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RE: SONET/Ethernet clock tolerance

Title: RE: SONET/Ethernet clock tolerance


My comments are interlaced...

You understanding is correct.

Correct again. The mechanism of pointer adjustment involves the H1-3 bytes.

Here there is a misunderstanding. The "R" for "Retime" in a "3R" (i.e. Regenerator) is
not for clock tolerance compensation. The function of each "R" is:

  1. Reamplify: increase optical amplitude, to increase reach.
  2. Reshape: using edge sensing reproduce a stream of pulses, to eliminate the ASE
  3. Retime: using a (filtered) recovered clock regenerate the data, this eliminates media
  4. jitter accumulated from propagation (e.g. Duty Cycle Distortion).

    It has been proposed that Transponders for
    coupling an Ethernet WAN PHY to SONET OC-192c can be either "Passive" or
    "Active" according to our agreed upon "WAN PHY Definitions": My
    observation is that a transponder which contains both 100 ppm and 4.6 ppm optics
    MUST perform re-timing. Therefore, it must be an Active Transponder.

An active transponder may include some LTE functionality (e.g. pointer processing).


David W. Martin
Nortel Networks
+1 613 765-2901  
+1 613 763-2388 (fax)