Faisal Shahzad wrote:
I have a question regarding vlsm subneting
i have an IP Address 150.80.0.0/16, i want to subnet it as follows
1.group of 200 subnet with 128 address each
2.group of 400 subnets with 16 address each
3.2048 subnets with 4 addrerss each
how to subnet it.
All at the same time? Or in different scenarios?
Does your 128 address requirement include network/broadcast addresses, or is it 128 distinct HOST addresses? Similar question for the 16 and 4 address subnets - do those requirements include the network/broadcast addresses, or do you need 16 (and 4) individual HOST addresses?
You can use contiguous /25 ranges starting at 150.80.0.0/25 and moving up, but each of those ranges will only give you 126 HOST addresses (plus one address for the network, and one for the broadcast). If you need 128 host addresses, your only option is to use a /24 - but then you have 254 addresses in each subnet, which wastes a lot.
If you want to do them ALL at once, and you only need 126 (and 14, and 2) hosts in each subnet, you could do something like this
150.80.0.0/25
150.80.0.128/25
150.80.1.0/25
150.80.1.128/25
and continue through
150.80.100.128/125
then you could start your next block at
150.80.101.0/28
150.80.101.16/28
150.80.101.32/28
etc through to you hit your 400 subnet requirement - which ends up being somewhere around 158.80.125.240/28
Then you start your 4 host subnet at
150.80.126.0/30 and go on until you hit your 2048 subnet limit - which would go close to running you out of addresses, but I'm not going to do any more binary math today. :-)
That way, you could have all your subnets co-exist in the same routing table without any cross over of subnets, but it'd be one *ugly* routing table unless you summarised it somewhere, especially if all the little subnets are heading off into different directions!
Cheers.
