Wednesday, 24 July 2013

Digression: IPv4 depletion

In order to secure our three fundamentals of air, food/drink, and internet connectivity, Midga and I dropped in on Carphone Warehouse in Spring Gardens. The service is excellent, the prices reasonable (we're paying a total of 45 GBP or roughly 75 AUD for a month to dwell in a telephone cell), and the people friendly. I recommend them if you need a month's service without a contract. (Unlike Australian telephony, this doesn't require five trips back home for more ID. All they needed was some basic details. Of course, this was a prepaid service, and the contract or post-paid ones do require rather more info; but in Australia, just getting a SIM card seems to require ridiculous anti-terrorism checks. The terrorists have already won, when ordinary actions require this much effort.) So we now have a UK SIM card in Midga's phone, and a USB 3G device for Traal.

Which brings me to my point, or my digression, or somesuch. A traceroute from Traal over the 3G connection shows that I have a 192.168/16 address, connecting to a 10/8 address, and - apparently - I do not get an actual internet-addressible device. This is large-scale NAT, one of the popular "solutions" to IPv4 depletion. Now, there's a huge difference between a 3G connection and something you'd want to run servers off, so it's possible that most people will not even notice, much less care, that they're behind NAT; but this is still a problem. NAT has its costs (eg when two devices try to use the same source port number and one of them has to be remapped - or, worse, what happens when there are simply more than 64512 (that's 65536 minus the first 1024 reserved) simultaneous connections), and they're going to become more of a problem as time goes on.

Once IPv4 becomes the subordinate and IPv6 the primary, it won't be a big problem to offer "dual stack IPv6 and NATted IPv4" services, because most work will be done with the v6 address and the v4 will be needed only for connecting to v4-only services (so there won't be too much traffic there, hopefully). But until then, we really need to lean on our telephony providers to roll out IPv6 support. One day it'll be a saleable feature (and then after that it'll become essential and assumed, and IPv4 will be the saleable feature), but for now it's more a matter of not getting left behind. Start sooner rather than later, be part of the future rather than the past, be part of the solution not the precipitate (err I mean problem), and all those cliches. It's far more important than many people give credit for.

2 comments:

Talldad said...

Presumably you have also been there long enough to find chocolate, so that you do not become thin and wizened in your solitary prison?

It is essential to keep up the vita-mins (or vital supplies).

Chris Angelico said...

Yes of course! I said that in the first sentence - food/drink. We have both forms of chocolate.