What is the total delay (latency) for a frame size of 10 million bits that is being set up on a link with 20 routers, each having a queuing time of 2 μs and a processing time of 1 μs? The length of link is 5000 km. The speed of light inside the link is $2\times10^8$ m/s. The link has bandwidth of 6 Mbps.

Transmission delay

$= \frac{\text{Frame size}}{\text{Bandwidth}}$

$= \frac{10\times10^6}{6\times10^6}$

$= 1.6667\ s$

Propagation delay

Distance $=5000\ km =5\times10^6\ m$

$= \frac{5\times10^6}{2\times10^8}$

$=0.025\ s$

Router delay

Each router delay $=2\mu s+1\mu s=3\mu s$

Total routers $=20$

Total delay $=20\times3\mu s=60\mu s=0.00006\ s$

Total latency

$=1.6667+0.025+0.00006$

$\approx1.691726\ s$