On Wed, 19 Dec 2018 21:11:39 +0100, Thomas Bellman said:
On 2018-12-19 20:47 MET, valdis.kletnieks@vt.edu wrote:
There was indeed a fairly long stretch of time (until the CIDR RFC came out and specifically said it wasn't at all canon) where we didn't have an RFC that specifically said that netmask bits had to be contiguous.
How did routers select the best (most specific) route for an address? If the routing table held both (e.g.) 10.20.30.0/255.255.255.64 and 10.20.30.0/255.255.255.32, then 10.20.30.97 would match both, and have the same number of matching bits.
That didn't stop sites getting creative with it on their internal networks, and I wouldn't be surprised if at least one router (Bay, Proteon, whatever) happened to have an implementation that Just Worked. Remember - there were enough ambiguities and odd implementations that RFC 1122/1123 had to be issued. *Lots* of "How the <expletive> did that ever work?" back in those days - and often the answer was "By accident".