A virtual tunnel method is described herein which implemented by a host and next hop routers to address a problem that is related to synchronizing active tunnel and active link between the host and next hop routers. This is useful for excluding traffic from consumption totals where the application traffic has been accounted for using other means, such as through billing as a separate or technically distinct service. The DC correction signal is output to a second input of the summing module. The marking process is conducted in compressed domain, thus reducing the computational burden of decompressing and re-compressing the content, and avoiding further perceptual degradation of the host content. The measured 2D temperature field is used as input for an ultra-fast inverse computational solver.