Change DHCP Scope

[LeMarchand]

So, we're running out of IP Addresses, even after setting a 2hr lease. The only way we can get more (we're an LA school) is a totally new scope.

 

I think I'm OK with that, but what do I do about setting our (sole) Hyper V host + the various clients up? Do I just log in and assign them appropriate addresses that are part of the new scope and replicate (with new details) the settings in the current scope? (Well, more or less - stuff is scattered all over the place, so I'm hoping to tidy up and keep the first 50 or so addresses for servers and "non-user" devices).

[slugshead]

Wouldn't this be a great opportunity to isolate your network entirely from the LA ranges and switch to 172.x.x.x internally

 

Have a range for servers, a range for cctv, a range for switches, 10 ranges to cover byod, 10 ranges for PCs.. you catch my drift. Makes it nice then seeing an IP in a log and knowing where it came from instantly...

 

172.1.1.43 is downloading stuff. Oh that's one of the servers

 

As for the HV, you should be okay to just update the IPs into the new ranges

[mavhc]

You'll have a bit of a problem in that the 2 ranges aren't in the same subnet.

 

You're still on a RBN? So you might have 10.1.2.0/24 and 10.2.3.0/24

 

You'll need a default gateway for each subnet, if that's currently your RBN's router it'll need to be set to let the 2 subnets communicate.

[TwistedHelixis]

When I did this a while back I added the new scope to DHCP while still keeping the old scope but set as disabled. If something goes wrong you can then jump back to the old scope.

 

All clients got updated to the new IP info when they booted up and I manually changed a few server IP's etc that didn't get an IP from DHCP.

[LeMarchand]

Thanks all.

 

The range is currently 192.168.XXX.XXX but another school is already on 192.168.(XXX+1).XXX so we can't just do it via subnet. We'll be moving to completely different/23 range as 500+ addresses should do us. 2 form/Junior entry so we don't need anything too fancy.

 

I'm liking @TwistedHelixis's idea. While I suspect the old system will only be good internally at least it gives me something to fall back on if I mess up. If you see a load of typo heavy posts about network scopes here over the holidays, you'll know I've messed up and using my phone to plead for help!

[mavhc]

I'm surprised the LA is handing out 192.168.x.0 subnets, when the standard was 10.x.y.0, what are they doing that requires you to follow their IP scheme?

[LeMarchand]

I'm surprised the LA is handing out 192.168.x.0 subnets, when the standard was 10.x.y.0, what are they doing that requires you to follow their IP scheme?

 

That scheme probably stems from when each school had a couple of office PCs and maybe a suite of a dozen. Certainly pre-Laptops for Teachers.

 

New range will be in 10.x.y.0, which we need to follow as the broadband and filtering is with them.

[LeMarchand]

So... Thought I'd done everything correctly yesterday, thanks to all the help here, but no internet. My trousers were turning brown when the LA rang to let me know that there was a problem (that's still unresolved). Just need to check the printers and work out why the Unifi points are working, but not showing in the controller. And wait.

 

At least the DHCP scope is much tidier!

[IrritableTech]

So... Thought I'd done everything correctly yesterday, thanks to all the help here, but no internet. My trousers were turning brown when the LA rang to let me know that there was a problem (that's still unresolved). Just need to check the printers and work out why the Unifi points are working, but not showing in the controller. And wait.

At least the DHCP scope is much tidier!

 

 

I did this a good while ago, now that it is done my advise would be..

 

check DNS for entries in the old subnet.

Double check DHCP is setup correctly and issuing the right gateway, IP helper, DNS servers etc.

Make sure you've added the new subnet in Active Directory Sites and Services

Reboot everything, like half a dozen times or something

It might be worth connecting a laptop on the old subnet with Angry IP scanner or something and scan all addresses in the old subnet to check nothing replies.

check DNS

[LeMarchand]

Thanks, I'd already gone through DNS. The internet problem is with our filter peeps - they've issued a temp proxy that is allowing connection. I think everything is working as it should apart from the Unifi points not showing in the controller. I suspect that the old SSH into each point and set-inform will solve that but, whilst we only have 14 points, I've got more urgent jobs at the moment.