6 ms·

The Future Without IPv6

17 points by prakash 18y ago

bandris 18y ago
When I worked at GE I was very suprised that _every_ computer had an ip adresses like 3.xxx.xxx.xxx even though we were on intranet.
- wmf 18y ago
  That's how the Internet was originally supposed to work, but now people are surprised by it.
  - bandris 18y ago
    Yes, but we were not directly on the internet. We used proxy and NAT.
    - axod 18y ago
      So if there becomes a call for it, I expect they could lanch an ISP arm and use their IPs. Or else lease out their IP space to ISPs that can't find enough IP space. The market will sort itself out and all will be fine.
tptacek 18y ago
The article's right that IPv6 isn't going to happen. I'm not sure it makes any points besides that. (1) It's hard to fear our NAT-ed future when we're all living in the NAT-ed present to little ill effect. A typical large company today has more than a /19 allocated to it; if we're really talking about exhausting the TCP endpoint space, that /19 offers 536,000,000 concurrent connections. ISP distribution layers might not do that many packets per second. (1a) If multiplexing is the problem, we can solve that in a subtransport-layer protocol without a worldwide ISP flag day that renumbers the whole world. There are already transports that are more multiplexing-friendly than TCP --- for instance, SCTP, a well-researched telco protocol. (2) IPv6 exacerbates routing problems; it doesn't solve them. Routing table explosion and address space size are orthogonal. (3) If we're embracing our NAT'd future anyways, I'm not sure I care how routable IPv4 are traded, or who has to go ask Halliburton to start paying for their obscene legacy allocation. You decided to work for the ISP, not me. Have fun!
- ovi256 18y ago
  Re: your 1. NAT breaks one of the founding principles of the Internet, that of end-to-end connectivity [1]. This is may not seem important, but universal end-to-end connectivity, coupled with lower-layer abstraction and transparency, is required for further innovation and deployment of new protocols and applications. Think about the trouble that VoIP protocols (SIP, H323) have when traversing NAT. We invented UPnP NAT Traversal, STUN or some equivalent, all patches for the lack of end-to-end connectivity, hoops that NAT makes us jump through, with no benefit (but added complexity) for the end user. Thus, we can see how NAT can slow and discourage innovation by raising starting cost. The alternative, IPv6, is simpler and solves a host of problems in a single shot. Unfortunately, inertia and fear of change will delay its adoption more than necessary. [1] http://en.wikipedia.org/wiki/End-to-end_connectivity http://en.wikipedia.org/wiki/End-to-end_connectivity
  - tptacek 18y ago
    That's just a religious argument. You can argue it exactly the opposite way: that applications requiring direct IPv4 addressing are enlisting the Internet to accomplish things the apps should be doing for themselves, and are in fact breaking e2e. For a concrete example, see FTP, arguably the most famously bad protocol we have. The "hoops" we have to jump through to traverse NAT seem kind of trivial when you compare them to the fluid-dynamic-theoretic modeling we had to go through to avoid congestion collapse in the early '90s. If you're new to the game, I'm sure NAT traversal seems like overkill, but you really should try BGP prefix filtering or writing a TCP-friendly transport protocol. The fact is, the overwhelming majority of Internet users are now NAT'd. The Internet works better today than it did when everyone got static IP addresses. And the problems that remain can be solved at the transport layer, without forklifting out routers. What problems does IPv6 really solve?
    - phaedrus 18y ago
      No, it's not just a "religious" argument. NAT really does violate the way the internet was supposed to work; it causes real technical problems, not just aesthetic ones. In fact, NAT is a nasty kludge by the strictest definition of the word. Have you ever written code that routes packets? I have! Not only does NAT break the end to end connectivity rule, but it also breaks data encapsulation. In order to work it has to open up the data and tweak IP and port numbers to give the illusion that the NATed networks have end to end connectivity. That's why NAT causes problems with VoIP and is stifles the development of new, innovative protocols because it doesn't transparently handle new protocols. IP was conceived in such a way that TCP, UDP, and other protocols could be layered on top of it, but because NATs break the encapsulation, with NAT each new protocol requires every router's NAT to be reprogrammed to know how to handle it. If IP had been designed with NAT in mind, it might not be so broken now. That's one of the problems IPv6 is supposed to solve - it doesn't need a NAT, but it also works better over NAT than IPv4! So if you think NAT beats static IPs, you should actually prefer IPv6 because it has non-broken NAT support! Furthermore, please define exactly what you mean when you say that applications which don't work with (leaky, broken IPv4 NAT) are "enlisting the Internet to accomplish things the apps should be doing for themselves, and are in fact breaking e2e." How exactly is an app supposed to "do something for itself" in getting a communication channel open when it can't get any packets through the NAT to communicate in the first place? For instance, most NATs don't allow unexpected incoming connections. Say I have a computer and a friend has another one on another ISP, so we're behind different NATs. Now say I'm developing (in fact I really am developing) an online MMO game. Without a public, static IP address for one of us, or a public server to bounce off of (which we don't have yet because we're only just starting our company) it will be impossible for us to connect directly to each other to test our setup over the internet. What IP:port would one of us type in to get to the other's machine? All each of us can reach is the public IP of the ISP's NAT. In order to make a connection, we have to punch out through the NAT first but punch out to where? We need a public IP, but in a world where every consumer is behind a NAT and all the IPv4 addresses are used up or cost more than we can afford, how are we going to get our start? On the other hand, if the world, right now, switched to IPv6, we'd have no trouble connecting to each other to test our game server, and we could do it from a consumer home internet connection. Ah, but that's the real reason we're stuck with IPv4 and NAT. The internet was meant to be a network where every computer is equal, and in that environment anyone could set up a server and start doing business or providing their own content. No more. Now, thanks to a completely avoidable numbering shortage and a NAT-hell, the internet is getting to be more like television - big company's servers provide the content, and you consume it, just as the media companies and cable companies like it. You won't be able to say, "hell with their Terms of Service, I'll host my site myself". And fat chance making much money for yourself off your web-2.0 company if you are forced to host your servers with a bigger company in order to get a public IP. That's what the world without IPv6 looks like.
anr 18y ago
Here's a good explanation of what went wrong: http://cr.yp.to/djbdns/ipv6mess.html http://cr.yp.to/djbdns/ipv6mess.html "The IPv6 designers made a fundamental conceptual mistake: they designed the IPv6 address space as an alternative to the IPv4 address space, rather than an extension to the IPv4 address space."
- xirium 18y ago
  I can highly recommend reading RFC1365 ( http://www.faqs.org/rfcs/rfc1365.html http://www.faqs.org/rfcs/rfc1365.html ) which defines IP extension blocks to provide huge address spaces within IPv4 while retaining full downward compatibility with legacy routers and hosts. Such extension blocks should also be compatible with NAT and jumbo frames.
mleonhard 18y ago
The limit of concurrent connections is only between two hosts. If a Host X can maintain 2^16 TCP connections to Host Y, then it should also be able to maintain 2^16 TCP connections to Host Z, Host A, Host B, etc. Thus, a host could theoretically maintain 65536 TCP sessions with every host on the Internet.
- cheponis 18y ago
  The problem, of course, is if the "host" is actually a huge collection of machines that hide behind a single IP of a NAT.

17 points by prakash 18y ago

When I worked at GE I was very suprised that _every_ computer had an ip adresses like 3.xxx.xxx.xxx even though we were on intranet.

wmf 18y ago
That's how the Internet was originally supposed to work, but now people are surprised by it.
- bandris 18y ago
  Yes, but we were not directly on the internet. We used proxy and NAT.
  - axod 18y ago
    So if there becomes a call for it, I expect they could lanch an ISP arm and use their IPs. Or else lease out their IP space to ISPs that can't find enough IP space. The market will sort itself out and all will be fine.

tptacek 18y ago

The article's right that IPv6 isn't going to happen. I'm not sure it makes any points besides that. (1) It's hard to fear our NAT-ed future when we're all living in the NAT-ed present to little ill effect. A typical large company today has more than a /19 allocated to it; if we're really talking about exhausting the TCP endpoint space, that /19 offers 536,000,000 concurrent connections. ISP distribution layers might not do that many packets per second. (1a) If multiplexing is the problem, we can solve that in a subtransport-layer protocol without a worldwide ISP flag day that renumbers the whole world. There are already transports that are more multiplexing-friendly than TCP --- for instance, SCTP, a well-researched telco protocol. (2) IPv6 exacerbates routing problems; it doesn't solve them. Routing table explosion and address space size are orthogonal. (3) If we're embracing our NAT'd future anyways, I'm not sure I care how routable IPv4 are traded, or who has to go ask Halliburton to start paying for their obscene legacy allocation. You decided to work for the ISP, not me. Have fun!

ovi256 18y ago
Re: your 1. NAT breaks one of the founding principles of the Internet, that of end-to-end connectivity [1]. This is may not seem important, but universal end-to-end connectivity, coupled with lower-layer abstraction and transparency, is required for further innovation and deployment of new protocols and applications. Think about the trouble that VoIP protocols (SIP, H323) have when traversing NAT. We invented UPnP NAT Traversal, STUN or some equivalent, all patches for the lack of end-to-end connectivity, hoops that NAT makes us jump through, with no benefit (but added complexity) for the end user. Thus, we can see how NAT can slow and discourage innovation by raising starting cost. The alternative, IPv6, is simpler and solves a host of problems in a single shot. Unfortunately, inertia and fear of change will delay its adoption more than necessary. [1] http://en.wikipedia.org/wiki/End-to-end_connectivity http://en.wikipedia.org/wiki/End-to-end_connectivity
- tptacek 18y ago
  That's just a religious argument. You can argue it exactly the opposite way: that applications requiring direct IPv4 addressing are enlisting the Internet to accomplish things the apps should be doing for themselves, and are in fact breaking e2e. For a concrete example, see FTP, arguably the most famously bad protocol we have. The "hoops" we have to jump through to traverse NAT seem kind of trivial when you compare them to the fluid-dynamic-theoretic modeling we had to go through to avoid congestion collapse in the early '90s. If you're new to the game, I'm sure NAT traversal seems like overkill, but you really should try BGP prefix filtering or writing a TCP-friendly transport protocol. The fact is, the overwhelming majority of Internet users are now NAT'd. The Internet works better today than it did when everyone got static IP addresses. And the problems that remain can be solved at the transport layer, without forklifting out routers. What problems does IPv6 really solve?
  - phaedrus 18y ago
    No, it's not just a "religious" argument. NAT really does violate the way the internet was supposed to work; it causes real technical problems, not just aesthetic ones. In fact, NAT is a nasty kludge by the strictest definition of the word. Have you ever written code that routes packets? I have! Not only does NAT break the end to end connectivity rule, but it also breaks data encapsulation. In order to work it has to open up the data and tweak IP and port numbers to give the illusion that the NATed networks have end to end connectivity. That's why NAT causes problems with VoIP and is stifles the development of new, innovative protocols because it doesn't transparently handle new protocols. IP was conceived in such a way that TCP, UDP, and other protocols could be layered on top of it, but because NATs break the encapsulation, with NAT each new protocol requires every router's NAT to be reprogrammed to know how to handle it. If IP had been designed with NAT in mind, it might not be so broken now. That's one of the problems IPv6 is supposed to solve - it doesn't need a NAT, but it also works better over NAT than IPv4! So if you think NAT beats static IPs, you should actually prefer IPv6 because it has non-broken NAT support! Furthermore, please define exactly what you mean when you say that applications which don't work with (leaky, broken IPv4 NAT) are "enlisting the Internet to accomplish things the apps should be doing for themselves, and are in fact breaking e2e." How exactly is an app supposed to "do something for itself" in getting a communication channel open when it can't get any packets through the NAT to communicate in the first place? For instance, most NATs don't allow unexpected incoming connections. Say I have a computer and a friend has another one on another ISP, so we're behind different NATs. Now say I'm developing (in fact I really am developing) an online MMO game. Without a public, static IP address for one of us, or a public server to bounce off of (which we don't have yet because we're only just starting our company) it will be impossible for us to connect directly to each other to test our setup over the internet. What IP:port would one of us type in to get to the other's machine? All each of us can reach is the public IP of the ISP's NAT. In order to make a connection, we have to punch out through the NAT first but punch out to where? We need a public IP, but in a world where every consumer is behind a NAT and all the IPv4 addresses are used up or cost more than we can afford, how are we going to get our start? On the other hand, if the world, right now, switched to IPv6, we'd have no trouble connecting to each other to test our game server, and we could do it from a consumer home internet connection. Ah, but that's the real reason we're stuck with IPv4 and NAT. The internet was meant to be a network where every computer is equal, and in that environment anyone could set up a server and start doing business or providing their own content. No more. Now, thanks to a completely avoidable numbering shortage and a NAT-hell, the internet is getting to be more like television - big company's servers provide the content, and you consume it, just as the media companies and cable companies like it. You won't be able to say, "hell with their Terms of Service, I'll host my site myself". And fat chance making much money for yourself off your web-2.0 company if you are forced to host your servers with a bigger company in order to get a public IP. That's what the world without IPv6 looks like.

anr 18y ago

Here's a good explanation of what went wrong: http://cr.yp.to/djbdns/ipv6mess.html http://cr.yp.to/djbdns/ipv6mess.html "The IPv6 designers made a fundamental conceptual mistake: they designed the IPv6 address space as an alternative to the IPv4 address space, rather than an extension to the IPv4 address space."

xirium 18y ago
I can highly recommend reading RFC1365 ( http://www.faqs.org/rfcs/rfc1365.html http://www.faqs.org/rfcs/rfc1365.html ) which defines IP extension blocks to provide huge address spaces within IPv4 while retaining full downward compatibility with legacy routers and hosts. Such extension blocks should also be compatible with NAT and jumbo frames.

mleonhard 18y ago

The limit of concurrent connections is only between two hosts. If a Host X can maintain 2^16 TCP connections to Host Y, then it should also be able to maintain 2^16 TCP connections to Host Z, Host A, Host B, etc. Thus, a host could theoretically maintain 65536 TCP sessions with every host on the Internet.

cheponis 18y ago
The problem, of course, is if the "host" is actually a huge collection of machines that hide behind a single IP of a NAT.