I spent 2 years writing multicast routing algorithm implementations for an overlay multicast startup I cofounded. The moral equivalents of PIM sparse and OSPF. I wouldn't do it this way again, knowing what I know now, but we did LSA forwarding between nodes the same way a Cisco would flood LSAs over a set of unruly PPP DS1 links. The hard way, is what I'm trying to convey here.

Anyways, I interviewed a company my friend Nate was working for, on a lark (my company was sort of winding down).

First question I got: "explain Bellman-Ford routing". Bellman-Ford is one of the simplest distributed systems algorithms there is, and certainly the simplest foundation for a routing protocol (it's what the RIP protocol does). I had, prior to that interview, implemented RIP twice, in two different jobs.

I totally bombed the interview! My mind just went blank. I could explain how link-state routing with shortest path graph reductions worked, but not how a much simpler algorithm worked.

The interview made some clucking noises about how interesting it was to be interviewing someone who wasn't a Stanford CS student.

The next interview asked me to implement Towers of Hanoi non-recursively. I refused.

Obviously, I didn't get an offer.