Vmware NSX Native Load Balancer pool members with a status of "down" do not display a "Failure Reason"

Products

• VMware NSX-T Data Center

Issue/Introduction

• VMware NSX Native Load Balancer (LB) Pool has one active monitor configured.
• A pool member is DOWN, but the NSX UI does not display the "Failure-Reason".
• The API does not return  "Failure-Reason" either:
  • GET https://<NSX Manager>/api/v1/loadbalancer/services/<UUID/status?source=realtime
• Running the following command as admin user in the edge Cli does return a "Failure-Reason":
  • get load-balancer <UUID> pool <UUID> status
    ...
    Monitor
    Display-Name : LB_Http_Monitor
    Type : HTTP
    Status : down
    Url : /
    Last-Check-Time : <date/time>
    Last-State-Change-Time : <date/time>
    Failure-Reason : Connect to Peer Failure
    ...

Environment

VMware NSX-T Data Center 3.1.x, 3.2.x

Cause

This issue occurs due to a mismatch with LB monitor index.

Resolution

Issue is resolved in VMware NSX-T Data Center 3.1.3.6 and 3.2.1

To workaround, there are 2 options:

Option 1: Use the Edge Cli to obtain the failure reason (get load-balancer <UUID> pool <UUID> status)
Option 2: Configure a second active monitor on the pool. The second active monitor can be of any type ICMP/TCP/HTTP.