Sendig VIP Syslog

Below Irule may help you

Code
    when HTTP_REQUEST {

    set http_request_time [clock clicks -milliseconds]
    set timestamp [clock format [clock seconds] -format {%d/%b/%Y:%H:%M:%S %z}] 
    set remote [IP::remote_addr]
    set client [IP::client_addr]:[TCP::client_port]
    set url [HTTP::host][HTTP::uri]
    set referer [HTTP::header "Referer"]
    set vip [IP::local_addr]:[TCP::local_port]
    set httpMethod [HTTP::method]
    set httpVersion [HTTP::version]
    set xforwardfor [HTTP::header X-Forwarded-For]
    set url [string map " x" $url]
    set referer [string map " x" $referer] 
    set hsl [HSL::open -proto UDP -pool POOL_SYSLOG]

     Limit the url variable to 300 characters
    if {[string length $url] > 300} {
      set url "[string range $url 0 300]..."   
    }

     Limit the referer variable to 300 characters
    if {[string length $referer] > 300} {
      set referer "[string range $referer 0 300]..."   
    }

     Build the Request log line
    set request_log_line " $timestamp  [virtual name]  $client  $remote  $vip  $url  $referer  $httpMethod  $httpVersion" 
    log local0.info "Request - $request_log_line"
    }

    when HTTP_RESPONSE {

     VARIABLES
     Initialize local variables used in this rule
    
    set http_response_time [ clock clicks -milliseconds ]
    set client [IP::client_addr]:[TCP::client_port]
    set node [IP::server_addr]:[TCP::server_port]
    set nodeResp [HTTP::status]
    set payloadLength [HTTP::payload length]
    set responseTime [expr $http_response_time - $http_request_time]

      Build the Response log line
     set response_log_line "$client  $node  $nodeResp  $payloadLength  $responseTime  $http_request_time  $xforwardfor" 
    log local0.info "Response - $response_log_line"

     Write Request and Response log lines to the LTM log
    HSL::send $hsl "IRULE_COMMON_LOG : $request_log_line  -  $response_log_line"
     }