Comment by cnvogel

So, I was working at a very small internet service provider in a rural area in the mid-nineties. For the lack of affordable hardware, we were using Linux machines for routing, and a lot of "unconventional" solutions were necessary due to insufficient hardware being used. Tunelling, and other virtual interfaces of any kind were used often.

I remember one particular case were we running both routed IP and bridged ethernet over a single frame-relay link, and there we had to resort to fixed ethernet-to-ip mapping (turning off ARP) on the bridged link for some reason I really can no longer remember.