diff --git a/pkg/controller/client_go_adapter.go b/pkg/controller/client_go_adapter.go
index 74379a923696..7211db793a87 100644
--- a/pkg/controller/client_go_adapter.go
+++ b/pkg/controller/client_go_adapter.go
@@ -30,7 +30,7 @@ import (
 )
 
 // this file contains setup logic to initialize the myriad of places
-// that client-go registers metrics. We copy the names and formats
+// that client-go registers metrics. we copy the names and formats
 // from Kubernetes so that we match the core controllers.
 
 var (
diff --git a/pkg/controller/external_vpc.go b/pkg/controller/external_vpc.go
index ed2b88be7cfe..877d3cf08bb5 100644
--- a/pkg/controller/external_vpc.go
+++ b/pkg/controller/external_vpc.go
@@ -13,42 +13,40 @@ import (
 	"github.com/kubeovn/kube-ovn/pkg/util"
 )
 
+// syncExternalVpc syncs the non kubeovn created ovn vpc, such as neutron ovn vpc
 func (c *Controller) syncExternalVpc() {
-	logicalRouters, err := c.getRouterStatus()
-	klog.V(4).Infof("sync over with %s", logicalRouters)
+	logicalRouters, err := c.getNonKubeovnRouterStatus()
 	if err != nil {
-		klog.Error("list lr failed", err)
+		klog.Error("failed to list ovn logical routers", err)
 		return
 	}
+	klog.V(3).Infof("sync external vpcs with ovn non kube-ovn created vpc")
 	vpcs, err := c.vpcsLister.List(labels.SelectorFromSet(labels.Set{util.VpcExternalLabel: "true"}))
 	if err != nil {
 		klog.Errorf("failed to list vpc, %v", err)
 		return
 	}
-	vpcMaps := make(map[string]*v1.Vpc)
-	for _, vpc := range vpcs {
-		vpcMaps[vpc.Name] = vpc.DeepCopy()
-	}
-	for vpcName, vpc := range vpcMaps {
-		if _, ok := logicalRouters[vpcName]; ok {
+	for _, cachedVpc := range vpcs {
+		vpc := cachedVpc.DeepCopy()
+		if _, ok := logicalRouters[vpc.Name]; ok {
+			// update vpc status subnet list
 			vpc.Status.Subnets = []string{}
-			for _, asw := range logicalRouters[vpcName].LogicalSwitches {
-				vpc.Status.Subnets = append(vpc.Status.Subnets, asw.Name)
+			for _, ls := range logicalRouters[vpc.Name].LogicalSwitches {
+				vpc.Status.Subnets = append(vpc.Status.Subnets, ls.Name)
 			}
 			_, err = c.config.KubeOvnClient.KubeovnV1().Vpcs().UpdateStatus(context.Background(), vpc, metav1.UpdateOptions{})
 			if err != nil {
-				klog.Errorf("update vpc %s status failed: %v", vpcName, err)
+				klog.Errorf("failed to update vpc %s status: %v", vpc.Name, err)
 				continue
 			}
-			delete(logicalRouters, vpcName)
-			klog.V(4).Infof("patch vpc %s", vpcName)
+			delete(logicalRouters, vpc.Name)
 		} else {
-			err = c.config.KubeOvnClient.KubeovnV1().Vpcs().Delete(context.Background(), vpcName, metav1.DeleteOptions{})
+			klog.Infof("external vpc %s has no ovn logical router, delete it", vpc.Name)
+			err = c.config.KubeOvnClient.KubeovnV1().Vpcs().Delete(context.Background(), vpc.Name, metav1.DeleteOptions{})
 			if err != nil {
-				klog.Errorf("delete vpc %s failed: %v", vpcName, err)
+				klog.Errorf("failed to delete vpc %s: %v", vpc.Name, err)
 				continue
 			}
-			klog.Infof("deleted vpc %s", vpcName)
 		}
 	}
 	if len(logicalRouters) != 0 {
@@ -59,7 +57,7 @@ func (c *Controller) syncExternalVpc() {
 			vpc.Labels = map[string]string{util.VpcExternalLabel: "true"}
 			vpc, err = c.config.KubeOvnClient.KubeovnV1().Vpcs().Create(context.Background(), vpc, metav1.CreateOptions{})
 			if err != nil {
-				klog.Errorf("init vpc %s failed %v", routerName, err)
+				klog.Errorf("failed init external vpc %s, %v", routerName, err)
 				return
 			}
 
@@ -74,34 +72,34 @@ func (c *Controller) syncExternalVpc() {
 
 			_, err = c.config.KubeOvnClient.KubeovnV1().Vpcs().UpdateStatus(context.Background(), vpc, metav1.UpdateOptions{})
 			if err != nil {
-				klog.Errorf("update vpc status failed %v", err)
+				klog.Errorf("failed to update vpc %s status, %v", routerName, err)
 				return
 			}
-			klog.V(4).Infof("add vpc %s", routerName)
+			klog.V(4).Infof("added external vpc %s", routerName)
 		}
 	}
 }
 
-func (c *Controller) getRouterStatus() (logicalRouters map[string]util.LogicalRouter, err error) {
+func (c *Controller) getNonKubeovnRouterStatus() (logicalRouters map[string]util.LogicalRouter, err error) {
 	logicalRouters = make(map[string]util.LogicalRouter)
-	externalOvnRouters, err := c.OVNNbClient.ListLogicalRouter(false, func(lr *ovnnb.LogicalRouter) bool {
+	nonKubeovnRouters, err := c.OVNNbClient.ListLogicalRouter(false, func(lr *ovnnb.LogicalRouter) bool {
 		return len(lr.ExternalIDs) == 0 || lr.ExternalIDs["vendor"] != util.CniTypeName
 	})
 	if err != nil {
-		klog.Errorf("failed to list external logical router, %v", err)
+		klog.Errorf("failed to list non kubeovn logical router, %v", err)
 		return logicalRouters, err
 	}
-	if len(externalOvnRouters) == 0 {
-		klog.V(4).Info("sync over, no external vpc")
+	if len(nonKubeovnRouters) == 0 {
+		klog.V(4).Info("no non kubeovn logical router")
 		return logicalRouters, nil
 	}
 
-	for _, externalLR := range externalOvnRouters {
+	for _, router := range nonKubeovnRouters {
 		lr := util.LogicalRouter{
-			Name:  externalLR.Name,
-			Ports: make([]util.Port, 0, len(externalLR.Ports)),
+			Name:  router.Name,
+			Ports: make([]util.Port, 0, len(router.Ports)),
 		}
-		for _, uuid := range externalLR.Ports {
+		for _, uuid := range router.Ports {
 			lrp, err := c.OVNNbClient.GetLogicalRouterPortByUUID(uuid)
 			if err != nil {
 				klog.Warningf("failed to get LRP by UUID %s: %v", uuid, err)