VM's on L2 extended segments unable to communicate when MON enabled due to missing Local Egress (LE) flag.

Products

• VMware HCX

Issue/Introduction

• VM's connected on different L2 extended segments unable to communicate with each other.
• HCX MON (Mobility Optimized Networking) is enabled on VM level, when MON is turned on, there's 100% packet loss—ping doesn't work.
• Disabling MON restores normal traffic flow through the on-premises gateway.

Environment

VMware HCX

Cause

• During MON enablement on the VM level, the remoteRtr property on the ESX host VM logical port set the Local Egress (LE) flag for routing.
• If the Local Egress (LE) flag isn't set on a VM’s port, its traffic will be dropped.

Resolution

Workaround:

• To resolve this missing LE flag, change the router location of impacted VM's  to 'on-prem' and then back to cloud, this process had to be complete for both source and destination VMs.
• To set the Target Router Location for each MON enabled VM's.
  Select a VM and expand the row.
Set the Target Router Location for VM by selecting the destination option from the drop-down menu. Click Submit.

Additional Information

The local egress (LE) flag on the VM port level can be verified from the ESXI host running these VM's by using net-dvs command.

#net-dvs -l |grep "com.vmware.nsx.port.extraConfig.remoteRtr" | grep "<gateway address>"

Non working VM port sample:.

com.vmware.nsx.port.extraConfig.remoteRtr =: "10.#.#.1 02:##:##:##:43:58 02:##:##:##:44:52 00:00:00:00:00:00" <-----LE flag is missing

Working VM port sample:

com.vmware.nsx.port.extraConfig.remoteRtr = "10.#.#.1 02:##:##:##:43:58 02:##:##:##:44:52 00:00:00:00:00:00 LE" ,  propType = POLICY