Characteristics of Layer 2 switching: which of the following are typically provided? (Hardware-based bridging using ASICs, wire-speed forwarding, low latency, and low cost)
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A1 and 3
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B2 and 4
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C1, 2 and 4
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DAll of the above
Answer
Correct Answer: All of the above
Explanation
Introduction / Context:Layer 2 switches forward frames using MAC address tables and specialized hardware. Recognizing their performance traits helps in designing cost-effective, high-throughput campus networks.
Given Data / Assumptions:
- Features listed: hardware-based bridging (ASICs), wire speed, low latency, and low cost compared to routers.
- Context: typical Ethernet switching platforms.
Concept / Approach:Switches leverage ASICs to perform lookups and forwarding at line rate, minimizing per-frame processing overhead and latency. Economies of scale make basic Layer 2 devices relatively inexpensive compared to higher-layer devices.
Step-by-Step Solution:
Hardware-based bridging → true; ASICs do L2 lookups quickly.Wire-speed → true; forwarding keeps up with interface line rates.Low latency → true; minimal processing compared to routing.Low cost → true; simpler feature set vs L3 routers.Verification / Alternative check:Vendor datasheets routinely specify wire-rate performance and microsecond-level latency for ASIC-based switches.
Why Other Options Are Wrong:Any subset excludes valid properties and is therefore incomplete.
Common Pitfalls:Assuming “wire speed” regardless of oversubscription; backplane and uplink capacities still matter.
Final Answer:All of the above