A highly-energy-efficient network using an optical aggregation network and a service cloud has been proposed to reduce the power consumption of today's Internet greatly. The optical aggregation network connects a solitary giant router to users by logical tree topology. This paper proposes a novel optical aggregation network architecture. The proposed architecture uses 2x2 optical switches and combines the features of a tree topology and a ring topology. The paper also introduces a design method of the proposed network architecture. It is shown that the method can design high-availability and low-optical-loss network with fewer optical switches compared to a duplex tree topology.