Austria-Hungary adopted the metric system in the 1870s. Back then: no cars, no highways, no speeding laws etc. Oxen-drawn wagons in the countryside were not built to a precise spec.
Only the railway, the architects and the artillery had to really switch. Ordinary people would still ask the grocer for half a pound of ham in the 1930s.
USA in the 1970s would have to remeasure all the land communications etc., or end up with a weird hybrid like the UK.
WHat we have in IPv4 and IPv6 is the weird UK-like hybrid...
* https://en.wikipedia.org/wiki/Metrication_in_Australia
It's going to take decades, mostly waiting for the non-metric folks to die off probably and the raised-on-metric folks to grow up, but if you don't start you'll never finish.
† Can Aussie HNer confirm?
These are all customary usage so I'd say we are completely switched over, we couldn't tell you generally what these units look like outside of "how big is a baby" or "how tall is that person" or "is my beer large or small" really.
That goes back to the fact that the imperial system replaced the older customary system after the American revolution. The US legislated a somewhat simplified version of the Customary System the English were using at the time, which was a piecemeal system based on several different acts of parliament over hundreds of years. We (much) later made slight changes so that our measurements are based on metric.
The Imperial System was instituted in the UK in 1826 and most of the measurements stayed the same, which is why our foot and pound are the same as your foot and pound. The biggest change was that imperial simplified the various liquid measurements to make them uniform. Before then, different liquids used different measurements. The gallon used in the US was originally based on the wine gallon whose value had been last set by parliament in 1709.
Construction: "two-bys" are used, with 16/19.2/24" offsets for studs and such (though the building code has millimetre equivalents).
There is no 'just' extending the address length:
So it's a matter of mathematical and physical fact that to expand
the address size, you must change the protocol, and that means
[three] things immediately:
You have to change the version number.
You have to add new code to handle the new version.
[…]
You need a coexistence technique so that updated systems,
with the new protocol, can connect to old systems that know
nothing of the new protocol.
Two minutes of thought show that this third requirement has only
two solutions:
(3A) Dual stack, in which the new machines speak both
the old (IPv4) and new (IPng) protocol.
(3B) Translation, in which something translates addresses
between the old and new protocols.
* https://datatracker.ietf.org/doc/html/rfc1671
You also have to update DNS to create new resource record types ("A" is hard-coded to 32-bits) to support the new longer addresses, and have all user-land code start asking for, using, and understanding the new record replies. Just like with IPv6. (A lot of legacy code did not have room in data structures for multiple reply types: sure you'd get the "A" but unless you updated the code to get the "A+" address (for "IPv4+" addresses) you could never get to the longer with address… just like IPv6 needed code updates to recognize AAAA, otherwise you were A-only.)
In any 'address extension' plan the legacy code cannot use the new address space; you have to:
* update the IP stack (like with IPv6)
* tell applications about new DNS records (like IPv6)
* set up translation layers for legacy-only code that cannot be update to reach extended-address-only destination (like IPv6 with DNS64/NAT64, CLAT, etc)
Of course, back here in the real world you can look at the RFCs yourself and see that they're credited to places like Ipsilon Networks, Xerox and Sun Microsystems. Boring corporate network companies.
This was not a "mistake":
So it's a matter of mathematical and physical fact that to expand
the address size, you must change the protocol, and that means
[three] things immediately:
You have to change the version number.
You have to add new code to handle the new version.
[…]
You need a coexistence technique so that updated systems,
with the new protocol, can connect to old systems that know
nothing of the new protocol.
Two minutes of thought show that this third requirement has only
two solutions:
(3A) Dual stack, in which the new machines speak both
the old (IPv4) and new (IPng) protocol.
(3B) Translation, in which something translates addresses
between the old and new protocols.
Except there will be a period of time when many 'network elements' (routers, firewalls, servers (web, SMTP, DNS, etc), clients) will not be updated for the new protocol so you may also need 3B.
And this will be true for any IPng, and not just the one that just happened to be chosen to be for "IPv6" (which was SIPP, over CATNIP and TUBA; see RFC 1752).
> Let me keep my old address on the new protocol.
You can/could. You can encourage people who have addresses in the older protocol to use the new one with "free" "automatic" address assignments in the new one to encourage translation and tunnelling:
> For any 32-bit global IPv4 address that is assigned to a host, a 48-bit 6to4 IPv6 prefix can be constructed for use by that host (and if applicable the network behind it) by appending the IPv4 address to 2002::/16.
> For example, the global IPv4 address 192.0.2.4 has the corresponding 6to4 prefix 2002:c000:0204::/48. This gives a prefix length of 48 bits, which leaves room for a 16-bit subnet field and 64 bit host addresses within the subnets.
* https://en.wikipedia.org/wiki/6to4
And the 'old' IPv4 addresses are available in the new IPv6 world:
> Addresses in this group consist of an 80-bit prefix of zeros, the next 16 bits are ones, and the remaining, least-significant 32 bits contain the IPv4 address. For example, ::ffff:192.0.2.128 represents the IPv4 address 192.0.2.128. A previous format, called "IPv4-compatible IPv6 address", was ::192.0.2.128; however, this method is deprecated.[5]
* https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresse...
There is no way around this limitation: you must have a separate network space because of physical limitations.
Your supposed solution, and many others, have been thought of already. Have been tried. You are not thinking of anything new in your proposal.
… except for the fact that you have to have completely new data structures and packet format to fit more address bits, and once you change the structures you need a new version field so any gear that sees a packet knows where to use the old code paths or new ones.
Then you're at the point where you have to push new code everywhere to handle these changes, and some nodes will have only the old code and some the new code, so now you're into translation and/or tunnelling to make sure the old addresses can talk to new addresses. Depending on their risk tolerance, some operators will enable the new code and some will not.
You also have to update DNS with new records, as A records are hard-coded to 32 bits. So now you're updating DNS libraries and user land.
There is no way to expand address space without going through all the same issues as what we call "IPv6" (originally SIPP) has gone through.
The v6 spec also has all these alternative ways to use it more like v4, commonly brought up as a cop-out against the above criticisms, but that's actually part of the problem. The spec is too big, and things only implement a subset of it, see Android not supporting DHCP6. Realistically you'll have 99% of people using anything like this the default way, and the spec does define SLAAC, no-NAT, etc as default.
But you could say v6 is better just cause it has more addresses, and that's fair.
...Imperial is better than metric because it lines up with everyday usage better unless you're specifically concerned about the physical properties of water. Especially ˚F vs ˚C. Not a big deal though.
Pounds vs kg, similar story as F vs C. Pound is pretty much the human-discernible granularity. Otherwise doesn't matter.
0-100 MPH lines up well with car speeds, which is usually the thing you're measuring with that. KPH is excessively granular for that. Probably not by design, but yeah.
The feet/inches vs meters/cm thing matters less. It's base-12 vs base-10. You can do decimal feet or fractional meters of course, but it's less common, so apparently both ways are fine.
Pounds vs kg: see above. All the non-American people seem to have "intuitive" grasp of metric measurements.
> 0-100 MPH lines up well with car speeds, which is usually the thing you're measuring with that. KPH is excessively granular for that. Probably not by design, but yeah.
So 'more granularity' is good for temperature but not for speed. Got it.
> The feet/inches vs meters/cm thing matters less. It's base-12 vs base-10. You can do decimal feet or fractional meters of course, but it's less common, so apparently both ways are fine.
By "foot" do you mean 'regular' foot or survey foot:
* https://www.nist.gov/pml/us-surveyfoot
Because there are two different units in the US customary system, used for basically the same purpose, that use the same name. And the "foot" isn't the only unit like that:
* https://en.wikipedia.org/wiki/Pound_(mass)
* https://en.wikipedia.org/wiki/Pound_(force)
Here's another one: which weighs more, a pound of feathers or a pound of gold? A pound of feathers. Because feathers use one 'pound-system' [1] and is 453g, while gold uses another pound-system [2] and is 373g. But of course an "ounce" of gold (31g) is more than an "ounce" of feathers (28g), because Troy is 1/12 of pound but Avoirdupois is 1/16. In addition to the above "ounces" there is also "fluid ounces".
Foot and pound have unambiguous meanings in the US. There's a reason the whole survey foot and gold-pound thing is trivia that nobody knows, they're niche or abandoned systems that you only use if you're being clear that it's not regular feet or pounds. I also know that the US system is technically not "imperial," but nobody cares.
The nice thing about imperial (as well as the customary system used in the US) is that it's based on measurements that people have found useful over thousands of years. They're human units, adapted to what people need to do with them, not the other way around.
It's difficult to explain to metric folks because it's really something you have to experience. But here's an example:
Reservoir volume in the US is measured in acre-inches. An acre is a unit of area used for measuring property, usually farmland. It's a bit less than half of a hectare. And of course an inch is 2.4cm. Acre-inches sounds totally bizarre when you first hear about it. But for the people that need to work with this value, it's an extremely useful way to measure reservoirs and gives you an intuition that you just don't get from cubic meters.
It's true that you can't just convert that to other units of volume without doing some math or looking up the conversion rate, but that rarely matters. If you're trying to figure out how fast the lake will rise or fall with a given inflow and outflow, you're going to have to have some way to account for the fact that the lake is a) an irregular shape and b) takes up more area the higher the water gets. You already need to know the area of the lake at any particular height to work out the evaporation rate anyway, so that's a number you're going to have. The units are designed to make that calculation easier, which was really important back in the days when slide rules were the state of the art.
All the customary units are like this in one way or another. They're units designed for a particular domain, and when used in their domain they work very well and calculations can be done in your head. They use fractions because that's what people have historically used (seriously - my grandfather could work fractions in his head faster than I could type them into a calculator, and he made asphalt for a living. Imagine what a carpenter could do.).
Think about it. Imagine you were never taught a measurement system. You find yourself needing to come up with a unit to make measurements for wooden planks you're going to use to build a house. Would you choose a unit as long as a meter? Or one as short as a centimeter or even a decimeter?
Bonus challenge to the fine folks clicking that downvote button: give me a real practical reason to prefer Celsius to Fahrenheit, besides the fact that Celsius is part of the metric system. No, the freezing and boiling points of water don't cut it - I work with hydrocarbon fuels, I salt my driveway and patio, I don't live at sea level, and quite honestly every American 8-year-old can spout off 32° and 212°. There's a Fahrenheit equivalent to Kelvin (Rankine) so the Kelvin to Celsius equivalence doesn't count either. My claim is that both scales are completely arbitrary, and only advantage one has over the other is that you're used to one of them. Go ahead, prove me wrong!
Never heard of an acre-inch before, and I'd have to get out a calculator to work out how much water that actually is in pints or gallons, or how much it weighs.
The metric equivalent would be a hectare-meter or a hectare-mm. I know a hectare is 100 m x 100 m, so 10,000 m². So I instantly know that a hectare-meter is 10,000 m³ (10 ML, or 10,000 tonnes of fresh water). A hectare-mm is 10 m³ (10 kL). If my 1 ha block gets 1 mm of rain, then that's 10 kL or 10 tonnes of water. So easy i can do it in my head.
> And of course an inch is 2.4cm
2.54 cm.
The recommendation for emergency supplies is about a gallon of water per person per day - or 3.7 liters if you're using metric.
I've also heard it claimed that the 0-100 Fahrenheit scale is more functionally useful because the endpoints of 0 and 100 represent the tipping point of serious danger for humans from hot or cold weather. The closer you get to 100 degrees the more care you need to take about heat stroke and keeping hydrated, and similarly the closer you get to 0 degrees the more care you need to take about retaining heat and staying out of the elements - the freezing and boiling point of water isn't a necessary marker for survival. And people like nice round numbers to serve as markers for such things, divisibility be damned.
Metric is sterile and functional for calculation and consistency, which is fine and necessary for many things, but that's not a reason to completely ditch Imperial.
US customary is not "thousands" of years; temperature (Fahrenheit) only came out in 1724 for example, and many other units were only standardize much more recently:
* https://en.wikipedia.org/wiki/History_of_measurement#History...
* https://en.wikipedia.org/wiki/System_of_units_of_measurement...
Second, even with-in the system itself there was also sorts of inconsistencies. Until just a few years ago there were two "foot" units; one was recently retired:
* https://www.nist.gov/pml/us-surveyfoot
Here's another one: which weighs more, a pound of feathers or a pound of gold? A pound of feathers. Because feathers use one 'pound-system' [1] and is 453g, while gold uses another pound-system [2] and is 373g. But of course an "ounce" of gold (31g) is more than an "ounce" of feathers (28g), because Troy is 1/12 of pound but Avoirdupois is 1/16. In addition to the above "ounces" there is also "fluid ounces". And let's not forget about the third system [3], which got replaced by… the metric system in 1971.[4]
[1] https://en.wikipedia.org/wiki/Avoirdupois
[2] https://en.wikipedia.org/wiki/Troy_weight
[3] https://en.wikipedia.org/wiki/Apothecaries'_system
[4] https://en.wikipedia.org/wiki/United_States_Pharmacopeia
Also:
* https://en.wikipedia.org/wiki/Pound_(mass)
* https://en.wikipedia.org/wiki/Pound_(force)
> Think about it. Imagine you were never taught a measurement system. You find yourself needing to come up with a unit to make measurements for wooden planks you're going to use to build a house. Would you choose a unit as long as a meter? Or one as short as a centimeter or even a decimeter?
Millimeters. That single unit gets you down to very small scales (finer than 1/16") and to large lengths: four significant digits (9999mm) gets you to the equivalent of >32' (~11yd).
* https://web.archive.org/web/20200516223819/https://themetric...
As evidence for this Australia/NZ/EU do everything in millimetres in construction.
You misunderstood me. It's based on measurements that people have been using for thousands of years. The Romans had feet and miles, for example - not exactly the same lengths, but for the same purposes. The Japanese shaku is almost exactly the same as a US foot. A Japanese Shō is about half a gallon. A Chinese jīn is just slightly larger than a pound. There's a reason for this.
> there was also sorts of inconsistencies
I never claimed otherwise. But do notice that the survey foot and standard foot weren't used for the same purposes, and the difference between them wasn't likely to confuse anyone except maybe people new to the field.
> Here's another one: which weighs more, a pound of feathers or a pound of gold?
Yep, Troy weights. And no one's sure where the Troy system came from. The main reason for its use is because of international trade. Also not something regular people (i.e. people that didn't work directly with precious metals) would have had contact with.
> Millimeters
Hah! Yeah right. Look at all the various non-metric systems that have existed throughout history. Did any of them use something like millimeters to measure wooden planks? Why not?
> As evidence for this Australia/NZ/EU do everything in millimetres in construction.
They do it because the metric system is mandated there and it doesn't give you reasonably sized unit for that scale of work.
Try this: go to a home center (or whatever it's called there - the place you buy building supplies) and measure some drywall. Do the measurements you made agree to the advertised ones within half a millimeter? Compare the dimensions of drywall sheets from different pallets and manufacturers. Do their dimensions agree to within half a millimeter? If not, that's a sure sign you're using units poorly adapted for purpose.
And you already don't have to use all 128 bits in v6. You're forced to use about 48 of them, but the rest is your choice. You can just... not use some of them. It's fine.
You're kinda forced to use 128 bits in v6 if you're an end user, cause that's the lowest common denominator. SLAAC is default, DHCP6 is widely unsupported. Most ISPs also only give out a /64 per spec minimum.