**Question: What is the total delay (latency) for a frame of size 5 million bits that is being sent on a link with 10 routers each having a queuing time of 2 μs and a processing time of 1 μs. The length of the link is 2000 Km. The speed of light inside the link is 2 × 108 m/s. The link has a bandwidth of 5 Mbps. Which component of the total delay is dominant? Which one is negligible?**

**Solution: **

Given data:

Distance (length of the link) =2000 Km

=2000

^{3}m

Propagation speed=2

^{8}m/s

Frame size=5million bits

=5000000bits

The Bandwidth=5Mbps

=5

^{6}bps (1Mbps=10

^{6}bps)

Queuing time=10

=20

Processing delay=10

=10

**Total delay (Latency) = Propagation time + Transmission time + Queuing time**

**+ Processing delay.**

Propagation time=

=

= 0.01s

**Therefore, Propagation time=0.01s**

Transmission time=

=

= 1s

**Therefore, Transmission time=1s**

Queuing time=10

=10

^{-6}s (1

^{-6}s)

=20

^{-6}s

= 0.00002s

**Therefore, Queuing time=0.00002s**

Processing delay=10

=10

^{-6}s (1

^{-6}s)

**Therefore, Processing delay=0.000010s**

Therefore, Total delay (Latency) =0.01+1+0.000020+0.000010

=1.01003s