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68 CHAPTER 5: PROBLEM SOLVING
If your IP network is internal to your organization only, that is, you do not
access the Internet, you may use any arbitrary IP address as long as it is
not being used by another device on your network. 3Com suggests you
use addresses in the range 192.168.0.0 to 192.168.255.255 with a
subnet mask of 255.255.255.0.
These suggested IP addresses are part of a group of IP addresses that
have been set aside specially for use ‘in house’ only.
A device is connected to a Switch 4500 PWR but power is not
being supplied
If power is not being supplied to a device connected to a Switch 4500
PWR, you should do the following checks:
■ Check that the device is compliant with the 802.3af standard ref. [18].
The 4500 PWR will only supply power through the front panel port to
802.3af compliant devices.
■ Check that power budget for the Switch has not been exceeded.
If the power budget has been exceeded, then by default, the powered
device connected to the Power over Ethernet port with the lowest
priority port will lose power. However, if all the devices connected to
the Switch have equal priority levels, then the port with the highest
number will lose power.
By default, the Switch will allow a device to receive power as long as
Power over Ethernet power supply has 18 watts spare in its power
budget. If this much power is not available, the device will not be
powered (unless it has a higher priority than existing powered ports)
and a PoE fault will be reported for that port. If enough power
subsequently becomes available, the port will be powered.
■ Check that the port has not had a power limit imposed on it.