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Ramesh_Polarapu's avatar
Ramesh_Polarapu
Icon for Nimbostratus rankNimbostratus
May 11, 2008

Load Balancer to forward the traffic when the Pool is down

In our setup we have a Virtual server MM1-Traffic and it has an iRule associated with it namely "Vantrix-v7.0". The purpose of this iRule is to differentiate the POST/GET in the HTTP requests and redirect the traffic to the pools Van-Get and Van-Post accordingly. Till now we have no issues as the traffic is going smooth and fine.

 

 

The customer have asked to implement redirection if any pools Van-Get or Van-Post are down redirect the traffic to another server/pool. I created Pool called MM1-Redirect, then created the iRules POST-Redirect & GET-Redirect and added this iRules to the MM1-Traffic virtual server but I am not able to see that the F5 redirecting the traffic if Van-Get or Van-Post pools are down.

 

 

Kindly advice and let me know if you need more information.
application delivery
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devops
iRules

3 Replies

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  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    May 12, 2008
    Hi,

     

     

    Can you post your rule and a sample of the ltm log file for a failure?

     

     

    Thanks,

     

    Aaron
  • Ramesh_Polarapu's avatar
    Ramesh_Polarapu
    Icon for Nimbostratus rankNimbostratus
    May 12, 2008
    Hi Aaron,

     

     

    Thanks for your reply. Check the below details. I do not have any log in the F5 as they were cleared. I will try to redo the test by getting the permission from customer as it will effect the traffic.

     

     

    iRule to differentiate POST/GET --- Vantrix-v7.0

     

     

    when HTTP_REQUEST {

     

    switch [HTTP::method] {

     

    "GET" {

     

    pool Van-Get

     

    }

     

    "POST" {

     

    pool Van-Post

     

    }

     

    }

     

    }

     

     

    iRule to forward the traffic when Van-Get pool is down --- GET-Redirect

     

    when CLIENT_ACCEPTED {

     

    if { [active_members Van-Get] == 0 } {

     

    pool MM1-Redirect

     

    }

     

    }

     

     

    iRule to forward the traffic when Van-Post pool is down ---POST-Redirect

     

     

    when CLIENT_ACCEPTED {

     

    if { [active_members Van-Post] == 0 } {

     

    pool MM1-Redirect

     

    }

     

    }

     

     

    Regards

     

    Ramesh
  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    May 12, 2008
    Hi Ramesh,

    If you set the pool in CLIENT_ACCEPTED and then set it to the GET or POST pools in HTTP_REQUEST in the second rule, the last rule's setting will override the first as the HTTP_REQUEST event is triggered after the CLIENT_ACCEPTED event. To fix this, you could either combine the rules or to set a flag in one rule which checks if the pool was specified in a previous rule. Here is an example of the first option: 

     
 when HTTP_REQUEST { 
  
     Select a pool based on the HTTP method 
    switch [HTTP::method] { 
       "GET" { 
          log local0. "[IP::client_addr]:[TCP::client_port]: GET request to [HTTP::host][HTTP::uri]" 
           Check if the selected pool has available members 
  if {[active_members Van-Get]}{ 
             log local0. "[IP::client_addr]:[TCP::client_port]: using Van-Get pool" 
             pool Van-Get 
          } else { 
             log local0. "[IP::client_addr]:[TCP::client_port]: using MM1-Redirect pool. Van-Get pool is down" 
             pool MM1-Redirect 
          } 
       } 
       "POST" { 
          log local0. "[IP::client_addr]:[TCP::client_port]: GET request to [HTTP::host][HTTP::uri]" 
           Check if the selected pool has available members 
  if {[active_members Van-Post]}{ 
             log local0. "[IP::client_addr]:[TCP::client_port]: using Van-Post pool" 
             pool Van-Post 
          } else { 
             log local0. "[IP::client_addr]:[TCP::client_port]: using MM1-Redirect pool. Van-Post pool is down" 
             pool MM1-Redirect 
          } 
  
       } 
       default { 
           Do something for non-GET/non-POST requests?   
           If nothing is done, the request will go to the default pool on the VIP if one is configured. 
          log local0. "[IP::client_addr]:[TCP::client_port]: Request method [HTTP::method] to [HTTP::host][HTTP::uri] was not GET or POST. " 
       } 
    } 
 }

    Aaron