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Amar_A_361783's avatar
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May 18, 2018

Configuring LB VIP With backend server with different set ports

Hi All, I need to setup a LB vip. In this setup i have a vip that would be listening on some random port(ex:-65001). There are backend server are using different ports(ex:-65002,65003).


To sumarize, setup would be like:- VIP:65001


Backend server


  • SrvA:65002
  • SrvA:65003
  • SrvB:65002
  • SrvB:65003

Now,i have a question how do we determine frontend VIP port. How user request will come. As LB VIP is by default in deny state. So using port no in the URL won't be taking. Another thing, how the LB will happen in such sort of setup.


1 Reply

  • Hi Amar,


    To resume you will have an VIP that will listnen on random port:


    VIP: IP:*


    With the following backend:


    • SrvA:65002
    • SrvA:65003
    • SrvB:65002
    • SrvB:65003

    TMM will perform destination address and port translation when load balancing to a pool. This is enabled by default and configurable using the address and port translation settings on the virtual server properties.


    SO to resume, F5 will LB to a pool depending LB setting then translate your dest port to the pool memeber dest port:




    • If F5 LB your request to SrvA:65003, F5 will translate your dest port to 65003.


    • If F5 LB your request to SrvA:65002, F5 will translate your dest port to 65002 (it is the same).


    can you clearly explain your need I can help you implement it!!!


    Just for information if you uncheck in VS settings "translated port" the request port done by client is use in memember pool. If user enter the server will manage the request on port 65002 even if he has another port defined on poolmemeber...