When developing a new networking standard, several attributes need to be balanced to optimize its implementation. To optimize the implementation of 40GBASE-T, the task force developing the standard (IEEE P802.3bq) appears to have settled on a reach of 30 meters. This is a tradeoff between power dissipation of the silicon physical layer (PHY) IC driving the cable, the complexity of the PHY which would impact cost, the implementation of the channel, and the reach of the link.
The question is: Is 30 meters long enough? Let’s take a look.