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Difficulty: MediumOSI Model Layers and Functions

A network technician is preparing a training matrix that maps network protocols and operations to their corresponding Open Systems Interconnection (OSI) model layers. Match each OSI layer on the left with its correct operational description and primary Protocol Data Unit (PDU) on the right.

  • Physical Layer (Layer 1)Manages bit synchronization, electrical signaling, and media specifications using Bits as its PDU.
  • Data Link Layer (Layer 2)Handles physical MAC addressing, media access control, and error detection using Frames as its PDU.
  • Network Layer (Layer 3)Provides logical IP addressing and path selection (routing) across interconnected networks using Packets as its PDU.
  • Transport Layer (Layer 4)Ensures end-to-end communication, segmentation, and flow control using Segments (TCP) or Datagrams (UDP) as its PDU.

Answer

Physical Layer matches with bit synchronization/Bits; Data Link Layer matches with MAC addressing/Frames; Network Layer matches with logical routing/Packets; Transport Layer matches with end-to-end segmentation/Segments or Datagrams.
Each OSI layer has distinct responsibilities and Protocol Data Units (PDUs): Physical Layer deals with raw Bits and signaling hardware; Data Link Layer packages data into Frames using MAC addresses; Network Layer routes Packets across subnets using IP addresses; and Transport Layer manages end-to-end communication via Segments/Datagrams using port numbers.

Step-by-Step Solution

1
Identify the primary PDU and core functions of Layer 1 (Physical).
Layer 1 processes electrical, optical, or radio signals representing raw bits.
Physical Layer operates at the lowest level without reading logical or hardware addresses.
2
Identify the primary PDU and core functions of Layer 2 (Data Link).
Layer 2 organizes bits into frames containing hardware (MAC) source and destination addresses.
Data Link handles local network segment delivery and framing.
3
Identify the primary PDU and core functions of Layer 3 (Network).
Layer 3 encapsulates data into packets with logical IP headers for inter-network routing.
Network Layer handles path selection and logical boundary crossing.
4
Identify the primary PDU and core functions of Layer 4 (Transport).
Layer 4 divides application data into segments (TCP) or datagrams (UDP) with source and destination port numbers.
Transport Layer facilitates host-to-host process communication and connection control.

Key Concept

OSI Layer Functions and PDU Mappings
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Topics

OSI Model Layers and Functions

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