Troubleshooting a Port Security Violation: Causes and Solutions for a MAC Address Error

What caused the following error message to appear? 01:11:12: %PM-4-ERR_DISABLE: psecure-violation error detected on Fa0/8, putting Fa0/8 in err-disable state 01:11:12: %PORT_SECURITY-2-PSECURE_VIOLATION: Security violation occurred, caused by MAC address 0011.a0d4.12a0 on port FastEthernet0/8.01:11:13: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/8, changed state to down 01:11:14: %LINK-3-UPDOWN: Interface FastEthernet0/8, changed state to down

The error message provided indicates that a security violation known as a Port Security Violation occurred on port FastEthernet0/8.

This violation was caused by a MAC address with the value of 0011.a0d4.12a0.

Port Security is a feature in network switches that allows you to limit the number of devices (MAC addresses) that can connect to a specific port. This feature is used to enhance network security and prevent unauthorized devices from connecting to the network.

In this case, the error message suggests that a device with the MAC address 0011.a0d4.12a0 attempted to connect to port FastEthernet0/8, but violated the configured Port Security settings. This violation triggered the switch to disable the FastEthernet0/8 port and bring down the line protocol and link state.

There are several common causes for a Port Security Violation:

1. MAC address spoofing: The device may have been trying to impersonate an allowed MAC address on the network, attempting to gain unauthorized access.

2. Rogue device: The MAC address may belong to a device that is not authorized to connect to the network, such as a malicious device or an unauthorized user’s device.

3. Misconfiguration: The MAC address in question may be legitimate, but it might not have been properly registered with the switch’s Port Security settings.

To resolve this issue, you need to investigate the MAC address in question to determine its legitimacy. If it is a rogue or unauthorized device, you should physically locate and remove it from the network. If it is a legitimate device, you should reconfigure the switch to allow its MAC address on the appropriate port or re-register it in the Port Security settings.

To prevent further occurrences of such security violations, you should review the Port Security configuration on the switch and ensure that all authorized devices are properly registered and any unauthorized devices are detected and removed from the network.

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