Lets say for a moment that everything that travels at speed below c has a rest frame.. All kinds of waves are produced from entities which has a rest frame... for example, Water waves produced from water surface which has a rest frame, similarly sound waves from physical objects, light waves from atoms and so on... If photon is created at the atom level by the transition of electrons from one energy level to another, then it should have rest frame, since electron has rest frame... I mean the speed of electron can never reach 'c', so the photon which is produced from the electrons must be initially accelerated to the speed of 'c'... If photon has no acceleration, then it can never reach 'c'... So photon initially travels at a speed below 'c' before it is accelerated... Hence it has a rest frame?