GarrettCom 6K25e manual F10ST

Magnum 6K25e Gigabit Fiber Switch Installation and User Guide (10/07)

Magnum 6K25e Switches implement the 802.3x flow control (non-blocking) on Full-Duplex ports, which provides for a “PAUSE” packet to be transmitted to the sender when the packet buffer is nearly filled and there is danger of lost packets. The transmitting device is commanded to stop transmitting into the 6K25e Switch port for sufficient time to let the Switch reduce the buffer space used. When the available free- buffer queue increases, the Switch will send a “RESUME" packet to tell 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 6K25e 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.

4.6Power Budget Calculations for Magnum 6K25e PM’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 Magnum products, 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 50/125∝m (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

and the “Cable Loss” for 9/125 (Single-mode) is 0.4 dB/km (LXSC25) and the “Cable Loss” for 9/125 (Single-mode) is 0.25 dB/km

(LXSC40)

and the “Cable Loss” for 9/125 (Single-mode) is 0.2 dB/km (LXSC70)

The following data has been collected from component manufacturer’s (Agilent’s and Lucent’) web sites and catalogs to provide guidance to network designers and installers.

Fiber

Port

Module

6KP4-

F10ST

Speed,		Std.	Wave	Cable	X’mitr	R’cvr	Worst	Worst*	typical	typical*
Std.	Mode	km	-	Size	Output	Sens.	OPB,	distance	OPB,	distance
		fdx	length	∝m	PT , dB	PR ,dB	dB	Km, fdx	dB	Km, fdx
		(hdx)	nm
10Mb	Multi-	2	850	62.5/125	-15.0	-31	14	5	17	6
FL	Mode	(2)		100/140	-9.5	-31	19.5	5.9	23.5	7
				50/125	-19.5	-31	19.5	3.4	13.5	4.8

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