Net Optics Fiber Mode Converters - Manual (Page 10)

Fiber Mode Converter
6
Maximum Round Trip Delay
There are certain rules of Fast Ethernet installation a user must understand
in order to be able to calculate valid cable lengths in a given set up situation.
Maximum round trip delay in bit times is 512; late collisions and/or CRC
errors are indicators that the path delays exceed 512 bit times.
For a network to be valid the worst-case path delay value (PDV) must be
512 bit times or less. Examine the network topology and choose the pair of
DTEs with the largest collision domain diameter, that is the two DTEs that are
farthest apart, and apply the following formula/rules to determine whether the
network is valid.
Network Component Delays
Component Maximum round trip delay in bit times
DTE TX to TX 100
DTE TX to FX 100
DTE FX to FX 100
FMC Converter 10
Class I repeater 140
Class II repeater (all TX/FX ports) 92
Cable Round trip delay in bit times per meter
Cat5 1 .112
STP 1 .112
F/O 1 .0
MII (.5m) 0 (delay included in DTE times)
Network Cable Maximums
Cable Segment Maximum cable length in meters
DTE TX to TX; Cat 5 or STP 100 (half or full-duplex)
DTE FX to FX; Fiber Optic 412 (half-duplex)
2007 (full-duplex)