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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: why use IPv6, was: Lazy network operators
On Apr 18, 2004, at 4:32 AM, Iljitsch van Beijnum wrote: On 18-apr-04, at 4:48, Paul Jakma wrote: Dunno what your problem is, I have no problem getting as much address space as I need as long as I can justify it. Perhaps you need to speak to your provider?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.Well, let's be honest, name one good reason why you'd want IPv6 (given you have 4)? 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.)Those are semi-nice features. Not sure I would use it as an excuse to migrate, though, since the need for them can easily be avoided in v4. Since there is no need for NAT, every IPv6 host can run a server for any protocol without trouble.Have you been reading this thread? There is a need for NAT in v6. In fact, the lack of multi-homing support in v6 alone outweighs all its nice features, IMHO. Because of the large address space, scanning address blocks is no longer an option.You have a /64, scanning that would be an issue. Is scanning a /96 really "no longer an option"? How about in a year? Two years? If you have multiple routers, you pretty much have HSRP/VRRP functionality automatically. Again, nice, but since I have that in v4.... Renumbering is much easier. I like this one. 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.s/v4/v6 I would not say this is an argument for v6 in particular, but maybe an argument to run two protocols simultaneously. 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.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. Certainly no customers on "The Web". Maybe some niche applications. This does not address the issue. If my /48 is filtered, I am still at the mercy of the provider with the super-CIDR. If that network is down, so am I. (And don't even think about saying backbones never go down.) The point of multi-homing is to _not_ be dependent on a provider.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.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.. Statements like "Obviously your /48 will be filtered" show why v6 is going to take much longer to catch on than people in the v6 camp probably would like. I should pay more attention to the multi6 list, but to be honest, it just does not seem to be worth the effort. IPv4 is doing fine, v6 is struggling to find a market.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.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?) IPv6 was designed with some very kewl features (thanx, AppleTalk :), but it obviously was influenced by "big providers" who thought the world should be run by the top 10 networks and everyone else should just shut up and do as they are told. Since that is not how the world does work, surprise, there was resistance. And the resistance is not going away until we stop trying to apply bandaids and give the *USERS* what they want and need. One of the biggest things the users want is a way for their corporate networks to have good connectivity to the Internet even if a backbone provider falls down. We have this in v4, we should have it in v6. Filtering (/19s, /48s), and other impediments to _real_ multi-homing have been a complete and miserable failure in the past. Any proposal which values the end-user's network (read: "THE PEOPLE WHO PAY FOR IT") less than the "backbone" networks will fail. All, IMHO, of course. :) -- TTFN, patrick
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