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We have windows 2012 AD environment with IIS & MS SQL running on it.

Our current IP range is from 192.168.100.* with subnet mask 255.255.255.0. We are getting very close to .254 IP (Only 10-15 IP's). I am not sure about how to increase scope IP & to be ready for keep adding devices as per organisations requirement.

Can someone let me know the how do I proceed for this.

Thanks,

Sandesh

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You have 2 options:

  1. Use a bigger subnet (e.g. instead of /24 use a /23)
  2. Add another VLAN and configure the router/firewall to forward required traffic.

Solution 1: You will need to change the network mask on all machines connected on the current VLAN. Because you are using only a slice of 192.168.0.0/16, you can grow your VLAN to have a maximum of 65534 IPs. For example if you want to use a /23 instead of /24 and keep the current assigned IPs, all you need to do is to change the netmask from 255.255.255.0 to 255.255.254.0. You will have all IPs in the range 192.168.0.* and 192.168.1.* in the same VLAN. This change must be done on all hosts and on router too. If you are using DHCP it will be much easier.

Solution 2: This solution has the advantage that you can increase the security by separating the traffic of some computers from the traffic of others. You can (and, probably, should) have a firewall between the VLANs. Another advantage is that you do not need to change anything on the machines in the original VLAN. To create another VLAN you will need to have either a switch with management (that supports IEEE 802.1Q), or multiple dump switches at least one for each VLAN. In the router you will need either to have support for VLAN encapsulation (IEEE 802.1Q) or you will need an ethernet interface for each VLAN. For the new VLAN you can assign any prefix you like, that doesn't intersect with the current one. e.g 192.168.1.0/24 or smaller ones, like 192.168.1.0/25.

No mater which solution you chose, having most of the IPs configured by DHCP will help you manage IP allocation easier.

  • Thanks for your reply Mircea... I have decided to go with 2nd option here after little of research. Basically I dont want to change the subnet on all 200+ systems manually as we are using static IP's. My network consist of Windows AD environment. I am not sure that after deploying 2nd solution, how users will communicate with AD/DC server in primary network. Will this cause any issues in server-client communications in two different network scopes. – user205223 Oct 1 '15 at 12:09
  • There will be no problems in short term. The biggest problem is that you are using static IP allocation instead of DHCP. As the network grows you will have more and more problems with typos in network config spread on each device. With DHCP you can have reservations so the you can keep the same IP for servers that need this. Now is the time to switch to DHCP. And you can roll it out one machine at a time. – Mircea Vutcovici Oct 2 '15 at 11:45

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