using "reserved" IPv6 space

Tom Cooper thomascooperca at gmail.com
Fri Jul 13 16:11:26 UTC 2012


On Fri, Jul 13, 2012 at 11:05 AM, TJ <trejrco at gmail.com> wrote:

> On Fri, Jul 13, 2012 at 10:38 AM, -Hammer- <bhmccie at gmail.com> 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 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.
> >
>
>
> Would using "just" Link Locals not be sufficient?
> *(Failing that, as others noted, ULAs are the next "right" answer ... )*
> *
> *
> /TJ
>

As an IPv6 newbie myself, I wonder how hosts handle link local, ULA and
global addresses.
For example, if you have some internal web traffic used for intranet use
only, do you bind those servers to use only ULA addresses? This way your
internal users with ULA addressing only have access to those servers? No
need to give intranet-only servers a global address if they're not needed
to be accessed globally.

Is there a way for hosts to "prefer" or "attempt" to connect to a service
by first trying a link-local scope, then a ULA and finally a global address
if its off the AS?
I really like the idea of ULA and think it makes much more sense than
RFC1918 + NAT. I just don't have any deployment experience with it yet so
I'm curious how the host would handle it.

On the router side, I'm sure ULA and global routing just run as
ships-in-the-night side-by-side anyways...right?

-- 
Thomas Cooper



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