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VLSM
19 years 5 months ago #8897
by stefke
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
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
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