Subnet Question

[scooter817]

I have a question about using certain networks, for example we have two different network schemes that we use. One is 192.168.X.X and the other is 10.X.X.X and we are in the process of moving everything to the 10.X.X.X network but I was told that you should never use 192.168.X.X in an enterprise network, that's more for residential use. I wanted to ask you guys since you do a lot more of this than me if this true or not.

Eric

[Julio E. Moisa · Accepted solution]

Hi

Actually the Private Class C is used at home. I recommend use Class B or A subnets for enterprises. If many companies use a class C you could have overlapping for VPNs domains and to avoid it you must configure NAT everywhere. In few words Class C is limited to 256 networks: 192.168.0.x/24 to 192.168.255.x/24 and there is more risk to have overlapping networks and subnetting limitations, The class A and B are more extense.

It does not mean you cannot use a private C into a company but from technical point of view it is not recommended. 

[Joseph W. Doherty · Accepted solution]

You can use 196.168.0.0/16 in Enterprise networks (as you could also use the private class A or B address blocks at home [although much home network equipment probably won't support it]). The question is really, will it provide enough address space? Often it can for smaller Enterprises. Sometimes it's even used for additional address space, in very large networks, if they are using private class A and/or B space too.

Julio mentions the private class C block is limited to 256 networks. Well, yes and no. Even if you're doing classful addressing, it's possible to subnet class C networks, although at additional risk of doing it wrong (as Julio mentions, but then subnetting class A or B address space has the same risks). However, if you're doing classless networking, it's really not different from using any other private unicast address space.

One problem I've seen when Enterprises use the private 10.0.0.0/8 address block, they often tend to be sloppy, i.e. they don't give much thought how to use such a large address block.