Expand Network with IP Address and subnet Mask

Hi, I want to upgrade my network, I am using - and subnet I have already used all my IP addresses. Now I want add another 100-200 Systems without major changes.
My Network Details #
Windows 2003 Standard Edition Sp2 PDC and Two BDC
Having three floor so for fast login I am using BDC in every floor.
PDC has two NIC - one for sttaic another for LAN.
one gateway , one mail server and one proxy server

Can you please Advise me for best possible solution as per my exixting network ?
Who is Participating?
Ron MalmsteadConnect With a Mentor Information Services ManagerCommented:
Best practice is to do it on a weekend for sure !.., but just so we're clear,...you only need to change the subnet mask not the IP addresses.....  Changing the mask will simply allow you to assign IP's in the 192.168.11.xxx range ...and all machines in 10.xxx and 11.xxx can still "talk" to each other without the need for any internal routing.
Ron MalmsteadInformation Services ManagerCommented:
Changing the subnet mask to give you addresses -

You will need to modify your DHCP scope to reflect the change, and any servers or devices that have static network configurations will need to be changed manually.

If you have a firewall or routers, you will need to make changes there as well.
Any other IP configured information on any device / server / applications...for example .... subnet relay rules on your e-mail server would need to have the subnet entry changed as well.

Do you have a network diagram ?
soumenbAuthor Commented:
I really appriciated for quick reply,
I am not using any DHCP server in Network.
I have few static ip servers and i am using one static ip for Windows PDC server and for internet,
PDC has two NIC card one for INTERNET and another for LAN. We have three floor all switches(UnMangaed) are connected through 1GB Uplink.

No hardware firewall using only ISA 2004 (Microsoft ISA server)
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Ron MalmsteadInformation Services ManagerCommented:
Then it looks like it's just a matter of changing your subnet mask to allow for more hosts.
You will need to change the mask on the internal network NIC on your PDC.

ISA firewall rules that include internal subnet information will need to be changed as well.

This should be relatively hassle free for you.
Ron MalmsteadInformation Services ManagerCommented:
Why don't you use DHCP ?....it's going to take a long time to change it on every client machine manually.
soumenbAuthor Commented:
Hi, I was thinking for same, But We have few machines for client access are using through ISA firewall web publishing, So I can't chnage heir Ips for now . I have to do it on weekend so I want to finish it Asap.

Thanks, Your answer seems to be solved my problem. Tomorrow, I will change the Ips and check. Once solved I will assign point.

Thanks a Lot.
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