Scalability and fault tolerance become a fundamental challenge of data center network structure due to the explosive growth of data. Both structures proposed in the area of parallel computing and structures based on tree hierarchy are not able to satisfy these two demands. In this paper, we propose Totoro, a scalable and fault-tolerant network to handle the challenges by using backup built-in Ethernet ports. We connect a bunch of servers to an intra-switch to form a basic partition. Then we utilize half of backup ports to connect those basic partitions with inter-switches to build a larger partition. Totoro is hierarchically and recursively defined and the high-level Totoro is constructed by many low-level Totoros. Totoro can scale to millions of nodes. We also design a fault-tolerant routing protocol. Its capability is very close to the performance bound. Our experiments show that Totoro is a viable interconnection structure for data centers.