As the Internet evolves, VPN (Virtual Private Network), which establishes secure connections between off-site clients and on-site servers, is getting important. In VPN, a part of network which is protected from the Internet is called "VPN domain." In the environment where VPN domains are hierarchically configured (Hierarchical VPN), the next hop VPN gateway (VGW) must be discovered depending on the destination host. In this paper, we propose some routing methods which are transparent from users. In these methods, the next hop VGW is automatically discovered by querying to DNS servers and/or receiving ICMP and TCP packets. We have implemented proposed methods by extending the VTun software. The effectiveness of these methods are experimentally confirmed.