This paper proposes a protocol called νLIN6 which supports both network mobility and host mobility in IPv6. There are several proposals to support network mobility and host mobility. Network Mobility (NEMO) Basic Support Protocol has several problems such as pinball routing, large header overhead due to multiple levels of tunneling, and a single point of failure. Optimized NEMO (ONEMO) and Mobile IP with Address Translation (MAT) are solutions to provide route optimization, but they generate a lot of signaling messages at a handover. In νLIN6, packet relay is required only once regardless of the nested level in network mobility while optimal routing is always provided in host mobility. A fixedsized extension header is used in network mobility while there is no header overhead in host mobility. νLIN6 is more tolerant of network failure and mobility agent failure than NEMO Basic Support Protocol. It also allows ordinary IPv6 nodes to communicate with mobile nodes and nodes in the mobile network. We implemented νLIN6 on NetBSD 2.0 Release. Our measurement results showed νLIN6 can provide host mobility and network mobility with low overhead.