4
power control, modulation transmission, signal probe, IV conversion, and limiting amplifier and decision
regeneration. In addition, transceivers provide some other functions, such as counterfeit-prevention query
and TX-disable. Common transceivers include XFP, SFP, SFP+, and QSFP+.
Data rate
Data rate is the number of bits transmitted per second. The unit of measure for data rate is Megabits per
second (Mbps) or Gigabits per second (Gbps). Fiber transceiver modules available for HP
Comware-Based devices mainly provide the following levels of data rates: 100 Mbps, 155 Mbps, 622
Mbps, 1000 Mbps, 2.5 Gbps, 10 Gbps, 40 Gbps, and 100 Gbps.
Transmission distance
The transmission distance of fiber transceiver modules is divided into short and long-range types. A
distance of 2 km (1.24 miles) and below is generally considered as short-range type. 10 km (6.21 miles)
is considered as long-range type.
Transmission distances provided by fiber transceiver modules are mainly limited by certain loss and
dispersion suffered during the transmission of fiber signals over fibers.
• Loss is the optical energy loss due to the absorption, dispersion and leakage over the media when
light travels through optical fibers. This loss increases in direct ratio to transmission distance.
• Dispersion happens mainly because electromagnetic waves of different wavelengths travel at
different rates over the same medium, causing different wave components of optical signals to
reach the receiving end early or late as the transmission distance increases, which in turn causes
impulse broadening, making the signal values indistinguishable.
To meet different transmission distance requirements, choose suitable fiber transceiver modules
according to actual networking conditions.
Central wavelength
Central wavelength represents the wave band used for optical signal transmission. The following central
wavelengths are available for common fiber transceiver modules: 850 nm, 1310 nm, and 1550 nm,
respectively representing three wavebands.
• The 850 nm wave band is used for short-reach transmission.
• The 1310 nm and 1550 nm wave bands are used for middle-reach and long-haul transmissions.
Fiber
Fiber types
Fibers are classified as multimode fibers and single-mode fibers.
• Multimode fibers
Multimode fibers (MMFs) have thicker fiber cores and can transport light in multiple modes.
However, the intermodal dispersion is greater and worsens as the transmission distance increases.
Multimode fibers can be classified into multiple grades according to their diameters and modal
bandwidth. For more information, see Table 2. T
he modal bandwidth of a multimode fiber is
determined by the expression the modulation frequency of the maximum modulation frequency
