Ethernet Cabling Requirements52 CSX400 and CSX400-DC User’s GuideBudget and Propagation Delay — When you determine the maximum fiber optic cable lengthto incorporate fiber runs into the network, calculate and consider the fiber optic budget (a total lossof 11.0 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-linesplices, and fiber optic connectors. Typical loss for a splice and connector (together) equals1 dB or less.Network propagation delay is the amount of time it takes a packet to travel from the sendingdevice to the receiving device. Total propagation delay allowed for the entire network must notexceed 25.6 μs in one direction (51.2 μs round trip). If the total propagation delay between anytwo nodes on the network exceeds 25.6 μs, you must use bridges or switches.Length — The maximum possible multimode fiber optic cable length is 2 km (1.24 miles).However, IEEE 802.3 FOIRL specifies a maximum of 1 km (0.62 miles).Single Mode Fiber Optic NetworkWhen connecting a single mode fiber optic link segment to the CSX400 (using an EPIM-F3),ensure that the network meets the following requirements:Cable Type — Fiber optic link segments should consist of 8/125 or 12/125 μm single mode fiberoptic cabling. You can also use 62.5/125 μm multimode cable with the EPIM-F3; however,multimode cable allows for greater optical loss, and limits the possible distance to 2 km.Attenuation — Test the fiber optic cable with a fiber optic attenuation test set adjusted for a1300 nm wavelength. This test verifies that the signal loss in a cable falls within the acceptablelevel of 10.0 dB or less for any given single mode fiber optic link.Budget and Propagation Delay — When you determine a maximum fiber optic cable length,you must calculate and consider the fiber optic budget (a total loss of 10.0 dB or less betweenstations) and total network propagation delay.To determine the fiber optic budget, combine the optical loss due to the fiber optic cable, in-linesplices, and fiber optic connectors. Typical loss for a splice and connector (together) equals 1 dBor less.Network propagation delay is the amount of time it takes a packet to travel from the sending deviceto the receiving device. Total propagation delay for the entire network must not exceed 25.6 μs inone direction (51.2 μs round trip). If the total propagation delay exceeds 25.6 μs, you must usebridges or switches to re-time the signal.
