Expand DHCP scope

[Jawloms]

Morning,

 

We currently use 10.161.2.x - 10.161.3.x with a subnet mask of 255.255.254.0. I need to increase the number of IP addresses available. I know that I am currently at the max number of IPs with that mask so how do I increase? Presumably I will also need to get my provider to change the mask and DG on their router which I don't have access to?

 

Thank you

 

Stuart

[supportman]

Change the subnet to 255.255.252.0 and that will give you 1000 internal IP range to use.

 

You will need to change it on all devices that have a static IP, but other than that its easy enough change.

[Jawloms]

Change the subnet to 255.255.252.0 and that will give you 1000 internal IP range to use.

 

You will need to change it on all devices that have a static IP, but other than that its easy enough change.

 

So would that give me 10.161.4.x and 10.161.5.x?

[supportman]

Yep you can confirm exactly with this:

 

Online IP Subnet Calculator (subnet-calculator.com)

[Jawloms]

That says;

 

10.161.0.1 - 10.161.3.254

 

So does that mean I have to use that rather than 10.161.2.1 - 10.161.5.255?

[supportman]

That says;

 

10.161.0.1 - 10.161.3.254

 

So does that mean I have to use that rather than 10.161.2.1 - 10.161.5.255?

 

No, in your DHCP scope you will choose the start IP youself so its onwards from that.

[chazzy2501]

With the static devices they may continue to operate correctly as long as they don't need a device outside of the new range. I've given static devices smaller subnets to limit their scope. (mostly to deny them seeing the gateway)

[psydii]

Just want to check: that range wasn't given to you by your broadband provider was it? (specifically are you on LGfL?)

[Foresthippy]

That says;

 

10.161.0.1 - 10.161.3.254

 

So does that mean I have to use that rather than 10.161.2.1 - 10.161.5.255?

 

Your scope would need to fall within 0.1 -> 3.254.

 

10.161.5.x is on a different subnet than 10.161.2.x using a subnet mask of 255.255.252.0 so won't talk to each other.

 

Also, it's likely that your ISP has allocated IPs either side of your 2.x - 3.x to someone else so it isn't as simple as just changing your local subnet mask. You would probably need to request a new range.

[Jawloms]

My IP range is historic from when I was with Suffolk LA. I have since moved to @SchoolsBroadband and as far as I am aware, I can use which ever range I like. I do realise though that I would need to co-ordinate with them to change the subnet mask, and possible gateway, at the same time.

[SchoolsBroadband]

My IP range is historic from when I was with Suffolk LA. I have since moved to @SchoolsBroadband and as far as I am aware, I can use which ever range I like. I do realise though that I would need to co-ordinate with them to change the subnet mask, and possible gateway, at the same time.

 

Morning @Jawloms,

 

we try to adhere to best practise with our customers so you don't use something like a /16 but we can support any private IP address range our clients wish to have, even if they are the same as our other clients.

 

If you need any help the support team can advise on 0 11 33 222 333. We will need to add the IP's to our core and to Netsweeper. Please give us 24 hours notice as we never add the IPs during the daytime to Netsweeper in case of any issues.

 

This means that when our customers move they don't have to change their IP address ranges unlike some other suppliers.

 

Thanks

 

Dave

[LWPerry]

All of your responses are great and clear, still nervous about it! We 192.168.10-12 subnets, with a 23 bit mask. For now, I'm thinking of going to a 20 bit mask which should allow me to use (I believe) .14 and .15 subnets. I will VLAN at some point but have some physical cleanup I want to do first.

 

My question or request for affirmation is: I should be able to change all my switches, static assets, and firewall to this mask without causing mass outage correct? (because the mask is wider not narrower). Then of course I'll go back and rework DHCP and the other details. I ask because I'm doing this remotely and can't get onsite until Monday.

 

Thanks folks!

LP