> -----Original Message----- > From: Richard A Steenbergen [mailto:r...@e-gerbil.net] > Sent: Monday, January 25, 2010 12:08 > To: TJ > Cc: nanog@nanog.org > Subject: Re: Using /126 for IPv6 router links > > On Mon, Jan 25, 2010 at 09:10:11AM -0500, TJ wrote: > > While I agree with parts of what you are saying - that using the "simple > > 2^128" math can be misleading, let's be clear on a few things: > > *) 2^61 is still very, very big. That is the number of IPv6 network > > segments available within 2000::/3. > > *) An end-user should get something between a /48 and a /56, _maybe_ as low > > as a /60 ... hopefully never a /64. Really. > > **) Let's call the /48s enterprise assignments, and the /56s home > > assignments ... ? > > **) And your /56 to /64 is NOT 1-256 IPs, it is 1-256 segments. > > It is if we are to follow the "always use a /64 as a single IP" > guidelines. Not that I'm encouraging this, I'm just saying this is what > we're told to do with the space. I for one have this little protocol > called DHCP that does IP assignments along with a bunch of other things > that I need anyways, so I'm more than happy to take a single /64 for > house as a single lan segment (well, never minding the fact that my > house has a /48).
Interesting. I have never seen anyone say "always use a /64 as a single IP" ... perhaps you mean as an IP segment or link? You are assigned a /64 if it is "known" that you only need one segment, which yields as many IPs as you want (18BillionBillion or so) - and the reality is that a home user should get a /56 and an enterprise should get a /48, at the very least - some would say a /48 per site. > > **) And, using the expected /48-/56, the numbers are really 256-64k subnets. > ... > > Note: "All we've really done is buy ourselves an 8 to 16 bit improvement at > > every level of allocation space" > > *) And you don't think 8-16 bits _AT EVERY LEVEL_ is a bit deal?? > > I'm not saying that 8-16 bits isn't an improvement, but it's a far cry > from the bazillions of numbers everyone makes IPv6 out to be. By the > time you figure in the overhead of autoconfiguration, restrictive > initial deployments, and the "now that the space is much bigger, we > should be reallocating bigger blocks" logic at every layer of > redistribution, that is what you're left with. So far all we've really > done with v6 is created a flashback to the days when every end user > could get a /24 just by asking, every enterprise could get a /16 just by > asking, and every big network could get a /8 just by asking, just bit > shifted a little bit. That's all well and good, but it isn't a > bazillion. :) There are some similarities between IPv6 and old classful addressing, but the bit-boundaries chosen were intentionally made big and specifically factoring in the then-ongoing scarcity (Ye olde Class B exhaustion). The scale of the difference *is* the difference. I am not quite sure what a bazillion is, but when we get into the Billion Billion range I think that is close enough! :) /TJ
