0

How strict is this standard today.

The 172.16.0.0/12 range is: 172.16.0.0 – 172.31.255.255


Conceptual Config

172.Location.VLAN.Host

  • Location A (10):

    • VLAN 10 - 172.10.10.0/24
    • VLAN 20 - 172.10.20.0/24
  • Location B (20):

    • VLAN 10 - 172.20.10.0/24
    • VLAN 20 - 172.20.20.0/24
  • Location C (30):

    • VLAN 10 - 172.30.10.0/24
    • VLAN 20 - 172.30.20.0/24

Would going outside of this scope a little with something like "Location D (40) - 172.40.10.0/24" cause issues?

  • 1
    If users ever need to contact those addresses on the public Internet, then it will not work. That works both ways because most protocols are bidirectional, so if people from those addresses need to access something on your network, replies from your network will not work. It is simply not worth doing as you have no idea what the future need for something like that may be, and will probably have forgotten or not associate the problem with the addressing. – Ron Maupin Jun 22 at 18:53
  • 1
    Your edit doesn't change the existing answers. This is not a matter of "good practice", it's about rules. There's nothing like breaking "a little" the rule. Now, nobody will sue you for breaching those rules, but you'll find out sooner or latter that you punished yourself. – JFL Jun 23 at 6:28
3

Internet works and was able to grow to its current size by following standards.

It is a very very bad idea to not follow them.

With a very basic and easy to use addressing scheme, wihtin 172.16/12 you can have 16 sites ID with 256 possible VLAN with /24 networks in each site.

And this doesn't prevent you from using additional networks within 10/8 if you need more later.

If you need more than that, then that means your network is big enough to be likely impacted in the future by conflict caused by your improper usage of pubic IP addresses internally.

Just abide by the standards, otherwise, yes, you would shoot yourself in the foot.

| improve this answer | |
2

As per RFC 1918, you can use

  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16

at your own discretion - any of their subnets, a whole scope, or all of them combined.

However, you cannot use as subnet from 172.32.0.0/16 or 172.40.0.0/16 or anything else that hasn't been reserved from public use. Doing so renders all machines in your network unable to connect to one of the real public IP addresses in those subnets.

Those reserved, private addresses haven't changed and cannot ever change (as long as IPv4 exists) because anyone trying to use any address from those ranges as a public address would get major difficulties being routed correctly since everyone is using those networks.

| improve this answer | |
2

Don't do that!

172.32.0.0/11 is assigned to T-Mobile. It's announced to the DFZ (since 2012) and most likely in use for real Internet traffic.

If you squat on that address space, some portion of the Internet will become inaccessible to your network!

I recommend you begin organizing your RFC1918 space using an IPAM so you don't re-create the problem you've got in 10/8. You may find it's easier to operate within the 172.16.0.0/12 block just by being more organized about it.

There's nothing wrong with using NAT for user pools within your intra-network, either. Most orgs could do NAT between their desktop subnets and their servers, printers, etc. with no problems.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.