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bmarlow_10657's avatar
bmarlow_10657
Icon for Nimbostratus rankNimbostratus
Feb 16, 2009

SNMP query in iRule/SNMP monitor variable for iRule?

Okay, so I've been looking all over and there seems to be relatively little information regarding using SNMP or SNMP parameters in iRules. Mind you I am an iRule Rookie.

 

 

My question has two parts:

 

1. Is it possible to do an SNMP query within an iRule, and if so what is the command?

 

2. Is there a way to call the values of an SNMP monitor in an iRule?

 

 

My scenario is this:

 

 

We have several web proxies that sit behind an LTM. To make maximum use of our proxies caching mechanism we want to use a spill-over method triggered by CPU thresholds of the proxies.

 

 

I imagine that the iRule will look something similar to this (note the IP's have been replaced with *'s), but what would I used for variable?

 

 

when HTTP_REQUEST {

 

if{ [ usage 1sec] <= 75} {

 

LB::reselect node *.*.*.* 8080

 

} else {

 

if{ [ usage 1sec] <= 75} {

 

LB::reselect node *.*.*.* 8080

 

} else {

 

if{ [ usage 1sec] <= 75} {

 

LB::reselect node *.*.*.* 8080

 

} else {

 

if{ [ usage 1sec] <= 75} {

 

LB::reselect node *.*.*.* 8080

 

} else {

 

 

}

 

}

 

 

 

Any help would be greatly appreciated!

 

 

Thanks!
application delivery
dev
devops
iRules

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  • hwidjaja_37598's avatar
    hwidjaja_37598
    Icon for Altostratus rankAltostratus
    Feb 17, 2009
    I don't think you can you do snmp query directly from an iRule. CMIIW ...

     

     

    Another approach, create another cron job to do snmp query and send it to a data group. Your iRule would be able to get the cpu usage information from data group instead of doing snmp query.
  • bmarlow_10657's avatar
    bmarlow_10657
    Icon for Nimbostratus rankNimbostratus
    Feb 18, 2009
    The plan wasn't to do an SNMP query for each connection, but rather every couple of seconds, and once the CPU utilization hit a certain threshold it would bleed new/non persisted sessions over to the other proxy.

     

     

    SNMP DCA will look at the stats, but it will only do for a dynamic ratio. It won't mark the node unavailable unless it doesn't respond in a timely manner to the SNMP request. I don't want a dynamic ratio load balance, only new connections to bleed over once the CPU gets to a certain point.
  • Thuchapon_92030's avatar
    Thuchapon_92030
    Icon for Nimbostratus rankNimbostratus
    Sep 25, 2012

    Can you tell me the example command that is send the snmp query data to the data group. please

     

  • Mohamed_Lrhazi's avatar
    Mohamed_Lrhazi
    Icon for Altocumulus rankAltocumulus
    Sep 25, 2012
    There is no command for sending SNMP, from an iRule.

     

     

    You can from the BigIP, from Linux space, using regular net-snmp commands.

     

     

    Or, from an iRule, you could send commands to some HTTP app, which would then do SNMP for you...