Cabletron Systems Cabletron CyberSWITCH CSX400 - Manual (Page 66)

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
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, 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
µ
m single mode fiber
optic cabling. You can also use 62.5/125
µ
m 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
µ
s in
one direction (51.2
µ
s round trip). If the total propagation delay exceeds 25.6
µ
s, you must use
bridges or switches to re-time the signal.