System and method for squelching a recovered clock in an ethernet network

1. A method for squelching, at a local node, a recovered clock signal in an Ethernet network comprising the local node coupled to a remote node by a link, the method comprising:

receiving a descrambler status signal;

receiving a remote receiver status signal;

receiving a link status signal;

receiving a signal indicative of whether an active link is in a 10BASE-T mode; receiving a signal indicative of whether the active link is in a 1000BASE-T master mode:

squelching the recovered clock signal based on the descrambler status signal, the remote receiver status signal, the link status signal, the 10BASE-T mode signal, and the 1000BASE-T master mode signal.

2. The method of claim 1 :

wherein the remote receiver status signal is indicative of a status of the link as reported by the remote node.

3. The method of claim 1 :

wherein the descrambler status signal is indicative of a status of a descrambler at the local node.

4. The method of claim 1 :

wherein the link status signal is indicative of a status of the link as determined by circuitry of the local node.

5. The method of claim 1 , wherein squelching the recovered clock signal based on the descrambler status signal, the remote receiver status signal, and the link status signal comprises squelching the recovered clock signal when any of the descrambler status signal, the remote receiver status signal, and the link status signal indicates failure.

6. The method of claim 1 , wherein the recovered clock signal is any of a clock signal recovered from a copper media and a clock signal recovered from a fiber media.

7. The method of claim 1 , further comprising:

receiving an external clock squelch signal;

wherein the squelching the recovered clock signal based on the descrambler status signal, the remote receiver status signal, and the link status signal comprises squelching the recovered clock signal when the external clock squelch signal is asserted.

8. The method of claim 1 , wherein the recovered clock signal is squelched within 1 millisecond of a link failure.

9. The method of claim 1 :

wherein the recovered clock signal is coupled to at least one downstream node; and

wherein the squelching the recovered clock signal prevents use of the recovered clock signal at the at least one downstream node.

10. A system for squelching a recovered clock signal in an Ethernet network comprising a local node coupled to a remote node by a link, the system comprising:

clock squelch circuitry configured to receive a descrambler status signal, a remote receiver status signal, a link status signal, a signal indicative of whether an active link is in a 10BASE-T mode, a signal indicative of whether the active link is in a 1000BASE-T master mode, and the recovered clock signal;

wherein the clock squelch circuitry is configured to squelch the recovered clock signal based on the descrambler status signal, the remote receiver status signal, the link status signal, the 10BASE-T mode signal, and the 1000BASE-T master mode signal.

11. The system of claim 10 :

wherein the remote receiver status signal is supplied to the clock squelch circuitry by receiver circuitry; and

wherein the remote receiver status signal is indicative of a status of the link as reported by the remote node.

12. The system of claim 10 :

wherein the descrambler status signal is generated by receiver circuitry; and

wherein the descrambler status signal is indicative of a status of a descrambler at he local node.

13. The system of claim 10 :

wherein the link status signal is generated by link monitor circuitry; and

wherein the link status signal is indicative of a status of the link as determined by the local node.

14. The system of claim 10 , wherein the clock squelch circuit is configured to squelch the recovered clock signal when any of the descrambler status signal, the remote receiver status signal, and the link status signal indicates failure.

15. The system of claim 10 , wherein the recovered clock signal is any of a clock signal recovered from a copper media and a clock signal recovered from a fiber media.

16. The system of claim 10 , wherein:

the clock squelch circuitry is configured to receive an external clock squelch signal; and

the clock squelch circuitry is configured to squelch the recovered clock signal when the external clock squelch signal is asserted.

17. The system of claim 10 , wherein the recovered clock signal is squelched within 1 millisecond of a link failure.

18. The system of claim 10 :

wherein the recovered clock signal is coupled to at least one downstream node; and

wherein the squelching the recovered clock signal prevents use of the recovered clock signal at the at least one downstream node.

19. An Ethernet switch configured to route data from a first port to a second port, the first port and the second port each configured for coupling to a transmission media connected to computer systems, the Ethernet switch including a switch coupled to each of the ports by at least a media access controller circuit and a physical layer circuit, the physical layer circuit configured to receive data from and transmit data to the transmission medium, the physical layer circuit including circuitry for squelching a recovered clock in an Ethernet network, the circuitry comprising:

clock recovery circuitry configured to generate a recovered clock signal;

receiver circuitry configured to generate a descrambler status signal and a remote receiver status signal;

link monitor circuitry configured to generate a link status signal;

clock squelch circuitry configured to receive the descrambler status signal, the remote receiver status signal, the link status signal, a signal indicative of whether an active link is in a 10BASE-T mode, and a signal indicative of whether the active link is in a 1000BASE-T master mode;

wherein the clock squelch circuitry is configured to squelch the recovered clock signal based on the descrambler status signal, the remote receiver status signal, the link status signal, the 10BASE-T mode signal, and the 1000BASE-T master mode signal.

20. A method for squelching a recovered clock in an Ethernet network, the Ethernet network comprising an Ethernet switch configured to route data from a first port to a second port, the first port and the second port each configured for coupling to a transmission media connected to computer systems, the Ethernet switch including a switch coupled to each of the ports by at least a media access controller circuit and a physical layer circuit, the physical layer circuit configured to receive data from and transmit data to the transmission medium and to execute the method, the method comprising:

generating a recovered clock signal;

generating a descrambler status signal;

generating a remote receiver status signal;

generating a link status signal;

receiving the descrambler status signal, the remote receiver status signal, the link status signal, a signal indicative of whether an active link is in a 10BASE-T mode, and a signal indicative of whether the active link is in a 1000BASE-T master mode; and

squelching the recovered clock signal based on the descrambler status signal, the remote receiver status signal, the link status signal, the 10BASE-T mode signal, and the 1000BASE-T master mode signal.