IPv6 site multihoming discussed at the Multi6 working group is one of the hottest topics among many IPv6 related issues in the IETF. We have already proposed a variant of end-to-end multihoming (E2E-MH), where an outgoing packet from a site is routed to a site-exit router by source address dependent (SAD) routing so that it goes out to the transit provider that gives the address prefix of the source address of it. In this paper, we first show that such SAD routing can be implemented with acceptable cost when we apply SAD routing only to default route entries on each router. Next we propose a hierarchical subdivision method for automatic address prefix assignment to links in a site. Connecting the SAD routing setting up on each router with the hierarchical address assignment, all needed configuration of routers can automatically be done, without any preconfigurations about IP address or routing information.