[Lugro-mesh] Repeat MAC-Address and the birthday paradox.

[Horacio Castellini]

What is the occurrence probability of "r"  MAC-Adress twon agree on their last two bytes?

This is similar to the birthday paradox: At a meeting of r> 2 people which is the number of people needed for the probability that two men have same birthday sould be 99%? The solution is in many books and that can view at:

http://en.wikipedia.org/wiki/Birthday_problem

Then, At a meeting of 60 people there is the 99% probability  of the least two men have a  birthday the same day. So,, Similarly to the case of MAC-Adress is:

P(r)=1-65536!/(65536^r * (65536-r)!) 

where *! is factorial operator, and "r" is the Mac-Adress.

Well if the calculations are not mistake, we obtain r = 13,107 MAC-Adress minimun in the same site then 99% probability two matches in his last two bytes.

Now a new MAC entering, which is the probability that given "n" MAC-Adress,,, all with two last byte differents this new MAC  matches with any MAC-Adress in its last two bytes? Well this is:

P(n)=1-(65535/65536)^n  then when n=13107 is  P(13107)=0.18 or 18%. That is MAC-paradox...

 		 	   		  
_________________________________________________________________
Volvé famosa a tu mascota con MSN
http://events.latam.msn.com/tumascota