subnetting

[carl_townshend]

Hi all, is there a quick and easy way to remember subnetting, ie, /26 etc

[JORGE RODRIGUEZ]

Easy and quick way may varied from people to people, there are few short cut methods out there. Go over this link which I think is the easiest way .

http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_9-1/ip_addresses.html

Rgds

Jorge

[frank.murray]

the way that works for me is this:

if you label the value of each bit position in a byte you get:

128 64 32 16 8 4 2 1

You have to commit this to memory.

Now for each bit over the classful boundry (8,16,24) you place the bit over the bit value. so for the /26, you're two bits over the classful 24:

1 1

128 64 32 16 8 4 2 1

this tells you that the subnet has a range of 64 addresses. If you had a /27 you would place an additional 1 over the 32 place:

1 1 1

128 64 32 16 8 4 2 1

this tells you a /27 is a 32 address range.