Which statements correctly describe packet switching in data networks?
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ASubdividing information into individually addressed packets and allowing alternate routing enables paths to change during congestion or link failure
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BIntelligence within the network enables sophisticated error control and link control procedures
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CUsing wide-bandwidth trunk circuits allows substantial economies via shared capacity
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DAll of the above
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ENone of the above
Answer
Correct Answer: All of the above
Explanation
Introduction / Context:Packet switching is the foundation of modern networks (e.g., the Internet). It segments data into packets and forwards them independently, exploiting statistical multiplexing and adaptive routing to improve efficiency and resilience.
Given Data / Assumptions:
- Networks support addressing of packets to their destinations.
- Routers/switches make per-packet forwarding decisions.
- Trunk links can carry many flows simultaneously.
Concept / Approach:
Three key advantages: (1) alternate routing around failures/congestion, (2) in-network control for reliability and flow management, and (3) cost efficiency by sharing high-capacity trunks among many bursty sources (statistical multiplexing).
Step-by-Step Solution:
Evaluate statement (a): Packets can follow different paths; dynamic routing adapts to faults/congestion ⇒ True.Evaluate statement (b): Network nodes implement error checks, retransmissions (on some links), and link management ⇒ True in many packet networks.Evaluate statement (c): Sharing wide trunks among many users increases utilization and reduces cost per bit ⇒ True.If (a), (b), and (c) are all true, choose 'All of the above.'Verification / Alternative check:
Operational Internet behavior (e.g., BGP/IGP reroutes, per-hop CRC/ECN/QoS, and statistical multiplexing on backbone links) exemplifies all three benefits.
Why Other Options Are Wrong:
Each individual statement is correct; picking only one would ignore the comprehensive nature of packet switching.
None of the above: False because all three are valid.
Common Pitfalls:
Confusing packet switching with circuit switching, which uses fixed dedicated paths and lacks per-packet routing flexibility.
Final Answer:
All of the above