Cabletron Systems CXRMIM, Installation Manual

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2-4 Repeater MIM
Chapter 2: INSTALLATION REQUIREMENTS/SPECIFICATIONS
2.1.3 FOIRL/10BASE-FL Multimode Fiber Optic Network
Requirements for the FORMIM
When connecting a multimode fiber optic segment to a FORMIM-22, EPIM-F1,
or EPIM-F2, your network must meet the following requirements:
Attenuation
You must test the fiber optic cable with a fiber optic attenuation test set adjusted
for an 850 nm wavelength. This test verifies that the signal loss in a cable is
within an acceptable level. Table 2-1 shows the attenuation for each Multimode
cable type.
Fiber Optic Budget and Propagation Delay
When determining the maximum fiber optic cable length, the fiber optic budget
delay and total network propagation should be calculated and taken into
consideration 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 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 25.6
µ
sec, if the total propagation delay between any two nodes on the
network exceeds 25.6
µ
sec, then bridges should be used.
Table 2-1. Multimode Fiber Optic Cable Specifications
Cable Type Attenuation Maximum Cable Length
50/125
µ
m 13.0 dB or less
The maximum allowable fiber
optic cable length is
2 km (2187.2 yards).
62.5/125
µ
m 16.0 dB or less
100/140
µ
m 19.0 dB or less