Issues with load balancing for SAP PI

Hello Experts, We are having issues with load balancing on our SAP PI application. ECC system has 5 application servers and PI has 2, the observation is that when an ECC application server sends a request; it generally gets stuck to one application server on PI. We are currently using the cookie persistence and a tcp connection is open, F5 will send traffic to the same node on PI all the time until the connection is closed or PI application is restarted. I want to check the best practice for SAP PI load balancing wrt persistence and also checked in the http://www.f5.com/pdf/deployment-guides/sap-pi-dg.pdf guide to implement the OneConnect profile for PI.

Please suggest Thanks Pankaj