A smart vehicle becomes a communication device with the advance of VANETs. In the WAVE standards, which is the well-known VANET standards, RSUs interconnect a VANETs to the Internet, and they act as default routers for the vehicles. However, the WAVE standards have eliminated the L2 portal function, which was included in the previous WAVE standards. Due to the short communication range of RSUs and vehicles’ high speed, a vehicle may have to change its point of attachment frequently. The change of the default router causes severe service interruption due to the standard IPv6 protocol’s functions such as the address auto-configuration, DAD and NUD. We propose a new seamless handover scheme with an L2 extension mechanism without any modification of the WAVE standards. It increases the coverage of an access router to multiple RSU coverage, while the frequency of the default router changes can be decreased. It also supports seamless packet delivery during the change of the points of attachment. By decoupling the RSU and the access router, the deployment of the WAVE can be more flexible. The proposed mechanism is simulated with ns-3 and its results show the effectiveness of the proposed scheme.