Network device with testing of forwarding rules using tunneling

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.