What is the difference between Latency & Delay?

Question

I have a stringent requirement to configure a router at run time to change the route of data for set of IPs automatically not human intervention. And if it is possible then how much time it will take since there is a time constraint for the Data plane.

Answer 1

Consider in simple terms,

Suppose you are writing a letter to someone and if you take 10 minutes to write letter, 5 minutes to get it to the receiver, again ten minutes for reply to reach you

then,

time taken to write letter=overhead
time taken to reach destination once=delay
time taken to get response=latency

So in the above example
overhead=10 minutes
delay=5 minutes
latency=25 minutes