As data centres evolve to support higher bandwidth requirements of 40G and even 100G capacities, innovations in cabling technology are emerging to meet the multiple demands of cost efficiency, reliability, uptime and high speed data transport (HSDT). Stephen Morris, product manager for cabling specialist Panduit, reports

Fibre Channel over Ethernet (FCoE), Top of Rack (ToR), and fabric-based design are emerging breeds of architecture that are gaining traction as data centre strategies evolve to meet cost, scalability and agility demands. Anticipating growth and technological changes can be difficult, however, the data centre should be able to respond to growth, changes in equipment, standards, and demands while remaining manageable and reliable.

These emerging architectures and virtualisation can demand less cabling, however, as more traffic migrates onto fewer circuits, as a result of network convergence, each circuit therefore becomes more mission critical.

One of the biggest challenges for many organisations is that of provisioning HSDT; cabling systems must meet the demands of high throughput and the increased need for future speeds of up to 100G.

Today’s cabling options for higher throughput of 10G include RJ-45, direct attach copper SFP+ (which has a short reach <15m) and, of course, fibre. If provisioning for 40G, options include Copper QSFP+ (<7m) and fibre. However, today fibre is the main contender for 100G, with MPO leading as the multimode connector interface as reflected in published standard IEEE 802.3ba.
100G multimode applications are based on parallel optic technology; to achieve 100G, 10 lanes of 10G are required, therefore, 20 individual glass fibres are required to transmit and receive 100G. MPO connector options include 12 fibre (these are the most common) and 24 fibre ferrule styles.

Many organisations may choose to deploy MPO-LC cassette based systems for applications running up to 10G, with MPO-MPO cable assemblies connecting cassette to cassette. MPO cabling infrastructure provides a migration path to 40G or 100G e.g. swapping MPO-LC cassettes with an MPO couplers, then adding addition MPO-MPO cable assemblies to extend 40G or 100G circuits as required.

The return on investment period for a data centre is, typically 10 to 15 years, therefore the physical infrastructure will need to outlast multiple refreshes of active equipment as higher throughputs are required.

The good news is that the IEEE high speed study group have reformed creating new 100G objectives (IEEE 802.3bj). When ratified, which is not expected before 2015, the new standard will support the same MPO connector interface, however, it’s probable fibre utilisation will increased to 4 x 25G parallel optics compared to today’s 10x10G.

This means far less glass would be required (100G) and any existing MPO cable plant, installed prior to 100G migration, would be better utilised. In fact, there is no change to the fibre cable plant from today’s 40G – further strengthening the businesses case and ROI for fibre.

However, it’s not over for the ‘twisted pair’: IEEE802.3bq which is anticipated to be released after 2015, will have an objective for 40G over copper shielded twisted pair , most likely supporting distances up to 30m.

For those considering HSDT cabling investment, we would advise the following to ensure uptime, performance certainty and ROI.
• Check there is an intuitive, 1:1 (rack space) migration path from 10G to 40G or 100G (assume 100G at 4x25G).
• Consider lower loss connectivity demands of 40/100G and plan accordingly
• Small diameter cabling and push-pull connectivity solutions e.g. push-pull LC connector can add value. Such products are designed to enhance cable management, improve cable – connector access, reduce cooling baffles and ease expansion into existing pathways. Optimising cabling design can contribute towards cooling efficiency and lower risk to adjacent circuits, to promote scalability and ‘up-time’.

Finally, demand performance certainty; this includes traceability back to product serial number for factory test results (optical) and check the small print with regards to low latency and bit error assurances.