Computer Networks · TEE · read

Delay example 1

Essential vocabulary and maths

TEE prerequisites

Practice question. A frame contains 1000 bytes. The link rate is 2 Mbps; its length is 2,000 m and propagation speed is 200,000,000 m/s. Find transmission and one-way propagation delays. [3 practice marks]

Answer

Given

QuantityValue
Frame length1000 bytes
Rate2 Mbps
Link length2,000 m
Signal speed200,000,000 m/s

To find

The two separate delays, in seconds and microseconds.

Formula and why

T_{\mathrm{frame}}=L/RLaTeX: T_{\mathrm{frame}}=L/R
T_p=d/vLaTeX: T_p=d/v

L must be in bits and R in bits/s. Link length and signal speed must use the same distance unit.

Step-by-step solution

Step 1. Convert bytes to bits

1000 × 8 = 8,000 bits.

Step 2. Convert the rate

2 × 1,000,000 = 2,000,000 bits/s.

Step 3. Divide for transmission time

8,000 ÷ 2,000,000 = 0.004000 s = 4000 μs.

Step 4. Divide for propagation time

2,000 ÷ 200,000,000 = 0.000010 s = 10 μs.

Final answer: Transmission = 4000 μs; propagation = 10 μs.