Havard, On Mar 25, 2008, at 11:50 AM, Havard Eidnes wrote:
The /64 for subnet I can understand, as automatic address assignment relies on it. However, I think I personally would be more cautious in using such big words about the /48 and /32 limits. Sure, they're fine round binary numbers, but are they *really* anything more than that?
They are conventions that some folks thought would help 'site' renumbering and aggregatability.
Maybe it's time to play the "site" card?
No. It's an icky card.
I can easily imagine ISPs having more then 64K (for the americans who might have a problem with math, that's 2^(48-32) :-) DSL users, and with the "one size fits all" address assignment policy outlined above, the ISP would blow through it's entire /32 by handing out IPv6 addresses to 65536 customers.
Yes. Leaving 35,184,372,023,296 (2^45 - 2^16) /48s left in the format prefix assigned to global unicast.
We should never make changes to this architecture without considerable thought and understanding of the reasons why these prefix lengths were chosen.
Which, briefly summarized, were...?
"We got bits. Lots o' bits."? I don't know the rationale myself, but I note that class Bs were once very popular... :-)
IPv6 is not the same as IPv4.
So I continue to see people say, but I've yet to see a justification for such broad sweeping statements which I can agree with justifies the statement. From my perspective it's *really* the same protocol done a second time with more bits,
I suspect it depends on where you look. From a network operations POV, most folks I think would agree that IPv6 is a backwards incompatibly tweaked IPv4 with more bits (giving you most if not all of the problems of IPv4 with little benefit of a new protocol to justify the cost of deployment). From an enterprise POV, you've got addresses coming out of every bodily orifice which is quantitatively different, albeit qualitatively since you're saddled with the same routing crap you have with IPv4, the difference isn't so useful. From an application programmer's POV, you get to touch every piece of network aware code (relinking at a minimum). The VAST TRACTS of address space _may_ provide for new network application architectures and communication techniques, although I'm not holding my breath.
and the number of bits is *not* infinite.
True. There are the same number of /19s, /20s, etc. in IPv6 as there are in IPv4... (I find it odd that some people don't seem to get this). Regards, -drc