DHCP Scope options for Security Devices

Jaime Campos
Jaime Campos used Ask the Experts™
on
Hello - I have a Security Device Scope set on my DHCP server.

10.201.192.20
10.201.207.254

255.255.240.0 /20

What I want to do is assign another scope within my Security Device Scope for 10 Camera, 10 Card Readers and 2 Media Servers. How would I break that scope up into other scopes for the following devices, however using the Security Device Scope?

Thanks,

nimdatx
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Commented:
Hi, are they the first and last IP addresses in your DHCP scope and subnet mask /20?
10.201.192.20
10.201.207.254

10 Cameras, 10 Card Readers and 2 Media Servers => Total is 22 devices => Need 5 bits for host portion, so that 2^5 -2  = 30 can cover 22 => there are 27 bits for network portion.

So you need to break your network with subnet mask /20 to smaller subnets which include the subnet /27

For example:
Your network: 10.201.192.0/20

Security Device Scope1: 1000 devices => subnet /22 since you need 10 bits (2^10 - 2 = 1022) to cover 1000 IP addresses

Security Device Scope2: 22 devices  => subnet /27


=> Subnet for Scope1: 10.201.192.0/22: Valid IP addresses from 10.201.192.1 to 10.201.195.254

=> Subnet for Scope2: 10.201.196.0/27: Valid IP addresses from 10.201.196.1 to 10.201.196.30  


Hope this help!
AlanConsultant

Commented:
Hi,

It looks like Spac3_Pirat3 has a solution - please confirm if so or not.

Since I am here, just for the avoidance of confusion, the actual subnet is, I would guess:

10.201.192.0 / 20

which contains:

10.201.192.0      through 10.201.207.255 inclusive

I suppose you can write:  10.201.192.20 / 20, but that still contains the same IPs as above, including 10.201.192.0 through 10.201.192.19 (inclusive) due to the way the bitmask works out.


Alan.

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