1. Definitions

<aside> 📖 Propagation Delay, $t_1$

The time it takes a single bit to travel over a link at propagation speed $c$

$$ t_l=\frac l c $$

The propagation delay is simply determined by

• how long the link is: $l$
• the speed the bit travels: $c$ </aside>

<aside> 📖 Packetization Delay, $t_p$

The time from when the first to the last bit of a packet is transmitted

$$ t_p=\frac pr $$

• The packetization delay is determined by the data-rate: how fast we can put bits onto the link
• The data-rate of a link is determined by how close together we can pack the bits </aside>

2. End-to-end Delay

The end-to-end delay is the time from when we send the first bit onto the first link, until the last bit of the packet arrives at the destination.

<aside> 📖 Expression

$$ t=\sum_i \left[ {\frac p{r_i} + \frac {l_i} c + Q_i(t)}\right] $$

• Delay of the packets in the queue $Q_i(t)$
• Everything is deterministic excepts the queueing delay </aside>