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Angel_Sosa_1662's avatar
Angel_Sosa_1662
Icon for Nimbostratus rankNimbostratus
Aug 15, 2014

1:1 SNAT to CLIENT IP

On my ltm I am running version 11.4.0 and 11.4.1 on two different chassis There is a line that is concerning with in the following link

 

https://devcentral.f5.com/wiki/irules.snat_pool_persistence.ashx

 

set static::i 0 // Which is line 15 incr static::i // Which is line 22

 

I am under the impression that for boxes that will run CMP or have multiples instances of TMM present and not running CMP You shouldn't alter the value of a static variable

 

According to the following link there is a nonte that states the following

 

https://support.f5.com/kb/en-us/solutions/public/13000/000/sol13033.html?sr=39629869

 

Important: While it is possible to use the set command to modify a static global variable within the iRule and outside of the RULE_INIT event, such modifications will not be propagated to each TMM instance; they will be visible to only the TMM process on which the modification was made, resulting in inconsistent values for the static global variable across TMM instances. As a result, F5 strongly recommends that you do not update the value of any static global variable within the iRule.

 

I am looking for an understanding if the first link

 

https://devcentral.f5.com/wiki/irules.snat_pool_persistence.ashx

 

set static::i 0 // Which is line 15 incr static::i // Which is line 22

 

Is correct incrementing the static variable "incr static::i" with out issue's

 

Thank You for your response in advance

 

Angel

 

application delivery
devops
iRules
LTM

6 Replies

  • IheartF5_45022's avatar
    IheartF5_45022
    Icon for Nacreous rankNacreous
    Aug 16, 2014

    Hi Angel, I think you'll find that the important phrase here is "outside of the RULE_INIT" - all the manipulation of static variables in the snat_pool_persistence iRule is done inside RULE_INIT, so it's all above board and will be visible to all TMM.

     

  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Aug 16, 2014

    additionally, you can alter global static variable as long as you are aware the change will make on the variable on specific tmm (the one which processes that traffic) only.

     

  • nitass_89166's avatar
    nitass_89166
    Icon for Noctilucent rankNoctilucent
    Aug 16, 2014

    additionally, you can alter global static variable as long as you are aware the change will make on the variable on specific tmm (the one which processes that traffic) only.