Transition Networks SSETF10XX-200 - Manual (Page 4)

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HALF-DUPLEX NETWORK
512-Bit Rule
In a half-duplex network, the maximum cable lengths are determined by the
round trip delay limitations of each Fast Ethernet™ collision domain. (A
collision domain is the longest path between any two terminal devices, e.g. a
terminal, switch, or router.)
The 512-Bit Rule determines the maximum length of cable permitted by
calculating the round-trip delay in bit-times (BT) of a particular collision
domain. If the result is less than or equal to 512 BT, the path is good.
To calculate the round-trip delay for a collision domain:
1. Find the collision domain, i.e. the longest
path between any two terminal devices
(e.g., terminal, switch, and/or router).
2. Calculate the round-trip delay in bit-times
for each length of cable.
4. Determine the bit-time values for each
device (see table to the right).
3. Add the bit-time values for each length of
cable and the bit-times for each device.
NOTE: The 512-Bit Rule applies separately to each collision domain.
The example below illustrates a collision domain bound by a router on one
end and a terminal on the other.
Since the total of the bit-times in this example is less than 512 (see chart
below), the path is good.
Terminal
= 50 BT
10 meters TP
= 11.1BT 150 meters fiber = 150BT
Class I Hub = 140BT Switch = 50BT
Media Converter
= 12BT
10 meters TP
= 11.1BT
Sum of the bit-times for the example collision domain:
Router
= 50.0 BT
10 m TP cable (10m x 1.11 BT/m) = 11.1 BT
SSETF101xx-200 = 12.0 BT
150 m fiber cable (150 m x 1.0 BT/m) = 150.0 BT
Class I hub = 140.0 BT
10 m TP cable (10m x 1.11 BT/m) = 11.1 BT
Terminal = 50.0 BT
Total = 424.2 BT
Class I hub 140 BT
Class II hub 92 BT
terminal/router 50 BT
1 meter TP cable 1.11 BT
1 meter fiber cable 1 BT
Fast Ethernet switch 50 BT
SSETF10xx-200
12 BT
8
SSETF10xx-200
Tech Support: 800-260-1312 International: 952-941-7600 7am-6pm CST (GMT-6:00)
FAULT ISOLATION and CORRECTION
If the Media Converter fails, isolate and correct the fault by determining the
answers to the following questions and then taking the indicated action:
1. Is the P(o)W(e)R LED on the Media Converter illuminated?
NO
• Is the power adapter the proper type of voltage and cycle frequency
for AC outlet?
• Is the power adapter properly installed in the Media Converter and in
the outlet?
• Does the grounded AC outlet provide power?
• Contact Technical Support: US/Canada: 1-800-260-1312,
International: 00-1-952-941-7600.
YES
• Proceed to step 2.
2. Is the LKC LED illuminated?
NO
• Check the twisted pair cables for proper connection.
• Contact Technical Support: US/Canada: 1-800-260-1312,
International: 00-1-952-941-7600.
YES
• Proceed to step 3.
3. Is the LKF LED illuminated?
NO
• Check the fiber cables for proper connection.
• Verify that the TX and RX cables on the Media Converter are
connected to the RX and TX ports, respectively, on the other device.
• Contact Technical Support: US/Canada: 1-800-260-1312,
International: 00-1-952-941-7600.
YES
• Proceed to step 4.
4. Is the 100 LED illuminated?
NO
• The Media Converter has selected 10 Mb/s operation. If this is not the
correct speed, disconnect and reconnect the 10/100Base-TX cable to
restart the initialization process.
• Proceed to step 5.
YES - SLOWLY FLASHING
• The Media Converter is selecting between 10 Mb/s and 100 Mb/s
speed or one or both of the links is down. If persistent, disconnect
and reconnect either cable to restart the initialization process.
• Proceed to step 5.
YES
• The Media Converter has selected 100 Mb/s operation. If this is not
the correct speed, disconnect and reconnect the 10/100Base-TX
cable to restart the initialization process.
• Proceed to step 5.