Cyclemaster synchronization in a distributed bridge
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Abstract
A method of synchronizing cyclemasters over a distributed bridge is disclosed. The method comprises: a local portal sending a synchronization signal to a peer portal through a bridge fabric upon occurrence of a cycle synchronization event on the local portal; the peer portal sampling its local cycle timer to obtain a sample value when the peer portal receives the synchronization signal; a bridge manager at an upstream portal communicating the sample value to a bridge manager at an alpha portal; the bridge manager at the alpha portal using the sampled time value to compensate for delays through a bridge fabric, calculate the correction to be applied to a cycle timer associated with the alpha portal, and correct the cycle timer.
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Citations
35 Claims
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1-5. -5. (canceled)
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6. In a 1394-compliant system of node devices in communication over a distributed bridge, a method of synchronizing cyclemasters over a distributed bridge, the method comprising:
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connecting an output signal means from a first portal with an input signal means of a second portal and connecting an output signal means from the second portal with an input signal means of the first portal;
sampling the output signal means of the first portal and storing the sampled value;
communicating the sampled value to a downstream portal;
if the sampled value is received by the downstream portal within an acceptable time period, the downstream portal adjusting its cyclemaster in response to the sampled value; and
if the sampled value is not received within an acceptable time period then communicating an error condition that indicates that cyclemaster adjustment cannot be performed. - View Dependent Claims (7, 8, 9)
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10. (canceled)
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11. A method of operating a computerized system, comprising:
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receiving a cycle synchronization event at a local portal;
sending a synchronization signal from the local portal via a bridge to a peer portal;
accessing a local cycle timer associated with the peer portal, and obtaining a value based at least in part thereon;
sending the value to a third portal; and
indicating an error if the value was not received by the third portal within a first time period. - View Dependent Claims (12, 13, 14)
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15. A computerized system, comprising:
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a plurality of buses interconnected by a plurality of bridges, said plurality of bridges comprising a first bridge and a second bridge, the second bridge comprising a first portal;
wherein the first bridge comprises a second portal, a third portal, and a bridge fabric, the first portal in communication with the third portal via the bridge fabric;
wherein the second portal is adapted to receive a cycle synchronization event and upon receiving said event, transmit a synchronization signal through the bridge fabric to the third portal;
wherein the third portal is adapted to receive the synchronization signal, sample a local timer to obtain a sample value, and transmit the sample value to the first portal;
wherein the first portal is adapted to receive the sample value, use the sample value to compensate for at least some delays in transmission over the bridge, and calculate a correction to be applied to a timer associated with the first portal. - View Dependent Claims (16, 17, 18)
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19. A bridge device for use with a first portal that is in data communication with a second portal via a bridge fabric, the device comprising:
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a first module adapted to measure delays in propagation over the bridge fabric;
a second module adapted to access a timer associated with the first portal, and provide a sample value based at least in part on said access;
a third module adapted to calculate a correction to be applied to a timer associated with a downstream portal if the sample value is provided within a first time period, wherein said correction is based at least in part upon the sample value and upon delays in propagation over the bridge fabric. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A bridge device for use with a first portal in data communication with a second portal, comprising:
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a first module adapted to generate an error condition if a downstream device does not receive a first sample value and a second sample value within a first time period;
a second module adapted to sample a timer associated with the first portal to obtain the first sample value;
a third module adapted to sample a timer associated with the second portal to obtain the second sample value;
a fourth module adapted to calculate delays in propagation over said bridge device;
and wherein the bridge device is adapted to communicate with software configured to transmit the first sample value and the second sample value to the downstream device. - View Dependent Claims (29, 30, 31, 32, 33)
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34. In a system of devices in communication over a distributed bridge, a method of synchronizing one or more processes over said distributed bridge, the method comprising:
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placing an output of a first portal in data communication with an input of a second portal, and placing an output of the second portal with an input of the first portal;
sampling the output of the first portal and storing the sampled value;
communicating the sampled value to a downstream portal;
if the sampled value is received by the downstream portal within an acceptable time period, adjusting a first process of said downstream portal at least partly in response to the sampled value; and
if the sampled value is not received within an acceptable time period, then communicating an error condition that indicates that adjustment of said first process cannot be performed. - View Dependent Claims (35)
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Specification