> 2 to the power of 128; > 2^128 > 3.4×10^38 It's not that many addressable machines.
Firstly, since we have a lot of address space we can sacrifice some for features. In fact 64b of the 128bit address space is used for the automatic configuration feature. Secondly, IP addressing is hierarchical, not flat. This allows the entire internet to be tracked in about half a million entries on the core routers. That hierarchy "wastes" about another third of the address space. In fact we hope to waste more with IPv6 than with IPv4, in order to keep the number of backbone routes lower. You end up with enough addressing for about a billion medium-sized businesses. That's a lot, but it is very finite, which is why the address delegation bodies manage the address space to limit wastage (eg, requiring a justification for the amount of addressing requested). -glen _______________________________________________ Link mailing list [email protected] http://mailman.anu.edu.au/mailman/listinfo/link
