Edge with network loop goes offline when upgraded from 4.5 to 5.2.x

Products

• VMware VeloCloud SD-WAN

Issue/Introduction

An edge with 2 LAN ports connected through a 3rd party switch that forms a loop.
When the edge is running 4.5 software, it is functioning.

When upgraded to 5.2.x, the preexisting network loop causes the edge to go offline and stops forwarding traffic.

Removing one of the switch port connections (breaking the loop) will restore function to the edge.
Downgrading to 4.5 will also restore function.

L2 Loop detected log is observed:

EDGE_L2_LOOP_DETECTED(kernel:[   64.036411] br-network20: received packet on ge1.20 with own address as source address (addr:AA:AA:AA:AA:AA:AA, vlan:0))

Environment

Example Topology:
            ┌──────────────────┐         
            │  Standalone      │         
            │  Edge  610       │         
            └───┬────────┬─────┘         
           Ge1  │        │Ge2            
                │        │               
         ┌──────┘        └─────┐         
         │ge4                  │ge6      
┌────────┼──────┐        ┌─────┼────────┐
│               │        │              │
│ Switch1       ┼────────┤  Switch2     │
└───────────────┘        └──────────────┘
 

Cause

In 4.5 software, the switched packets are not hitting the CPU.
This can allow the BPDU to be forwarded across the edge and let the 3rd party switch block the port.

In 5.2.x the switched packets are forwarded to the CPU, resulting in the BPDU not being forwarded and the looped packets overwhelming the CPU.

Resolution

Resolve the switching loop in the customer network.

Alternatively, the 2 ports could be converted to routed ports and would resolve the loop.