Systems and methods for implementing bi-directional synchronization propagation

Patent metadata

Field	Value
Publication number	US-9735905-B2
Application number	US-201213716463-A
Country	US
Kind code	B2
Filing date	Dec 17, 2012
Priority date	Aug 10, 2012
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Systems and methods for implementing bi-directional synchronization propagation between first and second communication devices are provided. The devices are arranged in a loop-timing configuration. A method includes detecting, by the second communication device, a switching signal comprising an indication to switch a timing role of the second communication device and engaging, by the second communication device, in a synchronization handshake with the first communication device over a communication link based on the detection of the switching signal. Engaging in the synchronization handshake includes determining whether the first communication device is configured to support bi-directional synchronization propagation. The method includes switching the timing role of the second communication device based on the synchronization handshake.

First claim

What is claimed is:

1. A method comprising:
detecting, by a communication device, an indication to switch a timing role of the communication device;
transmitting, by the communication device, a first signal to an other communication device;
determining, by the communication device, that the other communication device supports switching timing roles when a second signal corresponding to the first signal is received from the other communication device within a threshold amount of time from transmitting the first signal, otherwise determining that the other communication device does not support switching timing roles;
switching the timing role of the communication device when the other communication device is determined to support switching timing roles; and
maintaining the timing role of the communication device when the other communication device is determined not to support switching timing roles.

2. The method of claim 1 , wherein:
the other communication device is configured as an initial master,
the communication device is configured as an initial slave,
switching the timing role of the communication device comprises designating the timing role of the communication device as a timing master, and the method further comprises:
engaging a the synchronization handshake that comprises:
entering, by the communication device, into a slave switching update state for a predetermined update time;
entering, by the communication device, into a slave training initiation state at a conclusion of the predetermined update time, wherein entering into the slave training initiation state comprises determining whether the other communication device is prepared for duplex training; and

entering, by the communication device, into a slave training state based on the determination of whether the other communication device is prepared for duplex training.

3. The method of claim 2 , wherein entering into the slave switching update state comprises:
transmitting, from the communication device, one or more source low power idle (LPI) signals to the other communication device; and
updating one or more digital signal processing blocks of the communication device for switching the timing role of the communication device.

4. The method of claim 2 , wherein entering into the slave training initiation state comprises:
transmitting, from the communication device, one or more source zero signals to the other communication device;
detecting one or more return zero signals from the other communication device in response to transmission of the one or more source zero signals; and
determining that the other communication device is prepared for duplex training if the one or more return zero signals are detected.

5. The method of claim 2 , wherein entering into the slave training state comprises:
receiving a primary reference clock from a timing source of the communication device;
generating a transmit clock based on the primary reference clock;
transmitting, from the communication device, one or more source idle signals based on the transmit clock;
detecting one or more return idle signals from the other communication device in response to transmission of the one or more source idle signals; and
updating a recovery clock of the communication device based on a timing of the one or more return idle signals.

6. The method of claim 1 , wherein the other communication device is configured as an initial slave, wherein the communication device is configured as an initial master, and wherein switching the timing role of the communication device comprises designating the timing role of the communication device as a timing slave.

7. The method of claim 6 , wherein
the first signal comprises one or more source low power idle (LPI) signals and the second signal comprises
one or more return LPI signals.

8. The method of claim 1 , further comprising, when the other communication device is determined to support switching timing roles, engaging in a synchronization handshake that comprises:
entering, by the communication device, into a master switching update state;
detecting, in the master switching update state, a duplex training initiation request from the other communication device;
entering, by the communication device, into a master training initiation state based on the detection of the duplex training initiation request;
detecting, in the master training initiation state, a duplex training completion request from the other communication device; and
entering, by the communication device, into a master training state based on the detection of the duplex training completion request.

9. The method of claim 8 , wherein entering into the master switching update state comprises:
transmitting, from the communication device, one or more source low power idle (LPI) signals to the other communication device; and
detecting, by the communication device, one or more zero signals from the other communication device.

10. The method of claim 8 , wherein entering into the master training initiation state comprises:
receiving, by the communication device, one or more source zero signals from the other communication device;
transmitting, to the other communication device, one or more return zero signals in response to receipt of the one or more source zero signals to acknowledge that the communication device is prepared for duplex training;
receiving one or more source idle signals from the other communication device;
generating a recovery clock based on a timing of the received one or more source idle signals;
generating a transmit clock based on the recovery clock; and
locking a scrambler at a receiver of the communication device to synchronize with a scrambler at a transmitter of the other communication device based on the generation of the transmit clock.

11. The method of claim 10 , wherein entering into the master training state comprises:
transmitting one or more return idle signals to the other communication device in response to locking of the scrambler at the receiver of the communication device; and
receiving a timing update verification from the other communication device.

12. The method of claim 1 , wherein comprising:
engaging in a second duplex training with the other communication device upon completion of a first duplex training, wherein the switching occurs upon completion of the second duplex training.

13. The method of claim 12 , further comprising:
generating a recovery clock based on a timing of signals received from the other communication device; and
locking a second scrambler of the communication device to synchronize with a first scrambler of the other communication device based on the generated recovery clock,
wherein engaging in the second duplex training is initiated when the second scrambler is locked to be synchronous to the first scrambler.

14. A method comprising:
engaging, by a communication device, in a synchronization handshake with an other communication device over a communication link, wherein engaging in the synchronization handshake comprises:
receiving, by the communication device, a request from the other communication device to confirm that the communication device supports switching timing roles; and
transmitting, to the other communication device and within a threshold amount of time from receiving the request, confirmation that the communication device supports switching timing roles in response to the request when the communication device supports switching timing roles, otherwise not responding to the request within the threshold amount of time when the communication device does not

Assignees

• Broadcom Corp
• Avago Technologies General Ip

Inventors

• Wang Peiqing
• Wang Linghsiao
• Tazebay Mehmet Vakif

Classifications

• H04J3/0697 Primary

  Synchronisation in a packet node · CPC title

• H04J3/0658

  Clock or time synchronisation among packet nodes · CPC title