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N__197982's avatar
N__197982
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Dec 17, 2015

Identify the individual servers behind a VIP where the requests goes.

Folks, How best would we be able to identify which individual server gets the request from the F5 when the client/user hits that associated VIP? This is something that would be helpful during a troubleshooting case.

 

Thanks, N.

 

** sorry of this is a duplicate question, I asked this earlier but the question did not reflect. **

 

1 Reply

  • Hi N.,

    there are multiple ways to get it done.

    Without changing the configuration or adding iRules you can use the tcpdump utility with the

    😛
    switch in the context of tracing the internal interface:

    tcpdump -i 0.0:nnnp -c 100 -s 0 

    The

    p
    stands for "peer" and will return the serverside traffic associated with the traffic seen on clientside.

    This feature was added in v11.2 if I remember right.

    In case you are using cookie persistence you can use a browser plugin to monitor the inserted cookies as they reflect the servers IP and port after decoding.

    If you know specific patterns in traffic, i.e. a JSESSIONID containing a server specific string you can look after this.

    If you have the chance to modify your units configuration you can apply iRules to log an incoming connection/request i.e. in context of CLIENT_ACCEPTED or HTTP_REQUEST and the selected server i.e. in context of LB_SELECTED, SERVER_CONNECTED or HTTP_REQUEST_SEND.

    The options here depend on the protocol your are using to provide the service and applied features i.e. as

    one-connect
    . That´s why it is not possible to provide a detailed solution without further specification from your side.

    Thanks, Stephan