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Troubleshooting Guide

CloudEngine 16800, 12800, 12800E, 8800, 7800, 6800, and 5800 Series Switches

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What Precautions Should Be Taken When Using Optical Modules?

What Precautions Should Be Taken When Using Optical Modules?

Identifying Optical Module

Generally, an optical module has a label attached, identifying the speed, center wavelength, and mode (single-mode or multimode) of the optical module.

Depending on the transmit power and overload power, optical modules are classified in to short-distance and long-distance optical modules. Optical signals of different wavelengths can travel different distances. Transmission distances of optical modules are affected by attenuation and dispersion of optical signals during transmission. Generally, a distance of less than 2 km is considered a short transmission distance, a distance of 10 km to 20 km is considered a medium transmission distance, and a distance beyond 20 km is considered a long transmission distance. The optical modules used on CE series switches support a transmission distance of up to 100 km.

Center wavelengths of optical modules include:

  • 850 nm: multimode optical modules. They are often used for short-distance transmission.
  • 1310 nm: mostly single-mode optical modules and a few multimode optical modules. They are often used for medium- or long-distance transmission.
  • 1550 nm: single-mode optical modules. They are often used for long-distance transmission.

You can also obtain optical module information in the following ways:

  • Read documents about optical modules.
  • Install an optical module on an interface of the matching type, and then run the display interface transceiver command to check optical module information.

GE and 10GE optical modules look the same. You can identify them by the interface type and speed on the labels attached to the optical modules:

  • eSFP or SFP identifies a GE optical module. SFP+ or XFP identifies a 10GE optical module.
  • A GE optical module has GE or 1.25G on its label, whereas a 10GE optical module has 10G on its label.

Precautions for use of Optical Modules

  • The transmit power of a long-distance optical module is often larger than its overload power. Therefore, when using such optical modules, select optical fibers of an appropriate length to ensure that the actual receive power is smaller than the overload power. If the optical fibers connected to a long-distance optical module are too short, use an optical attenuator to reduce the receive power on the remote optical module. Otherwise, the remote optical module may be burnt.
  • It is recommended that idle optical modules be covered with dust-proof plugs to keep the optical modules clean. An unclean optical module may degrade the quality of optical signals or even cause link failures or error codes on the link.
  • An optical module usually has Rx/Tx flags or in/out arrowheads (▼/▲) to help you identify the transmitter and receiver. The transmitter on one end must be connected to receiver on the other end. Otherwise, the link between two ends cannot go Up.

To avoid injury to your eyes, do not look into optical modules on a device without eye protection, whether they are long-distance or short-distance optical modules.

Updated: 2020-01-07

Document ID: EDOC1000060766

Views: 615027

Downloads: 2962

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