Running out of IP addresses on LAN

By iderek ·
I have one subnet of which is very close to running out of available addresses. I am using Server 2003 as a DHCP server and all devices are currently on that subnet. My servers/printers/network devices are statically set within this subnet from to, and my dynamic clients are just being dished out from a DHCP scope from to

I have read somewhat about creating "superscopes" in DHCP and also I have read about just using subnetting to get the job done. For example, to create a new scope in the DHCP server from to with a mask of to give me a total of 510 addresses, but won't that pose a problem with the two subnets communicating with each other?

Basically I just need more addresses and I need all of the addresses to be able to communicate back and forth without any hickups or problems. Any ideas and suggestions are appreciated.

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by guaitaku In reply to Running out of IP address ...

First of all, I assume that you can't change the network type to a A or B network, this will be the cleanest way.

Changing creating a new scope from another mask probably drives you to more problems, because the static devices will be using the old mask.

Finally, if the DHCP server is also the gateway you can make another network and route betwen them, unortunately this will create a botleneck if the static devices make a lot of traffic with the clients.

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so you have 108 servers,printers, other network devices

by CG IT In reply to Running out of IP address ...

that are static addressed plus, you have 136 devices that get dynamic addresses?

Can't imagine why someone would have used the Class C if you had anywhere near that many hosts that needed to be on the same subnet.

But you can solve this by breaking up your one big broadcast domain into 2 or 3 smaller broadcast domains and still have resources on each subnet available to the other.

If you want to try out what NickNielsen and stress junkie said in that post [see here].;results

try it out... personally, I think I would opt to breakup the broadcast domain into a couple of smaller ones using Class B addressing.

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Okay so let me verify with you guys

by iderek In reply to so you have 108 servers,p ...

So my scope on my server 2003 DHCP server is currently just set to with a mask of

So if I delete that scope and re-create it as and a mask of then I will have 508 addresses of which all will be able to communicate back and forth with no problems?

So it should be this when I am finished: through with a broadcast address of

If this is the case, is there anything else I would need to adjust to make all the addresses communicate with each other back and forth?

Thanks in advance everbody,

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you will just need

by BizIntelligence In reply to Okay so let me verify wit ...

to change your subnet mask on servers or any device which is using static IP to match new subnet....
rest all clients are dhcp so they dont need to do anything ...they will acquire new IPs and subnet masks.
give a restart to your switches, machines and router after change..

hopefully it will work

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Sounds good, one more thing though...

by iderek In reply to you will just need

Just out of curiosity, since I have never setup a scope with a subnet mask like this, will the DHCP server hand out all the 2.x addresses first until it has depleted them AND THEN start handing out the 3.x addresses? Or will it just hand out 2.x and 3.x addresses right from the get-go?

And also, just to double verify, there won't be any problems with communication (file sharing, etc) from the 2.x addresses to the 3.x addresses and vica versa, correct?

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by Brenton Keegan In reply to Running out of IP address ...

You really need to break it down to binary to understand it.
A subnet mask determines which part of the IP address is the "Network" and which is the "client". The most common is In binary this is 1111111.1111111.1111111.0000000
1s = network address, 0s = client address. is 1111111.111111.11111110.000000
So yes will allow you to have a assignable addresses from 0.1 to 1.254 (note: not 2.1 to 3.245) This is because 2 in binary is 00000010 and 3 is 00000011. Remember whatever is a 1 in the subnet mask defines the network address, not client.

Honestly it sounds like you're network design isn't optimal. Instead of doing all this crap I'd suggest just breaking up it up into different networks. have Server LAN, Workstation LAN, Printer LAN etc. This way you can have more regarding the traffic between the networks. It will allow you to create a more stable and secure environment.

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