Routed networks tend to fail closed where switched networks tend to fail open. That usually seems to be the problem with layer two failures, they can easily spr

Routed networks tend to fail closed where switched networks tend to fail open. That usually seems to be the problem with layer two failures, they can easily spread traffic everywhere and it takes a while for things to calm down, in the meantime the network hardware is often overwhelmed. With layer three networks the failures tend to be that you lose the ability to route somewhere but in my experience it's often easier to recover from that situation.