IPv6 neighbor discovery learns wrong MAC on Service Interface Segment

Products

• VMware NSX

Issue/Introduction

VMs on IPv6 NSX-T Segment connected to service interface of T1 learns wrong MAC address for T1 gateway. This prevents communication to non local systems.

This issue occurs occurs only for neighbor discovery on IPv6 interface and there are no issues for VMs connected on IPv4 interfaces 

Environment

VMware NSX-T Data Center Version: 3.2.2.0.0 Build: 20737193

Cause

The cause for this issue is Segment association changes from T1 DR to T0 uplink. The protected entries of ND cache for the Downlink IPv6 entries should be cleaned. But the IPv6 Downlink LIF entries remains.

Resolution

Issue is fixed in NSX release 4.2.1

Workaround : To create a static MAC entry on the VMs connected to NSX T segment

Additional Information

Static MAC entry could be created on the VM connected to service interface using command  

ip -6 neigh change IPv6GW lladdr <MAC add of Tier1 GW> dev <interface>

For ex., ip -6 neigh change 2003:#:#:####::# lladdr 02:50:56:##:##:## dev ens256