Power Budget Calculations For Magnum 6K25E Pm's With Fiber Media; Magnum Gigabit Fiber Switch - GarrettCom Magnum 6K25e Installation And User Manual

Magnum 6K25e Gigabit Fiber Switch
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.
4.6

Power 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) = P
where P
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
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 Speed,
Port
Std.
Module
6KP4- 10Mb
F10ST
FL
www GarrettCom com .
(min) - P
T
= Transmitter Output Power, and P
T
Std. Wave
km -
Mode
fdx length
(hdx) nm
850 62.5/125
Multi- 2
Mode
(2)
.
Installation and User Guide (10/07)
(min)
R
R
Cable X'mitr R'cvr
Size Output Sens.
µm
P dB P dB
T , R ,
-15.0 -31
100/140 -9.5 -31
50/125 -19.5 -31
41
= Receiver Sensitivity
µm
(M.m) is 2.8 dB/km,
Worst Worst*
OPB, distance
dB Km, fdx
14
5
19.5 5.9
19.5
3.4
typical typical*
OPB, distance
dB Km, fdx
17
6
23.5 7
13.5
4.8