Almost at 255 IP addresses.

[jjjax0330]

Hi, we started out as a pretty small network but as things grew and grew, we find that we are approaching the 255 ip addresses that are available on our one subnet. We are currently using a range of addresses from 192.1.1.1 to 192.1.1.255 with a subnet mast of 255.255.255.0. I'm a little confused on this matter so if anyone can help with some simple step by step instructions. Thanks, Joe

 

[codered10]

What you can do is change your subnet to allow more address. For example, if you changed the subnet mask on each machine to 255.255.0.0, you could then use any IP address beginning with 192.1.x.x

Thanks a ton,
codered10

 

[trusted]

In a class C subnet there are a total of 256 address , but only 254 are usable. Let's look at the subnet the you are using.

192.1.1.0 is used for network identification.
192.1.1.1 - 192.1.1.254 can be assigned to clients (nodes)
192.1.1.255 is used for network broadcasts

Since you are using a public range of IP addresses you have two choices.

1.Try to lease an additional range of public IP addresses then create two routed subnets. This could be costly.

2. Switch to one of the private IP address ranges and use SNAT for access to the internet. The private ranges are as follows.

Class C 192.168.0.0 - 192.168.255.255
Class B 172.16.0.0 - 172.31.255.255
Class A 10.0.0.0 - 10.255.255.255

If you switched to the Class B private range of 172.16.0.0 - 172.16.255.255 it would give you a total of 65,536 IP addresses with 65,534 usable. 172.16.0.0 would be used for network ID and 172.16.255.255 would be used for broadcasts.

If you went with the Class A private you would have a total of 16,777,216 IP address's.

If you are using DHCP you could transistion to either class with relative ease. Your would have to either statically assign IP addresses to all of your servers or use DHCP resevations to accomplish the same thing. For your workstations you could create a group policy startup script that would run a simple batch job to release the old IP address's and then renew them with the new range. Then just have the users reboot there systems and they should all be assigned addresses from the new range.

All the batch job would have to contain would be the following lines.

ipconfig /release
ipconfig /renew

 

[Seaspray0]

Go with the class B private range 172.16.x.x and don't expect to get to the internet with a "home" router. If you don't already have a commercial router, get one.



A+/MCP/MCSE/MCDBA

 

[jjjax0330]

So, not matter what we do, we will still have to go to every device and change their ip information. Is there any downside to the first reply about just changing out subnet mask?

 

[codered10]

Yes...I misread your first message and didn't notice you were using a public IP address range

The other addresses I mentioned in the first post are likely assigned to someone else already, and would not work.

You are going to need to either lease more address or follow the advice given in the later posts.

Thanks a ton,
codered10

 

[jjjax0330]

Even though they are technically a public IP address range, they aren't really leased or used publicly. They are only used internally so couldn't we use the as if they were private or is that something that windows itself won't allow? Thanks.

 

[codered10]

If your network is connected to the internet you will run into problems. The new addresses you would use would not be routed to your network which would prevent you from doing anything on the internet. You are going to have to bite the bullet and switch to a private IP range and begin using NAT.

Thanks a ton,
codered10

 

[trusted]

Not to mention if you start using address's that are already leased to somebody you would be exposing your company to a possible lawsuit.

You setup a linux SNAT box on an extra system for a very reasonable rate and you could use the 172.16.0.0 range.

 

[ADB100]

Why not just buy a Layer-3 switch and introduce some more IP networks?

Andy