Thursday, October 22, 2009

Easy Way to Wildcard counting

If you are a network engineer and deal a lot with Cisco router configuration, this short post might help you, I hope :)

wildcard = host - 1
host = 2^(32-prefix)

For example:
/28 --> prefix 28
host = 2^(32-28)
host = 2^4
host = 16

wildcard = 16 - 1
wildcard = 15

So wildcard masking for: 172.30.16.0/28 --> 172.30.16.0  0.0.0.15

No comments:

Post a Comment

Hi, for all of those who already put comments on my blog post, thanks.. really appreciate it. And for those who have not, just put your comments here :)