser header to redirect visitors to the appropriate content version or identify the backend server pool best able to process a given type of content.

How A10 Networks Supports Layer 7 Load Balancing

Layer 7 load balancing uses traffic visibility and application awareness to enable intelligent routing decisions, optimizations, and performance enhancement. The A10 Networks Thunder® Application Delivery Controller (ADC) provides advanced layer 7 load balancing to ensure high availability and business continuity for application services.