Guide to Upgrading Data Centers with 10gbe Cabling

Are you frustrated with sluggish network speeds? Does your data center feel like it's stuck in the mud? It's time to upgrade your network and embrace the blazing-fast experience of 10GbE! This comprehensive guide will walk you through every aspect of 10GbE cabling, from cable types to connector choices and best practices, helping you build an efficient, stable data transmission environment that will truly make your data center soar.

Since its introduction in 2002, 10 Gigabit Ethernet (10GbE) technology has been regarded as the future of high-speed networking. While early adoption was slow due to partial backward compatibility issues with legacy Ethernet technologies and high costs, the explosive growth of cloud computing, big data, and artificial intelligence applications has created exponential demand for network bandwidth. Today, 10GbE is becoming the preferred solution for data centers and enterprise networks, thanks to its exceptional performance and increasingly affordable costs.

Choosing the right cable is crucial in the 10GbE world. There are two main types to consider: copper and fiber. As network speeds continue to increase, fiber optic cables are becoming more widely used. This is because at high gigabit rates (10Gb+), copper cables experience significant signal attenuation during high-frequency transmission, leading to degraded signal quality that affects transmission distance and stability. This signal attenuation is often referred to as "excessive noise" or "low signal-to-noise ratio."

For short-distance applications (such as within a cabinet or between adjacent cabinets), copper cables remain a cost-effective choice. However, for long-distance or high-performance scenarios, fiber optic cables offer superior advantages.

Fiber optic cables are further divided into single-mode fiber (SMF) and multi-mode fiber (MMF), distinguished primarily by the diameter of the fiber core and the light transmission mode.

• Single-Mode Fiber (SMF): With a core diameter of approximately 9 micrometers (μm), SMF allows only a single mode of light signal to pass through, resulting in lower intermodal dispersion and support for longer transmission distances. SMF typically supports distances exceeding 10 kilometers, with some implementations reaching 80-100 kilometers or more, depending on transmission speed, transceiver type, and buffer credit allocation in switches.
• Multi-Mode Fiber (MMF): Featuring larger core diameters (typically 50 μm or 62.5 μm), MMF allows multiple modes of light signals to pass simultaneously. Due to intermodal dispersion, MMF supports shorter transmission distances, usually within 600 meters, depending on transmission speed and transceiver type. Interestingly, the cost difference between single-mode and multi-mode fiber cables themselves is minimal, but other components in SMF links (such as transceivers) are typically more expensive than their MMF counterparts.

When planning data center cabling, it's essential to consider that fiber optic cables typically have a lifespan of 15 to 20 years. Therefore, selecting cables that support current, future, and legacy data rates is crucial. Additionally, deploying large quantities of new cables in existing data centers can be labor-intensive, requiring careful planning and implementation.

Fiber optic cables are also classified differently based on supported bandwidth:

• Multi-Mode Fiber: OM1, OM2, OM3, OM4
• Single-Mode Fiber: OS1

Currently, the most common 10GbE fiber optic cable type is 10GBASE-SR, which uses SFP+ connectors and is equipped with optical transceivers rated for 10Gb transmission. These cables are also known as "short-range" fiber optic cables, suitable for connections within data centers or between adjacent cabinets.

10GBASE-LR is a "long-range" fiber optic cable that supports single-mode fiber cables and connectors, making it ideal for applications requiring long-distance transmission. OM3 and OM4 are newer multi-mode fibers that have been "laser-optimized" (LOMMF) to support 10GbE applications. These cable types are also the only multi-mode fibers included in the IEEE 802.3ba 40G/100G Ethernet standard, approved in June 2010. Currently, 40G and 100G transmission speeds are achieved by bundling multiple channels in parallel using special multi-channel (or multi-lane) connector types.

The standard specifies that in 40GbE and 100GbE applications, OM3 supports an expected range of up to 100 meters, while OM4 supports up to 150 meters. Note that these are estimates, and actual supported distances may vary depending on future 40GbE and 100GbE products. For more details, refer to the "Connector Types" section below.

To accommodate increasingly complex data center cabling environments, new multi-mode OM2, OM3, and OM4 (50 μm) and single-mode OS1 (9 μm) fiber optic cables have been developed with enhanced bend resistance, allowing them to handle smaller bend radii. These cables are referred to as "bend-optimized," "bend-insensitive," or having "enhanced bend performance." Even at very tight turns or small bend radii, these cables maintain minimal signal loss or "bend loss." The term "bend-optimized multi-mode fiber" (BOMMF) is sometimes used.

OS1 single-mode fiber is typically used for long-distance transmission, supporting distances up to 10,000 meters (6.2 miles) with standard transceivers, and even greater distances with specialized transceivers and switching infrastructure. Each multi-mode and single-mode fiber cable type includes two wavelengths, with the higher wavelength used for longer-distance connections.

Indoor fiber optic cables are designed for building interiors, while outdoor cables (also known as outside plant or OSP) are suitable for exterior applications, featuring waterproof (against liquids and freezing) and UV-resistant properties. Indoor/outdoor cables combine the protective qualities of outdoor cables with fire-retardant jackets, allowing deployment beyond OSP maximum distances at building entrances, reducing the need for transition splices and connections.

The table below shows the distance and speed support for different fiber optic cable types at 850 nm wavelength. Note that 1300 nm wavelength cables can support longer distances.

Here are common 10GbE copper cable types:

The most common 10GbE copper cable type today is 10GBASE-CR, which uses Direct Attach Copper (DAC) cables with SFP+ connectors. These connectors share the same dimensions and form factor as SFP+ connectors for fiber optic cables, and many 10GbE switches accept SFP+ connector cables that support both copper and fiber. 10GBASE-CR cables are typically available in lengths of 1m, 3m, 5m, 7m, 8.5m, and longer, with 3m and 5m being the most commonly used.

Passive copper connections are common in many interfaces. However, as transmission rates increase, passive copper cables cannot provide the required distances and occupy excessive physical space. Consequently, the industry is moving toward active copper cable interfaces to meet higher-speed connection demands. Active copper cable connections include components that enhance signals and reduce noise, allowing for thinner wire gauges that improve transmission distance, cable flexibility, and airflow.

10GBASE-T cables and connectors are similar to those used for 1000BASE-T but not identical. 10GBASE-T cables use Cat6a (Category 6A) cables, also known as Class EA cables. These cables support the higher frequencies required for 10Gb transmission, with distances up to 100 meters (330 feet). Cables must be certified for at least 500MHz to ensure compliance with 10GBASE-T standards. Cat7 (Category 7, Class F) cables are also certified for 10GBASE-T compliance and are commonly deployed in Europe. Cat6 cables may work in 10GBASE-T deployments up to 55 meters but should be tested first. Some newer 10GbE switches support 10GBASE-T (RJ45) connectors.

10GbE cables are available with various connector types. Each connector type includes a specific number of lanes or channels. As of early 2011, the fastest commonly available connector speed was 10 Gbps per lane. Currently, higher speeds are achieved by bundling multiple lanes in parallel, such as 4x10 (40Gbps), 10x10 (100Gbps), 12x10 (120Gbps), etc. Most current 40GbE and 100GbE implementations use multiple 10GbE lanes and are considered "channel-bonded" solutions.

In summary, the most common 10GbE cable types today use SFP+ connectors.

• Short-distance connections: For connections within a cabinet or between adjacent cabinets, use DAC with SFP+ connectors, also known as 10GBASE-CR.
• Medium-distance connections: For medium-distance connections, use laser-optimized multi-mode fiber (LOMMF) cables with SFP+ connectors, specifically OM3 or OM4.
• Long-distance connections: For long-distance connections, use single-mode fiber cables (OS1), also known as 10GBASE-LR.
• 10GBASE-T connections: If your Ethernet switching infrastructure and network adapters support 10GBASE-T (RJ45) cables and connectors, use Cat6 or Cat6a cables. Remember that your cable choice depends on the switch, not the adapters in your environment.