Lectures notes for 2010 - KTH

Growth rates
n = number of users
Sarnoff’s Law: value of a broadcast network µ∝ (n)
• purely linear growth in the number of “viewers”
Metcalfe’s Law: value of a communication network ∝ n*(n-1) ≅ (n) 2
• represents the possibility of each user to choose who they want to communicate with
Briscoe, Odlyzko, and Tilly propose[7]: value of a network ∝n log(n)
• they claim this is a better guide for investors and developers
• less than quadratic, but it is still far greater growth than linear!
Reed’s Law: value of a network ∝2 n
• in networks that enable groups to form, the value goes up with the number of groups which
can form {This is why social networks can be very important to networking.}
So if Briscoe, Odlyzko, and Tilly are correct that “Metcalf’s Law is wrong”[7] -
then what is the growth law which is relevant to you?
Maguire Growth rates 13: 10 of 91
maguire@kth.se 2010.03.21 Internetworking/Internetteknik