A loop is seen when the Edge is configured with enhanced HA configuration

Products

• VMware VeloCloud SD-WAN

Issue/Introduction

There is a possibility of a loop occurring due to the Edge of the eHA [enhanced HA] configuration.

The reason is that Edges with eHA configuration forward the unicast packet not destined to their MAC address from Standby device link to Active device link.

This issue occurs in the below condition.

• There are some Edges with eHA configuration in customer environment.
• Active devise WAN link and Standby device WAN links belong to same subnet. And there are in same Layer 2 network.
  For example, it's the case that Active device WAN link GE3 is 192.168.0.3/24 and Standby device WAN link GE4 is 192.168.0.4/24 connected to same VLAN in same Layer 2 switch.
• Edges receive the unicast packet not destined to their MAC address from Standby device WAN link.

In above case, Edges forward the unicast packet from Standby device link to Active device link with decreasing TTL. If there are two or more similar Edges in the L2 network, this traffic will from a Layer 3 loop.

Environment

Velocloud SDWAN, VMware SDWAN, eHA, Enhanced HA

Cause

This issue is caused by known software issue #132004. Essentially, Edges should not forward the unicast packet not destined to their MAC address, should drop. The devices running software version 4.5.1.x and 5.0.x.x are susceptible to this issue.

Resolution

This defect is fixed in 5.2.4.0 and later.

For more information please see VMware SD-WAN Software Upgrade FAQs

Additional Information

Edges are supported the design which multiple links connect to the same network subnet.