Troubleshoot network monitoring

Some messages you get during Network monitoring might require actions from your side while some are just informational and do not need any reaction.

Potential network disruption during OneAgent installation on Windows

During OneAgent installation, the host might experience network communication disruption on all input and output ports. The disruption typically lasts until the end of OneAgent installation and is associated with the Npcap installation.

Before installing OneAgent, you need to uninstall any existing WinPcap driver to allow Npcap installation. Do this on all Windows versions except for Windows Server 2016 and Windows Server 2019 build 1809 without the KB4571748 hotfix. For details, see Uninstall WinPcap driver to allow Npcap installation.

You do not need to take any action to restore network communication, but if you prefer to prevent disruptions, you might need to:

• Upgrade your Windows Server version
  The disruptions have been observed on Windows Server 2016 and Windows Server 2019 build 1809 without the KB4571748 hotfix. Upgrading your Windows Server version should prevent such disruptions. Windows Server 2019 build 19042 is not affected.

• Disable Microsoft Network Monitor Driver
  Disabling Microsoft Network Monitor Driver on Windows Server 2016 and Windows Server 2019 build 1809 without hotfix KB4571748 might prevent potential disruptions.

OneAgent page allocation failure message on Linux

OneAgents operating on Linux might generate a page allocation failure message in the logs during network communication monitoring. The message format is:

Apr 29 08:07:54 (host name) kernel: oneagentnetwork: page allocation failure. order:4, mode:0xd0

This message is purely informational and does not indicate any problems with Dynatrace components, the network that you monitor, or any data loss.

Network Agent initialization failure on Windows

In some situations, Network Agent stops working and fails to restart on Windows. This may be because the pcap driver (either Npcap or WinPcap) has been removed or has malfunctioned. In such cases, the Network Agent logs include the IstallInfo: appName: serviceName:no-pcap message:

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2022-05-18 20:11:07.744 UTC [00003e90] info    [native] NetworkAgent::init:318: Running with IstallInfo: appName: serviceName:no-pcap dllPath:C:\Windows\system32 isInstalled:0 isRunning:0 isError:1
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] NetworkAgent::init:320: IstallInfo: appName: serviceName:no-pcap dllPath:C:\Windows\system32 isInstalled:0 isRunning:0 isError:1
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] NetworkAgent::init:321: Pcap not operational, Network Agent will shutdown gracefully
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] NetworkAgent::~NetworkAgent:136: pktReader.finalize()
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] NetworkAgent::~NetworkAgent:139: delete pcapIfc
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] DataReporter::~DataReporter:104: DataReporter::~DataReporter
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] pkt_analysis::SessAnalyzer::~SessAnalyzer:210: Session insert counter=0, session remove counter=0
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] ... last message repeated 2 times ...
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] Agent::~Agent:950: delete mTimeProvider
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] Agent::~Agent:952: delete mconfig
2022-05-18 20:11:07.744 UTC [00003e90] info    [native] Agent::~Agent:955: delete mlog

In such cases, Network Agent is repeatedly restarted by OneAgent Watchdog, but exits early without providing network metrics. In OneAgent versions earlier than 1.241, it also resulted in multiple Network Agent segmentation faults due to flawed error handling logic. Since OneAgent version 1.241, however, Network Agent initialization failure no longer results in a segmentation fault.

To verify that at least one pcap driver is installed, execute the driverquery command. If the driver is not installed, it will be installed automatically during the next upgrade.