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Indrajit_Basak_'s avatar
Indrajit_Basak_
Icon for Nimbostratus rankNimbostratus
Mar 22, 2014

ECV Health Monitor is not working properly in F5 LTM

Hi, We have same physical server where different applications are running . for example HC-HH and HC-APP. These two application can be accessed by URLS http://lmjedwmsap1.jeddah.cpksa.local:7778/forms/frmservlet?config=wmshcrdc-hh and http://lmjedwmsap1.jeddah.cpksa.local:7778/forms/frmservlet?config=wmshcrdc.

 

Now we are trying to configure ECV monitor and assign them to Pool to monitor members .

 

ECV Monitor settings are as below

 

Type = HTTP Interval = 5 seconds Timeout = 16 seconds Send string = GET /forms/frmservlet?config=wmshcrdc-hh HTTP/1.1\r\nHost:\r\nConnection: close\r\n\r\n Receive string = 200 OK Monitor port = 7778 But it is now working perfectly . Pool members are showing healthy ( green ) even if the particular application is down .

 

Can anybody assist where is the issue ???/

 

Regds...Indrajit

 

application delivery
availability
citrix
LTM
management
TMSH

4 Replies

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  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Mar 22, 2014

    I guess the bigger question would be what constitutes being "down"? Many applications will "fail", while the web server is still functional. You're looking for a 200 OK response, so that's likely what you're getting. There are generally a few ways to troubleshoot an HTTP monitor:

    1. Command line cURL is a great way to test an HTTP request and corresponding response:

      curl -v http://x.x.x.x:7778/forms/frmservlet?config=wmshcrdc-hh

    2. Tcpdump the monitor itself. This will allow you to see the monitor's request and the server's response:

      tcpdump -lnni 0.0 -Xs0 port 7778 and host x.x.x.x
  • Indrajit_Basak_'s avatar
    Indrajit_Basak_
    Icon for Nimbostratus rankNimbostratus
    Mar 22, 2014

    Thanks Kevin for quick answer . Actually we want to monitor the application not the web server . So in that case what should be the "receive string " parameter setting in monitor configuration . How to find it out ?

     

    I believe 200 Ok is the receive string for generic web application . So in our case it is not the correct settings .

     

    Can you help on this

     

    Regds....Indrajit

     

  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Mar 23, 2014

    200 OK is the generic (good) response string for ANY HTTP web server. I would start by trying the cURL command above. That should show you what the application response actually looks like. Find something in the payload of the response, preferably near the top, that definitively indicates a good application response. You may also want to try the same cURL command with a "down" application to see the differences.

     

  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Mar 26, 2014

    This is a tough one. The outputs you're displaying look almost identical. Is there some HTML content that in the working site and not in the non-working site?