Subnet mask change

[Lsat0902]

I need more IP addresses on my Network, if i change my Subnet Mask to class B from Class C, would that screw up my currently bookmarked/connected computers/printers/ect?

[Electronics Wizardy]

Well classes aren't really a thing anymore first off.

 

You need to change the subnet mask on all devices, and the dhcp server.

 

How are devices bookmarked? they should still work if the same ip/hostname is used.

[AbydosOne]

5 minutes ago, Lsat0902 said:

I need more IP addresses on my Network

How many devices do you have that you've exhausted an IP block? You should be able to have up to 254 IPs before you need to worry.

[Lsat0902]

2 minutes ago, AbydosOne said:

How many devices do you have that you've exhausted an IP block? You should be able to have up to 254 IPs before you need to worry.

Close to that number, its for the company I work for, we are expanding very quickly, and we are getting to the point where printers/computers/cellphones/ect ect are getting close to maxing out the IP block, so were looking to fix that problem before it becomes a large one. 

 

4 minutes ago, Electronics Wizardy said:

Well classes aren't really a thing anymore first off.

 

You need to change the subnet mask on all devices, and the dhcp server.

 

How are devices bookmarked? they should still work if the same ip/hostname is used.

I'm referencing (B= 255.255.0.0) (C=255.255.255.0) this is the way I was taught, if its different now is there a place i can go to learn newer terminology?

[Lsat0902]

6 minutes ago, Electronics Wizardy said:

Well classes aren't really a thing anymore first off.

 

You need to change the subnet mask on all devices, and the dhcp server.

 

How are devices bookmarked? they should still work if the same ip/hostname is used.

Also, they are reserved through the DHCP

[The_russian]

3 minutes ago, Lsat0902 said:

I'm referencing (B= 255.255.0.0) (C=255.255.255.0) this is the way I was taught, if its different now is there a place i can go to learn newer terminology?

Classful networking hasn't been used in quite some time, to look into what is used now research Variable Length Subnet Mask (VLSM)

 

Edit: To answer your original question about how it would affect your currently connected devices, it depends on how they get their address. If they get addresses automatically assigned by a DHCP server, you just need to update the information on the DCHP server with the new network information, then refresh the devices. If devices like the printers or servers have a static address (they should), you will need to manually change the addressing on each device. 

[Electronics Wizardy]

3 minutes ago, Lsat0902 said:

I'm referencing (B= 255.255.0.0) (C=255.255.255.0) this is the way I was taught, if its different now is there a place i can go to learn newer terminology?

The newer way of saying is just a /24 or a /20 network.

 

2 minutes ago, Lsat0902 said:

Also, they are reserved through the DHCP

Yea your gonna have to change all of those aswell

 

Or make a new subnet and keep the ips for existing devices.

[leadeater]

12 minutes ago, Lsat0902 said:

Close to that number, its for the company I work for, we are expanding very quickly, and we are getting to the point where printers/computers/cellphones/ect ect are getting close to maxing out the IP block, so were looking to fix that problem before it becomes a large one. 

Move your printers to their own VLAN and Subnet, change your wireless to also use it's own VLAN and Subnet. Both of these are a better future plan and will likely cause you less issues than changing the subnet mask, which may not go smoothly especially for static IP devices.

 

Also if you have multiple buildings or floors it may pay to create a VLAN and subnet for each of those then migrate computers across to those once you have DHCP and DHCP Relay all setup to support these changes. Then you can move each device by changing the switch port VLAN and reboot the device (or ipconfig /release & ipconfig /renew).

 

It's a lot easier and better on your sanity to use many /24 subnets than to start using /23 & /22 etc. If you can't do any of this just jump straight to /16.