Packet Duplication Detection

Within a Network Monitoring Session, if a packet is received twice by an agent, a Packet Duplication network issue will be raised with the severity level Information. Like Packet Reordering, once the issue is raised, it will be cleared after 10 minutes if no more duplicate packets are detected.

It is not normal to have packet duplication on a network. Sometimes, during configuration changes (logical or physical), it can happen that a few packets are duplicated. Packet duplication can be a sign of network loop or mis-configured Link Aggregation (LAG). If packet duplication happens a lot on your network, it is recommended to troubleshoot deeper. Note that Link Aggregation (LAG) can also be referred to as Etherchannel, Trunking, Bouding, Bundling, Teaming or Channeling.

The first thing to do is to segment your network, usually with Hardware Monitoring Agents, to find out where the packet duplication is occuring. Once the segment has been identified, check out the network equipment logs and configuration. If any Link Aggregation is used, verify the configuration and test, during a maintenance window, if the packet duplication is still there with a single link active within the link aggragation.

Users have reported software bugs that caused packet duplication, so all network equipment should run a stable recent version of their firmware as per their vendor recommendations.

you can disable the Packet Duplication alerts in the Monitoring Template Advanced Parameters.