Today I spent an hour trying to set up a simple as path prepending scenario and I couldn’t make it work. The task seemed impossible because it seemed that the router that was supposed to be making the decision based on the as-path length wouldn’t receive one of the routes, because the routes had its AS in the path already, so the bgp loop condition wasn’t met.
This is an important lesson – always spend time preparing for the task instead of trying to configure everything straightaway. Think, draw, configure. Trying to save time will get you into more trouble than it’s worth.