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SubjectRe: IPv6 and the "average user"

>>>>> "hpa" == H Peter Anvin <> writes:

hpa> Followup to: <3h7mnhjs36.fsf@Q.Net> By author: Bradley Ward
hpa> Allen <> In newsgroup:
>> For instance, IPv4 has an address space of 2^32, or
>> 4,294,967,296, addresses. That's a few billion less than there
>> are people on the earth, or thereabouts, and we double every 60
>> years anyway (remember, half the people ever alive still are,
>> or are dead, or however you prefer to look at two halves). At
>> first glance 4,294,967,296 looks like a big number, but if your
>> base is today's population, then it looks rather smallish (less
>> than 1).

hpa> It is also important to point out that for various technical
hpa> reasons, the actual number of possible hosts turn out to be
hpa> much lower than that. Someone proposed a law saying that
hpa> "the utilization of address space is inversely proportional
hpa> to the address length"; although I personally think this law
hpa> is overly optimistic, there is definitely a strong effect: as
hpa> the address space goes larger, the more hierarchial it needs
hpa> to become, and the less efficient the address utilization.

hpa> Either way, the results are the same -- 32 bits is just
hpa> hideously insufficient. Personally I think it was a bad move
hpa> of the IETF to pick a fixed-length standard for IPng (IP -
hpa> The Next Generation), but my understanding is that router
hpa> manufacturers (read: C*sc*) insisted...

Which is quite natural as nobody in it's right mind would want to route
variable length addresses. Variable length fields should only exist in
data to be processed in slow paths. Anyway, 128 bits is more than enought
for IPv6. Note that the 32 bits where a good choice for IPv4.


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