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Guide To Data Centre Cabling Best Practice

What is data centre cabling and why does it matter?

Data centre cabling, also known as structured cabling, provides network connectivity within a data centre, whether between racks or incoming carrier links and racks. A well-designed cable installation system ensures predictable performance, availability, and redundancy, as well as flexibility for future changes and additions. The cabling infrastructure is the operational heart of any data centre.

Structured vs unstructured cabling

Unstructured cabling is used in ad-hoc situations for simple cable management projects as no installation plan is required. Cabling installations need to be carefully considered due to the nature of flexibility required for efficient data centre cable management. While unstructured cabling is initially a cost-effective option, the maintenance cost is higher due to less reliability than the structured approach to cabling design that enhances data centre cable management.

Structured cabling infrastructure involves a detailed cabling design & installation plan to optimise transmission between voice, data and video signals from varying sources to multiple destinations, making it ideal for large-scale projects to transmit a high volume of data traffic. It comprises various connection points, patch panels and cable management systems and each part is specifically implemented into an installation plan which streamlines installation processes and ensures flexibility for future upgrades.

Types of data centre cabling

Copper cable – Copper cables use electrical signals to pass data between networks. There are many different types of copper cables for various projects, including unshielded and shielded, as well as cables that support different speeds of networks, including Cat6 and Cat6a. The standardised connector type for all copper ethernet cabling in the UK is the RJ45 connector. One advantage of copper cables is that they can also offer the benefit of providing Power over Ethernet (PoE) to end devices such as door access and CCT in the data centre space. The latest PoE++ Type 4 now offers 100W of power over a single 8-core ethernet cable.

Fibre optic cable – Fibre optic cables contain strands of glass fibres inside an insulated casing. They are designed for long-distance, high-speed networking and are becoming the go-to choice of cabling for data centres of the future. There are two main categories of fibre cabling: Singlemode (OS2) and Multimode (OM4/OM5). Fibre optic connector types are generally LC (same format as standard SFP), or MPO/MTP which provide various high-density connectivity options allowing speeds of up to 800G on a single trunk cable.

Data centre cable colour codes

Maximising uptime in data centres requires clear communication about the role of network cables. The Telecommunications Industry Association (TIA) publishes colour-coding standards for optical fibre cables in indoor environments. TIA defines six specifications for different fibre-grade cables, including both multimode (OM) and single mode (OS) fibres. The current colour coding includes Orange for OM1 and OM2, Aqua for OM3, Erika violet or Aqua for OM4, and Yellow for OS1 and OS2.

Data centre cabling standards:

Cabling standards for data centres ensure safety and provide the basis for building an integrated data centre infrastructure. Data centre infrastructure management consists of guidelines for maintaining high levels of cable performance to service both current and future requirements. There are a number of data centre standards for cabling. Here are three commonly referenced standards:

ANSI/TIA-942 – This standard outlines the functional areas specific to the data centre and provides a minimum recommendation for pathway and space, the distance between the backbone and the horizontal cable medium, redundancy, cable management and environmental considerations.

ISO/IEC 24764 – Based on TIA-942 and EN 50173-5, this international standard specifies the cabling used in the data centre. We refer to ISO/IEC 11801 and add information related to the data centre.

ANSI/BICSI 002-2014 – This standard provides guidelines for data centre design and operation. It covers planning, construction, commissioning, protection, management and maintenance of the data centre, as well as cabling infrastructure, pathways and spaces. It also covers modular data centres, container-type data centres, and energy efficiency, and also describes its own availability class structure for determining reliability.

Data centre cable management:

The containment system supports the structured cabling system; due to customer demands, many data centres are constantly changing, encouraging flexible design, enabling these changes to be completed rapidly and with little impact on the space. 

Choosing a containment system involves designing with compatibility in mind, including potential future customer requirements and new cable types. The size of the containment is crucial to support current needs and prevent undue strain on cables, as well as accommodate future moves, adds, and changes (MACs) by the customer.

Both of the main data centre cabling containment options (under-floor and overhead) have benefits and drawbacks, but the choice is often taken when considering things like what capacity the building can provide and where other equipment and cabling are being fitted, such as electrical and HVAC. In addition, ventilation and airflow are key in a data centre, especially with the latest methods of making data centre spaces more sustainable with techniques like hot and cold isles. 

Once the location of the containment has been chosen, there are two main types of horizontal cabling options for containment that can be installed:

  • Cable trays or baskets – These are generally the most cost-effective and may provide the best solution in a colocation centre where cabling change-outs and upgrades are common.
  • Raceways – These provide the best cable protection and partitioned pathway systems allow for both high and low-voltage cable to be co-routed, achieving high levels of systems integration

The benefit of using these methods as opposed to other cabling management systems, cable ties or various vertical cable managers is due to the level of organisation and protection that cable trays/ baskets & raceway systems provide. Implementing these into the design reduces costs over time and revisiting this in the future could create a costly rework; instead of trying to maintain equipment, new equipment would need to be purchased.

Data centre cabling installation:

Once the appropriate design has been completed for the DC cabling installation, the next step is the installation. Due to the nature of DCs, the preference is to always keep time working in the DC to a minimum, therefore reducing the risk exposure whilst working in a live environment. As with the design, the installation requires a strict following of standards to provide a safe, structured cabling design system that performs to the necessary standards. Some key points to follow are:

  • Routing of cabling – cables should be installed on suitable containment and bundled to the manufacturer’s guidelines to avoid crushing and going over the set parameters for minimum bend radius, which can affect both copper and fibre cabling performance. In addition, copper cabling can be susceptible to high-level electromagnetic interference, so care should be taken to avoid electrical wiring. For fibre optic cabling additional care should be taken to run them separately from copper cable bundles which can be heavy and damage the fibre cable’s glass cores
  • Termination of copper cabling – Leading manufacturers offer training and guidance to follow on their cabling systems; the UK follows a T568B pinout for all connectors. When terminating copper cabling, the appropriate length of cable sheath should be removed with a designated cable stripper and twists maintained until the termination point; using the stipulated termination tool (110 or Krone). For shielded cables, the drain wire must be inserted into the termination module to provide a grounding
  • Connecting fibre cabling – fibre cable connectors can be very susceptible to dust. When fitting pre-term MPO cables and connectors, dust caps should always be maintained until the testing phase. Prior to any test and rigorous cleaning process should be followed including click-cleaners for all connectors
  • Labelling of cables – all cables should be individually labelled for ease of identification. These are engraved labels at either end of the link and wrap-around labels on the cable behind the termination point. The labelling scheme should include the source and designation details, including DC hall, rack, panel and port IDs
  • Testing & certification – Any copper or fibre cable installed should be fully tested and certified with a standards-approved tester, be that a copper or MPO fibre cable. The tester should be calibrated by the manufacturer annually. The certification should then be provided in both proprietary and PDF format to the client, along with the cabling manufacturer’s performance warranty which is commonly 25 years

The future of data centre cabling:

To match constantly increasing speeds the network cabling market is constantly evolving and looking to the future needs of networking vendors’ technology.

The latest incarnation of copper ethernet cabling is Category 8. Category 8 cabling has been designed for the data centre market and the ever-increasing bandwidth requirements. Unlike other categories of copper cabling which have a maximum range of 100M, Category 8 will have only support 30M, something only practical in the DC space. A single Category 8 4-pair cable will support a 40G connection on a single RJ45 port. This is a four-fold increase over the generally adopted Category 6a cable which supports speeds of 10G per 4-pair RJ45 connection.

The market for fibre optic cables has generally adopted the MPO/MTP connector in the DC space, which enables higher speeds over both Singlemode and Multimode cabling formats. In addition, a move to a preterm trunk cable of splicing means the time spent installing cabling in a DC reduces, and as a result, so does the risk exposure. The MPO connector provides a whole host of advantages over the traditional LC connector, not only providing 12 cores on a single connector but reducing footprint via high-density connectivity and the ability to redeploy at ease and at speed.

With the soaring demand from cloud computing, streaming services and AI applications, speeds have increased dramatically over the last decade. The latest MPO systems support 400G, 800G and the emerging 1.6Tbps speeds. A specified fibre solution enables leading-edge network architectures to deliver greater capacity, in a more time and cost-efficient method.