Method and apparatus for measuring the timing difference between physical IMA links and for delivering a time difference to the IMA layer

DETAILED DESCRIPTION To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and apparatus for measuring the timing difference between physical IMA links and for delivering time difference to the IMA layer.
The present invention solves the above-described problems by measuring the timing difference between physical IMA links and delivering time difference to the IMA layer.
The timing differences is then used to generate stuffing cells with the proper rate on the transmit links.
The implementation of the physical interfaces with IMA can be a separate IMA chip and separate physical layer framers.
When the IMA chip and framers are attach to each other via a UTOPIA bus which doesn't carry the line timing, the IMA chip must receive the frequency difference by some other means.
A method in accordance with the principles of the present invention includes obtaining a first data value for use as a reference, obtaining a second data value, processing the first and second data values to obtain an indication of frequency difference and determining a number of stuffing cells to be added to an ATM link based upon the indication of frequency difference.
Other embodiments of a system in accordance with the principles of the invention may include alternative or optional additional aspects.
One such aspect of the present invention is that the first data value includes a reference clock signal and the second data value is a clock obtained from a first ATM link.
Another aspect of the present invention is that the processing further includes examining the reference clock signal and the clock from the first ATM link to obtain the indication of frequency difference.
Another aspect of the present invention is that the processing further includes measuring a phase difference between the reference clock and the clock from the first ATM link and calculating the indication of frequency difference in response thereto