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Review Questions – Lecture 9–10: ATM

1. Difference Between Circuit Switching and Packet Switching

Concept:

• Circuit Switching: A dedicated path is established before
  transmission begins and remains reserved throughout the session.
• Packet Switching: Data is divided into packets, and each packet
  may take a different path to the destination.

Examples:

• Circuit Switching: Traditional telephone systems
• Packet Switching: The Internet

Advantages of Circuit Switching:

• Guaranteed bandwidth
• Low latency
• Predictable performance
• Ideal for real-time communication (voice/video)

Disadvantages of Circuit Switching:

• Inefficient use of bandwidth when idle
• Limited scalability (finite circuits)
• High cost due to dedicated resources

Advantages of Packet Switching:

• Efficient bandwidth usage (shared among users)
• Flexible in handling different data rates and sizes
• Scalable for large networks
• Lower cost due to shared infrastructure

Disadvantages of Packet Switching:

• Higher latency due to routing
• Packet loss possible in congestion
• Limited QoS guarantees
• Not suitable for real-time services

2. Technology of Multiplexing

Definition:
Multiplexing (muxing) combines multiple signals or data streams into
one signal over a shared communication medium. At the destination,
demultiplexing (demuxing) splits the combined signal into its original
streams.

Applications:

• Analog/digital communications
• Radio, television, telephone
• Wide area networks (WANs)
• ATM networks

ATM Usage:
ATM uses asynchronous time-division multiplexing (TDM) to fill
slots with cells from active input channels. If no cell is ready, the
slot remains empty.

3. Why ATM is Referred to as Fast Packet Switching

ATM combines the best aspects of circuit and packet switching. It uses
small, fixed-size cells (53 bytes) to enable fast, hardware-based
switching. This design allows low latency like circuit switching, with
the flexibility and efficiency of packet switching.

Key reasons:

• High-speed performance
• Small fixed-size cells enable fast processing
• Efficient resource usage via statistical multiplexing

4. ATM: Transfer Mode, Cell-Based Transfer, Asynchronous Transfer

Transfer Mode:
ATM handles data in a transfer mode using fixed-size units (cells)
instead of variable-size packets or continuous streams.

Cell-Based Transfer:
Each cell in ATM is 53 bytes (5 bytes header + 48 bytes payload). The
header contains routing info, and the payload carries the actual data.
All types of data are segmented into cells for uniform handling.

Asynchronous Transfer:
Unlike synchronous systems, ATM sends cells only when data is
available. This avoids wasting bandwidth on empty slots and improves
efficiency. Timing is derived from the data, not from fixed intervals.

continue:./study_admin_l8_network_tools.md
before:./study_admin_l6_cmip.md