Allied Telesis AT-GS924MX Installation Manual page 113

Problem 5: Network performance between a twisted pair port on the
switch and a network device is slow.
Solution: There might be a duplex mode mismatch between the port and
the network device. This can occur when a twisted pair port using Auto-
Negotiation is connected to a remote device that has a fixed speed of 10
or 100 Mbps and a fixed duplex mode of full-duplex. If this is the cause of
the problem, adjust the duplex mode of the port on the network device or
switch so that both ports are using the same duplex mode. You can use
either the LEDs or management software on the switch to determine the
duplex mode settings of the ports. The LEDs are described in Table 6 on
page 38.
Problem 6: The switch functions intermittently.
Solutions: Check the system hardware status through the management
software:
Use the SHOW SYSTEM ENVIRONMENT command in the

Privileged Exec mode to verify that the input voltage from the
power source to the switch is stable and within the approved
operating range. The unit will shut down if the input voltage
fluctuates above or below the approved operating range.
Use the SHOW SYSTEM ENVIRONMENT command in the

Privileged Exec mode to verify that the fan is operating correctly.
Verify that the location of the switch allows for adequate airflow.

The unit will shut down if it is in danger of overheating.
Problem 7: The Switch ID LED on the front of the switch is flashing the
letter "F."
Solutions: One or more of the following problems has occurred:
A cooling fan has failed.

The input voltage on the power supply is outside the normal

operating range.
The internal temperature of the switch has exceeded the normal

operating range, and the switch may shut down.
Contact your Allied Telesis sales representative for assistance.
Problem 8: The AT-GS924MPX or AT-GS948MPX Switch is not providing
power to a PoE device.
Solutions: Try the following:
Review the PD's documentation to confirm that the device supports

Alternative B of the IEEE 802.3at standard. Alternative B is one of
two modes that define the connector pins that deliver the power
from the port on the line card to the PD. In Alternative B, the power
AT-GS900MX Series Installation Guide for Stand-alone Switches
113