NEtwork MObility (NEMO) provides that a moving network involving mobile network nodes (MNNs) can move around the Internet without loss of connection. NEMO Basic Support (NBS) has been developed as an extension of Mobile IPv6 (MIPv6) so that it succeeds to drawbacks of host-based mobility management protocol. In NBS, the moving network keeps its connectivity with its home agent (HA) through its registration procedure. In other words, the moving network is required to obtain its new address and to send its own mobility signaling to the HA for every movements. In this paper, a simple and lightweight mechanism for NEMO within Proxy Mobile IPv6 (PMIPv6), which is a network-based mobility management protocol, is introduced. The proposed mechanism enables a moving network to change its point of attachment at a given PMIPv6 domain without acquiring a new address and sending its own mobility signaling. Mobility service provisioning entities residing at the PMIPv6 domain are extended to support NEMO. The analytical performance analysis is conducted to demonstrate that the moving network in the proposed mechanism achieves the reduced traffic cost and handover latency compared to NBS.