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Appendix C: Ethernet Cabling Requirements
C-4 EMM-E6 Installation Guide
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 specifications
specify a maximum of 1 Km (0.62 miles).
C.1.3 Single Mode Fiber Optic Network
When connecting a single mode fiber optic link segment to a hub (using
an EPIM-F3), ensure 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: You must 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.
ICH1Book Page 4 Tuesday, August 6, 1996 3:06 PM