What best defines the latency budget in an optical network?

• A. The latency budget equals the sum of propagation delays
• B. The latency budget equals the sum of processing delays
• C. The latency budget equals the sum of queuing delays
• D. The latency budget equals the total permissible one-way delay across the path

Answer: (D)

Latency budget is the total permissible one-way delay across the path. It sets the maximum delay a signal can experience from source to destination to meet timing and QoS requirements. In an optical network, delays come from propagation through fiber, processing at network nodes, and any queuing in buffers. The budget must cover all these components combined, not just a single type of delay. So it isn’t merely the propagation delays, nor just the processing delays, nor just the queuing delays—the latency budget is the sum of all delays allowed along the path.