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N__197982's avatar
N__197982
Icon for Nimbostratus rankNimbostratus
Dec 16, 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. **

 

application delivery
BIG-IP

1 Reply

  • StephanManthey's avatar
    StephanManthey
    Icon for Nacreous rankNacreous
    Dec 16, 2015

    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