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What's so bad about IPv6?What's so bad about IPv6?Posted Jan 26, 2011 14:42 UTC (Wed) by dskoll (subscriber, #1630)Parent article: LCA: IP address exhaustion and the end of the open net
Like many other posters, I'm mystified by the notion that IPv6 is "slow" or "unreliable". I've found it just as fast and reliable as IPv4. Huston says "Whenever IPv6 is used, performance goes down the drain" without offering any evidence to back up that claim.
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What's so bad about IPv6? Posted Jan 26, 2011 15:08 UTC (Wed) by nettings (subscriber, #429) [Link]
I guess he was talking about big-iron border gateways. I could imagine that their performance suffers compared to IPv4 simply because of the longer addresses and more bookkeeping required. Cache tables and memory bandwidth don't magically increase when you switch.
And since this kind of hardware is a huge investment, it tends to be run at high loads even for standard use cases (i.e. IPv4). Switch to v6 and you suddenly max out your infrastructure. Sure, you could buy new routers, but where is the economic sense in that?
What's so bad about IPv6? Posted Jan 26, 2011 15:11 UTC (Wed) by dskoll (subscriber, #1630) [Link] I guess he was talking about big-iron border gateways. I could imagine that their performance suffers compared to IPv4 simply because of the longer addresses and more bookkeeping required. OK, possibly, but I thought IPv6 was designed to simplify border routers. The addresses are 4x as large as IPv4, but the header is only 2x. And routers don't need to recompute checksums when decrementing the hop counter. See http://en.wikipedia.org/wiki/Ipv6#Simplified_processing_by_routers
What's so bad about IPv6? Posted Jan 26, 2011 15:43 UTC (Wed) by drag (subscriber, #31333) [Link]
Yes.
IPv6 has massively simpler routing requirements then IPv6. Any core router will be able to handle the routing for the entire IPv6 routing space with a total of 4000 routes. Nowadays IPv4 requires 36000 or more.
The address space is also designed to be able to handled efficiently by 16 bit processors. The idea being, of course, that you would have most every electronic computer-controlled device with some sort of IPv6 support.
If anything IPv6 should provide a boost in performance over IPv4. It's just much more efficient since network addressing is much better designed.
What's so bad about IPv6? Posted Jan 26, 2011 16:00 UTC (Wed) by hmh (subscriber, #3838) [Link]
That, of course, assume you have the ASICs/switching fabric able to actually grok IPv6 enough to hardware-route it. And switches that can understand IPv6 multicasting. And protections against the insanely idiotic "rlogin-style" stupidity that is IPv6 auto-configuration.
And therein is the real problem. Replacing the old infrastructure is the single largest problem we face when deploying IPv6.
What's so bad about IPv6? Posted Jan 26, 2011 16:08 UTC (Wed) by drag (subscriber, #31333) [Link]
Most everything that has been deployed since 2004 should have IPv6 support. Most people's network supports it even if they don't know it.
What's so bad about IPv6? Posted Jan 26, 2011 16:43 UTC (Wed) by mstefani (subscriber, #31644) [Link]
Should. How well is a different story.
Some devices will support it only "in software"; hitting the CPU on a busy network devices is basically "game over". Other devices support IPv6 only in a limited way, e.g. no VRF support for IPv6. Of course for those type of problems the network vendors are more than happy to sell you new hardware for $$$ with a questionable ROI. But for some features your network might rely upon all you will get back is a "IPv6 support will be added next year"...
In theory, theory and practice are the same. In practice, they are not. Posted Jan 26, 2011 17:36 UTC (Wed) by khim (subscriber, #9252) [Link] No, they don't support it. It's easy, really: you claim that IPv6 is simpler to process and so it should provide performance boost. But let's check the facts up to 60 million packets per second (Mpps) of IPv4 unicast forwarding traffic and up to 30 Mpps of IPv6 unicast forwarding traffic Oops? Looks like simple and logical way to save half of equipment is to just disable IPv6 - and this is what ISPs are doing... It does not matter if hardware has support for IPv6 or not if it's disabled.
In theory, theory and practice are the same. In practice, they are not. Posted Jan 26, 2011 19:06 UTC (Wed) by ebiederm (subscriber, #35028) [Link]
Shrug line rate 10gbps software forwarded ipv6 in linux.
In theory, theory and practice are the same. In practice, they are not. Posted Jan 26, 2011 21:40 UTC (Wed) by bronson (subscriber, #4806) [Link]
Markov generated text seeded with the iptables manpage?
In theory, theory and practice are the same. In practice, they are not. Posted Jan 27, 2011 13:51 UTC (Thu) by hmh (subscriber, #3838) [Link]
Must be. It lacks everything, from content, to truth.
Being someone who has actually tried to do 10Gbps routing using Linux, I am well aware of its limitations. You need lots of tuning and the correct hardware to get high packets-per-second rates, and it gets nowhere close to the target 40Mpps. It really is useful only for large packets, or if you need nowhere near line-rate and don't care about DoS attacks with small packets.
One really needs hardware-assisted packet forwarding to do line-speed 10-gigabit routing at all packet sizes. Either that or a routing cluster, at which point TCO goes well above a proper 10Gbit Cisco/Juniper switch-router.
So, the question becomes: are there affordable, non-experimental hardware packet forwarding devices (preferably PCIe) that are compatible with Linux?
What's so bad about IPv6? Posted Jan 26, 2011 20:08 UTC (Wed) by hmh (subscriber, #3838) [Link]
That is a blatant lie. There are many vendors that still have IPv6 in *roadmap* for several of their product families. I should know, we have several here and it is being an effective deterrent to switching to IPv6.
What's so bad about IPv6? Posted Jan 26, 2011 18:00 UTC (Wed) by tialaramex (subscriber, #21167) [Link]
Back in 2003 I was testing Cisco's hardware (as much as the IPv4 version is) IPv6 multicast snooping and routing. We were playing different full-rate video streams over a large multi-site IP network with maybe a dozen switch clusters. Without multicast, this was a quagmire (each person viewing incrementally increases the bandwidth needed at pinch points, until performance becomes excruciating) and without IPv6 it requires lots of management because the (Class D in this case) addresses were scarce and must be handled very carefully. With both it was a joy.
Granted, we found several nasty bugs and spent long evenings on transatlantic telephone calls getting their engineers to reproduce them. But that was now almost EIGHT YEARS AGO. This stuff was available for production users when ISPs were buying the gear that's now dusty and old and being thrown out. But they didn't buy it, because less capable gear is always cheaper.
In some way it's our fault as consumers. Most ISPs live on razor thin margins. If everybody was happily paying 50% more for Internet access there'd be money to buy anything the ISP's engineers could want, have real coffee in the DC quiet area, and still buy the Chairman a yacht. But it's a cut-throat business, only specialist players can afford to charge more and deliver better service.
What's so bad about IPv6? Posted Jan 26, 2011 19:54 UTC (Wed) by cmccabe (guest, #60281) [Link]
> In some way it's our fault as consumers. Most ISPs live on razor thin
> margins. If everybody was happily paying 50% more for Internet access > there'd be money to buy anything the ISP's engineers could want, have real > coffee in the DC quiet area, and still buy the Chairman a yacht. But it's > a cut-throat business, only specialist players can afford to charge more > and deliver better service.
Our fault as consumers? That's outrageous.
Around here, people routinely get charged $50 a month by Comcast for mediocre internet service. And if Comcast has a technical problem, that requires a technician to solve, they will charge you for the time!
The real problem here is that the interests of the ISPs are not aligned with those of consumers. Consumer interests are best served by open markets and open standards. ISP interests are best served by creating high barriers to entry, locking in consumers, and offering the minimum acceptable level of service.
Nearly every place in the US has either a local ISP monopoly or duopoly. Comcast or AT&T are your choices. They're not even bothering to pretend that the different parts of AT&T are independent any more. It's not a free market, it's a monopoly. And they know how to milk it.
What's so bad about IPv6? Posted Jan 26, 2011 18:32 UTC (Wed) by paravoid (subscriber, #32869) [Link]
Not to mention that IPv6 forbids fragmentation by routers, hence saving precious CPU (or ASIC) time.
I work at a relatively big ISP where we were an early deployer of IPv6 -- been running it for more than a decade. It was a bumpy road but we've stopped having problems for several years now. We even participate on Google's trusted partner programme.
I have IPv6 connectivity on all of my desktops (office & home) for over three years now and I don't remember to ever having a single connectivity problem with it.
I wholeheartedly believe that dual-stacking *is* the way to go.
What's so bad about IPv6? Posted Jan 26, 2011 15:09 UTC (Wed) by BrucePerens (guest, #2510) [Link] The header overhead is larger and the payload size is limited by the path MTU, so it's probably smaller. But it's not enough to send performance down the drain.
What's so bad about IPv6? Posted Jan 29, 2011 5:48 UTC (Sat) by jzbiciak (✭ supporter ✭, #5246) [Link] The main place I've seen / heard of enabling IPv6 sending performance down the drain was when someone had it enabled, but some piece of the network they had to pass through or interact with (whether it was their weak ISP-supplied router or a crappy DNS server) didn't actually support it. So, you'd send out a DNS request via IPv6, wait for that to time out, and then fall back to IPv4. Or, at least, so the story goes. Since I'm not really any sort of IPv6 expert, I can only comment on the existence of reports such as these that I've seen go by the last year or two.
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