Switch User's Guide

Ethernet Cabling Requirements

52 CSX400 and CSX400-DC User’s Guide

Budget and Propagation Delay — When you determine the maximum ﬁber optic cable length

to incorporate ﬁber runs into the network, calculate and consider the ﬁber optic budget (a total loss

of 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-line

splices, and fiber optic connectors. Typical loss for a splice and connector (together) equals

1 dB or less.

Network propagation delay is the amount of time it takes a packet to travel from the sending

device to the receiving device. Total propagation delay allowed for the entire network must not

exceed 25.6 µs in one direction (51.2 µs round trip). If the total propagation delay between any

two 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 Network

When 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 ﬁber

optic 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 a

1300 nm wavelength. This test veriﬁes that the signal loss in a cable falls within the acceptable

level 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 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.

Network propagation delay is the amount of time it takes a packet to travel from the sending device

to the receiving device. Total propagation delay for the entire network must not exceed 25.6 µs in

one direction (51.2 µs round trip). If the total propagation delay exceeds 25.6 µs, you must use

bridges or switches to re-time the signal.