Folklore of robust network routing

This paper describes various types of fragility that can occur in networks, along with various types of defenses that can mitigate these issues. Although some of the techniques suggested in this paper are novel, most of them are “known”, but only as folklore, instead of being written down. Because these issues are not well-documented, many protocols do not implement these well-known techniques. We include technologies that are considered “layer 2” as well as “layer 3”, because we use the term “routing” to include any technology in which paths are dynamically computed and packets are forwarded. This paper focuses on wired networks. Wireless networks face additional challenges.