It’s the “S” word we don’t like to hear, and often times it has degraded networks or even took them down entirely. (All Systems Down – an older but classic story) It’s also one of those things that nobody really likes, we even had network companies, as well as IEEE try to replace it with something else. Remember the names like TRILL, and IEEE 802.1aq (SPB) or Cisco’s FabicPath technologies? You had all of these different flavors that showed a lot progress, but they never really took off for one reason or another. The funny part is this protocol we are all trying kill off is still alive and doing well, so let’s look at spanning tree in the meantime because you will likely run into it.