[arin-discuss] Trying to Understand IPV6

[Owen DeLong]

On Sep 13, 2010, at 12:43 PM, Gary T. Giesen wrote:

> Using anything less than /64 for a subnet can be dangerous, especially
> as a lot of devices are hard-coded to not accept any other subnet mask.
> 
Those devices are broken and violate the RFCs. They should be fixed.

I agree that you should not be using non /64 subnets unless you have
a very good reason and know what you are doing and why you are
doing it. However, the mere existence of bad IPv6 stack implementations
is not the reason to use /64s.

> While I'd argue /64's should be used everywhere, there is some merit to
> using /112's or similar on point-to-point links between routers, where
> it's a known quantity what the devices support. In an environment where
> you could have a large number of heterogeneous devices, you're asking
> for a support headache to use anything else. 
> 
What, exactly, is this supposed merit?

Owen