3Com 5104M-FL1 installation and operation guide Sample Configuration Distance Calculation

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10BASE-FL Module
	Concentrator A
	230 m	Unshielded Twisted Pair	1.	Maximum	4200 m
		- 10BASE-T Module		Diameter
		A
		150 m	2.	10BASE-FL	2 m x 560 m
	10BASE-FL Module
				Modules	= 1120 m
		Concentrator B		Equivalent Distance
		10BASE-T Module	3.	10BASE-T	585 m
				Modules
		Unshielded Twisted Pair		Equivalent Distance
1000 m	330 m	B	4. Distances Between
		75 m		Transceivers
	500 m 10BASE-FL Module			A & B 150 m + 1000 m
				500 m + 75 m
				= 1725 m

Concen trat or C

Unshielded Twisted Pair	Remaining	770 m
	Distance

C

560 m

10BASE-T Module

Figure 2-7. Sample Configuration Distance Calculation

To make the configuration in Figure 2-7 work, ensure the fiber equivalent distance between transceiver A and transceiver B is less than 4200 meters. To determine if the network configuration is legal:

1.Use 4200 meters as the maximum network diameter for a pure fiber network as defined by the 802.3 specification.

2.Subtract the equivalent fiber distance for each intervening ONline Concentrator with a 10BASE-FL Module in the path. Figure 2-7 has three concentrators between the two 10BASE-T Transceivers A and B (Rule 4). The signal transverses three 10BASE-FL Modules from a delay perspective (230 m on Concentrator A + 560 m on Concentrator C + 330 m on Concentrator B = 1120 m).

3.Subtract the fiber equivalent distance for the two 10BASE-T Modules in Concentrators A and B between the two 10BASE-T Transceivers A and B (Rule 4).

2 - 22 ONline Ethernet 10BASE-FL Installation and Operation Guide