Reselect pool on status code 500 or above...

when LB_SELECTED {
  if { $myretry >= 1 } {
    LB::mode rr
    LB::reselect pool $mypool
  }
}

when LB_SELECTED {
  if { $myretry >= 1 } {
    LB::reselect pool $my_new_pool
  }
}

this counter is used to limit the number of retrieswhen CLIENT_ACCEPTED {set retries 0}Try a new node if we have retried the connection once, set the method to rrThis is just an idea right nowwhen LB_SELECTED {if { $retries >= 1 } {log "Reselecting from node=[LB::server addr] in pool=[LB::server pool]"set mypool [LB::server pool]LB::mode rrLB::reselect pool $mypool}}we need to capture the request data to send the request again after receiving a 500 errorwhen HTTP_REQUEST {set myhttprequest [HTTP::request]}This is the guts here, examine each HTTP response. If you get an HTTP 500 error do the following:  Check to ensure we have not tried multiple times  Detach from the current node  Select a new node from the current pool  when HTTP_RESPONSE {if { [HTTP::status] starts_with "5" } {log "$myhttprequest has generated a [HTTP::status]"if { ($retries < [active_members [LB::server pool]] ) } {incr retriesHTTP::retry $myhttprequest  log "500 error received. HTTP request $myhttprequest has been retried to [LB::server addr]."}}}  Mark the node down and select a new node on LB failure.when LB_FAILED {log "Failure of node=[LB::server addr] in pool=[LB::server pool]"set mypool [LB::server pool]LB::downLB::mode rrLB::reselect pool $mypoool} 

when HTTP_REQUEST {

   if {[HTTP::method] eq "GET"}{
      set request_headers [HTTP::request]
      set method "GET"
   } else {
      set method ""
   }
}
...
when HTTP_RESPONSE {
   if { [HTTP::status] starts_with "5" and $method eq "GET"} {

   ...
}

when HTTP_REQUEST {
set my_url [HTTP::host][HTTP::uri]
log "Request for URL=$my_url received."
if { [HTTP::cookie BIGIP] contains "Redirect" } {
set retries [findstr [HTTP::cookie BIGIP] "Redirect_" 9 1]
} else {
set retries 0
}
}
This is the guts here, examine each HTTP response. If you get an HTTP 500 error do the following:
  Check to ensure we have not tried too many times
  force current node down
  Select a new node from the current pool
  
when HTTP_RESPONSE {
if { [HTTP::status] starts_with "5" && $retries < [active_members [LB::server pool]] } {
log "$my_url has generated a [HTTP::status]. Sending 307 for response."
incr retries
LB::down
HTTP::respond 307 Location "http://$my_url" Set-Cookie "BIGIP=Redirect_$retries" Connection "Close"
} elseif { [HTTP::status] starts_with "5" && $retries >= [active_members [LB::server pool]] } {
set retries 0
HTTP::respond 404 Set-Cookie "BIGIP=Not_Found" Connection "Close"
}
if { ($retries < [active_members [LB::server pool]] ) } {
incr retries
HTTP::retry $myhttprequest  
log "500 error received. HTTP request $myurl has been retried to [LB::server addr]."
}
}  
Mark the node down and select a new node on LB failure.
when LB_FAILED {
log "Failure of node=[LB::server addr] in pool=[LB::server pool]"
set mypool [LB::server pool]
LB::down
LB::mode rr
LB::reselect pool $mypool
} 

 
POST /Services/TransReportIIS/HttpServiceHoster.aspx HTTP/1.1
Content-Type: text/xml
Host: 
Content-Length: 927
Expect: 100-continue

HTTP/1.0 307 Temporary Redirect
Location: 
Set-Cookie: BIGIP=Redirect_1

Server: BigIP
Connection: close
Content-Length: 0

HTTP/1.1 503 Service Unavailable
Content-Type: text/html; charset=us-ascii
Server: Microsoft-HTTPAPI/2.0
Date: Wed, 05 Oct 2011 16:39:12 GMT
Connection: close
Content-Length: 326