The maximum number of connections on the NSX Edge L7 load balancer

Products

• VMware NSX for vSphere

Issue/Introduction

Symptoms:
In case the NSX Edge L7 Load Balancer is not sized properly, and current connections (con_curr) hit the hard limit of maximum connections (max_conn), the new connections towards the NSX Edge L7 load balancer will not be established until one of the old sessions is released, and slot opened.

The issue usually presents itself as a intermittent connectivity issues over the NSX Edge L7 Load Balancer

Environment

VMware NSX for vSphere 6.3.x
VMware NSX for vSphere 6.4.x

Resolution

When designing the NSX Edge L7 Load Balancer, you need to consider the number of concurrent connections the NSX Edge L7 Load Balancer will handle. The maximum limit (max_conn) per appliance size is as follows:

• Compact Edge: max_conn=1024
• Large Edge: max_conn=8192
• Quad Large Edge: max_conn=8192
• X-Large Edge: max_conn=100000

The maximum connection (max_conn) and current connections (cur_conn) can be viewed on the NSX Edge directly by issuing the command:  

show service loadbalancer