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Sarah's avatar
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Dec 21, 2023

iRule - unexpected behavior

Hello Community,

I have recently experienced an unexpected behavior from an iRule, where the http responses were intermittent and failure detected on the last event in the iRule HTTP_RESPONSE_RELEASE.

We have noticed the odd behaviour started when the log destination pool members failed to respond to health-check monitor (server down).

Below is a snippt of the iRule event where the failure observed.

    # figure out the final duration and add it to the IPFIX log
    set stop [expr {[clock click -milliseconds] - $start}]
    IPFIX::msg set $rule1_msg1 flowDurationMilliseconds $stop
    # send the IPFIX log
    IPFIX::destination send $static::http_rule1_dest $rule1_msg1

 I'm questioning two things:

  1. Why the failure was intermittent and havent affeted all responses?
  2. Why the pool memebrs status affected the iRule when they went down?

I'd appreciate any explanation.





6 Replies

    • Sarah's avatar
      Icon for Cirrus rankCirrus

      Hi zamroni,

      I was using the default udp health monitor (timeout 16).

      if "IPFIX::destination send" waits for the completion of the ipfix transmission, why do you think the http responses were intermittent since the pool went down? i suspected it will affect all responses. 

      the ipfix pool was down for a while, which in result affected the application response stability, where the iRule was applied to.

      and it only got fixed when I removed the health monitor from the pool.