Abstract: A network device is described that injects probes for exercising its own forwarding rules (e.g., layer 2 and layer 3). One or more probe packets can be injected into an ingress pipeline of the network device using the agent executing on a local processor. The probes are detected before or after performing at least layer 2 and layer 3 lookups. Hardware in switching logic redirects the probes to an external testing system in order to verify the actual forwarding behavior applied to the probe packet. In order to deliver the probes to the external server, the network device performs an additional layer 3 lookup and generates an encapsulated packet incorporating results of a lookup on the probe packet. In this way, the external server can analyze the lookup on the probe packet to determine whether the lookup was performed correctly.

Abstract: In a computer network, network-connected devices generate and encode diagnostic information using an orthogonal code specific to each of the network-connected devices. In some implementations, the orthogonal code is a Walsh Code, a Walsh-Hadamard code, or a prime number. The encoded diagnostic information is transmitted to a router. The router aggregates and combines the encoded diagnostic information into a combined diagnostic value. Additional diagnostic information may be generated, encoded, and added to the combined diagnostic value by the router. The combined diagnostic value may be transmitted to additional upstream routers where additional diagnostic information is encoded and multiplexed into the combined diagnostic value.