Transparent IPv6 network mobility is realized by the usage of at least two special nodes, a mobile router (MR) and a mobile router home agent (MRHA). These two nodes are able to provide mobility for entire networks consisting of several other nodes, not necessarily aware of mobility. The MR attaches to different access networks and communicates its current care-of address to the MRHA. The MRHA at the home link of the vehicle assures the permanent reachability of the mobile network via its home prefix. It forwards all respective packets to the MR's currently registered care-of address. From an architectural point of view, vehicles can be looked at as ideal example of mobile networks. The MR inside the vehicle is responsible for the connection of intra-vehicular sub-networks to different external access routers within a fixed IPv6 infrastructure, i.e. the Internet. One can imagine the following scenario. Three persons drive in a car. Two of them use personal devices (Laptop or PDA) that are connected via Bluetooth or WLAN to the car's internal network. They use the car's uplink connection (e.g. UMTS) to be able to communicate with the Internet. At the same time, the navigation system receives updated traffic information from a traffic service station. In contrast to mobile hosts, a mobile network as discussed in this paper allows efficient route updates only once for the entire in-vehicular network instead of an individual update for every host in the network. Furthermore, it allows that hosts participate which are not aware of mobility. In contrast to ordinary routers, a mobile router has to adapt its routing while it is moving. This article examines which modifications to the routing mechanism of standard IPv6 router have to be accomplished to provide network mobility as a mobile router (MR). A router's packet routing mechanism is controlled by entries in routing tables. Thus in case of network mobility, the natural approach consists in extending the capabilities of routing table management. The authors describe limitations of standard routing table management and propose extensions for mobile networks. The solution requires only minor changes to a normal router and provides good performance.