In this paper, the authors have a tendency to propose an automatic and systematic approach for testing and debugging networks called "AuTomatic check Packet Generation" (ATPG). ATPG reads router configurations and generates a device independent model. The model is employed to come up with a minimum set of check packets to (minimally) exercise each link within the network or (maximally) work out each rule out the network. Check packets are sent sporadically and detected failures activate a separate mechanism to localize the fault. ATPG will observe each practical (e.g., incorrect firewall rule) and performance issues (e.g., full queue).