HCX - NSX TAGs modifies host route for an MON enabled extended segment

Products

• VMware HCX
• VMware NSX-T Data Center

Issue/Introduction

• The NSX segment was extended by HCX and has MON (Mobility Optimized Networking).
• Once user performs TAG addition for HCX MON enabled extended segment using cloud NSX-T UI, the host route (/32) will be replaced with actual OnPrem gateway subnet/CIDR(for example: /24) in NSX forwarding table. However, HCX Policy Based MON for subnets (/32) will remain visible under NSX-T static route wizard.
• MON Segment routes will be dropped as routes are set to empty and traffic will no longer flow.

Environment

HCX
NSX-T 3.x
NSX 4.0

Cause

NSX UI defect where the policy route is not re-instantiated after making changes to the segment via NSX after MON is configured. As such the route is dropped and traffic no longer can flow.

Resolution

This issue is resolved in VMware NSX 4.0.1.1, available at Broadcom downloads.
If you are having difficulty finding and downloading software, please review the Download Broadcom products and software KB.

Workaround:
Users are suggested not to apply any TAGs for an extended segment using NSX-T Policy UI.

Additional Information

• This will only impact MON enabled segments having TAG enabled on cloud NSX-T.
• MON enabled Segments without TAG will not have any impact in the traffic forwarding.