Appendix C: Network Planning and Configuration
Page C-4
MicroMMAC Installation Guide
C.1.3 Multimode Fiber Optic Cable
Table C-1 shows Multimode Fiber Optic Cable specifications for the
EPIM-F1 and EPIM-F2.
Attenuation
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 C-1 shows the attenuation for each
multimode cable type.
Fiber Optic Budget and Propagation Delay
When determining the maximum fiber optic cable length to incorporate
fiber runs into the network, calculate and consider the fiber optic budget
(a total loss of 10.0 dB or less is permissible between stations) and total
network propagation delay.
To determine the fiber optic budget, combine the optical loss due to the
fiber optic cable, in-line splices, and fiber optic connectors. Typical loss
for a splice and connector (together) equals 1 dB or less.
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
s in one direction (51.2
µ
s round trip). If
the total propagation delay between any two nodes on the network
exceeds 25.6
µ
s, then bridges must be used.
Table C-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). However, IEEE 802.3
FOIRL specifications specify a
maximum of 1 km (1093.6 yards).
62.5/125
µ
m
16.0 dB or less
100/140
µ
m
19.0 dB or less
