Patent ID: 8693497

Claim:
A relay, applied to a long-reach Ethernet system comprising two Ethernet devices, wherein a Power Sourcing Equipment (PSE) unit is configured in one of the two Ethernet devices, a Powered Device (PD) unit is configured in the other one of the two Ethernet devices, and the two Ethernet devices communicate with each other via the relay, the relay comprises: a conventional Ethernet interface unit, a data relaying unit, a long-reach Ethernet interface unit, and a power transmission tunnel between the conventional Ethernet interface unit and the long-reach Ethernet interface unit; wherein the conventional Ethernet interface unit is connected with an outside conventional Ethernet link and is configured to perform conventional Ethernet physical layer processing for received bi-directional Ethernet data; the data relaying unit is configured to transmit Ethernet data from the conventional Ethernet interface unit to the long-reach Ethernet interface unit and transmit Ethernet data from the long-reach Ethernet interface unit to the conventional Ethernet interface unit; the long-reach Ethernet interface unit is connected with an outside long-reach Ethernet link and is configured to perform long-reach Ethernet physical layer processing for received bi-directional Ethernet data; and the power transmission tunnel is configured to transmit power; the relay further comprises a PD unit, configured to receive the power from the power transmission tunnel, convert a voltage of the power into a working voltage of the relay and take the power as a working power of the relay; when the relay acts as a data and power relay of a Powered over Ethernet (POE) system, the PD unit of the relay is connected with a PD unit of an Ethernet powered terminal of the POE system and PD units of other relays in parallel to be equivalent to a combined PD; the PD unit of the relay comprises a rectifier, a PD control circuit module and a voltage converting circuit module; the rectifier is configured to rectify the power received from the power transmission tunnel; the PD control circuit module comprises a main control circuit and an in-position equivalent resistance adjusting circuit; the main control circuit is configured to provide the rectified power to a power converting circuit module and perform a control operation in PD detection; the in-position equivalent resistance adjusting circuit is configured to make the PD control circuit module where the in-position equivalent resistance adjusting circuit is located present a pre-defined equivalent resistance value during a PD detection phase, where the pre-defined equivalent resistance value makes an in-position indication equivalent resistance of the combined PD meet requirements of IEEE802.3af; and the power converting circuit module is configured to convert a voltage of the power received from the PD control circuit module into a working voltage of the relay and take the power as the working power of the relay.