During V2T migration post edge cutover, VM traffic is disrupted

Products

• VMware NSX

Issue/Introduction

During V2T migration, post edge cutover, VM traffic disrupts when DRS moves the VM's to NSX-V TN which matches either of the below 2 cases 

1. NSX-V TN previously didn't have any workloads.

2. In a Multi VTEP environment if the controller has learned some but not all TEPs of a given NSX-V TN.

Symptoms:

• VM Traffic disruption when traffic is routed through NSX-T edge TN. 

Environment

VMware NSX-T Data Center

Cause

If a VTEP in a host is not in any VNI span, NSX-V controller does not have the VTEP and NSX-T migration co-ordinator ignores it when pushing VTEP table of the host to NSXT. If a VM moves to the host after North south-cutover, the VM's traffic will break because NSXT edge does not have the VTEP in its routing domain and so will drop the packets from the VM.

 

Resolution

This issue is resolved in VMware NSX-T Data Center 3.1.3.7 available at Broadcom Downloads 



Workaround:

Note: This workaround is applicable only for releases of NSX-T 3.1.3.1. 

1. SCP the overlay_plugin.py and utils.py files (attached to the KB) to the /tmp dir of the Policy appliance where the migration coordinator service runs
2. ssh to the Policy appliance where the migration coordinator service runs
3. cd /opt/vmware/migration-coordinator-tomcat/bin/v2t/config-migrator/plugins
4. back up the old files by “cp overlay_plugin.py overlay_plugin.py.org” and “cp utils.py utils.py.org”
5. cp /tmp/overlay_plugin.py .
6. cp /tmp/utils.py .
7. rm __pycache__/overlay_plugin.*
8. rm __pycache__/utils.*