Most Network vendors work quite well with /31 Prefixes as smallest possible Non-Host-only network - a.k.a. Point-to-Point link.
As in /30 it is possible to interconnect two Routers with a /31 network, but am consuming only 50% of my IP address space.
This /31 is specified in RFC3021 https://tools.ietf.org/rfc/rfc3021.txt
I use /31 for IPv4 on Cisco, Juniper and Nokia Boxes as well as /127 Prefixes in my IPv6 Topology. The only boxes i had problems with /31 were Forigate firewalls.
