-- On Sun, 12/23/07, Chris Adams <cmadams@hiwaay.net> wrote:
From: Chris Adams <cmadams@hiwaay.net> Subject: Re: v6 subnet size for DSL & leased line customers To: nanog@merit.edu Date: Sunday, December 23, 2007, 2:21 PM Once upon a time, Florian Weimer <fw@deneb.enyo.de> said:
Right now, we might say "wow, 256 subnets for a single end-user... hogwash!" and in years to come, "wow, only 256 subnets... what were we thinking!?"
Well, what's the likelihood of the "only 256 subnets" problem?
There's a tendency to move away from (simulated) shared media networks. "One host per subnet" might become the norm.
So each host will end up with a /64?
How exactly are end-users expected to manage this? Having a subnet for the kitchen appliances and a subnet for the home theater, both of which can talk to the subnet for the home computer(s), but not to each other, will be far beyond the abilities of the average home user.
As I see it, one of the big benefits IPv4 provided was logical addresssing in an easy-to-understand and easy-to-aggregate manner, with small layer-2 networks divided by routers. What we've gone to with IPv6 is a gigantic layer-2 network (the flat autoconfiguration space). I think we got here when "site-local" went away - we've effectively redefined link-local to mean "site-local," while using globally unique addressing. Personally, I don't relish the idea of millions of hosts participating in spanning-tree, so I'd rather see us move back toward the direction of using layer-3 addresses to break up layer-2 islands. How about this for a modest proposal for a capability: Allow autoconfigured generation of IPv6 interface addresses to use this format: (one byte VLAN ID) (48 bit MAC address) instead of: (24 bit half-mac) (FFFE) (24 bit half-MAC) This would allow a CPE router to serve as the gateway for up to 64K VLANs, and wouldn't waste a byte in the middle of the address space. How about it? David Barak Need Geek Rock? Try The Franchise: http://www.listentothefranchise.com ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ