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Difficulty: HardOSI Model Layers and Functions

A network host receives an incoming Ethernet frame containing formatted user data over a wired connection. Arrange the following OSI layer processing actions in the correct chronological order from first (earliest) to last (latest) as decapsulation takes place on the receiving host.

  1. 1Bit synchronization occurs, and incoming physical signals are converted into a binary bit stream.
  2. 2The Frame Check Sequence (FCS) is verified for transmission errors, and the destination MAC address is validated.
  3. 3The destination IP address is evaluated, and packet fragmentation headers are processed.
  4. 4Segment checksums are calculated, sequence numbers are aligned, and the target port number is identified.
  5. 5Payload data is decrypted, uncompressed, and converted into the character encoding required by the destination service.

Answer

The correct sequence of decapsulation actions from first to last is: 1) Bit synchronization and signal conversion at the Physical layer, 2) FCS error verification and MAC validation at the Data Link layer, 3) Destination IP evaluation and fragmentation reassembly at the Network layer, 4) Segment checksum calculation and destination port identification at the Transport layer, and 5) Payload decryption and syntax formatting at the Presentation layer.
During decapsulation on a receiving host, data moves bottom-up through the OSI model layers. First, physical signals are converted to bits at the Physical layer. Next, the Data Link layer validates the MAC address and frame checksum (FCS). Then, the Network layer processes IP headers and routing/fragmentation parameters. Following this, the Transport layer processes TCP/UDP checksums, sequence tracking, and destination ports. Finally, the Presentation layer decrypts and formats the data syntax before passing it upward.

Step-by-Step Solution

1
Identify the initial physical reception of network media signals.
The network interface receives physical signals and converts them into raw binary data at the Physical layer (Layer 1).
All incoming network communication enters the host stack starting at the lowest physical boundary.
2
Process node-to-node framing and link integrity.
The Data Link layer (Layer 2) validates the Frame Check Sequence (FCS) to confirm frame integrity and checks the destination MAC address.
A frame must be verified for hardware addressing and error-free transmission before stripping the Layer 2 header.
3
Process logical network addressing.
The Network layer (Layer 3) evaluates the IP packet header, validates the destination IP, and handles IP-level fragmentation.
Logical end-to-end addressing must be verified after link-layer decapsulation.
4
Process process-to-process transport control and multiplexing.
The Transport layer (Layer 4) evaluates segment headers, checks integrity via port checksums, and routes the data to the appropriate destination port.
Transport protocol processing identifies the recipient application process.
5
Format payload syntax and representation.
The Presentation layer (Layer 6) performs data decryption, decompression, and character set translation.
Data syntax transformation ensures the application receives data in a readable standard format.

Key Concept

OSI Layer Decapsulation Sequence and Functional Responsibilities
Estimated Time:2m 0s
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Topics

OSI Model Layers and Functions

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