There are two copper cabling types defined for 10Gigabit Ethernet, one using the usual UTP cabling that must be at least Cat6 or higher standard. This table show the key differences.
|SFP+ CU copper||Twinax||10m||10GBase-CX1|
|RJ45 10GbaseT Copper||Cat6, Cat6A, Cat7||100m||10GBaseT|
The twinax cable uses a different signal propagation method, my understanding is that it’s more like a radio wave than an electrical signal. A UTP signal needs a lot of electronics to drive generate and receive the signal.
The end result is that Twinax uses much less power (something around 1 – 1.5W per port) compared to UTP (4 – 6 W per port). When you have a lot of ports this power consumption can be significant factor in design.
You can see this in Cisco UCS designs where it is recommended to use the Twinax cables from the server to the Nexus 5000 switch as a server to Top of Rack cabling solution (not entirely unlike Infiniband). Of course, your connections from the Nexus 5K to the network core are likely to fibre or UTP since the maximum distance of the twinax solution is only 10 metres.
The EtherealMind View
Twinax is an ideal 10GbE solution for server to Top of Rack switch connection. Since it uses less power and is more reliable that UTP solution as the cable is physically more robust and not subject to physical damage, an important consideration for 10GbE over copper. Any damage to the copper cable due to crushing or bending can cause intermittent failures on Cat6 cabling (although less likely on Cat6A).
But the main reason for choosing twinax for 10GbE is lower power consumption for server to top of rack connections for integrated storage and data networks.