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Re: Question on the Maximum number of packets per second


Before the St Louis clock vote, a "box vendor" could have the system provide clocking for all of the PHYs, LAN and WAN, as well as the rest of the system.  In that case, no inter-clock-domain compensation was required.

If the system clock is at +100PPM and the WIS is at +20PPM, there are two separate, independent, clock domains now operating between the MAC Client and the PHY.   That will require some form of compensation.  The alternative is to require the "box vendor" to have a +20PPM clock, which is now an implementation specification issue.

Thank you,
Roy Bynum

At 04:02 PM 6/4/01 -0400, Tim Warland wrote:
Roy Bynum wrote:

> Tim,
> Where, in the resolution that was passed in St Louis, was additional
> compensation added to the rate adaptation to compensate for a system clock
> running at +100PPM and a transmitter with another clock operating at
> +20PPM?  That is a total compensation delta between the MAC Client/RS and
> the WIS of 120PPM.  From what I understand, the current rate adaptation
> scheme was based on the system clock and the WIS clock being the same.

Under the resolution from St. Louis, there was no added compensation.
The system clock is still required to provide 10.000 Gb/s +/- 100ppm
while the transmit clock in WIS mode operates at 9.95328 Gb/s +/-20ppm.
If anything the compensation is simplified since there is now a narrow
range of frequency extremes within which to perform compensation.

Tim Warland     P.Eng.
Hardware Design Engineer  Broadband Products
High Performance Optical Component Solutions
Nortel Networks                (613)765-6634