Cleaning Fiber-Optic Connectors - Cisco ASR 9000 Series Installation Manual

Installing and Removing Line Cards and Transceiver Modules
Warning
Invisible laser radiation may be emitted from disconnected fibers or connectors. Do not stare into beams or
view directly with optical instruments. Statement 1051
Note
It is not necessary to remove the interface cables from the line card cable management bracket.
3. Insert a dust plug into the optical port openings of each port that is not being used.
4. Use a screwdriver to loosen the captive installation screw of the line card cable management bracket.
5. Detach the line card cable management bracket and optical fiber cable bundle from the line card and place
it carefully out of the way.

Cleaning Fiber-Optic Connectors

Fiber-optic connectors are used to connect two fibers together. When these connectors are used in a
communication system, proper connection becomes a critical factor. They can be damaged by improper
cleaning and connection procedures. Dirty or damaged fiber-optic connectors can result in communication
that is inaccurate or not repeatable.
Fiber-optic connectors differ from electrical or microwave connectors. In a fiber-optic system, light is
transmitted through an extremely small fiber core. Because fiber cores are often 62.5 microns or less in
diameter, and dust particles range from a tenth of a micron to several microns in diameter, dust and any other
contamination at the end of the fiber core can degrade the performance of the connector interface where the
two cores meet. Therefore, the connector must be precisely aligned and the connector interface must be
absolutely free of foreign material.
Connector loss, or insertion loss, is a critical performance characteristic of a fiber-optic connector. Return
loss is also an important factor. Return loss specifies the amount of reflected light: the lower the reflection,
the better the connection. The best physical contact connectors have return losses of better than –40 dB, but
–20 to –30 dB is more common.
The connection quality depends on two factors: the type of connector and the proper cleaning and connection
techniques. Dirty fiber connectors are a common source of light loss. Keep the connectors clean at all times,
and keep the dust plugs or covers installed when the connectors are not in use.
Before installing any type of cable or connector, use a lint-free alcohol pad from a cleaning kit to clean the
ferrule, the protective tube or cone that surrounds the fiber core, and the end-face surface of the fiber core.
As a general rule, any time you detect a significant, unexplained loss of light, clean the connectors. To clean
the optical connectors, use a CLETOP fiber optic cleaning cassette and follow the manufacturer's usage
instructions.
If a CLETOP cleaning cassette is not available, follow these steps:
Warning Because invisible laser radiation may be emitted from the aperture of the port when no cable is connected,
avoid exposure to laser radiation and do not stare into open apertures. Statement 70
1. Use a lint-free tissue soaked in 99 percent pure isopropyl alcohol and gently wipe the end-face of the fiber
core. Wait for five seconds for the surfaces to dry and wipe the surfaces a second time.
Cisco ASR 9000 Series Aggregation Services Router Ethernet Line Card Installation Guide
Cleaning Fiber-Optic Connectors
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