E1 to Optical Ethernet Interface Converter with fiber optic interface is a multifunction and high performance L2 switch which build in three port cross engine to realize the conversion between two Ethernet interface and E1 interface. The equipment supports the function used as Ethernet transceiver or Ethernet net bridge or fiber optic modem. As the extension of Ethernet, This converter may realize Ethernet interconnection at low cost via the E1 channel provided by existing network. The optical Ethernet Interface Converter( also as Optical Ethernet Interface bridge) is a high performance, which accomplishes the converting between the 10/100M Ethernet port、the 100M Ethernet Optic Interface and E1 interface. As an extended device of the Ethernet, the optical Ethernet Interface Converter realizes interconnection of two Ethernet by using the E1 channel provided by exiting networks with the low-cost. 10/100Base-T (RJ45) interfaces are provided at the end of Ethernet LAN to accomplish various functions including MAC address self-learning, address filtering, address table maintenance and flow control, support the protect of net storm. Ethernet electric interface (RJ45) realizes 10/100M and HDX/FDX Auto-Negotiation. It can realizes DTE/DCE auto-negotiation (support "straight"-thru and crossover two Ethernet interface) E1 interfaces conforming to ITU-T G.703 and G.704 proposals are provided at the end of WAN, supporting RJ45 and BNC connection modes. The E1 ports support both framing and un-framing architecture. The user can select an operating mode for the E1 interface according to the connected E1 environment. This provides flexibility of network application. In the framing mode, the E1 interface provides a rate of N*64Kbps（N=1~31）. In the un-framing mode, the E1 channel provides a rate of 2.048Mbps and accomplishes transparent transmission. If the Optical Ethernet Interface Converter is used in the framing mode, the transmission clock can be either provided internall