Cabletron Systems MicroMMAC-24E Installation Manual

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Cabletron Systems MicroMMAC-24E Installation Manual Manual pdf 73 page image

Appendix C: Network Planning and ConfigurationPage C-4MicroMMAC Installation GuideC.1.3 Multimode Fiber Optic CableTable C-1 shows Multimode Fiber Optic Cable specifications for theEPIM-F1 and EPIM-F2.AttenuationTest the fiber optic cable with a fiber optic attenuation test set adjusted foran 850 nm wavelength. This test verifies that the signal loss in a cable iswithin an acceptable level. Table C-1 shows the attenuation for eachmultimode cable type.Fiber Optic Budget and Propagation DelayWhen determining the maximum fiber optic cable length to incorporatefiber 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 totalnetwork propagation delay.To determine the fiber optic budget, combine the optical loss due to thefiber optic cable, in-line splices, and fiber optic connectors. Typical lossfor a splice and connector (together) equals 1 dB or less.Propagation delay is the amount of time it takes data to travel from thesending device to the receiving device. Total propagation delay allowedfor the entire network is 25.6 μs in one direction (51.2 μs round trip). Ifthe total propagation delay between any two nodes on the networkexceeds 25.6 μs, then bridges must be used.Table C-1 Multimode Fiber Optic Cable SpecificationsCable Type Attenuation Maximum Cable Length50/125 μm 13.0 dB or less The maximum allowable fiber opticcable length is 2 km (2187.2yards). However, IEEE 802.3FOIRL specifications specify amaximum of 1 km (1093.6 yards).62.5/125 μm 16.0 dB or less100/140 μm 19.0 dB or less