The 3G cellular system has infiltrated into market and the next generation wireless system called Beyond 3G is discussed at ITU-R. The Beyond 3G system integrates various wireless accesses including 3G and wireless LANs and provides an all IP wireless solution to offer services taking advantage of each wireless communication of the system. Current approach to integrate wireless systems is to localize wireless dependent functions and to integrate into all IP network using IP technologies. We propose a scalable Mobile Ethernet architecture for the all IP integrated network using MAC layer technologies, such as Provider Bridge, RPR, and IEEE802, and the fast vertical handover introducing common radio resource and signaling managements. We discuss network segmentation with mobility management and multicast management for the scalability of the Mobile Ethernet by reducing network traffic. We evaluate the network from the viewpoint of scalability. In the evaluation we understand that the design that the gateway swatch of a segment forwarding MAC frames as an anchor point becomes effective in case that the gateway switch of each segment cannot hold entries for all mobile terminals. We also evaluate the vertical handover comparing to Mobile IPv6 fast handover, and understand that the fast vertical handover consumes less network resources and flexible in having an anchor point for handover.