18
FIBRE OPTIC CABLING
Optimum
flexibility
Kai Theile, Territory Sales
Manager Data Centres, Nexans
Cabling Solutions Germany,
Austria, Switzerland
www.nexans.com
MTP connectors are being used in
data centres to meet the demands
40/100 Gigabit Ethernet
To get started, let’s take a closer look at the origins of MTP
PRO. ‘Regular’ MTP connectors are derived from ‘Multifibre
Push On’ (MPO) interfaces, developed to enable multi-fibre
connectivity for higher density, and higher bandwidth-
based applications requiring parallel optics. The MTP
(Mechanical Transfer Push-On) connector is a type of MPO
interface connector from manufacturer US Conec. This is
a high-performance MPO connector featuring multiple
product enhancements, such as different springs, holds
and floating ferrules. These enhancements improve optical
and mechanical performance compared to generic MPO
connectors and make the connector much more usable in
data centres. MPO and MTP look identical, follow the same
standards and are fully interoperable.
The MTP connector has been specifically designed for
data centre applications, with components being fully
compliant with IEC Standard 61754-7 and TIA 604-5.
Various existing LAN protocols, such as for 40, 100 and
even 200G, are covered by MTP. Introducing MTP makes
it possible to use the same type of data centre cable
infrastructure for at least three generations – an important
consideration considering the move from 40G to 100G
to 200G, and the fact that 400G development work is
underway at IEEE.
Using MTP in data centre applications
In this section, we’ll take a closer look at how MTP is used
in data centres in order to better explain the benefits of
MTP PRO. When installing cabling in data centres, there are
two ways of using MTP connectors – the first is to use it as
a jumper. In this way transceivers, for example, are linked,
mainly over a direct connection. If you want to connect two
switches ‘point-to-point’, you can use MTPs but these are
always female.
The second method is to use MTP connectors on trunks,
which is done together with MTP-LC modules. When using
MTP as a trunk you can use patch panels, into which you
insert cassettes that have MTP connectors at the back and
LC connectors at the front. Be aware of the gender: male-to-
male or female-to-female.
A third method is including MTP adapters at the front
of the panel when installing for parallel transmission.
This can be done as part of a migration path from duplex
transmission to parallel transmission by swapping out the
MTP-LC modules. Alternatively, the adapters can be installed
directly for a new project.
A closer look at polarity
The EIA /TIA 568-B.1-7 standard lists three official polarity
methods. Method A: for duplex transmission with MTP-LC
modules the signal that goes in on fibre 1, comes out on
fibre 1. Optical straight duplex patch cords are used on side
A and crossed cords on side B.
Method B: this uses a key-up/key-up MTP pre-term. The
fibre sent in at the first position will come out at the 12th
position. This method is used for parallel transmission, with
the same MTP-MTP patch cords on both sides.
Method C: this uses a flipped pair into a trunk. Light that
goes in at first position will come out at second position for
duplex transmission. The same duplex patch cords can be
used on both sides.
In addition, the methods mentioned above there are
several proprietary polarities on the market, which are all
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