Method and system for transporting constant bit rate clients across a packet interface
AssigneePMC-Sierra US, Inc.
InventorsWinston Ki-Cheong Mok, Karl Scheffer, Michael Smith
Life of this patent
Estimating the term…
Abstract
This disclosure describes a method and apparatus for signaling the phase and frequency of OTN and Constant Bit Rate (CBR) clients in an OTN network. The principles discussed are applicable when multiple stages of OTN multiplexing and demultiplexing are utilized. They are also applicable for use with the Generic Mapping Procedure (GMP) and Asynchronous Mapping Procedure (AMP). A method to use the phase and frequency of an ODUk/ODUflex to adjust a local reference clock to enable the recovery of the phase and frequency of a CBR client demapped from the ODUk/ODUflex is described.
Claims34
A method for transporting a constant bit rate (CBR) client stream from an ingress element to an egress element, wherein the ingress element has an ingress reference clock and the egress element has an egress reference clock, the method comprising, at the ingress element:
- a) measuring a CBR client clock rate of the CBR client stream;
- b) encoding the CBR client clock rate into a sequence of client segment size indications;
- c) generating a CBR client rate value from the CBR client stream, comprising:
- accumulating a variance (−Ni, 0, +Ni) of the sequence of client segment size indications;
- determining a sum of the accumulated variances with a base client rate value once every Tifr cycles of the ingress reference clock, where Tifr is a rational number;
- and
- filtering the sum with a lossless low-pass filter once per Tifr cycles of the ingress reference clock to produce a filtered sum being the CBR client rate value;
- d) inserting the CBR client rate value and the CBR client stream into a CBR carrier stream;
- and
- e) transmitting the CBR carrier stream to the egress element.
A system for transporting a constant bit rate (CBR) client stream from an ingress element to an egress element, wherein the ingress element has an ingress reference clock and the egress element has an egress reference clock, the system comprising, the ingress element comprising:
- an ingress rate measurement block configured to measure a CBR client clock rate of the CBR client stream, and to encode the CBR client clock rate into a sequence of client segment size indications;
- a Cn generator block configured to generate a CBR client rate value from the CBR client stream, wherein the Cn generator block comprises:
- a packet size decision accumulator configured to accumulate a variance (−Ni, 0, +Ni) of the sequence set of client segment size indications;
- a summer configured to determine a sum of the accumulated variances with a base client rate value once every Tifr cycles of the ingress reference clock, where Tifr is a rational number;
- and
- a lossless low-pass filter configured to filter the sum once per Tifr cycles of the ingress reference clock to produce a filtered sum being the CBR client rate value;
- a mapper configured to insert the CBR client rate value and the CBR client stream into a CBR carrier stream;
- and
- a transmitter configured to transmit the CBR carrier stream to the egress element.
Dependencies are inferred from the claim text.