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We operate on one class C network, let's say 192.168.1.0/24 But the problem is we have 262 devices! I propose upgrading the network to a class B. The opposition proposes purchasing new hardware and using VLANs. We have VPNs setup and we talk to other locations on different domains.

It has been said that to re-configure the network to operate as a class B network would cost 100 times more than setting up virtual LANs. Mostly due re-configuring routes and VPNs. Due to this my proposal was shot down. Help me understand why it is more cost effective to VLAN an existing class C network and purchasing new hardware, than to upgrade it to a class B?

I'll admit, my question is worded a bit biased since I must purchase a new switch regardless.

Oxymoron
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  • Maybe my question is a little bit stupid but can't you move to a larger private network like 10.0.0/8? – Glueon Oct 08 '14 at 19:43
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    Nothing personal, but it sounds like neither camp has the foggiest idea of what they're talking about. Why not just change the subnet mask to /23? – joeqwerty Oct 08 '14 at 19:50
  • Glueon, This is my suggestion. A class B network is 172.16.0.0 – Oxymoron Oct 08 '14 at 19:53
  • joeqwerty, None taken, Please be as direct as possible. Would your solution still be feasible when our network grows to over 500 devices? or even 1000? – Oxymoron Oct 08 '14 at 19:54
  • @Oxymoron - Sure. If you're in a /24 in 192.168.0.0/16 address-space now you can continue to grow until you reach a /16 (65,534 hosts). You'll have a legitimate need for VLANs and multiple subnets long before you get there, though. – Evan Anderson Oct 08 '14 at 19:54

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VLANs have nothing to do with your IP addressing scheme. You're conflating layer 2 and layer 3. At the risk of shamelessly plugging myself I'll suggest you have a look at "How do VLANs work?" and "Best way to segment traffic, Vlan or subnet" (and maybe also "Network: Many subnets in 1 VLAN =? possible").

As a "quick fix": Assuming you're using 192.168.1.0/24 currently, just change the subnet mask on your servers to 255.255.254.0 and you can begin using addresses in the 192.168.0.1-192.168.0.255 range for clients immediately. For whatever "/24" you're using there's a directly-adjacent "/24" that you can expand into. If the 3rd octet of your current addressing scheme is even then the adjacent subnet is the next odd number. If the 3rd octet is odd then the adjacent subnet is the prior even number.

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Evan Anderson
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