| Event | Description | Severity | Threshold | Possible causes and solutions |
| ICMP Destination Unreachable | A station receives an ICMP destination unreachable message. | Warning | | The destination network does not exist. |
| ICMP Host Unreachable | A station receives an ICMP host unreachable message. | Warning |
| The destination host does not exist. |
| ICMP Net Unreachable | A station receives an ICMP network unreachable message. | Warning | | The destination network does not exist. |
| ICMP Parameter Problem | A station sends an ICMP message indicating a parameter problem. | Warning | | |
| ICMP Port Unreachable | A station receives an ICMP port unreachable message. | Warning | | The destination port is not active on the station that sent the message. |
| ICMP Redirect for Host | A station receives an ICMP redirect message with the Code value set to 1 (redirect
datagrams for the host).
| Warning | | A router may have sent the message to inform this station that a better route exists to its intended destination. |
| ICMP Redirect for Network | A station receives an ICMP redirect message with the Code value set to 0 (redirect datagrams for the network). | Warning | | A router may have sent the message to inform this station that a better
route exists to its intended destination.
|
| ICMP Source Quench | A station receives an ICMP source quench message. | Warning | | The station that sent the message may be down or rebooting. |
| IP Invalid Header Checksum | The checksum of an IP header is in error. The checksum value is calculated by the sender and written to the packet, and then recalculated from the received packet by the receiver. It indicates an error if the two values are different. | Warning | | There is a faulty device on the network. |
| IP Time-To-Live Too Low | An IP packet with a time-to-live field set to 0 or 1 indicates that the packet is about to expire. | Notice | | There is a routing table error somewhere in the network.
The packet is looping.
The originating IP host transmitted the packet with a low TTL to begin with.
Try to locate the source of the original packet.
|
| IP Fragment Missing | An IP packet has been fragmented and one of the fragments is missing. This will usually result in a retransmission. | Notice | | A fragment has been dropped by a switch or router.
The traffic on the LAN is heavy.
|
| IP Zero Broadcast Address | An IP packet is being sent with the old IP broadcast address of 0.0.0.0. | Notice | | This is an obsolete form of TCP/IP broadcast address.
Check the source endpoint for applications that may be sending this packet.
|
| IP Duplicate Address | There is more than one MAC Address associated with the same IP address. | Warning | | The newly assigned network address is not unique in the network and conflicts with the existing network addresses.
The dynamically allocated network address is not proper.
If the MAC addresses are routers, this is not a problem.
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