I believe anyone who did a fair amount of network development in the kernel sooner or later arrives at the idea of a virtual networking framework with switches,

I believe anyone who did a fair amount of network development in the kernel sooner or later arrives at the idea of a virtual networking framework with switches, hubs and configurable links in between. Half of those will make an attempt to implement it, because it is a fun project, but only few will move beyond tinkering to having something functional. However getting something like this into a shippable production state is a genuinely remarkable achievement :)