Switch Ports and Network Cables
Mode Conditioning Patch Cord for Gigabit-LX
Mode Conditioning Patch Cord for Gigabit-LXThe following information applies to installations in which multimode fiber- optic cables are connected to a Gigabit-LX port.
Mode Conditioning Patch Cord cables only apply to one Gigabit operation. Mode Conditioning Patch Cord cables are not supported for 10 Gigabit operation.
Unlike Gigabit-SX, which connects to only multimode fiber-optic cabling, Gigabit-LX can use either single-mode or multimode cable. Multimode cable has a design characteristic called “Differential Mode Delay”, which requires that the transmission signals be “conditioned” to compensate for the cable design and thus prevent resulting transmission errors. Since Gigabit-SX is designed to operate only with multimode cable, Gigabit-SX mini-GBICs can provide that transmission conditioning internally.
Gigabit-LX mini-GBICs, since they are designed to operate with both single- mode and multimode cable, do not provide the transmission conditioning internally. Thus, under certain circumstances, depending on the cable used and the lengths of the cable runs, an external Mode Conditioning Patch Cord may need to be installed between the Gigabit-LX transmitting device and the multimode network cable to provide the transmission conditioning.
If you experience a high number of transmission errors on the Gigabit-LX ports, usually CRC or FCS errors, you may need to install one of these patch cords between the Gigabit-LX port in your switch and your multimode fiber- optic network cabling, and between the Gigabit-LX transmission device and the network cabling at the other end of the multimode fiber-optic cable run. A patch cord must be installed at both ends.
The patch cord consists of a short length of single-mode fiber cable coupled to graded-index multimode fiber cable on the transmit side, and only multimode cable on the receive side. The section of single-mode fiber is connected in such a way that it minimizes the effects of the differential mode delay in the multimode cable.
If you are using good quality graded-index multimode fiber cable that adheres to the standards listed on page 3, there should not be a need to use mode conditioning patch cords. This is especially true if the fiber runs in your network are relatively short. If you are using single-modefiber-optic cabling, there is no need to use mode conditioning patch cords. Connect the single- mode network cable directly to the Gigabit-LX mini-GBIC.
