VLSM

urban30 · New Member Joined: May 31, 2005 Posts: 1

please could you tell me how i would vlsm 192.168.1.0 for 1)60 hosts 2)12 hosts 3)12hosts 4)28host.I have looked at the examples which you have given however i still do not get vlsm please could you guys help me many thanks Very Happy

stefke · Posted: Sat Jun 18, 2005 9:08 pm Post subject:

Hmm.. one of the key thing to VLMS is using none classfull subnetmasks..so based on your IP given I don't have any idea what your mask is.

For the purpose of this exercise lets presume that the mask is /24

Given:

192.168.1.0/24 --> You have 32-24=8 bits to play with

You need :

a) 60 hosts --> You need at least 6 bits (2^6=64-2=62 hosts) so you are left with 8-6= 2 bits for your subnets ---> you can create 2^2=4 subnets ==>

Subnet 1: 192.168.1.0/26
Subnet 2: 192.168.1.64/26
Subnet 3: 192.168.1.128/26
Subnet 4: 192.168.1.192/26

b) 12 hosts --> You need at least 4 bits (2^16=16-2=14 hosts) so you are left with 8-4= 4 bits for your subnets ---> you can create 2^4=16 subnets ==>

Subnet 1: 192.168.1.0/28
Subnet 2: 192.168.1.16/28
Subnet 3: 192.168.1.32/28
Subnet 4: 192.168.1.48/28
etc.. (keep adding 16 hosts in the 4th octet)

This can be done for every other nulber of hosts or subnets you need.

Hope you got the hang of it.

PS: You should google for 3COM IP subnetting document. I is a verry well explained document about subnetting and VLMS.

Greetings,

Stefan