Extending IP address range

[dibekem]

Hi guys.

 

Our school is running out of IP addresses.

Currently we have 254 IP addresses. Our server runs on Windows Server 2008.

I requested a bigger range of IP addresses from our network provider. They told me that they have changed the subnet mask from 255.255.255.0 to 255.255.254.0 and now we have 510 IP addresses providing I configure our end.

Does IpV4 supports that amount of addresses or do I have to change to IpV6?

 

I have never done this before and I just wonder how to do it.



Any help would be much appreciated.

 

 

Thanks

[pantscat]

Hi,

 

Yep - IPv4 is absolutely fine. In fact, technically, IPv4 is good for up to 16,777,214 devices, and very few organisations will be using IPv6 for internal addressing.

 

What you need to do is change your subnet mask - so... The way I'd do it is this:

 

1. Edit your DHCP scope so that the lease time is down to something like an hour (or possibly less).

2. Change the configuration of all devices with fixed IPs to the new subnet mask.

3. Create a new DHCP Scope with the appropriate subnet mask and a new larger address pool.

4. Deactivate the old scope.

5. Do an "IPconfig /release" and "IPconfig /renew" on a few machines to make sure that they're getting the new scope settings from DHCP.

6. Wait an hour for all the others to catch up...

 

Ant

[dibekem]

Thanks mate.

 

Sounds very logical I think I can do it now:)

 

Cheers

[pantscat]

No problem - feel free to shout if you need any pointers.

[TomHD]

I'm going to be doing this soon so thanks for the info pantscat

[twin--turbo]

Hold on.....

 

Servers, routers, printers, etc... anything non DHCP. Will still have a /24 subnet. It will only talk to the lower half of the range.

 

You need to sort all of these before looking at DHCP.

 

TT

[synaesthesia]

I would strongly suggest planning how many addresses you need and double it.

Say you're currently using 250 addresses but don't yet have sitewide wifi, but it's in your plans 3 years down the line. Assume you'll have a device for every pupil and every member of staff. So that could be 500 you need. In which case, look at 1000 addresses at least on a /22 subnet (255.255.252.0). It'll save worrying about it further down the line.

[pantscat]

Hold on.....

 

Servers, routers, printers, etc... anything non DHCP. Will still have a /24 subnet. It will only talk to the lower half of the range.

 

You need to sort all of these before looking at DHCP.

 

TT

 

Yep... Step 2 ought to cover that.