There are several factors that influence the greatest distance that black fibre can travel including signal attenuation and switch optical design. Typical dark fibre links would be 20km or less however it is possible to achieve distances of up to 80km for 10 GbE traffic and 40km for 8 GB fibre channel traffic in some specific instances. These sorts of links must be constructed to fulfill extremely high performance criteria and require specialist optics to achieve these distances. Dark fibre is currently capable of supporting bandwidths of up to 100Gbps.