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[802.3_NGAUTO] Reduced Link Segment Limits for 2.5Gbps?

802.3ch Task Force,


At the conclusion of the meetings in San Diego, I volunteered to investigate the loosening of the 2.5Gbps link segment limits.   Before putting too much effort into this topic, I would like to get some opinions from the group to see if there are any benefits to having lower link limits for 2.5Gbps only. 


Some questions I have are: 


1.  Will 2.5Gbps only PHY’s be needed and/or available considering 2.5/5/10 Gbps designs are closely linked to one another?        


2.  If the Insertion Loss and Return Loss Limits could be relaxed for the 2.5Gbps PHY, do you also think the coupling attenuation, i.e. shielding requirement, limit could be relaxed?


If I look at the link segment components designed for 1000BASE-T1, which has a similar frequency requirement as 2.5Gbps implemented with PAM4, many of them are designed for unshielded operation to provide the most economical solution. This economic benefit would be reduced if we consider shielded cables are necessary for 2.5Gbps operation. I would like to get input from other component manufacturers if they think it still makes sense to have relaxed requirements for the 2.5Gbps link segment even though the basic design, i.e. shielding, will be similar to the higher speed grades.


Thanks and best regards,



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