Abstract: Various embodiments relate to a network node and method thereof including a high stability oscillator and a holdover phase-locked loop (“PLL”) wherein the holdover PLL is configured to perform a holdover function by receiving a system clock signal, disciplining the high stability oscillator using the system clock signal to generate a local reference signal, and providing the local reference signal as the system clock signal when the system clock signal becomes unavailable.

Abstract: Various embodiments relate to a network node and method thereof including a high stability oscillator and a holdover phase-locked loop (“PLL”) wherein the holdover PLL is configured to perform a holdover function by receiving a system clock signal, disciplining the high stability oscillator using the system clock signal to generate a local reference signal, and providing the local reference signal as the system clock signal when the system clock signal becomes unavailable.

Abstract: A method and apparatus for handling, maintaining, and controlling network synchronization information emanating from a plurality of line card circuits is described. The technique described may be applied to a redundant pair of line card circuits, where one line card circuit is active, while the other is inactive. Line card activity latches are managed by means of hardware logic that may be configured at the time of line card commissioning. The activity latches are coupled to a logic element. An incoming clock signal is applied to the logic element. If an activity latch indicates that a line card circuit is active, the logic element provides the incoming clock signal as an outgoing clock signal to a control card circuit. If the activity latch indicates that the line card circuit is inactive, the logic element blocks the incoming clock signal from being passed and provides a static output level as the outgoing clock signal to the control card circuit.

Abstract: A method and apparatus for handling, maintaining, and controlling network synchronization information emanating from a plurality of line card circuits is described. The technique described may be applied to a redundant pair of line card circuits, where one line card circuit is active, while the other is inactive. Line card activity latches are managed by means of hardware logic that may be configured at the time of line card commissioning. The activity latches are coupled to a logic element. An incoming clock signal is applied to the logic element. If an activity latch indicates that a line card circuit is active, the logic element provides the incoming clock signal as an outgoing clock signal to a control card circuit. If the activity latch indicates that the line card circuit is inactive, the logic element blocks the incoming clock signal from being passed and provides a static output level as the outgoing clock signal to the control card circuit.

Abstract: A method and apparatus for handling, maintaining, and controlling network synchronization information emanating from a plurality of line card circuits is described. The technique described may be applied to a redundant pair of line card circuits, where one line card circuit is active, while the other is inactive. Line card activity latches are managed by means of hardware logic that may be configured at the time of line card commissioning. The activity latches are coupled to a logic element. An incoming clock signal is applied to the logic element. If an activity latch indicates that a line card circuit is active, the logic element provides the incoming clock signal as an outgoing clock signal to a control card circuit. If the activity latch indicates that the line card circuit is inactive, the logic element blocks the incoming clock signal from being passed and provides a static output level as the outgoing clock signal to the control card circuit.