Troubleshoot Connectivity Tests issues

This page covers common issues with Connectivity Tests.

To learn more about Connectivity Tests, see the overview.

To interpret the states for a Connectivity Test configuration analysis, see the Configuration analysis states.

General issues

It takes too long to get test results

Because Connectivity Tests queries the latest snapshot of a Virtual Private Cloud (VPC) network configuration, getting results can take some time. For details, see expected query response times.

If you are experiencing long or unstable latencies when running Connectivity Tests, report the issue to Support and describe how to reproduce it.

My test's configuration analysis isn't picking up the configuration change I made

After you make a configuration change to the Google Cloud resources in your testing path, you might want to use the test's configuration analysis to validate the change. However, it takes between 20 and 120 seconds for Connectivity Tests to receive a configuration update and incorporate it into analysis. Make sure that you wait long enough between making the configuration change and running your tests.

Certain types of configurations can take longer to complete. If your configuration change is not verified by Connectivity Tests after an extended period of time and is reproducible, report the issue to Support and describe how to reproduce it.

This delay does not apply to dynamic verification. Therefore, you might see a temporary mismatch between the results shown by dynamic verification and configuration analysis. For example, if you create a firewall rule, dynamic verification generally responds to the new rule right away. However, you might have to wait 20 seconds or longer before the configuration analysis can evaluate the firewall rule along with the other resources in the testing path.

Test state issues

I can't access details about a hierarchical firewall policy

The trace for your test might reference a hierarchical firewall policy that you don't have permission to view.

However, even if you don't have permission to view the policy, you can still see the policy rules that apply to your VPC network. For details, see Effective firewall rules in the hierarchical firewall policies overview.

Access to hierarchical firewall policies is defined at the organization and folder level. For details about the permissions that you need to view these policies, see Identity and Access Management (IAM) roles in the hierarchical firewall policies overview.

My test shows a final configuration analysis state of Deliver, but connectivity is broken

In some cases, the configuration analysis suggests that a source and destination endpoint are reachable. However, you might find that, in practice, connectivity is broken between the two endpoints, or that dynamic verification shows 100% packet loss.

To understand this situation, remember that Connectivity Tests uses two types of analysis: a configuration analysis, which detects issues in active configurations within your project, and dynamic verification, which sends probes on the data plane.

A final configuration analysis state of Deliver means that Connectivity Tests didn't detect any configuration issues. However, there could still be data path issues that cause connectivity problems. To troubleshoot, consider the following:

  • The source or destination VM is experiencing guest OS issues such as guest OS kernel panic, a network interface controller (NIC) that is not initialized, or incompatible network drivers. Check the VM state and NIC configuration.
  • A widespread issue is affecting the network data plane. Consult your project's Performance Dashboard, paying particular attention to packet loss for the relevant zone pair. Additionally, check the Google Cloud Status Dashboard.
  • Your network is experiencing sporadic network programming issues, such as issues with network configuration propagation to specific Google Cloud entities. Consider rerunning the test after a delay of five minutes. If the issue persists, stop and start either the source or destination VM, as described in Stopping and starting an instance, and then rerun the test.

My test returned an overall configuration analysis result of Undetermined

An overall reachability result of Undetermined means that the configuration analysis could not determine connectivity. This result can appear for any of the following reasons:

  • A permissions error occurred—for example, the user might not have read permissions for all of the resources named in the test.
  • An internal error occurred.
  • The analyzer received an invalid or unsupported argument or was unable to identify a known endpoint.
  • You are trying to verify a route that extends beyond Google Cloud. Connectivity Tests has no access to network configurations outside Google Cloud.

My test returned an overall configuration analysis result of Ambiguous

An overall configuration analysis result of Ambiguous means that Connectivity Tests returned multiple traces and that there is a mixed final state.

The following table lists some common reasons and fixes for this state.

Reason Example How to fix
The source location is not unique. You specified an internal source IP address without also specifying the VPC network where the IP address is located (an internal source IP address is an address that you can't access from the internet). Because this address can be accessed from multiple VPC networks, Connectivity Tests could start a trace from each location. Update the test with the VPC network where this IP address is located.
The trace has multiple possible destinations. You specified the trace destination as a load balancer VIP that has multiple backends, and not all backends are reachable. Research why this is happening and fix the issues as needed before re-running the test.

My test returned an overall configuration analysis result of Abort with an Invalid Argument message

Some common reasons for an Invalid Argument message are the following:

  • The IP address that you provided is not supported. Examples include a loopback address, a multicast IP address, or an IPv6 address to a VM instance that has only an IPv4 address assigned to it.
  • The VM instance or specified network does not exist. This situation can occur when the VM instance or the VPC network was deleted while you were creating the test.

When using the Network Management API, the Invalid Argument message is usually returned for one of the following reasons:

  • A misspelled name or incorrect location for the VM or the network URI.
  • An incorrectly specified project ID. This mistake occurs if you used the project name instead of the project ID.
  • A mismatch between the specified internal IP address and the selected network. Even though the Cloud console for Connectivity Tests performs a strict validation of the specified Compute Engine instance, network, and project, this type of mismatch can still occur.

The configuration analysis result is Packet could not be delivered, but dynamic verification indicates all packets were delivered

This apparent mismatch can occur for several reasons. Consider the following possible causes and remediation:

  • Recent VPC network configuration changes caused inconsistency between the configuration analysis and active probing. Re-run the test, making sure, if possible, that the network configuration does not change just before the test or during the test.

  • Sporadic network programming issues occurred. Stop and start either the source or destination VM, as described in Stopping and starting an instance, and then rerun the test.

Configuration analysis result is Packet could be delivered, but dynamic verification indicates partial packet loss

This apparent mismatch can occur for several reasons. Possible causes and solutions include the following:

  • The source or destination VM is being throttled while exceeding allowed egress or ingress bandwidth. Analyze the VM traffic volume by going to the VM instance details page and reviewing the details on the Monitoring tab. Look at the Network Bytes metric and compare it with the bandwidth limits described for the machine type in Network bandwidth.

  • A widespread issue is affecting the network data plane. Consult your project's Performance Dashboard, paying particular attention to the relevant zone pair. Additionally, check the Google Cloud Status Dashboard.

Configuration analysis result is Packet could be delivered and dynamic verification shows full delivery, but my application experiences loss

This apparent mismatch can occur for several reasons. Possible causes and solutions include the following:

  • Traffic might be blocked by the guest OS (for example, by internal firewall rules). Verify that traffic is not blocked and try the test again.
  • Application data packets might traverse a different network path than the dynamic verification probes. Consider re-establishing the network connection. For example, try using a different source port.
  • Dynamic verification detects uni-directional packet loss. In your case, packet loss could be occurring on the return path. Consider running a test in the opposite direction.

The test results don't include a dynamic verification result

Not all configurations supported by Connectivity Tests can be dynamically verified. Make sure the test satisfies the conditions required for dynamic verification, as specified in the overview.

The Network Management API returned an INTERNAL_ERROR

This event should not normally happen. If it does, report the issue to Support and describe how to reproduce it.

Google Cloud console issues

The Cloud console for Connectivity Tests crashed

The Cloud console should not normally crash. If it does, report the issue to Support and describe how to reproduce it.

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