Tech Brief: HP ProCurve 10-Gigabit Media Alternatives

ProCurve Networking Technical Brief
10-Gigabit Media Alternatives
Introduction
For the IT manager, the future is optimistic but
confusing. Having 10-Gigabit backbones within your
network infrastructure is going to allow performance
levels, and scalability for future applications, that is
mind boggling. But also boggling the mind will be
choosing which of the various 10-Gigabit media
options to use, and making sure your selections live as
long as your network.
Following is some information on the 10-Gigabit
media options available or on the horizon, to help you
navigate the thicket of 10GBASE alternatives.
10GBASE-SR, -LR, and -ER
In 1999, the IEEE 802.3 committee started a project to
develop a standard for 10-Gigabit-per-second Ethernet.
As committees often find themselves pulling diverse
groups together, they also find themselves in
disagreement over how to solve a particular problem.
When it came to lowest-cost media, multimode fiber
was the clear choice because the committee was
convinced that copper would not make the grade at
that speed. So 10GBASE-SR was defined as the low-cost
optical solution to support multimode fiber with
850 nm Vertical Cavity Surface Emitting Laser (VCSEL)
optics. To run up to 10 km on single-mode fiber, a
1310 nm wavelength was needed and so 10GBASE-LR
was adopted. To run extremely long distances,
10GBASE-ER was defined with 1550 nm optics to run
as far as 40 km on single-mode fiber.
10GBASE-LX4
Unfortunately, life could not be as simple as three
options. The 10GBASE-SR optics could run only 26 m on
existing FDDI-grade fiber, which severely limits its
application. While SR can run up to 300 m on OM3
grade fiber, the installed base of this fiber is very small.
So another technology known as 10GBASE-LX4, which
uses four wavelengths of light on a single fiber
running at one-quarter the speed, was chosen to fill
the gap. 10GBASE-LX4 runs on multimode and single-
mode fiber, but it requires four times as many optical
components and a special optical multiplexer that
makes it pricey, as well as difficult to integrate into
smaller optical form factors.
10GBASE-LRM
In order to improve the cost/performance benefits of
10-Gigabit on multimode fiber, the IEEE 802.3
committee started a project in 2003 called 10GBASE-
LRM. Using long wavelength optics on multimode fiber
with a technology called Electronic Dispersion
Compensation (EDC), the IEEE developed a long-
distance multimode solution that operates with a
single wavelength. The EDC function is one that can be
integrated into the serializer, and perhaps even done in
CMOS over time, which suggests that it can achieve a
very low cost and fit into very small form factors. EDC
is a form of signal processing that removes
interference from the received optical signal and
recovers an open “eye” from a closed eye.
The 10GBASE-LRM specification was adopted in
November 2006.