Let me count the ways... At home it's great because of the extra
address space. I have a /29 at home, which is pretty luxurious
compared to what most people have, but not nearly enough to give
all my boxes a real address if I turn them all on at the same time.
Not that luxurious really, if you have a need, find a reasonable ISP
and ask and you'll receive.
this is a breeze: a single /64 gives you all the addresses you'll
ever need and boxes configure themselves with the same address each
time they boot, even when using different routers and no need for
Right, the sparse density of v6 is definitely a win. But why care
about getting same address? Anyway, see below about the NAT premise.
(v4 also has reasonably abundant site-local space).
Another thing I really like about IPv6 is the much smarter
Right, yes, but hardly a killer feature.
But it also handles this situation much better, if it comes up:
routers can advertise additional prefixes as "on-link" so hosts
know they can reach destinations in those prefixes directly over
layer 2. Redirects also work across prefixes. (Similarly, routing
protocols use link local addresses which make it possible to run
RIP or OSPF between two routers that don't share any prefixes.)
Since there is no need for NAT, every IPv6 host can run a server
for any protocol without trouble.
But there _will_ be NAT, that is the very premise of this discussion,
as offered by Paul Vixie. So that one doesnt count, unless you knock
down the premise: There will be site-local and NAT with v6 because of
the multihoming problem.
Because of the large address space, scanning address blocks is no longer an
If you have multiple routers, you pretty much have HSRP/VRRP
Right, but you can do this router-side with v4 anyway. v6 makes it
more integrated, but its hardly something which v4 does not have.
Renumbering is much easier.
I dont see how though. I can switch v4 addresses with DHCP as easily
as with RAs on v6. Sure, the routing will be slightly more fluid with
v6, but I can route multiple logical subnets with v4 anyway during
transition. The hard bits of renumbering are _not_ in changing the
actual assigned and used addresses IMHO.
It's also very handy to be able to log in to a box, completely
screw up its IPv4 configuration and rebuild it from scratch without
having to worry that the host becomes unreachable and needs a
That's hardly a reason to upgrade to v6. You could as well insert any
non-v6 protocol in there that gives you access. That is as much an
argument for running DEC LAT as it is for IPv6.
Multihoming can be done the same way many people do it for IPv4:
take addresses from one ISP and announce them to both.
Obviously yes. In which case, why bother? If you have a need for PI
IPv4 addresses you can get them, and v6 will operate the same way -
demonstrate need and you get them. If you cant demonstrate a need,
you'll have to use PA. Indeed, for v4 the bar is much _lower_, if you
can show you would use 10 bits of routable space you very likely will
get PI assigned space, however, for v6 not only must you be able to
show reasonable usage of the 16 bits provided for by standard PA, you
would need to demonstrate you have a further need for the additional
16 bits needed for the minimum v6 PI assignments.
So, for smaller players wishing to get PI, v4 is much easier.
(and yes, i know at moment RIR requirements are relaxed, but only so
as to encourage some kind of v6 up take, and its still very low.)
Obviously your /48 will be filtered, but as long as you make sure
it isn't filtered between your two ISPs, you're still reachable
when the link to either fails.
So you're restricted to upstreams who not only peer with each other,
but will cooperate sufficiently to allow a joint customer to announce
sub-assignment of one to the other. The vague impression I have is
that this is extremely rare
ISP. Not much fun, despite the fact that renumbering is much easier
Hence the premise of this thread, v6 will have site-local and NAT.
Michel is no longer in the IPv6 business, and I've failed miserably
at convincing people that geographic aggregation is helpful here.
Very very sad. But obviously geo-aggregration is not in providers
So currently, multi6 is looking at approaches that allow transport
protocols to jump addresses in the middle of a session.
And these approaches will equally apply to v4. Still no reason to
switch to v6.