diff --git a/pkg/apis/v1alpha2/ippool_types.go b/pkg/apis/v1alpha2/ippool_types.go
index 2d629259f..469dc43ef 100644
--- a/pkg/apis/v1alpha2/ippool_types.go
+++ b/pkg/apis/v1alpha2/ippool_types.go
@@ -37,6 +37,7 @@ type IPPoolList struct {
 // IPPoolSpec defines the desired state of IPPool.
 type IPPoolSpec struct {
 	// Type defines the type of this IPPool, Public or Private.
+	// +kubebuilder:validation:Enum=Public;Private
 	// +optional
 	Type string `json:"type,omitempty"`
 	// Subnets defines set of subnets need to be allocated.