This topic discusses the pre-requisites and steps to configure Preserve client IP for NSX-T overlay deployments
Load balancing solutions for some applications (particularly in Layer 4 mode) require the Client IP address to be presented as the source IP address when the packet lands on the backend pool server member. NSX Advanced Load Balancer supports this functionality as Preserve Client IP section in VMware NSX Advanced Load BalancerConfiguration guide.
This solution is generally deployed by making the default gateway of the backend server point to a floating IP. The floating IP is hosted on the active Service Engine’s backend interface. However, in this mode, the servers’ default gateway has to be modified/ updated to point to the floating IP. The NSX-T overlay deployment model being in layer three mode has complications for preserving the client IP.
Service Insertion Framework
VMware NSX-T provides the service insertion, framework which has the ability to redirect traffic. The NSX-T service insertion framework has been utilized to achieve the return traffic from backend server to the floating IP of Active SE without needing to change the default gateway of the backend server. Avi Load Balancer automatically creates and manages the required redirection rules for each Virtual Service configured for Preserve Client IP.
