[STDS-802-3-25G] some question about the current D1.1, can any one help me to understand it right

[Zhongqiwen <zhongqiwen@xxxxxxxxxx>]

Hi, everyone:

 

1,  in table 105-2, the clause 74  are mark “M” BASE-R FEC for the 5 PMDs,  and Clause 108(~Clause91) are Mark “M” for CR, KR, SR,

     My question is:  are those 2 FEC options need to be select one for use? Or …???

 

2, the current 25GMII and PCS are scale up from 10GE, while using RS-FEC, AMs need to be inserted. The rooms for AMs are ready in 100GE for 802.3bj clause 91 FEC(remap), but not ready for 25GE that scale up from 10GE PCS.

So the Figure 108-2 shows a rate compensation for making rooms for codeword markers. This implying Idle insert and delete operations. And thus imply descrambling, (decode), Idle insert/delete, (encode) descrambling.

 

My understanding is, this functionality of making rooms for AMs were done in PCS over CGMII/XLGMII, we should move this functionality to the Clause 107, as one of the optional enhancements to clause 49 PCS(simple text described 107.1.2 consist with 802.3ba, rather than to  show it in figure 108-2, we can refer to Figure 82-2) while using RS-FEC.  

 

Is my understanding right ? or there are other considerations?

 

Best regards

 

Qiwen