Cables and connectors can cause some confusion when purchasing new optical transceivers for servers. There are many options across many vendors. This technical brief provides generic information about 10GBASE-CR Cables, DAC cables, 10GBASE-T cables and connectors for transceivers and adapters in a 10Gb Ethernet (10GbE) network environment. Note that the cable you select is determined by the switch in your environment.
10GbE has been in existence since 2002, yet it seems only recently that serious interest in 10GbE has taken hold. Due to the history of 10GbE, it has not been completely backward compatible with previous generations of Ethernet technology, which has contributed to some confusion about the cables and connectors required for 10GbE.
Copper cables Common forms of 10GbE copper cables are as follows:
10GBASE-CR Cable
Currently, the most common type of copper 10GbE cable is the 10GBase-CR cable that uses an attached SFP+ connector, also known as a SFP+ Direct Attached Twinax Copper. This fits into the same form factor connector and housing as the fiber-optic cables with SFP+ connectors. Many 10GbE switches accept cables with SFP+ connectors, which support both copper and fiber-optic cables, also known as SFP+ direct attach copper cables. These cables are available in 1m, 1.5m, 2m, 3m, 5m, 7m, 10m and longer distances. The most commonly deployed distances are 3m and 5m.
Passive and Active DAC Cable
Passive copper connections are common with many interfaces. The industry is finding that as the transfer rates increase, passive copper does not provide the distance needed and takes up too much physical space. The industry is moving towards an active copper type of interface for higher speed connections. Active copper connections include components that boost the signal, reduce the noise and work with smaller gauge cables, improving signal distance, cable flexibility and airflow.
10GBASE-T Cable
These cables and connectors are similar to, but not the same as the cables used for 1000BASE-T. 10GBASE-T cables are Cat6a (Category 6 augmented), also known as Class EA cables. These support the higher frequencies required for 10Gb transmission up to 100 meters (330 feet). Cables must be certified to at least 500MHz to ensure 10GBASE-T compliance. Cat7 (Category 7, Class F) cable is also certified for 10GBASE-T compliance, and is typically deployed in Europe. Cat6 cables may work in 10GBASE-T deployments up to 55m, but should be tested first. Some newer 10GbE switches support 10GBASE-T (RJ45) connectors.
Connectors Several types of connectors are available for 10GbE cables. Each of the connector types includes a specific number of lanes, or channels. As of early 2011, the fastest generally available connector speeds supported were 10 Gbps per lane. Significantly higher speeds are currently achieved by bundling multiple lanes in parallel, such as 4×10 (40Gbps), 10×10 (100Gbps), 12×10 (120Gbps), etc. Most of the current implementations of 40GbE and 100GbE use multiple lanes of 10GbE and are considered “channel bonded” solutions.
Cables and Transceivers for 10GbE Network:
| Transceivers | Type | Lanes | Max. speed per lane (Gbps) | Max. speed total (Gbps) | Cable type | Usage |
| Copper CX4 | CX4 | 4 | 5 | 20 | Copper | 10GbE, SDR and DDR Infiniband |
| Small Form-factor Pluggable | SFP | 1 | 4 | 4 | Copper, Optical | 1GbE, Fibre Channel: 1, 2, 4Gb |
| Small Form-factor Pluggable enhanced | SFP+ | 1 | 16 | 16 | Copper, Optical | 10GbE, 8Gb & 16Gb Fibre Channel, 10Gb FCoE |
| Quad Small Formfactor Pluggable | QSFP | 4 | 5 | 20 | Copper, Optical | Various |
| Quad Small Formfactor Pluggable enhanced | QSFP+ | 4 | 16 | 64 | Copper, Optical | 40GbE, DDR, QDR & FDR Infiniband, 64Gb Fibre Channel |
To summarize, the most common types of 10GbE cables currently use SFP+ connectors.
- For short distances, such as within a rack or to a nearby rack, use DAC with SFP+ connectors, also known as 10GBASE-CR.
- For mid-range distances, use laser optimized multi-mode fiber (LOMMF) cables, either OM3 or OM4, with SFP+ connectors.
- For long-range distances, use single-mode fiber-optic cables (OS1), also known as 10GBASE-LR.
- If your Ethernet switching infrastructure and network adapters support 10GBASE-T (RJ45) cables and connectors, use Cat6 or Cat6a cables.
In addition, 10GBASE Twinax cable or Direct Attach Cable for short, is a kind of optical transceiver assembly widely applied in 10GbE storage area network, data center, and high-performance computing connectivity etc. The DAC cables are used to connect one mobility access switch with another when forming a stack.
