Detection of invalid routing announcements in RIP protocol

Traditional routing protocol designs have focused solely on the functionality of the protocols and implicitly assume that all routing update messages received by a router carry valid information. However operational experience suggests that hardware faults, software implementation bugs, operator misconfigurations, let alone malicious attacks can all lead to invalid routing protocol announcements. Although several recent efforts have developed cryptography-based authentication for routing protocols, such enhancements alone are rendered ineffective in the face of faults caused by misconfigurations or hardware/software errors. In this paper we develop a simple routing update validation algorithm for the RIP protocol, RIP with triangle theorem checking and probing (RIP-TP). In RIP-TP routers utilize a triangle theorem to identify suspicious new routing announcements, and then use probing messages to verify the correctness of the announcements. We have evaluated the effectiveness of RIP-TP through simulation using various faulty node behaviors, link failure dynamics and network sizes. The results show that, with an overhead as low as about one probing message per received update message in the worst case, RIP-TP can effectively detect 95% or more invalid routing announcements.