subnets and addressing

[surfer100]

I am looking for a answer to a challenge for dividing a network into several subnets for certain traffic, devices. Problem is when using a subnet calculator what i want is according to the calculator not possible, but there must be a logical solution may hope.

For example. We have a network with 192.168.0.0/16
I would like to divide this network into several subnets, let's say 10 subnets.

192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/21 -subnetmask: 255.255.248.0 divided into: 192.168.3.0/24
192.168.4.0/24
192.168.5.0/24
192.168.6.0/24
192.168.7.0/24
these devices stay all in the same vlan

192.168.8.0/24
192.168.9.0/24
etc


According to the calculator the iprange of the 192.168.3.0/21 starts with ipadres 192.168.0.0 and not 192.168.3.0 till 192.168.7.0
Is this correct must i divide the larger subnets into 192.X.X.X/21 and cannot stay in the 192.168.x.x subnet?

I need 4 /24 subnets and 5 larger subnets like more then 2046 devices but within a subnet are devices where the third number be different so i can easally see which devices are ipnumbers given
Device group a then has 192.168.2.0
devicegroup b then: 192.168.3.0
etc

Is this logical are must this be solved otherwise?

 

[JackMDS]

Technology/Science does not necessarily follows human "verbiage",. e.g 2 and 2 is not 22 it is 4

If Logical decimal is needed to please your users you need to use subnet 255.255.255.0, But if the outcome does not provide the correct network structure then you are out of luck.

https://www.aelius.com/njh/subnet_sheet.html

 

[mxnerd]

You asked the same question before.
https://forums.anandtech.com/threads/subnets.2553982/

And subnetting <> vlan, it's different thing. Please don't call subnet a vlan anymore.

use the calculator below

http://www.vlsm-calc.net/

9 subnets, 5 x 2046 devices and 4 x 254 devices = 11246 devices.

To get device numbers more than 11246 you need /18

(2^14=16384>11246, 32 bit netmask -14=18 )

so 192.168.0.0/18

You get


===

As you can see, if you use /21 notation then it means you want 2048 IP addresses. That makes 192.168.3.0 falls in between 192.168.0.1 and 192.68.7.254 and whole subnet must use /21 mask.

===

another subnet calculator that let you subdivide networks dynamically

http://www.davidc.net/sites/default/subnets/subnets.html

 

[mv2devnull]

The X in 192.168.3.X can have 256 different values. If the subnet has more devices than that, then they cannot all have 192.168.3. In other words, larger "device group a" will have more than one value in the third place. Not "easy to see", until you learn and understand.

All addresses in 192.168.0.0/16 have form 192.168.Y.X, where both X and Y have 256 possible values. The /16 subnet has thus X*Y possible addresses. 65536. Way more than you need, isn't it?

 

[Genx87]

For future reference OP. As mxnerd pointed out, VLAN does not equal subnet.

VLAN = Layer 2
Subnet = Layer 3

Important to not interchange them due to their location on the OSI model.