The theory put forward by the IETF was simple enough… while there were still enough IPv4 addresses, use transition technologies to migrate to dual stack and then wean IPv4 off over time. All nice and tidy. The way engineers, myself included, liked it. However those controlling the purse strings had a different idea. There was, don't spend a cent on protocol infrastructure improvement until the absolute last minute — there's no ROI in IPv6 for shareholders. Getting in front of the problem at the expense of more marketable infrastructure upgrades was career suicide.
Graph from my 2008 sales presentation… sound but not convincing
By considering this a technical issue rather than a business one, it was easier to delay the inevitable but this had unintended consequences. The fewer IPv4 addresses there were, the fewer technical options there were to address the problem. This coupled with a simpler user experience/expense led us to today and the emergence of the so called Carrier Grade NAT (CGN).
[For a thorough overview of the various flavors of CGN and the choices in front of us, see Phil's post, The Hatred of CGN on gogoNET. Don't let the title fool you.]
By deploying CGNs, ISPs are sharing single IPv4 addresses with more and more households and this isn't good. Why? Because two levels of NAT break things and that leads to unhappy customers. Case in point, British Telecom. BT recently put their retail Option 1 broadband customers (lowest tier) behind CGNs and they are now feeling the pain for a variety of brokenness but mostly because Xbox Live stopped working.
Asian fixed line operators were the first to deploy CGN as a Band-Aid to cover over the problem until the rest of the world standardized on a transition solution. Japan and South Korea notwithstanding I suspect the reasons we haven't heard the same outcry earlier are cultural and the result of lower expectations/SLAs. However in a mature broadband market like the UK where customers are vocal and expectations/SLAs are high you are going to hear about it. And since there isn't a steady stream of new customers to offset the churn, this can turn into a PR nightmare resulting in the loss of high acquisition-cost customers.
Expect to see more of these reports as more European and North American ISPs follow suit. The irony here is it was the British who coined the term, "Penny wise and pound foolish".
Below are a selection of reader comments from the article, "BT Retail in Carrier Grade NAT Pilot”.
Posted by zyborg47 13 days ago:
This IPv4 should have been sorted out a few years back if the larger ISPs have got off their backside and started to change to IPv6 then we would not have this problem and IPv6 routers/modems would not have stayed at such a high price for so long. The problem is now, we the paying public, will suffer because of this, or the poor sods on Bt option one anyway.
Posted by Kushan 13 days ago:
If you start trialing CGNAT before you trial IPv6, you're doing something wrong.
Posted by driz 13 days ago
Is CGNAT even technically an 'internet connection' anymore?
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