OK, so you've never actually been involved in peering between providers. That explains things.

If you are buying transit for multihomed site, you just mostly need to worry about advertising your few local routes and receiving a table.

These words mean specific things in a provider environment. Peering between providers is not transitive. You should not give a peer's routes to another peer-- else you are offering to provide transit to that peer.

None of the three parties involved (the peer the route came from, the peer the route would go to, or you), generally, want this.

> As soon as I peer with two big sites that don't peer directly with each-other, they both gotta let me forward announcements unfiltered across them.

So -- this is true for neither scenario. If you buy transit from two people, you don't want to "forward" routes between them. Likewise for two peers. You only want to pass on your own routes, plus routes for your downstream customers or to your downstream customers.

The other topic that caused confusion: leaking a route to somewhere won't change where traffic goes unless that new leaked route wins. If it wins, the traffic will come to you (regardless of AS path). If it doesn't win, the existing route will still be used.

I'm retired-ish now, too (now I'm mostly a high school teacher for the funsies). But if you find yourself with BGP infrastructure in HE.NET Fremont, or somewhere that can peer with FREMIX, or somewhere that can access KCIX, feel free to send me a peering request. I currently have 2 direct upstream transit providers and 55 peers across 3 sites and export 6 prefixes plus 2 downstream prefixes :P