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Supernetting or superscope? Need more IPs!


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#1 ubelsteiner

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Posted 22 October 2015 - 10:56 AM

Greetings! I just started working for a company that has been seeing a bit of growth over the past year, and our DHCP server is running out of IPs to assign on an almost daily basis (which I've temporarily remedied by reducing lease time). I am looking for the quickest and most painless way of increasing the number of IPs available on the network, and, through my reading, have narrowed it down to configuring a superscope or supernet.

The existing network its 192.168.2.0 /24 and my original plan was to change the subnet mask to /23 to allow for 192.168.2.1-255 and 192.168.3.1-254 IPs to be assigned through DHCP. I know that the subnet mask would need to be changed to 255.255.254.0 in the router/gateway and my DHCP, DNS and other servers. 

However, as I have been looking things over on the network, I am realizing just how many workstations, printers and other devices have statically assigned IPs. My biggest question now is: Will I have to go around to each and every device on the network with a static IP and change the subnet mask in order for these devices to still communicate on the network, or will they still be able to communicate as long as the router/servers mask have been updated and their IPs stay the same, within the original IP range? 

I was thinking that, if it is necessary to go to each and every device and update the subnet mask, that maybe creating a superscope would be an easier option. But then I am thinking that all of the servers and network printers and such would need to be able to be configured with a second IP addess?

Any help/suggestions would be most appreciated.



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#2 Wand3r3r

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Posted 22 October 2015 - 12:25 PM

Since /24 is contained within /23 you don't need to change the subnet mask on the devices assigned statically in the 192.168.2.0 subnet.

Servers, switches and other statically assigned devices should be updated to /23 so they are addressable by the entire subnet.

 

When you supernet you don't have 192.168.2.1-255 and 192.168.3.1-254  You have 192.168.2.0 to 192.168.3.255.  This is important to understand since you have different broadcast and network ids with a supernet than you do with a class c subnet.

 

You would delete the existing dhcp scope and recreate it with the supernet range.

 

There is no point in supernetting if configuring with a second subnet ip address at the nic level.



#3 ubelsteiner

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Posted 22 October 2015 - 12:57 PM

Since /24 is contained within /23 you don't need to change the subnet mask on the devices assigned statically in the 192.168.2.0 subnet.

Servers, switches and other statically assigned devices should be updated to /23 so they are addressable by the entire subnet.

 

When you supernet you don't have 192.168.2.1-255 and 192.168.3.1-254  You have 192.168.2.0 to 192.168.3.255.  This is important to understand since you have different broadcast and network ids with a supernet than you do with a class c subnet.

 

You would delete the existing dhcp scope and recreate it with the supernet range.

 

There is no point in supernetting if configuring with a second subnet ip address at the nic level.

 

Thanks a lot for the response!  Ok, so that's good that I won't need to change every static IP device on the network.  

 

So on this network, the first 50 or so IPs are reserved for static devices like the servers and printers, so the current scope is something like 192.168.2.50 - 192.168.2.254.  When I create a new scope with the 255.255.254.0, I should make the range 192.168.2.50 - 192.168.3.254 (I'm under the impression that 255 is broadcast address?)?



#4 Wand3r3r

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Posted 22 October 2015 - 01:34 PM

.0 is network id and .255 is broadcast.  You wouldn't/couldn't include those in the dhcp scope though the scope would contain 192.168.2.255 which is a legitimate host ip address given the supernet.

 

"192.168.2.50 - 192.168.3.254" is correct.



#5 ubelsteiner

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Posted 22 October 2015 - 02:36 PM

Thanks for clarify!






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