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The Internet Networking News

UK ISPs Respond To the Dangers of Using Carrier Grade NAT Instead of IPv6 165

Posted by Unknown Lamer
from the ten-years-warning-insufficient dept.
Mark.JUK writes "Several major Internet Service Providers in the United Kingdom, including BSkyB, Virgin Media, TalkTalk, AAISP and Fluidata, have warned that the adoption of Carrier Grade NAT (IPv4 address sharing) is likely to become increasingly common in the future. But the technology, which many view as a delaying tactic until IPv6 becomes more common place, is not without its problems and could cause a number of popular services to fail (e.g. XBox Live, PlayStation Network, FTP hosting etc.). The prospect of a new style of two tier internet could be just around the corner." A few of the ISPs gave the usual marketing department answers, but three of them noted that they've been offering IPv6 for ages and CGNAT is only inevitable for folks that didn't prepare for what they knew was coming. Which, unfortunately, appears to be most of the major UK ISPs.
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UK ISPs Respond To the Dangers of Using Carrier Grade NAT Instead of IPv6

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  • by somersault (912633) on Wednesday January 23, 2013 @12:56PM (#42670637) Homepage Journal

    Judging from what I've read about US telcos and ISPs, and the plans I've seen for mobile and broadband access here, it sounds like you have that the wrong way round. We have way more competition and better pricing in the UK.

  • by lattyware (934246) <gareth@lattyware.co.uk> on Wednesday January 23, 2013 @01:29PM (#42671057) Homepage Journal
    I disagree - in some areas, no ISP that offers IPv6 covers the area, and tunnels are hard to set up (for average joe) and relatively slow.
  • by tlhIngan (30335) <(ten.frow) (ta) (todhsals)> on Wednesday January 23, 2013 @01:32PM (#42671115)

    Usually when you see a "demand" for NAT on ipv6 its people who don't understand the relationship between a statefull firewall and NAT, and they really are "demanding" their existing firewall minus the NAT part.

    2 advantages of NAT beyond firewalling:

    1) Apps know there's NAT, and cannot assume end-to-end connectivity. With IPv6, determining if there's end to end connectivity is much hardware because firewalls are transparent - you may be able to establish a partial link, but not a full one because the firewall lets some of the packets through. In the early days of NAT, this caused no end to confusion with old protocols (e.g., FTP) where one could connect to the FTP server, but fail to transfer data. These days, FTP clients often check to see if their IP address is in the reserved range and default to passive mode.

    And trust me, trying to figure out why some client only worked partially is a royal annoyance until everyone started designing protocols to be smarter with their connections so you don't have to open 100 ports to play a game anymore.

    2) It isolates the internal network numbering from the external. For 90% of home users, this would lead to blissful ignorance - their ISP can give them a new prefix and if they lose connectivity, they reboot the router and away they go. Do it in a traditional router environment where every PC needs ot use the prefix, and it's bound to happen that the next time their ISP changes prefixes, users get messed up. And diagnosing why would mean having to talk to family on the phone as remoting in is impossible (no connectivity, remember?), or a long drive out. Or family meetings where there's a pile of PCs in the corner as "they can't get on the internet".

    Sure, it's supposed to be transparent and smooth, but that just means it likely won't. And since every internet-connected IPv6 machine will have at least two IPv6 addresses, chances are it's going to be some VERY long conversations with family leading to guilt trips and having to do onsite support. Just get me a box that does NATv6, DHCPv6 that I can drop in and tell my parents to reboot if they have issues and things revert back to how it works right now in the IPv4 era.

    Plus, for me, i don't want to have to know the new IP address of my printer just because my ISP renumbered and gave me a different prefix, which means I'd probably have to use the reserved address space for that stuff so my IPv6 addresses don't keep wandering around, or having to update my )(@&#% firewall rules if there are some devices I don't want on the internet (data caps, remember?) but which always helpfully sniff router advertisements and other such autoconfiguration things in attempts to get on the 'net.

  • Already happened (Score:5, Informative)

    by homb (82455) on Wednesday January 23, 2013 @02:36PM (#42671929)

    CGN has already happened in countries that were late on the Internet bandwagon and got too few IPs.
    I am currently an unfortunate subscriber going through CGN, and let me tell you, the time I spent debugging connectivity issues is mindblowing.
    For those who don't understand the extent of the problem, CGN is also called NAT444:
    Your internal network has an IPv4 subnet, say 10.17.0.x. Then your router is allocated an IPv4 from your ISP. You think that's your IP, but it isn't. Your ISP itself is running NAT internally, and ultimately your data is being sent through the wire to the wider Internet with yet another IP.
    So you have 3 networks: IPv4 IPv4 IPv4
    Practically speaking, nothing that acts as a server will work. i.e. none of the modern multiplayer networking stacks work reliably, for example. When testing your PS3 networking, it will say (correctly) that you are screwed because you have a "Type 3 NAT", which is Sony speak for NAT444.

  • by Anonymous Coward on Wednesday January 23, 2013 @04:01PM (#42672855)

    The copper PSTN network that means everyone has a telephone exchange near them was originally built by the Post Office (ie by the government). The telephone service half of the Post Office was then privatised as BT (the postal part became Royal Mail).

    Regulations to avoid BT becoming a monopoly mean that BT has to offer other companies the ability to provide their own DSL services hosted on BT's DSLAMs (BT Wholesale). LLU (Local Loop Unbundling) then meant that BT had to allow the companies access to the exchanges to install their own DSLAMs.

    The result is that in all built up areas you have dozens of companies offering LLU products. Using their own DSLAMS means they can provide better services than BT Wholesale, so for example ADSL2 was rolled out on a small number of LLU products before BT rolled it out. Even in rural areas where it's not cost effective for companies to install LLU options you still get a large number of companies able to provide a reasonable service via BT Wholesale, even if the older DSLAM tech and longer distances limit you to 8MB there.

  • by Alomex (148003) on Wednesday January 23, 2013 @04:27PM (#42673113) Homepage

    As you Brits say, bollocks.

    Here's just one example:

    In 2008, the European Commission announced that costs for sending roaming texts were also too high and, if the mobile industry didn't voluntarily drop prices, further mobile roaming regulations could follow.

    Mobile service providers ignored this warning, so the Commission has now regulated mobile roaming text prices, too. From 1 July 2009, all mobile service providers were forced to drop their text prices to 11p per text sent. Receiving texts while abroad is free.

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