Black Box LE14XXA, Modular Switches manual

Black Box Modular SwitchesInstallation and User Guide (8/99)

reduce the buffer space used. When the available free-buffer queue increases, the Switch will sen a “RESUME" packet to indicate the transmitter to start sending the packets. Of course, the transmitting device must also support the 802.3x flow control standard in order to communicate properly during normal operation.

Note: When in Half-Duplex mode, the Modular-switch implements a back- pressure algorithm on 10/100 Mb ports for flow control. That is, the switch prevents frames from entering the device by forcing a collision indication on the half-duplex ports that are receiving. This temporary “collision” delay allows the available buffer space to improve, as the switch catches up with the traffic flow.

4.7Power Budget Calculations for LE14XXA-Series 4PM’s with Fiber Media

Receiver Sensitivity and Transmitter Power are the parameters necessary to compute the power budget. To calculate the power budget of different fiber media installations using LE14XXA models, the following equations should be used:

OPB (Optical Power Budget) = PT(min) - PR(min)

where PT = Transmitter Output Power, and PR = Receiver Sensitivity

Worst case OPB = OPB - 1dB(for LED aging) - 1dB(for insertion loss) Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

where the “Cable Loss” for 62.5/125 and 50/125μm (M.m) is 2.8 dB/km, and the “Cable Loss” for 100/140 (Multi-mode) is 3.3 dB/km,

and the “Cable Loss” for 9/125 (Single-mode) is 0.5 dB/km

The following data has been collected from component manufacturer’s (HP’s and Siemens’) we sites and catalogs to provide guidance to network designers and installers.

Fiber	Speed,		Std.	Wave	Cable	X’mitr	R’cvr	Wors	Worst*	typica	typical*
Port	Std.	Mode	km	-	Size	Outpu	Sens.	t	distanc	l	distanc
Module			fdx	lengt	μm	t	PR	OPB,	e Km,	OPB,	e
			(hdx)	h		PT , dB	,dB	dB	fdx	dB	Km, fdx
				nm
LE1424C	10 Mb	Multi-	2		62.5/12	-15.0	-31	14	5	17	6
				850	5	-9.5	-31	19.5	5.9	23.5	7
	FL	mode	(2)
					100/14	-19.5	-31	9.5	3.4	13.5	4.8
					0
					50/125
LE1428C	100Mb	Multi-	2	1300	62.5/12	-20	-31	9.0	2.5	14	5
	FX	mode	(0.4)		5	-23.5	-31	5.5	2.0	12	4
					50/125
LE1421C	100Mb	Single-	18+	1300	9/125	-15	-31	14	28	17.5	35
	FX	mode	(0.4)
LE1422C	100Mb	Multi-	2	1300	62.5/12	-20	-31	9.0	3.0	15.8	5.5
	FX	mode	(0.4)		5	-23.5	-31	5.5	2.0	12.2	4.0
					50/125

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