Propagation Delay

networking

Definition

Propagation Delay

Let a link of length $d$ metres connect two nodes. Let $s$ be the propagation speed of the signal through the physical medium ($s\approx 2\cdot 10^8$ m/s for copper and fibre).

The propagation delay $d_{\text{prop}}$ is the time for a single bit to travel from the sender to the receiver:

$$d_{\text{prop}}=\frac{d}{s}$$

$d_{\text{prop}}$ depends only on distance and medium, not on packet size or link rate. It is a component of the total packet delay.