The Journey of Data: Encapsulation and De-encapsulation

If you are wondering how data is wrapped..

Data Encapsulation (Sending Side):

• Application Layer (Layer 7): Data is created (e.g., HTTP request).

• Transport Layer (Layer 4): Adds a header (TCP/UDP), creating a segment/datagram.

  • Header contains sequence numbers and port numbers

• Network Layer (Layer 3): Adds an IP header, creating a packet.

  • Header contains source/destination IP addresses.

• Data Link Layer (Layer 2): Adds a header (e.g., Ethernet) and trailer, creating a frame.

  • Header include soure/destination MAC addresses

• Physical Layer (Layer 1): Frame is converted to bits for transmission.

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Data De-encapsulation (Receiving Side):

• Physical Layer (Layer 1): Bits are received.

• Data Link Layer (Layer 2): Header and trailer are removed, revealing the packet.

• Network Layer (Layer 3): IP header is removed, revealing the segment.

• Transport Layer (Layer 4): TCP/UDP header is removed, revealing the original data.

• Application Layer (Layer 7): Data is delivered to the application.

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Things to remember:

These terms all refer to units of data transmitted over a network, but they operate at different levels of the OSI model.

• Datagram/Segment: Transport Layer (Layer 4) data units.

  Datagram: unit of data transmitted over a network, particularly in connectionless protocols like UDP

• Packet: Network Layer (Layer 3) data unit.

• Frame: Data Link Layer (Layer 2) data unit.

Mnenomic to help you remember: SPF cream → TND dynamite