Data centre wiring

Data centers underwent a network convergence in the early and mid-'90s as Ethernet became the de facto standard. But as new applications created a need for high-speed and low-latency network fabrics, the data center networks became more fragmented. In today’s data center you might find 100Base-T Ethernet, Gigabit Ethernet over copper or fiber, 10 Gigabit Ethernet over fiber, Fibre Channel for storage, InfiniBand for server interconnects, and so forth.

All of these different network types require specialized skills, different media, and various types of smart switches to interconnect them. The end result is increased cost, increased complexity and limited flexibility. If we are to realise the flexible data centre of the future, where servers and storage are pooled and made available to applications on demand, it will be helpful to standardise the networking fabrics and protocols.

With every generation of LAN technology, we’ve always heard reports of the imminent demise of Ethernet. At every new wave of innovation, some seemingly impassable barrier stood in the way of higher capacity. Yet Ethernet always seems to re-invent itself, and any bets against it seem to be short-lived. Granted, there are always going to be some special circumstances where a non-standard or highly specialized fabric is more appropriate. But in general, standardizing on a few fabrics, link-layer protocols and media types can make data center networks easier to manage and more flexible.

A few recent developments foretell a re-convergence on Ethernet in the near future, most important of which is the ratification of 10GBase-T. Also known as 802.3an-2006, this standard describes a physical layer (PHY) transmission device for 10Gbps Ethernet over twisted-pair copper. While there are still power consumption issues and the inevitable price issues, 10GBase-T could revolutionize data center networking. It could now be possible to build a data center with Cat-6 UTP cabling throughout, supporting 10M, 1G and 10G Ethernet on a single medium and plug type (RJ-45). “The initial applications for 10G over copper in data centres are for aggregating multiple 1G LANs and SANs,” says Keith Kosanovich – Senior Product Manager, Copper Structure Cabling System, Leviton.

The data center of the future could be based on a single cabling format (Cat-6 or Cat-7 UTP) and link-level protocol (10GBase-T) providing for all types of networking:

* Server-to-client connections

* Data center-to-Internet connections

* Server-to-server interconnect replacing InfiniBand

* Storage-to-server interconnect replacing Fibre Channel

* Data center-to-data center interconnect over metro Ethernet

Companies could conceivably consolidate InfiniBand and Fibre Channel-based networks, replacing them with 10GBase-T. This could lead to rapid adoption of iSCSI and even more adoption of blade server systems. The chief benefit to implementing 10 Gigabit Ethernet will be for applications that require high bandwidth for continuous data flow, such as traditional backup to tape, disk-to-disk backup, data archiving and data replication for disaster tolerance. .

“10GBase-T, InfiniBand and Fiber Channel each have different media (cable), connectors and distance capabilities. For these reasons, the foreseeable future will be some mix of these high-speed network technologies in the data center. While Ethernet (10/100 & 1G) has dominated enterprise networks, the cost of 10GBase-T electronics is still fairly high and not available from every major electronics vendor. Once 10GBase-T electronics are widely available, the market will experience some pricing pressure which may give IT mangers and cable planners more reason to consider 10GBase-T. Cabling planners working in a data center will need some understanding of the legacy equipment, planned growth, distances required, applications and budget to consider recommend an appropriate cabling solution,” says Kosanovich.

If the recent industry analysts reports are anything to go by, the market for the high-bandwidth form of the networking technology is already gaining momentum. Dell'Oro Group expects the 10 Gigabit Ethernet market to grow to $4 billion in 2010. The research firm also forecasts 10 Gigabit Ethernet port shipments to grow to almost 10 million in 2010. Meanwhile, the average selling price for the switches is expected to drop from $5,200 to just over $400 during the same period.

However, users considering 10GBase-T for data centre cabling will have to pay special attention to the standards. Vendors such as R&M recommend the recently ratified ISO/IEC 11801 Class EA. “The deployment of copper cabling for 10GBase-T in data centre is demanding since the transmission parameters have been pushed to certain limits in order to realize this high speed data transmission. Therefore we recommend ISO/IEC 11801 class EA. This standard offers the user more margin and therefore higher operational reliability. The confusing situation in the standard abbreviations between TIA and ISO makes it necessary to take special care and requires users to ask for a real class EA certification,” says Stephan Klein, Executive Vice President for R&M MEA.