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Darthw_20046's avatar
Darthw_20046
Icon for Nimbostratus rankNimbostratus
Jan 31, 2013

Ping members of the pool

I'm a noob to the F5 Big IP LTM devices we have. I've set up a SharePoint virtual IP to loadbalance connections to two front-end servers. The developer would like to be able to ping from a client workstation and have the ping request reply with the IP address of the member server of the pool, not the virtual IP address the load balancer uses for the pool. He would like this in order to know to which of the two servers the client is connected. He says he's used other balancers that had this enabled, and it would make sense. However, I'm not finding anyone - or not querying sites using the correct terms - that discusses setting this up on a Big-IP LTM. Can anyone assist?

 

 

I did get on the iRules forum and set up an iRule that adds the member server IP to a responding HTTP packet, and we can use Wireshark to review a comment in the HTTP heard to find the IP, however it requires an HTTP header utility, or Wireshark on the client. A ping request would be helpful so as not to require an additional software install.

 

Thanks.

 

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  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Jan 31, 2013

    The iRule solution is unfortunately the only one I believe. <

     

    You could use an iRule that returns this information when you request a certain URL not used by the application;

     

    when LB_SELECTED {

     

    Set variable ‘whichserver’ value to the selected Pool Member IP

     

    set whichserver [LB::server addr]

     

    }

     

    when HTTP_REQUEST {

     

    if { string tolower [HTTP::uri] equals "/whichserver" } {

     

    HTTP::respond 200 content "Real server IP is: $whichserver"

     

    noserver Content-Type "text/html" Connection "Close"

     

    Stop processing the iRule for this event here

     

    return }

     

    }

     

  • Darthw_20046's avatar
    Darthw_20046
    Icon for Nimbostratus rankNimbostratus
    Feb 04, 2013
    Thanks Steve. I do already have an iRule set up like this, and it works great, but requires an HTTP header utility or Wireshark. I also have an iRule that updates log files on the client (but the developer doesn't have advanced enough access to view those logs.) The developer keeps hounding me that he's seen other load balancers with the ability to ping members, but I'm still not finding any information that it's possible. I was waiting to get my F5 support ID approved, which it is now, so we'll see what I get officially from support.
  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Feb 04, 2013
    Darthw, this rule sends a 'proper' page as a response, it doesn't require a header utility or Wireshark; it'll simply display the selected Pool Member in the client browser.