Cisco XR 12000 Series Installation Manual page 48

Cabling and Specifications
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Gigabit Ethernet SFP Modules
The Gigabit Ethernet laser optical transceiver module is a field-replaceable small form-factor pluggable
(SFP) module that plugs into the receptacle on the Ethernet port adapter (EPA) located on the Modular
Ethernet line card and provides the Gigabit Ethernet optical interface. (See
two optical interfaces—laser transmit (TX) and laser receive (RX)—and an electrical interface (to the
line card). The 4-Port Gigabit Ethernet ISE, 10-Port 1-Gigabit Ethernet, and Modular Gigabit Ethernet
line cards use SFP modules.
Figure 35
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Cisco XR 12000 Series Router Ethernet Line Card Installation
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Always connect from transmit (TX) to receive (RX) when connecting GBICs to other equipment:
Connect GBIC TX to equipment RX
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Connect GBIC RX to equipment TX
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Optical transceivers—such as the Cisco CWDM GBICs—have a maximum optical receive power,
above which damage might occur to the receive diode. The incoming power level might be too high
if the fiber lacks sufficient attenuation, which might occur in a short run of fiber (less than
approximately 25 km). Attenuators are used to lower the incoming optical signal below the
maximum optical receive power of the Cisco CWDM GBIC (–7 dB).
When the length of the fiber-optic link is less than 15.5 miles (25 km), you must insert a 10-dB inline
optical attenuator (Cisco product number AT-10DB-SC=) between the fiber-optic network and the
receiving port on the Cisco CWDM GBIC at each end of the link to ensure that the maximum receive
power is always less than –7 dBm.
SFP Module and Fiber-Optic Cable
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Component side of line card
Top surface of SFP module
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3 Card carrier side of line card
Figure 35.) The module has
OL-7861-01