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E-8
A
PPENDIX
E: C
ABLING
R
EQUIREMENTS
(500 MHz
•
km) / 2 km = 250 MHz
The same cable would have 500 MHz of bandwidth at 1 km. A fiber cable
with a bandwidth specification of 200 MHz
•
km would have only 100
MHz of bandwidth at 2 km, which would not support ATM. In this case,
another type of fiber would be required.
Single Mode Fiber
Standards
The SMF-PMD standard defines the requirements for an ATM cable plant
to support a connection distance of up to 14.4 kilometers (8.6 miles) of
single mode fiber. The cable plant includes all fiber optic components
between any two communicating ATM devices and their connectors at
each end.
To determine whether the cable plant complies with the SMF-PMD
standard, do the following:
1
Compare the specifications of the fiber you are using to standard
specifications, as described in Table E-6.
2
If you mix equipment supporting Category 1 and Category 2, verify the
maximum attenuation between the equipment, as described in Table E-7.
The following pages describe each of these steps and give examples.
Comparing Fiber to
Specifications
Compare the specifications of the fiber you are using to those in
Table E-6. If the fiber does not meet the specifications, use a different
fiber or contact 3Com Technical Support.
The single mode PMD specification (SMF-PMD) defines two optical power
categories: Category 1 and Category 2. These categories refer to the
optical power that must be launched into the fiber by the transmitter or
detected by the receiver. 3Com currently supports only Category 1 single
mode fiber.
The specifications for the standard single mode fiber are listed in
Table E-6. Refer to the Category 1 specifications in this table for fiber
connecting 3Com equipment. For fiber used with Category 2 equipment
from another vendor, refer to the Category 2 specifications.
The cable plant for a Category 2 implementation must have a minimum
loss of 15.0 dB. In a Category 2 implementation, minimum cable plant
losses are required to avoid saturating (blinding) the receiver.