The AEI 10 m Prototype is in its designing phase and will provide a test-bed for very sensitive interferometric experiments, such as the sub-SQL interferometer. It will test new techniques to reach - and even surpass - the Standard Quantum Limit. The experience and knowledge that can be gained from this experiment can be applied to large-scale interferometric gravitational detectors to improve the detector sensitivities. In order for the sub-SQL interferometer to achieve the required sensitivity all limiting noise sources need to be suppressed sufficiently. Noise sources can include seismic noise, thermal noise, and laser noise; laser frequency noise will be the main focus of this document. The laser frequency noise will be suppressed to a level of 10-4 Hz/√Hz at 20 Hz dropping to below 10-6 Hz/√Hz at 1kHz. The proposed design to suppress the laser frequency noise with a ring cavity is described in this paper.