In this paper, we numerically evaluated an optically switched multi-user Quantum Key Distribution (QKD) network for the end-to-end secure signal transmission with the metropolitan area network (MAN) applications. The multi-user network performance can be enhanced via MEMS (Micro-Electro-Mechanical Systems) technology to get the maximum secure key rates due to the less insertion loss and crosstalk for switching operation. We have analyzed a four-state, quadrature-phase shift keying (QPSK) transmitter to generate quantum keys, i.e. Alice, while a classical coherent receiver aided by the digital post-processing unit is being used as Bob. To route the secure QKD traffic to the end-users, 1x2, 1x4, 1x8 and 1x12 switching configurations have been analyzed for the transmission distance ranging from 0 to 60 km. We have achieved the secure key rates of 30 Mbit/s and 100 Mbit/s for the 1x12 and 1x2 switching configurations, respectively. We have also compared the performance of routed QKD traffic with a simple point-to-point QKD system and the classical DV-QKD protocol. The QKD networks need an effective low-loss fibre channel and a distribution system to enhance the transmission distance of the secure keys and applications. This paper provides multi-user used case as an important paradigm with the corresponding scheme and simulation performances.