3com 2500 Quick Setup Guide
Single Mode Fiber Standards
D-7
Verifying Maximum Attenuation for Mixed Fibers
If you mix Category 1 and Category 2 receivers and
transmitters, use
transmitters, use
attenuation for each possible combination.
Example
If a Category 2 transmitter is outputting to a
Category 1 receiver, the maximum attenuation is
26.0.
Category 1 receiver, the maximum attenuation is
26.0.
Using Unkeyed Single Mode Cables
The SMF-PMD standard specifies that keyed single
mode connectors must be used with single mode
cables.
mode connectors must be used with single mode
cables.
shows a cross-section of a keyed
single mode connector.
Figure D-1 Keyed Single Mode Connector
Because of the limited availability of these keyed
connectors, however, you must be able to get only
those cables with unkeyed connectors.
connectors, however, you must be able to get only
those cables with unkeyed connectors.
shows a cross-section of an unkeyed single mode
connector.
connector.
Figure D-2 Unkeyed Single Mode Connector
If you are using unkeyed single mode cables, you
can modify the transceiver and connector housing
so that they fit together. Follow these instructions.
can modify the transceiver and connector housing
so that they fit together. Follow these instructions.
The following procedure reverses the transmit and
receive fiber bundles. Be sure to make a
corresponding reversal at the opposite end of the
cable.
receive fiber bundles. Be sure to make a
corresponding reversal at the opposite end of the
cable.
Table D-7 Acceptable Cable Plants for Combinations of
Category 1 and Category 2
Output
Category
Category
Input
Category
Category
Minimum
Loss
Loss
Maximum
Attenuation
Attenuation
1
1
0.0
10.0
1*
2*
1.0
16.0
2
1
14.0
26.0
2
2
15.0
32.0
*This combination is dispersion-limited rather than
loss-limited. The expected maximum length is approximately
35 km.
loss-limited. The expected maximum length is approximately
35 km.
Front of connector
Molded single mode key