nanog mailing list archives
Re: ISP customer assignments
From: William Herrin <herrin-nanog () dirtside com>
Date: Mon, 5 Oct 2009 14:37:49 -0400
On Mon, Oct 5, 2009 at 2:10 PM, Brian Johnson <bjohnson () drtel com> wrote:
What would be "wrong" with using a /64 for a customer who only has a local network? Most home users won't understand what a subnet is.
It's a question of convenience... your customers', but more importantly yours. Every time you have to deviate from your default, whatever default you pick, that's an extra overhead cost you have to bear. Absent a compelling reason not to, you should structure your default choice so that it accommodates as many customers as possible. There are too many good reasons why someone might want to use two subnets with two different security policies and not enough reasons (zero in fact) why it would help you to give them less subnets than the 16 in a /60.
So a customer with a single PC hooked up to their broad-band connection would be given 2^64 addresses? I realize that this is future proofing, but OMG! That’s the IPv4 Internet^2 for a single device!
Some clever guy figured out that if you use 64 bits you can write algorithms that automatically assign an interface's IP address based on its MAC address without having to arp for it. Since the details of IPv6 were not yet firmly fixed at that point and ram is cheap, why not add an extra 64 bits for that very convenient improvement? This is called "stateless autoconfiguration." Some even more clever guy figured out that if the first clever guy's strategy is used, it becomes a trivial matter to track someone online... based on the last 64 bits of their IP address which will remain static for the life of the hardware they use regardless of where they connect to the 'net. Given this rather blatent weakness and given that you still need DHCP to assign DNS resolvers and the like, stateless autoconfiguration will probably end up being a waste. That's unfortunate, but look at it this way: the important part is not how many addresses are wasted, it's how many addresses are usable. Regards, Bill Herrin -- William D. Herrin ................ herrin () dirtside com bill () herrin us 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004
Current thread:
- RE: ISP customer assignments, (continued)
- RE: ISP customer assignments TJ (Oct 05)
- Re: ISP customer assignments Owen DeLong (Oct 05)
- Re: ISP customer assignments Kevin Loch (Oct 06)
- Re: ISP customer assignments Joe Greco (Oct 05)
- Re: ISP customer assignments Joel Jaeggli (Oct 05)
- Re: ISP customer assignments Carsten Bormann (Oct 05)
- Re: ISP customer assignments Seth Mattinen (Oct 05)
- Re: ISP customer assignments William Herrin (Oct 05)
- RE: ISP customer assignments Brian Johnson (Oct 05)
- Re: ISP customer assignments Chuck Anderson (Oct 05)
- Re: ISP customer assignments William Herrin (Oct 05)
- Re: ISP customer assignments Ricky Beam (Oct 05)
- Re: ISP customer assignments Dan White (Oct 05)
- Re: ISP customer assignments Valdis . Kletnieks (Oct 05)
- Re: ISP customer assignments Dan White (Oct 05)
- Re: ISP customer assignments Ricky Beam (Oct 05)
- Re: ISP customer assignments Dan White (Oct 06)
- RE: ISP customer assignments Brian Johnson (Oct 05)
- RE: ISP customer assignments TJ (Oct 05)
- Re: ISP customer assignments Valdis . Kletnieks (Oct 05)
- Message not available
- Re: ISP customer assignments Dan White (Oct 06)
- Re: ISP customer assignments TJ (Oct 06)