Eli5: How does a hotel always have hot water for every occupant?
In: 1975
Lots of answers here, which is great. But trunking efficiency has not been mentioned. There’s unit of measure called and erlang [https://en.wikipedia.org/wiki/Erlang_(unit)](https://en.wikipedia.org/wiki/Erlang_(unit)) that tries to encapsulate some this concept.
Works like this: Assume average human needs 50L of hot water per day, but that figure varies by +/- 10%. How many litres of hot water would you need for a 100 person population to have a less than 1% chance of running out?
About 5050L. Because all the + and – 5L of each of the 100 people actually smooths out. For each person who is having a heavy usage day, someone else was in the pool, or left early for their flight, etc.
An Erlang is the measure of trunking efficacy for long distance telephone (back when we didn’t have gobs and gobs of internet bandwidth to carry it all). You didn’t need 1 connection for every customer, and the more customers you had the fewer per-customer capacity you needed to plan for.
Same applies to internet bandwidth. Because not everyone’s usage at any give time period (second, minute, hour, day) is the same and it’ll all spread out.
Latest Answers