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Magnum DS880 Dual-Speed Stackable Hubs Installation and User Guide (05/01)
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2.2.1 Magnum DS880 Chassis
The Magnum DS880 chassis houses one main PC board, a bridge module daughter-
board in the Model DS880-B, and an internal power supply unit. The front side of the chassis
has eight RJ-45 twisted-pair ports and one cascading (UP-LINK) switch for Port 8 on the right.
LEDs to indicate operating status are on the left front side. There are power (PWR)
and bridge-inside (BR)
indicators for the unit.
There are activity (ACT)
and collision (COL)
indicators for each of the
10Mb and 100Mb domains, Magnum DS880 Dual-Speed Hub
1 2 3 4 5 6 7 8
COL
ACT
100 10
PWR
LK
RX
BR
100
UPLINK
1 2 3 4 5 6 7 8
set unto a “square” arrangement, for visual indication of the operating status of each domain.
And there are link (LK), receive (RX) and speed (100) indicators for each port. (See Section
1.1 “Specifications” for a technical description of the LEDs). The unit has a cooling fan on the
bottom left corner which sends warm air out away from the unit to the rear. Stacking cables
connect in the rear (see Section 2.3 for stacking information).
The AC power cord connector, a universal recessed-male IEC type, is in the left
rear of the chassis. The internal power supply is auto-ranging for any AC power input of 115 -
230 vac, 50 - 60 Hz. (An internal DC power supply is optional).
2.2.2 10 / 100 Speed Auto-sensing
All eight RJ-45 twisted pair ports support auto-sensing for speed, independent of the
other ports. Speed-sensing is performed by the DS880’s electronics in accordance with the
standards of the IEEE 802.3u auto-negotiation standard. If the connected device or node
indicates that it is capable of 100Mb speed, then operation on that port will be at 100Mb/s. If
the connected device does not positively indicate that it is capable of 100Mb speed, then the
operation on that DS880 port will be at 10Mb/s. Of course, the hubs’ auto-negotiation technique
is only for 10 / 100 speed, and does not provide for any full-duplex operation.
When a port is connected and LINK is present, the speed on that port that has been
sensed by the DS880 hub will be indicated by the ‘100’ LED for that port. The ‘100’ LED is ON
when 100Mb speed is sensed, and is OFF when 10Mb speed is in use. When a port is not
connected, the ‘100’ LED corresponding to that port will be blinking to indicate that it is trying
to auto-negotiate. (See section 4.3 for operation of the LED’s).