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)