Switching device and loopback detecting method

1. A switching device in communication with a partner device, and comprising a plurality of Ethernet ports, an Ethernet switch integrated circuit (IC), a processor, a storage system, and one or more programs stored in the storage system and operable to be executed by the processor and comprising:

an automatic negotiation module that transmits a link code word related to the Ethernet switch IC to the partner device by one of the Ethernet ports for automatic negotiation with the partner device, and subsequently receives and records a first response link code word corresponding to the automatic negotiation;

a changing module that changes the link code word related to the Ethernet switch IC, wherein the automatic negotiation module further transmits the changed link code word to the partner device by the one of the Ethernet ports for automatic negotiation with the partner device, and determines if the automatic negotiation by the changed link code word is successful, and subsequently receives and records a second response link code word corresponding to the automatic negotiation by the changed link code word when the automatic negotiation by the changed link code word is successful;

a loopback determining module that determines the one of the Ethernet ports experiences loopback upon the condition that the first response link code word is unequal to the second response link code word, and further determines the one of the Ethernet ports does not experience loopback upon the condition that the first response link code word is equal to the second response link code word; and

a delaying module that presets a delaying time period, wherein the automatic negotiation module further determines if the partner device requests to re-negotiate with the switching device during the delaying time period.

2. The switching device as claimed in claim 1 , wherein the loopback determining module further determines the one of the Ethernet ports does not experience loopback upon the condition that the automatic negotiation by the changed link code word is unsuccessful.

3. The switching device as claimed in claim 1 , wherein the loopback determining module further determines the one of the Ethernet ports does not experience loopback upon the condition that the partner device requests to re-negotiate with the switching device during the delaying time period.

4. The switching device as claimed in claim 1 , wherein the changing module changes the link code word related to the Ethernet switch IC upon the condition that the partner device does not request to re-negotiate with the switching device during the delaying time period.

5. A loopback detecting method of a switching device, the switching device communicating with a partner device and comprising a plurality of Ethernet ports and an Ethernet switch integrated circuit (IC), the method comprising:

transmitting a link code word related to the Ethernet switch IC to the partner device by one of the Ethernet ports for automatic negotiation with the partner device;

receiving and recording a first response link code word corresponding to the automatic negotiation;

changing the link code word related to the Ethernet switch IC;

transmitting the changed link code word to the partner device by the one of the Ethernet ports for automatic negotiation with the partner device;

determining if the automatic negotiation by the changed link code word is successful;

receiving and recording a second response link code word corresponding to the automatic negotiation by the changed link code word if the automatic negotiation by the changed link code word is successful;

determining the one of the Ethernet ports experiences loopback if the first response link code word is unequal to the second response link code word, or determining the one of the Ethernet ports does not experience loopback if the first response link code word is equal to the second response link code word;

presetting a delaying time period;

determining if the partner device requests to re-negotiate with the switching device during the delaying time period; and

changing the link code word related to the Ethernet switch IC if the partner device does not request to re-negotiate with the switching device during the delaying time period.

6. The method as claimed in claim 5 , further comprising determining the one of the Ethernet ports does not experience loopback if the automatic negotiation by the changed link code word is unsuccessful.

7. The method as claimed in claim 5 , further comprising determining the one of the Ethernet ports does not experience loopback if the partner device requests to re-negotiate with the switching device during the delaying time period.