If the unit is to be part of a free-standing stack, apply the pads to
each marked corner area on the underside of the unit. Place the
unit on top of the lower unit, ensuring that the pads locate with
the recesses of the lower unit.
Rear Panel
8 Recovery Button
This button has no function on this Switch.
9 Power Supply
The Baseline Switch 2226-PWR Plus automatically adjusts to the
supply voltage. Use only the power cord that is supplied with the
unit.
This section outlines the use of Power over Ethernet (802.3af),
explains its benefits, and gives examples of how you can use it on
your network.
What is Power over Ethernet?
A Power over Ethernet switch such as the Switch 2226-PWR Plus
can supply power to compliant devices over a Category 5 or
better Ethernet cable. The same cable connects the device to the
network.
Power over Ethernet is a self-configuring protocol. When you plug
a PoE-compliant device into one of the ports on the Switch, the
Switch will supply the power required by the device, providing
that the total power budget for the Switch would not be
exceeded by doing so.
Benefits of PoE
A PoE switch combines the functionality of a standard Ethernet
switch with a single power supply that can provide power to
multiple devices. Using a PoE switch helps reduce cabling on the
network.
A PoE-compliant device that has its power supplied over its
Ethernet cable no longer requires a separate power supply. If, for
example, the Switch is used to connect the 3Com 11 Mbps
Wireless LAN Access Point 8500 to the network, then only a
network cable is required to provide both power and network
connectivity. Since the Access Point is frequently wall-mounted,
this can significantly reduce its installation costs.
Planning Power Budgets
The Switch 2226-PWR Plus can supply a maximum of 15.4 watts
to any of its 24 10/100 ports, provided that the total power
delivered does not exceed 180 watts.
When you plan your network, you need to calculate the
maximum power that you will need to make sure the Switch is
not expected to supply more than its maximum capacity.
To calculate the power budget for the Switch, add together the
power requirements of the devices that will be connected at any
one time. The power requirements of the PoE-compliant devices
can be found in the documentation supplied with the device.
If the maximum power for the Switch is exceeded, the Switch
follows the following rule:
Any device connected to a lower port number will take
priority over a device connected to a higher port number.
If the Switch needs to remove power from a device, it
will remove power from the highest numbered port.
When the Switch is power-cycled, it will supply power to
the ports starting with the lowest numbered port first.
Implementing a Power Plan
If the total power required by PoE-compliant devices is less than
the Switch’s power budget, then you can guarantee power to
every port.
If the power required by PoE-compliant devices is more than the
Switch’s power budget, then you will not be able to guarantee
power to all devices. If this is the case, you may choose to:
Add additional PoE switches – This will enable you to
guarantee power to every port on the Switch that powers a
PoE-compliant device. The remaining ports can be used to
supply networking to those devices that are powered by
other means.
Prioritize PoE-compliant devices – Since the Switch supplies
power to the lowest numbered port first, you should connect
PoE-complaint devices based on their order of importance,
the most important device being connected to the lowest
numbered port. By monitoring power consumption and
checking if any devices have been refused power, you can
decide whether you need additional PoE switches.
Monitoring the PoE LEDs
The Switch’s PoE LEDs show Power over Ethernet information.
When the PoE LED is green, it means that port is supplying power
to the PoE-compliant device on that port and there are no
PoE-related problems.
If a PoE-compliant device is plugged into a port but the PoE
Status LED remains off, this means:
Either there is insufficient power available to provide power to
this device, or
There is a problem with either the device or the cable. Refer
to the
“Troubleshooting“
section of this guide.
PoE Devices
The Switch is designed to operate with both IEEE 802.3af
compliant and pre-standard devices.
This Switch has been designed to be upgradeable to a smart
managed switch when the software is available. When the
software is released on the 3Com Web site
(www.3com.com)
,
you can download it and upgrade the Switch.
To upgrade the device on the software, follow the instructions
provided with the software.
P
OWER
M
ANAGEMENT
U
PGRADING
4
