Topic: "Understanding IP Addressing" document terminology

The OpenBSD FAQ suggest reading:

http://www.3com.com/other/pdfs/infra/co … 501302.pdf

and I'm having a hard time understanding their use of 2 number in which one is in parenthesis, can you help me?

On pg. 11 they say:

"...if an organization needs nine subnets, 23 (or 8) will not provide
enough subnet addressing space, so the network administrator will
need to round up to 24 (or 16)."

23 or 8 what? 24 (or 16) looks like it would be describing alternatives for either a class A or class B network, in which 8 bits are used to extend the prefix, but that must be wrong, since I don't see how that relates to alternatives 23 or 8.

If you had network address:

172.16.0.0/16 with subnet mask 255.255.254.0

This would be a prefix length of 23, correct? So that would give me 254 subnets each with 510 hosts, I think.

What is the relationship between 23 and 8 in their example?

Re: "Understanding IP Addressing" document terminology

Doesn't make sense to me either. Not even the first number. Their entire use of numbers in that chapter is very confusing... for example, later they say [i]

Re: "Understanding IP Addressing" document terminology

Various people on the openbsd misc list pointed out that the PDF drops formatting of exponents. So, 30 (25-2) means (2^5)-2=30.

Re: "Understanding IP Addressing" document terminology

I have an old page I did on subnetting--it's MS biased, but some people have found it helpful. 

http://home.nyc.rr.com/computertaijutsu/subnet.html

(Don't ask for help with it from me though, I haven't had to subnet in a long time.)  smile

<@andre> i would be so much more efficient if i wasn't so stupid