Comments
By isThereClarity 2025-09-0712:104 reply Daniel Karrenberg, co-author of RFC1918, said this 2017-10-06 on the NANOG mailing list:
https://web.archive.org/web/20190308152212/https://mailman.n...> On 05/10/2017 07:40, Jay R. Ashworth wrote: > > Does anyone have a pointer to an *authoritative* source on why > > > > 10/8 > > 172.16/12 and > > 192.168/16 > > > > were the ranges chosen to enshrine in the RFC? ... > > The RFC explains the reason why we chose three ranges from "Class A,B & > C" respectively: CIDR had been specified but had not been widely > implemented. There was a significant amount of equipment out there that > still was "classful". > > As far as I recall the choice of the particular ranges were as follows: > > 10/8: the ARPANET had just been turned off. One of us suggested it and > Jon considered this a good re-use of this "historical" address block. We > also suspected that "net 10" might have been hard coded in some places, > so re-using it for private address space rather than in inter-AS routing > might have the slight advantage of keeping such silliness local. > > 172.16/12: the lowest unallocated /12 in class B space. > > 192.168/16: the lowest unallocated /16 in class C block 192/8. > > In summary: IANA allocated this space just as it would have for any > other purpose. As the IANA, Jon was very consistent unless there was a > really good reason to be creative. > > Daniel (co-author of RFC1918)By JdeBP 2025-09-0715:50 And said the same on SuperUser the day after.
By notepad0x90 2025-09-081:441 reply And I suppose 127/8 because it's the highest /7 or highest /8 without the MSB on?
By zinekeller 2025-09-0811:38 Technically, the last Class A space (https://en.wikipedia.org/wiki/Classful_network)
By binary132 2025-09-0715:09 [flagged]
The entire thread:
>>> This is a fuzzy recollection of something I believe I read, which might well be inaccurate, and for which I can find no corroboration. I mention it solely because it might spark memories from someone who actually knows:
>>> A company used 192.168.x.x example addresses in some early documentation. A number of people followed the manual literally when setting up their internal networks. As a result, it was already being used on a rather large number of private networks anyway, so it was selected when the RFC 1597 was adopted.
>> sun
> Wasn't 192.9.200.x Sun's example network?
of course you are correct. sorry. jet lag and not enough coffee.
---
So no answers.
By nickdothutton 2025-09-0711:34 I worked in the early 90s getting UK companies connected. The number of people who had copied Suns (and HPs and others) addresses out of the docs was enormous. One of them was a very well known token ring network card vendor.
It was 1994.
We're a 2-man crew, about to start one of America's biggest ISP's.
We'd just gotten the closet cleared, the racks assembled, the modems installed, the terminal server wired up, the USENET machine booted, and we're waiting for the T1 to go live. The modems are answering calls, but there's nowhere for our new subscribers to go .. yet.
The tech line rings, its the T1 guy on the other end "Ready to configure your router with you if you're ready .. "
Sure, I say .. whats our IP address ..
"198.162 .. "
"WAIT!", I say. "Are you SURE about that?"
He sure was.
The line comes up, the routes flow, customers get online for their first time.
But for months afterwards I was constantly in fear of our IP address.
Junior network guys would call me up in the middle of the night, adding some NOC somewhere or other "it doesn't work!" - "did you mix a 2 and an 8?", I'd say .. and much swearing would be heard until things started working again.
Man, that was fun. Getting that IP address assigned to us definitely was an act of mischief on the part of some devil somewhere, I'm quite sure ..
Hooking up that first T1 was super exciting! I worked at an early ISP (not a big one) in 1995. They were still on a 56K dedicated line and a very small bank of modems. I still remember when the guy from MCI showed up to test the new T1 we were getting. The first frame relay customers I brought up were also super fun. I sometimes miss networking.
By aa-jv 2025-09-108:02 They were fun days but I wouldn't go back to it for anything. I realize now, we were building a monster.
LoRA is all the world needs. ;)
By urbandw311er 2025-09-0821:571 reply Oh wow. Genuine question - if you could go back, would you go through the hassle of getting a different one assigned?
By aa-jv 2025-09-108:03 No - it was a nuisance, but it was also kind of cute to see other network engineers brains reboot when they saw the IP .. ;)
