The VMware SD-WAN Standby Edge on a High Availability site becomes unavailable for failover.

Products

• VMware SD-WAN by VeloCloud
• VMware VeloCloud SD-WAN

Issue/Introduction

• This KB article documents the issue encountered under internal ticket # 77525.
• This issue may affect a site with a High Availability topology (either Standard or Enhanced) running one of the following software versions : 3.4.6, 4.2.1, 4.2.2, 4.3.1, 4.5.0.

Symptoms:

This issue has several symptoms. The following list summarizes what has been observed in the field: 

• The Standby Edge activation fails.
• Standby Edge becomes Unknown / Failed (can be observed on the Orchestrator under the Monitor section for the HA site). 
• High Availability site upgrade fails. 
• Configuration synchronization between the Active Edge and Standby Edge fails. 

Environment

VMware SD-WAN by VeloCloud Edge

Cause

When the Active Edge detects the Standby Edge, it tries to fetch the Standby Edge's software version and if the version is greater than 3.4.0, the Active Edge copies the network configuration file to the Standby Edge. While fetching the Standby Edge's software version, there could be an error which leads to an exception. This exception is not handled in the Edge's High Availability code, which results in the HA worker thread being stopped and any further communication with the Standby Edge fails and the Standby becomes unavailable for failover. 

Resolution

A fix for issue # 77525 included in the following Edge builds:

• 4.2.2 (R422-20220119-GA or later)
• 4.3.1 (R431-20220316-GA or later)
• 4.5.0 (R450-20220203-GA or later)
• 5.0.0.0 (R5000-20220225-GA or later) 

Workaround:
Please reach out to VMware SD-WAN Support to recover from this state and restore full High-Availability for that site. 

Moreover, if you have VMware SD-WAN High Availability site on one of the affected builds, please reach out to  VMware SD-WAN Support before you upgrade it (to one of the fixed builds).

Additional Information

For more information on the VMware SD-WAN High Availability feature, please consult the VMware SD-WAN Administration Guide. 

Impact/Risks:

• The Standby Edge is unavailable for failover, making the Active Edge effectively a standalone with the risks associated with that should the standalone Edge itself experience any issues.
• There is no communication between the Active and Standby Edges and no configuration updates or image upgrades will be sent to the Standby Edge by the Active.
• While upgrade, since the Active and Standby edge communication is failed, there are chances that edges goes offline.