Traceflow fails with error: "Traceflow round does not have a packet injection observation" in Simplified UI.

Products

• VMware NSX

Issue/Introduction

Symptoms:

• Traceflow created through Simplified UI returns empty packet trace result.
• You see a warning: Traceflow round does not have a packet injection observation.

Environment

VMware NSX-T Data Center
VMware NSX-T Data Center 3.x

Cause

When a user leverages Simplified UI to perform traceflow, Policy API framework may schedule MP API call to different manager nodes. The manager node that is scheduled with traceflow creation API writes the timestamp at which the traceflow request is expected to be finished into Corfu DB, and other manager nodes will read this timestamp to determine whether the received traceflow observation message corresponds to a stale traceflow request or not. If the received observation message corresponds to a stale or non-existent traceflow request, it will be ignored. Thus, when clocks of manager nodes are out of synchronization, manager nodes other than the one where traceflow creation API is scheduled may ignore the received observation messages. When Policy API framework schedules the result querying API to the manager nodes other than the one where traceflow creation API is scheduled, empty result is returned.

Resolution

To resolve this issue, ensure that the user has manager node's clock synchronized. Clock synchronization can be achieved by leveraging NTP or just the system clock manually on each node.