Media Options for 10 Gigabit Ethernet

Despite strong growth in 10GbE deployments, 10GbE has yet to achieve mass market Data Center adoption, due to a number of limitations, primarily around cost, power consumption, and cabling options. The following section outlines several of these limitations in greater detail and discusses how the current generation of 10GBASE-T technologies removes them going forward.

10GBASE-CX4

10GBASE-CX4 was an early favorite for 10 GbE deployments, but its adoption was limited by bulky and expensive cables and limited reach of 15 meters. The large size of the CX4 connector, when compared to other interface options, prohibited higher switch port densities, specifically with 1RU top of rack switches and modular switch chassis. Moreover, pathways and spaces were not sufficient to handle the larger cables.

SFP+ Transceiver

SFP+'s support for both fiber optic cables and DAC make it a more flexible solution than CX4. SFP+ connectors are smaller than CX4 connectors and offer comparable port densities to their GbE counterparts. SFP+ DAC is the leading 10GbE interface today, but its limitations in reach and cost will prevent this media from becoming the de facto cabling and interface technology for 10GbE.

10GBASE-SR (SFP+ Fiber)

Cabling with Fiber is great for latency and distance (up to 300 meters). Fiber cabling coupled with optical transceivers offers the best power consumption footprint, however it is more expensive than other 10GbE media types; optical transceivers can add up to 30-40% to server, switch, and storage interface costs. The fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is also more expensive. This drives up both the acquisition costs as well as the ongoing annual maintenance contracts. Further, the vast majority of SFP+ connections are sold as add-in server adapters, as opposed to 10GBASE-T connections, which are now integrated on server motherboards. This add-in model adds cost and maintenance overhead.

10GBASE-SFP+ DAC

DAC cable is a copper 10 Gigabit Ethernet cable which comes in either an active or passive Twinax (twinaxial) cable assembly and connects directly into an SFP+ housing. The active Twinax cable has active electronic components in the SFP+ housing to improve the signal quality; the passive Twinax cable is just a straight "wire" and contains no active components. The adoption rate of DAC for LAN on Motherboard (LOM) will be low, since it does not have the flexibility and reach of 10GBASE-T. With top of rack deployments, it is very difficult to use all the switch ports purchased due the generally lower number of server adapter ports and the limited reach of the cables. These unused ports carry an initial cost outlay and require power (even in idle mode) and maintenance costs, making them expensive on an ongoing basis.

Meida Options for 10 Gigabit Ethernet

10GBASE-SR (SFP+ Fiber)

• OEM 10GBASE-SR SFP MMF multi-mode 850nm 300m transceiver for duplex optical data communications such as 10GBASE-SR and 10GBASE-SW
• Cisco SFP-10G-SR compatible 10G SR SFP+ 850nm Transceiver Module MMF
• Finisar FTLX8571D3BCV compatible 1000BASE-SX, 10GBASE-SR and 10GBASE-SW 850nm 300m Transceiver Module MMF
• HP JD092B X130 compatible 10GBASE-SR SFP+ 850nm 300m Transceiver Module
• Brocade 10G-SFPP-SR compatible 10GBASE-SR SFP+ 850nm 300m Transceiver Module

10GBASE-SFP+ DAC

• Cisco SFP-H10GB-CU1M, Up to 10.5G, 1m AWG30, passive copper
• Cisco SFP-H10GB-CU1-5M, Up to 10.5G, 1.5m; AWG30, passive copper
• Cisco SFP-H10GB-CU2M, Up to 10.5G, 2m; AWG30, passive copper
• Cisco SFP-H10GB-CU3M, Up to 10.5G, 3m; AWG30, passive copper
• Cisco SFP-H10GB-CU5M, Up to 10.5G, 5m; AWG24, passive copper
• Cisco SFP-10G-AOC1M, SFP+ AOC, fiber, 10G, 1m
• Cisco SFP-10G-AOC3M, SFP+ AOC, fiber, 10G, 3m