How do you change from subnet classes? 1

[blfrd76]

We have network addresses that have the following:

192.168.10.X
192.168.11.X
192.168.12.X

I want to change it so everyone is on the same subnet. There are 3 Cisco switches in the building that connect everyone to one domain controller. All the workstations are Win98. Servers are running Win2K Server.

Where do I start and are there any good links I can read up on to avoid pitfalls.

Thanks,
BIll

 

[Serbtastic]

I assume that all subnets are currently using a 255.255.255.0 subnet mask. If you change the mask to 255.255.0.0 all machines will be on the same subnet.

 

[Parcival21]

Might also work if you try the following network address:
192.168.0.0 /22 should be enough addresses for your networks.
The subnet mask would be 255.255.252.0 then, if I calculated this right(Please correct me if I didn't).

bye, busche

 

[Serbtastic]

Why do you think that would be enough addresses for his network? He didn't state any numbers (other than 3 Cisco switches) in his original post?

 

[Parcival21]

I thought he had three class C networks.
Each one has a max of 253 users. Makes 759 max users for the three networks. With a /22 network you can connect 1022 users (I'm not very good at this so I might be wrong). If he wants to resize his network with more users then you are completly right.
bye, busche

 

[Serbtastic]

Using a 255.255.252.0 address, 192.168.12.X would be in a different subnet than 192.168.10.X and 192.168.11.X.

You'd have to use a 255.255.248.0 (/21) mask to have all three in the same subnet.

 

[Parcival21]

Good argument. Didn't realize that point(That will give you a star. In some cases it might be an alternative to rearrange your IP addresses (should be quite easy if you use dhcp/ a lot of work(probably not worth the work)if you hand out static IP's), because using /21 network would mean wasting 1000 or more adresses that you could use in other subnets.
So if you want to invest a lot of work I think it's better to use subnets that are as small as possible.
But with Serbtastic's proposal you will always be on the right way.

One more thing:
The usage of the network addresses 10,11,12 let me think that there are also networks with the addresses 0,1,2,3,4...
In this case you need to know that using my or Serbtastics proposal might cause you the trouble that for example the subnet with the network address 192.168.9.0 255.255.255.0 can have a conflict with the new subnet build that would for example be 192.168.0.8 255.255.248.0. In that case you will have to rearrange your IP addresses either way.
Good luck, busche

 

[blfrd76]

The reason I want to make everyone on the same subnet is strictly for connectivity issues. I've been told that if we switched our network (about 100 users) to ONE subnet, then it would resolve some of the connectivity issues we've been plagued with.

Here's some more backstory:
We have a BDC that is multihomed. All 3 subnets connect into this BDC through the 3 NICS in the back. Ideally, I want to use only ONE of these NICS. Then change the entire network to ONE subnet. I'm hoping this will solve alot of problems.

Here's my plan so far:

CHange all the subnet masks to 255.255.0.0
Check DHCP and purge leases if necessary
CHeck RRAS to make sure dial in Clients still have access
Change subnet masks on all printers to 255.255.0.0
Change our internet radio address ( not sure here?)
Power cycle all switches and hubs
Boot up several workstations, then check connectivity

Any suggestions?

Thank you very much.
Bill