using "reserved" IPv6 space

[-Hammer- <bhmccie () gmail com>]

OK. I'm pretty sure I'm gonna get some flak for this but I'll share this 
question and it's background anyway. Please be gentle.

In the past, with IPv4, we have used reserved or "non-routable" space 
Internally in production for segments that won't be seen anywhere else. 
Examples? A sync VLAN for some FWs to share state. An IBGP link between 
routers that will never be seen or advertised. In those cases, we have 
often used 192.0.2.0/24. It's reserved and never used and even if it did 
get used one day we aren't "routing" it internally. It's just on 
segments where we need some L3 that will never be seen.

On to IPv6

I was considering taking the same approach. Maybe using 0100::/8 or 
1000::/4 or A000::/3 as a space for this.

Other than the usual "Hey, you shouldn't do that" can anyone give me 
some IPv6 specific reasons that I may not be forecasting that would make 
it worse doing this than in an IPv4 scenario. I know, not apples to 
apples but for this question they are close enough. Unless there is 
something IPv6 specific that is influencing this....

--


-Hammer-

"I was a normal American nerd"
-Jack Herer