Layer 5 (Session)

Conversation that is kept session from the tohers, it’s a 1 on 1 conversation b

Sesson Layer - keeps conversaitons separate to prevent intermingling of data.

Set up : Checking of user credentials and assisngn gnumbers to assign to the session to help identify them.

maintain : where data is transfered back and forth across the network.

Transfer data, reestablish connetion if lost

acknowledge recipt of data.

tear down Session - ending of a session after transfer id done or when the other party disconnects.

Layer 5 examples:

h.323 - used to set up maintain and tear down video and voice calls.

RTP- Real time transport protocol streaming audio/video (phone call or FaceTime Session)

Netbios- used to share fieles over a network. You see it a lot on networks.

🔐 Layer 5 – Session Layer (OSI Model)

Purpose: Manages and maintains individual sessions between applications.

Key Role: Keeps multiple conversations separate and organized.

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✅ Core Functions

| Phase | Description | | --- | --- | | Set up | Authenticates user credentials and assigns a unique session ID | | Maintain | Transfers data and can reestablish connection if interrupted | | Teardown | Gracefully ends the session when communication is complete |

🧠 Think: a private 1-on-1 phone call kept separate from other calls.

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🎯 Key Responsibilities

• Session establishment, maintenance, and termination
• Prevents data intermingling between multiple conversations
• Can resume sessions after brief interruptions
• Coordinates dialog control (half-duplex vs full-duplex communication)

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🔌 Common Protocols at Layer 5

| Protocol | Use Case | | --- | --- | | H.323 | Sets up, maintains, and tears down voice/video calls | | RTP | Streams audio/video in real time (used in VoIP, video conferencing) | | NetBIOS | Allows file/printer sharing over a LAN (common in Windows networks) |

💡 NetBIOS bridges communication between apps on separate machines.

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🧠 Memory Trick

"Session = Separation"

Layer 5 ensures every chat, stream, or connection stays isolated.

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⚡ Rapid Review Questions

1. What does the session layer prevent?

   → Intermingling of conversations

2. What protocol sets up VoIP sessions?

   → H.323

3. Which layer reestablishes a connection if it drops mid-transfer?

   → Session Layer (5)

4. Which protocol helps with Windows file sharing?

   → NetBIOS

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💡 Exam Tip:

If the question is about setting up, maintaining, or ending communication sessions, it's Layer 5 — not the Transport Layer (which handles segmentation and delivery).

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