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krish90's avatar
Icon for Nimbostratus rankNimbostratus
Aug 23, 2022

Connections not flowing equally to pool with same pool member ip and different port

We have two VIP for HTTP and HTTPS and its configured with single same pool in F5. And the pool members configured with mixed port like same ip configured with 80 and 10200 port. We have observed a unusual behaviour in LB pool that traffic only flowed to member which is configured with 80 port. But the expected flow is it should flow traffic to all members ( both 80 and 10200 port ) as per the loadbalancing method - round robin. 

Traffic is equally distributed when i have pool with same port for all members ( 10200 ) and it is not working when we configured member with 80 port in same pool. 


All members configured in same priority group and ratio is 1  



9 Replies

  • Check that the VS has Translate Port enabled.

    Presumably both pool members are showing as up

  • PeteWhite 

    Hi yes I have verified below items and its enabled on both VIP ( HTTP and HTTPS  ) 

    • Port Transaltion 
    • Address Translation 

    Yes all members are up and showing like online and attached with pool( total member count is eight ). And 7 members configured with 10200 port and 1 member alone configured with 80 port. 


  • Hello,

    Based on the below answer in this link, the port translation is the only mandatory option to allow traffic on different pool members ports.

    you can check the pool statistics and see whether F5 is sending traffic to this pool member *80* or no traffic is sent at all. Also, try adding the pool member 80 alone and use this pool and check whether it is going to work or not. if it didn't work, check the backend server itself and try to access it directly.

  • Check that you haven't configured something like OneConnect or Persistence profiles. Those can impact the choice of pool member.

    You can also change the configuration of source port from "preserve" (default) to "change". I know it seems unrelated, but I've solved issues similar to yours using this option.


  • We dont configured anythiing like OneConnect / Persistence profile . 

  • Is there any chances like if traffic comes to VIP with 80 port( we have VIP for https and http )  and this all gone for only member with 80 port in LB pool? 

    We have same ip with different port in pool and most of the traffic is flowing to only member with 80 

      • PeteWhite's avatar
        Icon for Employee rankEmployee

        Can I suggest you provide more information about this - the software version, the configuration, the output of the commands, an iHealth link or suchlike.

        I would be very suprised if this were a software bug, it is probably a configuration error - as you say, it could be that the pool is referenced by multiple virtual servers or suchlike.

        Alternatively, raise a case with F5 Support and they will help you with troubleshooting etc