Running out of IPs

[Jawloms]

I currently use 10.163.2.x and 10.163.3.x with a subnet mask of 255.255.254.0. My Internet is with Schools Broadband using a cloud based NetSweeper. I am running out of IP addresses. Am I right in thinking that if I try and use IP addresses in, for example, 10.163.4.x and a different subnet mask then it won't work on the Internet as the SchoolsBroadband router can't see them due to its current settings? If I ask SchoolsBroadband to just change the subnet mask in their box to 255.255.0.0, will that stop anything current working and enable me to then play internally and make more IPs available at my leisure or is there more to it than that?

 

Don't know if it's relevant, but I have no VLANs set up.

 

Thank you

 

Stuart

Edited March 13, 2019 by Jawloms

[SchoolsBroadband]

Hi Stuart,

 

we can give you a bigger subnet that shouldn't be a problem. If you get in touch with the support team then we can do the necessary changes for you.

 

Regards

 

David

[Jawloms]

Thanks for replying, and I'm sure you can, but I wanted to understand the workings before actually getting anything done. Is it as simple as I've put (I wish) or is there more to it?

 

Stuart

[Jawloms]

Can someone vouch for my logic/lack of logic please?

[jezi55]

We was in the same issue last year, we ended up moving from a 225.225.254.0 to a 225.225.240.0 subnet which allowed much more devices. All switches were configured with a new management vlan and dhcp scope was increased.

[Sephiroth]

It depends on how many more addresses you want. Going to a /22 subnet (255.255.252.0) will give you double what you have now (/23 subnet), between 10.163.0.0 and 10.163.3.255 (1022 usable addresses).

 

This should help, it's what I use to figure these things out!

[FishCustard]

If you're currently on a /23 (mask 255.255.254.0) and move to a /16 (which is what you'd get with a subnet mask of 255.255.0.0) that contains that original /23 then things will just work providing the default gateway is updated if necessary (it almost certainly will be necessary as they'd probably put the gateway at the start of the range).

 

You'd then be able to use 10.163.0.0 - 10.163.255.255, and the gateway would probably end up being 10.163.0.1.

 

EDIT: @Sephiroth, use the CIDR version at Online IP CIDR / VLSM Supernet Calculator, nobody's used classful routing in about twenty five years

[Sephiroth]

use the CIDR version at Online IP CIDR / VLSM Supernet Calculator, nobody's used classful routing in about twenty five years

 

Yes, fair point. I leaned from an old hand and don't refer to it often enough!

[Jawloms]

If you're currently on a /23 (mask 255.255.254.0) and move to a /16 (which is what you'd get with a subnet mask of 255.255.0.0) that contains that original /23 then things will just work providing the default gateway is updated if necessary (it almost certainly will be necessary as they'd probably put the gateway at the start of the range).

 

You'd then be able to use 10.163.0.0 - 10.163.255.255, and the gateway would probably end up being 10.163.0.1.

 

EDIT: @Sephiroth, use the CIDR version at Online IP CIDR / VLSM Supernet Calculator, nobody's used classful routing in about twenty five years

 

Exactly what I was after, thank you. Presumably they would change the DG as that would make sense, but if they didn't then everything would just carry on working?

 

Thanks to all others too.

[FishCustard]

Exactly what I was after, thank you. Presumably they would change the DG as that would make sense, but if they didn't then everything would just carry on working?

 

Thanks to all others too.

 

Yes, although then you'd have the DG in the middle of your IP range. Nothing inherently wrong with that, it's just a little odd and may trip you up in future.

[Jawloms]

Yes, although then you'd have the DG in the middle of your IP range. Nothing inherently wrong with that, it's just a little odd and may trip you up in future.

 

I would get it changed at some point it's just for the benefit of getting more IPs now, I might leave the DG where it is until a holiday.

 

Stuart

[SchoolsBroadband]

Hi @Jawloms,

 

sorry for my late reply. Everything everyone has said is correct.

 

Before you start changing everything please contact support to make sure its possible. In theory it all should be and we've done this numerous times before but I don't know which customer you are or which package you are in.

 

Thanks

 

Dave

[Jawloms]

Hi @Jawloms,

 

sorry for my late reply. Everything everyone has said is correct.

 

Before you start changing everything please contact support to make sure its possible. In theory it all should be and we've done this numerous times before but I don't know which customer you are or which package you are in.

 

Thanks

 

Dave

 

That's fine, I wouldn't. I'll be in touch, probably tomorrow. Thank you for your help.

 

Stuart