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Forum Discussion

Thiyagu_343098's avatar
Thiyagu_343098
Icon for Nimbostratus rankNimbostratus
Jan 21, 2018

Assigning multiple iRULES to a VIP

Hello All, I need your suggestion on assigning multiple iRULES to the same VIP. What would be the best approach to be followed while assigning multiple iRULES to the same VIP? - Does the traffic to t...
application delivery
iRules
LTM
Hannes_Rapp's avatar
Hannes_Rapp
Icon for Nimbostratus rankNimbostratus
Jan 21, 2018

If you do not use Priority command, then all iRules are silently allocated priority of 500. All equal. Then the order in which they are mapped to Virtual Server will have significance, as you already guessed. But this is bad practice with no benefits. Occasional bugs due to config reload can mess up the order those rules are mapped to your Virtual Servers.

Note that only the current event that is taking place will be affected by 

priority
command.

A snapshot of how multiple iRules are actually processed will look as follows

RULE_INIT event of iRule that has priority (or event priority) set to 1
...
RULE_INIT event of iRule that has priority set to 999
...
HTTP_REQUEST event of iRule that has priority set to 1
...
HTTP_REQUEST event of iRule that has priority set to 999
...


Does LTM support Nested irule for example calling an another irule from the irule?

  • With standard TCL iRules, nope. Maybe you can do it with iRulesLX but cannot confirm.

Regards,