This document describes the causes of collision error alerts.
Collision error alerts are generated when the Ethernet settings on your Cisco Email Security Appliance (ESA) are incorrectly configured. Typically these errors occur when the media settings of the ESA and the switch port to which it is attached do not match.
Verify your network settings and make sure that both your network switch and your ESA are set to the same speed and duplex setting.
How do I configure the duplex settings of the network interfaces on the ESA?
The etherconfig CLI command can be used to configure various ethernet settings such as the duplex settings (full/half) and the throughput of the interface (10/100/1000 Mbps).
By default, interfaces automatically select the media settings; however, if the system is generating collision errors it might be necessary to override this setting.
For information about media settings on ethernet interfaces, see the AsyncOS Advanced Configuration Guide.