3com DUA1770-0AAA04 User Manual
The Power-up Sequence
27
If there is evidence of a problem, see
Connecting a
Redundant Power
System
You can connect a SuperStack 3 Advanced Redundant Power System to
the Switch. This unit, which is also known as an RPS, is designed to
maintain the power to your Switch if a power supply failure occurs.
the Switch. This unit, which is also known as an RPS, is designed to
maintain the power to your Switch if a power supply failure occurs.
For normal redundancy, the unit requires one Type 3 Power Module (part
number 3C16075).
number 3C16075).
For full redundancy, the unit requires two Type 3 Power Modules
combined using a Type 3 Y-Cable (part number 3C16077).
combined using a Type 3 Y-Cable (part number 3C16077).
WARNING: If you are connecting the Switch to a Type 3 Power Module,
read the Safety Information section in the Type 3 Power Module User
Guide.
read the Safety Information section in the Type 3 Power Module User
Guide.
CAUTION: The Switch can only use a SuperStack Advanced Redundant
Power System output.
Power System output.
CAUTION: The Switch has no ON/OFF switch; the only method of
connecting or disconnecting mains power is by connecting or
disconnecting the power cord.
connecting or disconnecting mains power is by connecting or
disconnecting the power cord.
Choosing the Correct
10/100/1000BASE-T
Cables
If your Switch has 10/100/1000BASE-T ports, these ports are Auto-MDIX,
that is they have a cross-over capability. These ports can automatically
detect whether to operate in MDI or MDIX mode. Therefore you can
make a connection to one of the ports with a straight-through (MDI) or a
cross-over cable (MDIX).
that is they have a cross-over capability. These ports can automatically
detect whether to operate in MDI or MDIX mode. Therefore you can
make a connection to one of the ports with a straight-through (MDI) or a
cross-over cable (MDIX).
The Auto-MDIX feature only operates when auto-negotiation is enabled.
If auto-negotiation is disabled, all the Switch ports are configured as
MDIX (cross-over). If you want to make a connection to another MDIX
port, you need a cross-over cable. Many ports on workstations and
servers are configured as MDI (straight-through). If you want to make a
connection to an MDI port, you need to use a standard straight-through
cable. See
MDIX (cross-over). If you want to make a connection to another MDIX
port, you need a cross-over cable. Many ports on workstations and
servers are configured as MDI (straight-through). If you want to make a
connection to an MDI port, you need to use a standard straight-through
cable. See
.
3Com recommends that you use at least Category 5 twisted pair cable —
the maximum segment length for this type of cable is 100 m (328 ft).
the maximum segment length for this type of cable is 100 m (328 ft).