— The importance of the routers in the network and the vulnerability in the nature of the link state routing protocol highlight the necessity of effective routing protection against variant attacks. One of the severe attacks is from the faulty intermediate router (FIR) which intentionally compromises the LSA messages passing by and pollutes the routing tables of its downstream routers. Current security mechanisms are either too expensive or vulnerable to prevent this type of inside attack. To address the FIR attack, in this paper, we present a novel costreduced integrated solution which combines both fault-detection operations from routers and fault-tracing response from network management components. The significant properties of our system are the detectability of the abnormal behavior toward the LSAs and the traceability of the FIRs generating those bogus LSAs. The analysis of the memory requirement and the communication cost in our design demonstrate the feasibility and efficienc...