Enabling the future,
whatever it may be
A few of the technologies covered in articles
within this issue underscore the wide range of
transmission speeds that users currently re-
quire or anticipate requiring, and the cabling that
supports those speeds. In one case, it's single-
mode fiber deployed in data centers providing the
throughput capability necessary for the 400-Gbit/
sec speeds on the horizon ("Long-wavelength opti-
cal networking brings singlemode fiber into data
centers," page 17). In another case, it's Category 5e
twisted-pair cabling supporting the 2.5-Gbit/sec
backhaul for wireless LANs ("Protocol and hardware testing for 2.5GBase-T and
5GBase-T," page 12).
2.5G and 400G exist at opposite ends of the spectrum in terms of transmission speeds. The IEEE 802.3bz standard specifying 2. 5 and 5GBase-T is still
new, having been finalized in September 2016. And the IEEE 802.3bs standard
specifying 400-Gbit Ethernet isn't even "new" yet; it may publish at the end of
this year. But it's noteworthy that the respective cabling technologies aimed at
supporting these speeds have been around for a long while. Early iterations of
Category 5e cabling (some of which ended up complying with the eventual standard ... right?) were installed into commercial office buildings in the late 1990s.
And singlemode fiber ushered in the era of communication via fiber optics. Yet
here both are today, each having stood the test of time in its own right, poised
to be an enabling technology for a new protocol for data communication.
Both singlemode fiber and Category 5e cabling will have to prevail over other
options. On the 400G landscape, singlemode faces competition from parallel-optic permutations of multimode fiber supporting short-wavelength optical
transmission. Among them is short-wavelength division multiplexed (SWDM)
technology that recently was specified by the SWDM Multi-Source Agreement
Group. SWDM is not yet incorporated into an IEEE draft specification, but
many expect it soon will be.
Category 5e faces a different challenge. Whereas alternatives to singlemode
for 400G make an economic case for deployment, some skeptics of 2.5G over
Category 5e say the just-about-20-year-old systems simply won't be up to the
task. For those who plan to give it a try, test specifications exist to characterize
the installed base.
How far into the future will decades-old technology take us? The answer to
that question is yet to be revealed.
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