3 ms·

Pardon my ignorance, but why does it matter that a website is accessible also via an alternative IP-that-happens-to-be-longer? If you have a perfectly good IPv4

by kilian 10y ago

Pardon my ignorance, but why does it matter that a website is accessible also via an alternative IP-that-happens-to-be-longer? If you have a perfectly good IPv4 address, why also get an IPv6 one?

imtringued 10y ago
Because a lot of people don't have a perfectly good (defined as not shared with anyone else) IPv4 adress. Especially not with mobile internet.
phicoh 10y ago
What if you don't have a perfectly good IPv4 address? Fraud relating to obtaining IPv4 addresses is really ramping up, so I guess they must worth serious money now.
sneak 10y ago
It requires that your users maintain dual-stack access and infrastructure, and there are a lot more of them than of you.
hollander 10y ago
Because the IPv4 space has ran out. Nowadays they have to use all kind of tricks to share these addresses. With all mobile phones, and millions of new users in Africa, Asia and South America, plus the Internet of Things, you simply have to use a new system, and you have to transition to that. In the future, people might not be able to use IPv4 at all, or all the time, and then you need your website to be available via both IPv4 and IPv6.
- Symbiote 10y ago
  Can anyone from Africa (especially), Asia, South America or a Pacific island comment on the difference with IPv4 and IPv6 sites? Can you measure a difference in speed, and is it noticeable to the average user? We have a /23 of nice IP addresses. There's no ugly NAT or private addressing at our end, so that's not an argument for us to add IPv6 support. They're part of a university's /15 assignment, so it's not realistic to give them up or sell them. We'll get IPv6 support eventually, I'd guess in 2018-19 or so, but I'm curious if the lack of support causes problems for users in Africa in the mean time.
- exclusiv 10y ago
  How does this matter for the top websites? If a user types in a domain, eventually a root dns responds with an ipv4 A record and resolves to a server the site has configured. Am I missing something?
  - daenney 10y ago
    Because the top websites want user traffic too. If you come from a country that doesn't have IPv4 left the usual deployment scenario is a carrier grade DNS64 with NAT64. You're basically stuck behind a huge ISP NAT which makes quite a few things unpleasant and others downright break down. By supplying v6 you ensure anyone in the world can access it regardless of which IP protocol is deployed by your carrier and how they are or aren't translating from one to the other.
    - exclusiv 10y ago
      Thanks for the explanation. I was under the impression all the ISPs would have ipv4 and handle all the translations to ipv6 clients. Sounds like this is mostly the case, but it has some issues and any new ISP on v6 would have a hard time because a lot of the big sites would be unreachable.
      - bluecmd 10y ago
        Any form of NAT is also much much more expensive than just normal routing. For n:m NAT you need to keep track of sessions for example. This is going to hurt things like BitTorrent among a lot of things.
  - marcus_holmes 10y ago
    According to my understanding, you are correct and it's new domains that suffer. Of course, this becomes political soon enough. As new countries see mass adoption of the interwebs and find out that they have massively smaller allocations of IP addresses than the existing countries they might feel annoyed and do something about it. Tempers flare, shoes are thrown, everyone gets sulky and unhappy. All this could be avoided if we just flipped a few switches, wrote some code, and all moved to IPv6. It's such an easy, small thing to do. Why not just do that and not irritate the living buggery out of everyone?
- prof_hobart 10y ago
  I get why IPv6 is going to be massively important in the future, but we're not (as far as I know) in that future yet, and these sites aren't going to be dropping their v4 addresses as soon as they get V6 ones, so it's not going to be freeing any old addresses up. So - and this is a genuine question - what is the issue right now with, for example, the BBC not yet having an IPv6 address, as long as they have plans in the pipeline for when v6-only clients need to access them?
  - Nullabillity 10y ago
    > So - and this is a genuine question - what is the issue right now with, for example, the BBC not yet having an IPv6 address, as long as they have plans in the pipeline for when v6-only clients need to access them? Because of the catch-22 problem. The BBC sees that no consumers use IPv6 exclusively, and don't bother supporting IPv6 "yet". ISPs see that "no" content providers support IPv6 at all, and then claim that it doesn't provide any real benefit over CGNAT bullshit. And so we'll be stuck in this mess for another century at least...
laksjd 10y ago
NAT. If your server is only available via IPv4 then the client (user) needs an IPv4 address. Sadly there are so few IPv4 addresses that virtually everybody has to share with at least some people/devices and go through NAT (your home/office router, or for countries where ISPs don't have large ip blocks, some large NAT style router at your ISP). NAT is a horrible hack and causes all sorts of issues (port forwarding being the most common issue). If you make your server available on IPv6, too, then I can use my non-shared IPv6 address to communicate with you which means that the packets don't need to undergo NAT which means a less horrible, faster connection without messy port forwarding requirements.
yaantc 10y ago
The IPv4 address may be a private one, with a NAT box between you and the web site. This is very common on cellular networks (because of the large number of devices), even in developing countries with good allotment of IPv4 addresses. They have to do large scale NAT (CGNAT = Carrier Grade NAT), and it can have a bad influence on performance. During peak time those boxes can become a bottleneck. Let's take an example I got from a Cisco presentation, when NAT is used. A map web application may have to download a lot of tiles quickly. It's best done using several parallel TCP connections. Each of those connections must be tracked by the NAT box. At scale and for peak time load, this can become a nightmare and some connections may be dropped --- leading to retries and delays in completing the web page display. With IPv6 this issue doesn't exist. Supporting IPv6 can help providing a better mobile user experience in this case, and is why a lot of the big companies do support IPv6 already. Bypassing CGNAT helps with latency in a situation as in the above example.
vbernat 10y ago
More and more clients are now IPv6 only (notably on mobile). If your service is only accessible through IPv4, the client will access it some kind of stateful equipments to do the conversion between IPv6 and IPv4. You are likely to get a small latency hit but also a lower reliability. As the bigger sites are IPv6 ready (Google/Facebook), the reliability of the translator equipment may not be the top priority.
belorn 10y ago
For one, who would have guessed that bouncing through several layers of nat and a fragmented routing table would mean higher latency? Any website that care about latency should test their servers/cdn's to check if using ipv6 improves loading speed in that area.

by kilian 10y ago

Pardon my ignorance, but why does it matter that a website is accessible also via an alternative IP-that-happens-to-be-longer? If you have a perfectly good IPv4 address, why also get an IPv6 one?

imtringued 10y ago

Because a lot of people don't have a perfectly good (defined as not shared with anyone else) IPv4 adress. Especially not with mobile internet.

phicoh 10y ago

What if you don't have a perfectly good IPv4 address? Fraud relating to obtaining IPv4 addresses is really ramping up, so I guess they must worth serious money now.

sneak 10y ago

It requires that your users maintain dual-stack access and infrastructure, and there are a lot more of them than of you.

hollander 10y ago

Because the IPv4 space has ran out. Nowadays they have to use all kind of tricks to share these addresses. With all mobile phones, and millions of new users in Africa, Asia and South America, plus the Internet of Things, you simply have to use a new system, and you have to transition to that. In the future, people might not be able to use IPv4 at all, or all the time, and then you need your website to be available via both IPv4 and IPv6.

Symbiote 10y ago
Can anyone from Africa (especially), Asia, South America or a Pacific island comment on the difference with IPv4 and IPv6 sites? Can you measure a difference in speed, and is it noticeable to the average user? We have a /23 of nice IP addresses. There's no ugly NAT or private addressing at our end, so that's not an argument for us to add IPv6 support. They're part of a university's /15 assignment, so it's not realistic to give them up or sell them. We'll get IPv6 support eventually, I'd guess in 2018-19 or so, but I'm curious if the lack of support causes problems for users in Africa in the mean time.
exclusiv 10y ago
How does this matter for the top websites? If a user types in a domain, eventually a root dns responds with an ipv4 A record and resolves to a server the site has configured. Am I missing something?
- daenney 10y ago
  Because the top websites want user traffic too. If you come from a country that doesn't have IPv4 left the usual deployment scenario is a carrier grade DNS64 with NAT64. You're basically stuck behind a huge ISP NAT which makes quite a few things unpleasant and others downright break down. By supplying v6 you ensure anyone in the world can access it regardless of which IP protocol is deployed by your carrier and how they are or aren't translating from one to the other.
  - exclusiv 10y ago
    Thanks for the explanation. I was under the impression all the ISPs would have ipv4 and handle all the translations to ipv6 clients. Sounds like this is mostly the case, but it has some issues and any new ISP on v6 would have a hard time because a lot of the big sites would be unreachable.
    - bluecmd 10y ago
      Any form of NAT is also much much more expensive than just normal routing. For n:m NAT you need to keep track of sessions for example. This is going to hurt things like BitTorrent among a lot of things.
- marcus_holmes 10y ago
  According to my understanding, you are correct and it's new domains that suffer. Of course, this becomes political soon enough. As new countries see mass adoption of the interwebs and find out that they have massively smaller allocations of IP addresses than the existing countries they might feel annoyed and do something about it. Tempers flare, shoes are thrown, everyone gets sulky and unhappy. All this could be avoided if we just flipped a few switches, wrote some code, and all moved to IPv6. It's such an easy, small thing to do. Why not just do that and not irritate the living buggery out of everyone?
prof_hobart 10y ago
I get why IPv6 is going to be massively important in the future, but we're not (as far as I know) in that future yet, and these sites aren't going to be dropping their v4 addresses as soon as they get V6 ones, so it's not going to be freeing any old addresses up. So - and this is a genuine question - what is the issue right now with, for example, the BBC not yet having an IPv6 address, as long as they have plans in the pipeline for when v6-only clients need to access them?
- Nullabillity 10y ago
  > So - and this is a genuine question - what is the issue right now with, for example, the BBC not yet having an IPv6 address, as long as they have plans in the pipeline for when v6-only clients need to access them? Because of the catch-22 problem. The BBC sees that no consumers use IPv6 exclusively, and don't bother supporting IPv6 "yet". ISPs see that "no" content providers support IPv6 at all, and then claim that it doesn't provide any real benefit over CGNAT bullshit. And so we'll be stuck in this mess for another century at least...

laksjd 10y ago

NAT. If your server is only available via IPv4 then the client (user) needs an IPv4 address. Sadly there are so few IPv4 addresses that virtually everybody has to share with at least some people/devices and go through NAT (your home/office router, or for countries where ISPs don't have large ip blocks, some large NAT style router at your ISP). NAT is a horrible hack and causes all sorts of issues (port forwarding being the most common issue). If you make your server available on IPv6, too, then I can use my non-shared IPv6 address to communicate with you which means that the packets don't need to undergo NAT which means a less horrible, faster connection without messy port forwarding requirements.

yaantc 10y ago

The IPv4 address may be a private one, with a NAT box between you and the web site. This is very common on cellular networks (because of the large number of devices), even in developing countries with good allotment of IPv4 addresses. They have to do large scale NAT (CGNAT = Carrier Grade NAT), and it can have a bad influence on performance. During peak time those boxes can become a bottleneck. Let's take an example I got from a Cisco presentation, when NAT is used. A map web application may have to download a lot of tiles quickly. It's best done using several parallel TCP connections. Each of those connections must be tracked by the NAT box. At scale and for peak time load, this can become a nightmare and some connections may be dropped --- leading to retries and delays in completing the web page display. With IPv6 this issue doesn't exist. Supporting IPv6 can help providing a better mobile user experience in this case, and is why a lot of the big companies do support IPv6 already. Bypassing CGNAT helps with latency in a situation as in the above example.

vbernat 10y ago

More and more clients are now IPv6 only (notably on mobile). If your service is only accessible through IPv4, the client will access it some kind of stateful equipments to do the conversion between IPv6 and IPv4. You are likely to get a small latency hit but also a lower reliability. As the bigger sites are IPv6 ready (Google/Facebook), the reliability of the translator equipment may not be the top priority.

belorn 10y ago

For one, who would have guessed that bouncing through several layers of nat and a fragmented routing table would mean higher latency? Any website that care about latency should test their servers/cdn's to check if using ipv6 improves loading speed in that area.