Remco van Mook wrote:
Michael
key words here are 'average' and 'generous'. Perhaps you should try to read first. Same goes for your statement of counting addresses. In cases like these, I think orders of magnitude are more interesting than narrowly defined numbers. 4 million is roughly 0.1% of the IPv4 pool. Since I think the AVERAGE ISP is probably smaller than that (either in customer count or allocated space), giving all of them 32 bits (or the full IPv4 space) PLUS 4-8 bits of network space (not host space!) for their 6rd plan sounds wasteful to me.
The 6rd draft has prefix compression for a reason. Sparse number spaces for expansion and automation are fine. Very sparse number spaces you know from the outset will never be filled or usable for other purposes, are not.
Actually, the main reason we added this is for easy and obvious compression for when an SP has decided to run NAT. The RFC1918 space is nicely aggregated. Please don't give SPs more reasons to deploy NATted IPv4 service. Most SPs I talk to don't really like the idea of compressing the global space, if nothing else because they have no assurance that the global IPv4 space they have now will be the same in the future. They'd sooner give the customer a /64, which I've already stated why I personally think is dangerous.
That is why deploying multiple instances of 6rd in order to benefit from prefix compression to collapse that required number space without losing functionality sounds like the right direction for me.
There is nothing prohibiting multiple instances of 6rd in the current version of the draft, however note that this does not come without operational complexity - which is exactly what 6rd is trying to allow an SP to avoid. So, there's a cost tradeoff here. Increased prudence of IPv6 space vs. increased cost for ISPs to deploy IPv6. It's quite easy to be penny-wise and pound-foolish here, and given the rate of native deployment of IPv6 thus far, I'd err on the side of getting IPv6 out the door in the short term until we are sure it no longer needs a boost. Consider it similar to stimulus funds to counter a depression if you must, but if an ISP which would otherwise qualify for a /30 needs a /28 or /26 to get IPv6 deployed now vs. later, I'd choose handing out a few more bits until we no longer think it necessary for native IPv6 adoption to occur. - Mark