Going beyond RFC 1918 class A 10.0.0.0/8 address space ?

[kude]

I need a second private class A - what is the best choice ? So I'm looking for another class A currently not routable on the Internet. Suggestions ?

Other RFC 1918 class B's and C's are not possible - I want to make a secondary overlay for my existing 10/8.

[roger.jones]

Would it not be best to further subnet your 10.0.0.0 /8 network to 10.0.0.0 mask 255.255.0.0 or something then you will have loads of subnets!!

If this is not possible if you have a firewall hiding your internal addresses from external users/ the internet then you could use any subnet you like

Regards

[kude]

My 10/8 is already subnetted (VLSM multilevel core and summarization) over a couple of thousand (!)sites. What is the next best step after RFC1918 ?

[t.baranski]

There really isn't one. Addresses not allocated now will most likely be allocated someday. Then you'll be in trouble. The "best" thing to do may be some IP restructuring to increase efficiency. There are over 16 million IP addresses in 10/8 -- are you using even 1 million of them right now?

Another option is to request public IP addresses from an RIR (RIPE if you're in the UK). I don't believe that advertising IP addresses to the Internet is a requirement for getting an allocation, so you could explain that you're running out of private IP's to use and potentially be allocated a public block. But if your actual utilization of the RFC1918 blocks is low due to inefficient subnetting, you may run into trouble trying to justify the need for a public netblock.