The document presents PACK (Prediction-based ACKs), a novel end-to-end traffic redundancy elimination system designed for cloud computing. It aims to reduce bandwidth costs by offloading the processing to end clients, minimizing server costs. Unlike previous sender-based solutions, PACK is receiver-based and does not require the server to continuously maintain client status. The receiver sends predictions to the server, which responds with ACKs if redundancy is detected instead of sending the data. This makes PACK suitable for mobile and elastic cloud environments. Experiments show the approach can reach speeds over 3Gb/s, faster than traditional methods.