Although 10 Gigabit Ethernet (10GbE) equipment was introduced to the world as long ago as 2001, it is still a technology with a comparatively niche market. This is largely because firms were put off by the high price of early offerings and the dearth of standards-based solutions.
The technology has moved on a lot since then, however. There are now plenty of products that conform to approved specs, and some organisations see 10GbE as ideal for network traffic aggregation, server clustering and enterprise backbone duties.
Increased demand has also led to price cuts across the board, but many companies have yet to be convinced that there is a business case for investing in a 10GbE infrastructure at present. Most network managers still find that Gigabit Ethernet provides enough capacity for their needs, particularly as costs have dropped so low as to make it possible to deploy high-speed networking to the network edge and even the desktop PC.
Consequently, this month's grouptest looks at Gigabit switches with 10GbE uplink ports. All the main LAN switch manufacturers are represented with the exception of Cisco, which declined to participate, and Allied Telesyn, which advised us it did not have a suitable product available.
Standard problem
One of the biggest conundrums surrounding 10GbE is the sheer number of standards
that have either already been ratified or are in draft state, as well as the
multitude of cable types and distances supported. There are currently three main
options for fibre cabling, for example.
10GBase-SR operates over multimode fibre and supports distances up to 300 metres, but this distance limitation is for the very latest OM3 cabling; if network managers are planning to use their trusty old FDDI cabling, the reach drops to a mere 26 metres. Next is 10GBase-LR, which can operate over single-mode fibre up to 10km; then 10GBase-ER, which stretches to 40km, again over single-mode.
The later 10GBase-LX4 standard supports distances of 300 metres over multi-mode cable and 10km over single-mode, but it uses four sets of laser transmissions and equipment is currently very expensive.
Ratified in 2004, the IEEE 802.3ak standard, or 10GBase-CX4, attracted a lot of interest as it calls for 10GbE over copper cabling up to distances of 15 metres. This specification is designed primarily for server clustering and high-speed switch-to-switch links using standard InfiniBand cabling, however.
By far the most promising 10GbE standard is the IEEE 802.3an or 10GBase-T specification. This defines the delivery of 10Gbit/s bandwidth over conventional UTP copper cabling, including Cat5e, Cat6 and Cat7. There is also an Augmented Cat6 cable under development designed to reduce crosstalk, allowing 10GbE to run over 100 metres.
Unfortunately, the 802.3an standard is not expected to be ratified until the end of this year at the earliest, though in the meantime, SMC has surprised a few of its competitors by delivering a proprietary solution that supports 10GbE operations over standard Cat5e cable up to 10 metres.
