2. Physical Layer

2.4. Session Layer

5. Session Layer (Layer 5)

Function: Establishes, manages, and terminates communication sessions between applications on different devices.

Key Responsibilities:

Sets up and maintains sessions (e.g., login sessions).

Synchronizes data exchange (e.g., checkpoints for recovery).

Controls dialogue modes (e.g., full-duplex, half-duplex).

Examples:

Protocols: NetBIOS, Remote Procedure Call (RPC), Server Message Block (SMB).

Technologies: Session Initiation Protocol (SIP) for VoIP, session management in web applications.

Example: Maintaining a user’s session during an online banking transaction.

Analogy: A phone call coordinator, initiating the call, keeping it active, and ending it when complete.