The Session Layer

The Session Layer
Protocols that operate at the Session layer of the OSI model are responsible for establishing, maintaining, and breaking sessions, or dialogs. This is different from the connection services provided at
the Transport layer because the Session layer operates at a higher level and looks at the bigger picture— the entire conversation, not just one sentence. Many gateways operate at the Session layer.
Novell’s Service Advertisement Protocol (SAP) is a Session layer protocol, as well as NetBIOS.