Mode Conditioning Patch Cord - HP ProCurve 2910al Series Installation And Getting Started Manual

Cabling and Technology Information

Mode Conditioning Patch Cord

The following information applies to installations in which multimode fiber-
optic cables are connected to a Gigabit-LX port or a 10-Gigabit LRM port.
Multimode cable has a design characteristic called "Differential Mode Delay",
which requires the transmission signals be "conditioned" to compensate for
the cable design and thus prevent resulting transmission errors.
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 or 10-Gigabit LRM transmitting device and
the multimode network cable to provide the transmission conditioning. If you
experience a high number of transmission errors on those ports, usually CRC
or FCS errors, you may need to install one of these patch cords between the
fiber-optic port in your switch and your multimode fiber-optic network
cabling, at both ends of the network link.
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.
N o t e
Most of the time, if you are using good quality graded-index multimode fiber
cable that adheres to the standards listed in Appendix B, there should not be
a need to use mode conditioning patch cords in your network. This is
especially true if the fiber runs in your network are relatively short.
For 10-Gigabit LRM using OM3 cable (50 μm multimode @ 1500/500 MHz*km),
a mode conditioning patch cord is not required. Other multimode cables may
require mode conditioning patch cords to achieve the LRM maximum
distances.
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