fixed HTTP page automatically when the # connections for the node is reached

If the node limit is reached the LB_FAILED event will be triggered. This iRule should do the trick:

when LB_FAILED { 
     HTTP::redirect "http://mysite.com/over-limit.html" 
 }

-George

George,

 

 

thanks a million!

 

 

So, will putting the LB_FAILED when statement right after the pool selection work ok?

 

 

when HTTP_REQUEST {

 

HTTP::header insert "X_CLIENT_IP" [IP::client_addr]

 

HTTP::header insert "X-Forwarded-For" [IP::client_addr]

 

if { [string tolower [HTTP::uri]] contains "pmcserver" } {

 

pool pm3_qa_pmcserver

 

when LB_FAILED {

 

HTTP::redirect "http://mysite.com/over-limit.html"

 

return

 

}

 

return

 

} elseif { [string tolower [HTTP::uri]] starts_with "/partner" } {

 

pool pm3_qa_soap

 

return

 

} else {

 

pool pm3_qa_web

 

return

 

}

 

}

 

 

Also, i was reading this article:

 

https://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/50/aft/15238/showtab/groupforums/Default.aspx

 

 

and, inside it states this:

 

LB_FAILED is triggered in a variety of circumstances. I'll list a few off the top of my head:

 

a) no pool selected

 

b) no available pool members in selected pool

 

c) no route to pool member

 

d) failed to connect to pool member With regard to

 

d). The "max retrans syn" option in the TCP profile will affect the timeout.

 

 

Looks like "Maximum Syn Retransmissions" is set to 4 in LTM's default tcp profile though, so LB_FAILED would be triggered if server didn't respond in 45 seconds:

 

 

1st SYN: 0

 

2nd SYN: +3 seconds

 

3rd SYN: +6 seconds

 

4th SYN: +12 seconds

 

5th SYN: +24 seconds

 

====================== LB_FAILED: 45 seconds

 

 

So, would that mean that the user would have to wait 45 seconds to be redirected to the http://mysite.com/over-limit.html URL? If so, is there any way to speed up this redirect if the node's connections are all used up?

 

 

 

thanks much,

 

Keith

Keith,

You cannot nest events in iRules: LB_FAILED cannot reside inside of HTTP_REQUEST. Your iRule will probably look something like this:

when HTTP_REQUEST {  
     HTTP::header insert "X_CLIENT_IP" [IP::client_addr]  
     HTTP::header insert "X-Forwarded-For" [IP::client_addr]  
  
     if { [string tolower [HTTP::uri]] contains "pmcserver" } {  
         pool pm3_qa_pmcserver  
     } elseif { [string tolower [HTTP::uri]] starts_with "/partner" } {  
         pool pm3_qa_soap 
     } else {  
         pool pm3_qa_web 
     }  
 } 
 when LB_FAILED {  
     HTTP::redirect "http://mysite.com/over-limit.html"  
 }

The LB_FAILED event will be triggered the instant that a new connection attempt is made to a pool whose connection limit has already been reached. There are a number of different circumstances that trigger LB_FAILED event and they all have different criteria for load balancing failure. Hope that helps,

-George

George,

 

 

Can't thank you enough for the help. You've answered all our questions.

 

 

Thanks very much!

 

-Keith