Uneven Traffic Distribution on pool members on NSX T native load balancer with Source IP Persistence

Products

• VMware NSX

Issue/Introduction

• Customer is using NSX Native load balancer.
• Configured Source IP persistence.
• Customers may observe a significant imbalance in traffic distribution across NSX Load Balancer pool members, where one specific pool member receives a disproportionately high volume of sessions compared to others in the same pool.
• 
• This leads to underutilization of other backend servers and potential overload on the single overused server.

Environment

VMware NSX

Cause

Source IP persistence on an NSX Load Balancer, when combined with a single client IP source (like a proxy), forces all traffic to one backend member.

Source IP persistence is designed to route all subsequent connections from a particular client IP to the same backend pool member.

Resolution

• Understand Application Behavior: Work with the application team to determine if traffic from a single source IP (e.g., a proxy) is expected.
• Modify LB Configuration: If this single-source behavior is intentional, disable Source IP persistence on the load balancer.

Additional Information

Please find below the technical documentation that explains the persistence profile in detail:

Persistence Profile - Broadcom Tech Docs