FibreLINK Capacity

Citylink's FibreLINK service specification offers guaranteed performance in two wavelength "windows" - 1310nm and 1550nm. The majority of optical transmission systems offer solutions at either one or both of these frequencies.

Transmission optics for Ethernet networking are readily available today up to 10Gbps bandwidth. The IEEE, the body that oversees the development of Ethernet standards, is currently working on 40Gbps and 100Gbps transmission standards. 40Gbps transmission systems are already available for some other telecommunications systems such as Synchronous Digital Heirarchy (SDH).

CityLink's FibreLINK service will support transmission optics in the specified windows up to 100Gbps, however this will depend on the FibreLINK circuit length.

Other ways to increase optical capacity...

Coarse Wave Division Multiplexing (CWDM) is another technique available for increasing the bandwidth of a fibre optic link. This technique introduces additional devices, known as mutliplexers/demultiplexers, which enable multiple transmission systems to share a single fibre circuit.

Each of the up to 18 transmission systems that can share a single fibre must operate at a different optical wavelengths (colour). Sixteen of these optical wavelengths fall outside of the two operational "windows" specified for the FibreLINK service.

CityLink has been asked by a number of customers if they can use CWDM on their FibreLINK service? General speaking, the answer is "yes", but there are a number of factors that must be considered as the majority freqencies that could be used fall outside of CityLINK's FibreLINK service specification.