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

Products

• VMware NSX

Issue/Introduction

• 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
VMware NSX-T Data Center

Cause

When a user leverages Simplified UI to perform Traceflow, Policy API framework may schedule MP API call to different manager nodes. The NSX 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 NSX 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 NSX Manager nodes are out of synchronization, NSX 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 NSX Manager nodes other than the one where Traceflow creation API is scheduled, empty result is returned.

Resolution

This is a condition that may occur in a VMware NSX environment.

To resolve this issue, ensure that the NSX Manager nodes' clocks are synchronized. Clock synchronization can be achieved by leveraging NTP (see NSX documentation) or just the system clock manually on each node.