Multimode Specifications for the FE-100FX
BRIM-E100 User’s Guide
Page 2-3
2.2 MULTIMODE SPECIFICATIONS FOR THE FE-100FX
The BRIM-E100 supports the Cabletron Systems FE-100FX. The
FE-100FX meets IEEE 802.3u standards. When connecting a fiber optic
segment to the BRIM-E100 with the FE-100FX module installed, the
network must meet the following requirements:
Cable Loss
Test the fiber optic cable with a fiber optic attenuation test set adjusted for
an 850 nanometer (nm) wavelength. This test verifies that the signal loss
in a cable is within an acceptable level. The maximum loss for a
multimode fiber optic cable is 11.0 decibels (dB).
Fiber Optic Budget and Propagation Delay
Determine the maximum fiber optic cable length by calculating the fiber
optic budget delay and total network propagation before fiber optic cable
runs are incorporated in any network design.
Fiber optic budget is the combination of the optical loss due to the fiber
optic cable, in-line splices, and fiber optic connectors.
Propagation delay (collision delay) is the amount of time it takes data to
travel from the sending device to the receiving device. Total propagation
delay allowed for the entire network is 256 bit times (2.56
µ
s). If the total
propagation delay between any two nodes on the network exceeds
2.56
µ
s, then further segmentation of the network through the use of
bridges or other devices is required.
2.3 NETWORK CABLE LENGTHS
This section details the maximum network cable lengths specified by the
IEEE 802.3u standard. As stated in the previous sections, the physical size
of the network is limited primarily by propagation delay. The propagation
delay cannot exceed 256 bit times.
A 100BASE-TX/FX network might use all copper (UTP) links, all fiber
links or a combination of both. The maximum length of any segment is
determined by the types and combination of links and by the type of
repeater (if any) between segments. IEEE 802.3u standards specify two
repeater classes (Class 1 and Class 2) and the maximum cable lengths for
each media type.
book Page 3 Friday, April 19, 1996 9:53 AM
