10 Gigabit Ethernet Cabling Solutions: 10GBASE-T vs. SFP+
Driven by dramatic growth in data center, there is an increasing usage of and demand for higher-performance servers, storage and interconnects. Consequently, an expansion of higher speed Ethernet solutions occurs, especially for 10 Gigabit Ethernet (10GE, 10GbE, or 10 GigE). Actually, selecting the appropriate 10-gigabit physical media faces a problem, as 10GbE is offered in two broad categories: copper and optical, namely 10GBASE-T and SFP+ interfaces.
Firstly, an introduction to each 10GbE cabling solution is below.
10GBase-T is defined by an IEEE standard, 802.3an-2006 to provide 10 Gbit/s connections over unshielded or shielded twisted-pair cables, over distances up to 100 meters (330 ft). In the early days of Ethernet, there were several physical (PHY) standards, including various forms of coaxial cable, but Ethernet only gained widespread adoption once it was run on twisted-pair cable, and as point-to-point rather than an unstructured loop. The connector used for twisted pair was the RJ45 connector. 10GBase-T requires the Cat 7 or Cat 6A to reach 100 meters, but can work on Cat 6, Cat 5E, or even Cat 5 cable at reduced distances.
The name SFP+ reveals that this standard is derived from the SFP (small form-factor pluggable) standard, which is the most commonly used optical interface for Fibre Channel and 1 gigabit Ethernet. SFP+ interfaces take approximately the same space on a switch front panel as the ubiquitous RJ45 connector. In fact, SFP+ can support both fiber optic cables and DACs (direct attach cables). Instead of installing an optical transceiver at each end, a cable was invented with each end physically resembling a SFP+ transceiver, but with none of the expensive electronic components. This innovation, called DAC, is a low cost solution for shorter distances. SFP+ transceiver modules come in different types to drive signals across fiber optic cables with different maximum distances. 10GBASE-SR is one of the most commonly used type. For example, Fiberstore New Compatible HP J9150A is designed for multi-mode fibers and operates at a nominal wavelength of 850nm.
Then let’s begin to compare 10GBASE-T with SFP+ interfaces.
- Latency—10GBase-T PHY standard uses block encoding to transport data across the cable without errors. This block encoding requires a block of data to be read into the transmitter PHY, a mathematical function run on the data before the encoded data are sent over the link. The reverse happens on the receiver side. The standard specifies 2.6 microseconds for the transmit-receive pair, and the size of the block requires that latency to be less that 2 microseconds. In contrast, SFP+ uses simplified electronics without encoding, and typical latency is around 300 nanoseconds (ns) per link.
- Distance—10GBase-T can reach 100 meters using the latest Cat 6A or Cat 7 cables. As for SFP+ interfaces, for longer runs, fiber optic transceivers and fiber cables can be intermixed with DACs, allowing distances of 300 meters at a reasonable cost and up to 80 kilometers at a higher cost.
- Power Consumption—When it comes to power consumption, early versions of 10GBASE-T switches required up to 12 Watts per port, but switch vendors now offer a range of 1.5 to 4 W per port depending on distance due to recent advancements. By comparison, SFP+ interface uses less power—typically less than 1 W per port.
Finally, after comparison, you may have a clear mind while choosing 10GbE cabling solutions. In Fiberstore, both 10GBASE-T and SFP+ interfaces are supplied, like 10GBASE-T 100m RJ45 Copper SFP and HP JD094B (10GBASE-LR). Certainly, other 10GBASE-SFP+ transceivers are also available, including 10GBASE-ZR SFP+, 10GBASE-ER SFP+, etc. For more information about 10GbE cabling solutions, please visit Fiberstore for more information.
