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Getting more out of your fibre

Monday, June 14, 2010

UK Telecoms Equipment Manufacturer Metrodata Ltd. has helped a UK North Sea rig operator get more capacity out of their existing fibre optic communications - by combining multiple traffic payloads over individual fibre links between three offshore rigs.

It installed converters on the platforms to interface each of telephony, serial and (Gigabit) Ethernet data signals to Fibre , and then deployed optical multiplexing using CWDM (Coarse Wavelength Division Multiplexing) technology to carry the combined data down a fibre optic network much more efficiently.

An alternative way of doing this could be to convert the phone and serial data  to Ethernet / IP first and then run pure Ethernet/IP over the fibre. "This would have potentially been technically possible, but certainly more costly, more complex to configure, and more difficult to install (requiring greater technical skills) " says Metrodata's Managing Director Richard Kirby.

The optical multiplexer devices themselves are "passive", i.e. they require no power connection, which means that there is no optical re-transmission or amplification on the way, with sufficient Transmit power coming from the fibre conversion devices to pass data directly between rigs within the network. This set-up can work readily over distances of up to around 100km and is inherently extremely reliable.

You might be surprised to learn that companies are running out of data communications capacity in a fibre optic network.

Fibre optic installations typically consist of a limited number of transmit / receive pairs, each designed to carry between 100 mpbs to 10 gbps, inside an armoured pipe along the seabed.

The problem the client faced in this instance was that nearly all of its fibre optic transmit / receive (Tx/Rx) pairs were already being used on other services.

It wanted to use the system for conventional voice lines (trunk circuits between traditional PBX devices), data (gigabit Ethernet) and alarm signalling from a power management system (serial data), all through a single  fibre Tx/Rx pair.

For resilience, the company deployed a 'ring' topology between the rigs, ensuring that traffic could pass either 'east' (or 'clockwise) or 'west' (counter clockwise) around the ring to protect against the possibility of a link failure, i.e. if the route from rig A to rig B failed, the data could be routed via rig C.

In reality, in order to provide maximum resilience for this critical network, a second separate ring was constructed using a single additional Tx/Rx fibre pair. In this way, the network offered resilience to multiple link or component failures.

Mr Kirby suggests that the same technology could be use for anyone running out of fibre space. The installation proved to be simple, needing less skills offshore and with minimal impact on operations, he says.

Metrodata Ltd. is a specialist manufacturer and integrator  of fibre interface conversion and multiplexing equipment and can be reached at

Associated Companies
» Metrodata

External Links
» Metrodata

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