dealing w/ heavy load via try again later site

Try this:

 
 when RULE_INIT { 
 set ::MaxConn 500 
 set ::CurConn 0 
 set ::RejectList [list / .html .htm .asp .pl ] 
 } 
  
 when CLIENT_ACCEPTED { 
 incr ::CurConn 
 } 
  
 when CLIENT_CLOSED { 
 incr ::CurConn -1 
 } 
  
 when HTTP_REQUEST { 
 if {  
 ($::CurConn > $::MaxConn) and \ 
 ([matchclass [HTTP::path] ends_with $::RejectList]) \ 
 } { 
  
 HTTP::respond 200 content " 
  
 Please Try again later 
  
 Please Try again later 
  
  
 " 
 drop 
 }  
 } 
 

The iRule will only block html document and still allow non-html document (eg. image/flash/video).

It's using global variable which means it doesn't work perfectly in CMP platform (1600, 3600, 8400, 8800 and Viprion). As a 'workaround', you divide MaxConn with number of tmm process in yous system (eg. ps | grep npus). Statistic Profile might be better in CMP platform.

Modify it according to your environment.