using "reserved" IPv6 space

Fred Baker (fred) fred at
Mon Jul 16 19:06:45 UTC 2012

On Jul 13, 2012, at 8:05 AM, TJ wrote:

> On Fri, Jul 13, 2012 at 10:38 AM, -Hammer- <bhmccie at> wrote:
>> 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 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.
> Would using "just" Link Locals not be sufficient?

If they're on the same link, of course. My understanding of the question said "they're not on the same link".

> *(Failing that, as others noted, ULAs are the next "right" answer ... )*
> *
> *
> /TJ

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