diff --git a/ui/scripts/system.js b/ui/scripts/system.js
index f355059daa4..7f638d880da 100644
--- a/ui/scripts/system.js
+++ b/ui/scripts/system.js
@@ -1257,9 +1257,8 @@
 															  var $form = $(this).closest("form");
 																var selectedNetworkOfferingId = $(this).val();
 																$(networkOfferingObjs).each(function(){
-																  if(this.id == selectedNetworkOfferingId) {
-																	  //networkoffering.specifyipranges
-																		if(this.guestiptype == "Isolated") {
+																  if(this.id == selectedNetworkOfferingId) {																	  
+																		if(this.guestiptype == "Isolated") {																		  
 																			if(this.specifyipranges == false) {
 																				$form.find('.form-item[rel=guestStartIp]').hide();
 																				$form.find('.form-item[rel=guestEndIp]').hide();
@@ -1268,18 +1267,25 @@
 																				$form.find('.form-item[rel=guestStartIp]').css('display', 'inline-block');
 																				$form.find('.form-item[rel=guestEndIp]').css('display', 'inline-block');
 																			}
+																																								
+                                      //cloudStack.dialog.createFormField.validation.required.remove($form.find('.form-item[rel=guestGateway]'));	//make guestGateway optional 	                                      							
+                                      //cloudStack.dialog.createFormField.validation.required.remove($form.find('.form-item[rel=guestNetmask]'));	//make guestNetmask optional  																			
 																		}
 																		else {  //this.guestiptype == "Shared"
 																			$form.find('.form-item[rel=guestStartIp]').css('display', 'inline-block');
-																			$form.find('.form-item[rel=guestEndIp]').css('display', 'inline-block');
+																			$form.find('.form-item[rel=guestEndIp]').css('display', 'inline-block');																			
+																			
+                                      //cloudStack.dialog.createFormField.validation.required.add($form.find('.form-item[rel=guestGateway]'));	  //make guestGateway required		
+																			//cloudStack.dialog.createFormField.validation.required.add($form.find('.form-item[rel=guestNetmask]'));	  //make guestNetmask required			
 																		}
-
-																		//networkoffering.specifyvlan
+																		
 																		if(this.specifyvlan == false) {
 																		  $form.find('.form-item[rel=vlanId]').hide();
+																			//cloudStack.dialog.createFormField.validation.required.remove($form.find('.form-item[rel=vlanId]'));	//make vlanId optional 	 	
 																		}
 																		else {
-																		  $form.find('.form-item[rel=vlanId]').css('display', 'inline-block');
+																		  $form.find('.form-item[rel=vlanId]').css('display', 'inline-block');																			
+																			//cloudStack.dialog.createFormField.validation.required.add($form.find('.form-item[rel=vlanId]'));		//make vlanId required		
 																		}
 																		return false; //break each loop
 																	}
diff --git a/ui/scripts/ui/dialog.js b/ui/scripts/ui/dialog.js
index 3e2f0b27784..709fabfefc7 100644
--- a/ui/scripts/ui/dialog.js
+++ b/ui/scripts/ui/dialog.js
@@ -398,6 +398,42 @@
       }).closest('.ui-dialog').overlay();
     },
 
+		/**
+     * to change a property(e.g. validation) of a createForm field after a createForm is rendered
+     */
+		createFormField: {
+			validation: {
+				required: {					
+					add: function($formField) {            
+						if($formField.find('.name').find('label').find('span.field-required').length == 0) {																			
+							$formField.find('.name').find('label').prepend($('<span>').addClass('field-required').html('*'));
+							
+							var $input = $formField.find('input');
+							var validationRules = $input.data('validation-rules');																				
+							if(validationRules == null)
+								validationRules = {};																		
+							validationRules.required = true;																				
+							$input.data('validation-rules', validationRules);																				
+						}						
+					},
+					remove: function($formField) {            
+						if($formField.find('.name').find('label').find('span.field-required').length > 0) {																						
+							$formField.find('.name').find('label').find('span.field-required').remove();	
+							
+							var $input = $formField.find('input');
+							var validationRules = $input.data('validation-rules');	
+							if(validationRules != null && validationRules.required != null)																				  														
+								delete validationRules.required;																				
+							$input.data('validation-rules', validationRules);		
+														
+							//$formField.find('.value').find('label.error[generated=true]').remove();
+							$formField.find('.value').find('label.error').hide();																				
+						}						
+					}
+				}
+			}  
+		},
+		
     /**
      * Confirmation dialog
      */