Cabletron Systems EMC39-12 User Manual page 28

Appendix A: Cable Requirements
Budget and Propagation Delay
When determining a maximum fiber optic cable length, the user must
calculate and consider the fiber optic budget 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 half duplex network must not exceed 25.6 s in one
direction (51.2 s round trip). If the total propagation delay exceeds
25.6 s, use bridges or switches to re-time the signal.
Length
If all system budgets are met, the fiber optic ports will drive a single mode
signal for a distance of 5 km for half duplex and 10 km for full duplex
operation.
If all system budgets are met, the fiber optic ports will drive a multimode
signal for a distance of 2 km for half duplex and full duplex operation.
The maximum fiber optic cable length is dependent on the
NOTE
cable type, system optical budget, and collision timing
constraints (for half duplex).
All single mode distances are based on Corning SMF-28 fiber
NOTE
and multimode distances are based on Corning 62.5/125 fiber.
A-2 EMC39-12 User's Guide