[8023-10GEPON] Start-of-Packet Alignment in Fig 77-14

[Glen Kramer <glen.kramer@xxxxxxxxxxxx>]

Dear Colleagues,

 

I have submitted the following comment against D3.3:

 

Comment Text:

In the past, the TF has decided to remove Start of Packet (S-character) alignment function from the PCS sublayer. The arguments were that it was unnecessarily complex for the small amount of bandwidth saving. Besides, implementers may or may not implement this function without affecting interoperability. However, with the new ONU Control Multiplexer state diagram in D3.3, it appears there is a different and a very small modification that will always guarantee alignment of S character of the first frame in a burst to lane 0 of the first column.

 

Suggested Remedy:

In Figure 77-14 in transition from FRAME READY to START OF GRANT, change "1" to "2"

 

Old condition:  grantStart * fecOffset[1:0] = 0

New condition: grantStart * fecOffset[2:0] = 0

 

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The proposal suggests to align the first frame in a burst not to column boundary, as it is now, but to vector (2 columns) boundary.

 

I would like to ask the TF ( and especially Jeff, since he spent much time optimizing this state machine) to review this proposal and let me know if there are any issues found or any objections to do this change. Most important thing right now is to avoid introducing new problems, which will require further fixes in draft D3.4.

 

Thank you,

Glen