In this paper, a communication protocol has been designed for the two-layer scalable optical interconnectinn network (TgOlNet) designed in Tianjin University. The communication protocol has been designed based on TCP/IP (transmission control protocol/intemet protocol) protocol. But it is more efficient than TCP/IP for data Iransmissinn in TSOINet. An auxiliary channel has been introduced in TSOINet for transmission of the commtmicatinn status messages among the sub-layer rings. Many network management functions, such as flow control, hand shaking, etc., can be achieved via the auxiliary chalmel, so the commtmication overheads can be decreased. The performance of the corrtmunication protocol has been evaluated compared to TCP/IP protocol for data transmission in TSOINet.