cabling
Category 6A cabling is well suited to support a variety of
architectures for switch-to-server connections, including
switches placed in ToR, MoR and EoR configurations.
compatibility with the reach to
support a much broader range of
architectures than direct attach
twinaxial connections.
Another future option for edge
connections is the upcoming IEEE
802.3 standard currently under
development that will define 25Gb/s
operation over up to 100m of
multimode optical fibre cabling and up
to 5m over two pairs (ie. one ‘lane’)
of twinaxial cable. This standard is
expected to support switch-to-server
connections at the edge with SFP28
direct attach cable assemblies, and
may be ideal for migration to higher
speeds among those that are already
familiar with using SFP+ or other cable
assemblies in ToR configurations.
Considering the backbone
While copper cabling’s position
is stable at the data centre edge,
backbone switch-to-switch data
centre deployments for networking
and storage area networks (SANs)
are better served by multimode
optical fibre. The distances in these
environments typically extend beyond
the range supported by copper and
transmission speeds here are evolving
from 10 to 40 and 100Gb/s for
Ethernet based networks and from 8
18
to 16 and 32Gb/s for Fibre Channel
based SANs. But again there are
cabling considerations.
Both 40Gb/s (40GBase-SR4)
and 100Gb/s (100GBase-SR4)
transmission is based on eight
multimode optical fibres – four
transmitting and four receiving at
10Gb/s or 25Gb/s each. These
applications use 12-fibre MPO/MTP
interfaces with 12- or 24-fibre trunk
cables. With MPOs/MTPs being a
12-fibre connector but only requiring
eight for transmission, 33 per cent
of the optical fibre goes unused. An
ideal way for data centre managers
to ensure 100 per cent utilisation of
optical fibre in both 40 and 100Gb/s
applications is to use conversion
cords or modules that transition two
12-fibre or one 24-fibre trunk from
backbone cabling to three 8-fibre
MTPs for connecting to 40 and 100
Gb/s equipment.
Staying within optical insertion,
loss budgets is another consideration
and is essential for ensuring
proper transmission of data signals
between switches, b