[SI-LIST] PICMG3.1 : is length matching really necessary?

Hi all,
In PICMG3.0, there is a requirement for length matching between the pairs 
of a fabric interface channel : 2.54mm max.
Even for 10G backplane Ethernet type applications (PICMG3.1 / 10GBase-CX4) 
this seems exagerated, as data are aligned at PCS level.
--> in 802.3 clause 48.2.4.2.2 there is a skew budget table, which 
allocates 2UI (=2x320ps) for PCB (board) skew and 18UI for the 
transmission medium (backplane) skew.

Is my understanding of the standard correct or do I miss something?

Thanks for your help.
Regards.

Daniel Peron


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