On 18-apr-04, at 4:48, Paul Jakma wrote:
Oh oh I see another one taking the path that leads to the dark side.
Michel, you forgot to include the audio: http://www.bgpexpert.com/darkside.mp3
Well, let's be honest, name one good reason why you'd want IPv6 (given you have 4)?
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. Worse, I still haven't figured out a way to give some machines always the same address (if available) but also use that address for something else if the "owner" is turned off. In IPv6 all of 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 DHCP.
Another thing I really like about IPv6 is the much smarter "on-link" behavior. In IPv4, it's not uncommon to have two hosts on the same physicial subnet, but with addresses from different prefixes. These hosts will then have to communicate through a router, which in this time of cheap 10/100/1000 cards usually isn't the fastest option. In IPv6 each subnet prefix has enough addresses to hold all hosts that you can possibly connect to a layer 2 network in the first place. 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.
Because of the large address space, scanning address blocks is no longer an option.
If you have multiple routers, you pretty much have HSRP/VRRP functionality automatically.
Renumbering is much easier.
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 powercycle.
And, to be more on-topic, name one good reason why a network operator would want it? Especially given that, apart from the traditional bleeding edges (academic networks), no customers are asking for it.
I think "no customers" is rounding it down slightly. Yes, demand is low, but so is supply, hard to tell which causes which. And customers who do ask, are routinely turned down.
As Paul Vixie points out, without a multihoming solution beyond that offered by 4, v6 networks will look just v4 - most of it will be on non-global address space and NAT. Not really interesting..
Multihoming can be done the same way many people do it for IPv4: take addresses from one ISP and announce them to both. 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. However, this means renumbering when switching to another primary ISP. Not much fun, despite the fact that renumbering is much easier in IPv6.
[snip darth vader]
I know, what's worse is that I know it need not be so. (how's your MHAP doing? How's Iljitsch's geo-assigned addressing proposal?)
Michel is no longer in the IPv6 business, and I've failed miserably at convincing people that geographic aggregation is helpful here. So currently, multi6 is looking at approaches that allow transport protocols to jump addresses in the middle of a session.
