IPV6 BGP neighbors may be showing "down" on the NSX 3.X UI when actually established. Cosmetic issue

Products

• VMware NSX

Issue/Introduction

Symptoms:

• IPv6 BGP neighbors status is showing as DOWN even though neighbors are realized on edge properly and BGP functionality is working fine.
• When clicking on the Information icon next to “Down”, it says, “No BGP Neighbor Connectivity Status Found.” 
• Checking "show ipv6 bgp summary" from upstream Router reveals that NSX-T peering is ESTABLISHED and routes are been learned as expected. 
• Homologous commands from the NSX-T T0 like "get logical-router <T0 UUID> bgp neighbor summary" reveals ESTABLISHED as well.
• We do not see a functional impact, it's purely cosmetic. 

From Edge syslog you see similar output to:

Location var/log/syslog.

2020-08-03T09:29:59.752Z hostname NSX 1664 - [nsx@6876 comp="nsx-edge s2comp="nsx-monitoring" entId="521633a8-XXXX-XXXX-XXXX-XXXXXXXXX" tid="1909" level="ERROR" eventState="On" eventFeatureName="routing" eventSev="error" eventType="bgp_down"] In Router ########-####-####-####-########f3be, BGP neighbor fd00:0:0:247::247 is down, reason: Network or config error.

Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.

Environment

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

Cause

This issue is occurs because we fetch neighbor status from neighbor address, we compare string representation of neighbor address instead of comparing actual value.
 
For example here in this case ipv6 neighbor address "fd00:0000:0000:0246::1" did not match with "fd00:0:0:246::1" which is present in neighbor status API response. 

Though these two addresses are same, these are considered as different and hence status was displayed as DOWN(as it does not find status object for "fd00:0000:0000:0246::1").

Resolution

This issue will be resolved in NSX-T maintenance release 3.0.2

Workaround:
We can create neighbors with short addresses without unnecessary zeros in addresses, for example - we should use address "fd00:0:0:246::1" instead of  "fd00:0000:0000:0246::1". 

If we were to select  address with extra zeros, this issue will occur. Though there is no BGP functionality impact, only status of neighbor will be displayed as DOWN.