diff --git a/internal/api/agent/subnet_test.go b/internal/api/agent/subnet_test.go
index 23745a0..ca6ec2c 100644
--- a/internal/api/agent/subnet_test.go
+++ b/internal/api/agent/subnet_test.go
@@ -161,6 +161,51 @@ func TestPostSubnet_VPCDeleting(t *testing.T) {
 	}
 }
 
+func TestPostSubnet_BridgeMode_Success(t *testing.T) {
+	s, db := newTestServer(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	req := SubnetCreateRequest{
+		Name:      "sn-br",
+		VPC:       "vpc-1",
+		Mode:      "bridge",
+		IfaceType: "vms",
+		GatewayIP: "10.0.0.1",
+		CIDR:      "10.0.0.0/24",
+	}
+	body, _ := json.Marshal(req)
+	w := httptest.NewRecorder()
+	s.SubnetsHandler(w, httptest.NewRequest(http.MethodPost, "/subnets", bytes.NewReader(body)))
+	if w.Code != http.StatusAccepted {
+		t.Fatalf("attendu 202, obtenu %d: %s", w.Code, w.Body.String())
+	}
+	var result Subnet
+	json.NewDecoder(w.Body).Decode(&result)
+	if result.Mode != "bridge" {
+		t.Errorf("mode attendu bridge, obtenu %q", result.Mode)
+	}
+	if result.VxlanID != 0 {
+		t.Errorf("vxlan_id devrait être 0 en mode bridge, obtenu %d", result.VxlanID)
+	}
+}
+
+func TestPostSubnet_UnknownMode(t *testing.T) {
+	s, db := newTestServer(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	req := SubnetCreateRequest{
+		Name:      "sn-1",
+		VPC:       "vpc-1",
+		Mode:      "vlan",
+		GatewayIP: "10.0.0.1",
+		CIDR:      "10.0.0.0/24",
+	}
+	body, _ := json.Marshal(req)
+	w := httptest.NewRecorder()
+	s.SubnetsHandler(w, httptest.NewRequest(http.MethodPost, "/subnets", bytes.NewReader(body)))
+	if w.Code != http.StatusUnprocessableEntity {
+		t.Errorf("attendu 422, obtenu %d", w.Code)
+	}
+}
+
 func TestPostSubnet_InvalidBody(t *testing.T) {
 	s, _ := newTestServer(t)
 	w := httptest.NewRecorder()
diff --git a/internal/dispatcher/agent/subnet_commands_test.go b/internal/dispatcher/agent/subnet_commands_test.go
index 3b118bc..b0fba3d 100644
--- a/internal/dispatcher/agent/subnet_commands_test.go
+++ b/internal/dispatcher/agent/subnet_commands_test.go
@@ -111,6 +111,68 @@ func TestCreateSubnetCommand_Prepare_VPCDeleted(t *testing.T) {
 	}
 }
 
+func TestCreateSubnetCommand_Prepare_DefaultsToVxlanMode(t *testing.T) {
+	_, db := newTestDispatcher(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	cmd := CreateSubnetCommand{
+		Name: "sn-1", VPC: "vpc-1", VxlanID: 100,
+		IfaceType: "vms", GatewayIP: "10.0.0.1", CIDR: "10.0.0.0/24",
+	}
+	cmd.Prepare(db, testCfg())
+	mode, _ := kv.GetFromDB(db, "subnet/sn-1/mode")
+	if mode != "vxlan" {
+		t.Errorf("mode attendu vxlan, obtenu %q", mode)
+	}
+	if _, err := kv.GetFromDB(db, "subnet/sn-1/vxlan_id"); err != nil {
+		t.Error("vxlan_id devrait être écrit en mode vxlan")
+	}
+}
+
+func TestCreateSubnetCommand_Prepare_BridgeMode_Success(t *testing.T) {
+	_, db := newTestDispatcher(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	cmd := CreateSubnetCommand{
+		Name: "sn-1", VPC: "vpc-1", Mode: "bridge",
+		IfaceType: "vms", GatewayIP: "10.0.0.1", CIDR: "10.0.0.0/24",
+	}
+	if err := cmd.Prepare(db, testCfg()); err != nil {
+		t.Fatalf("Prepare a échoué : %v", err)
+	}
+	mode, _ := kv.GetFromDB(db, "subnet/sn-1/mode")
+	if mode != "bridge" {
+		t.Errorf("mode attendu bridge, obtenu %q", mode)
+	}
+	iface, _ := kv.GetFromDB(db, "subnet/sn-1/local_iface")
+	if iface != "br-vms" {
+		t.Errorf("local_iface attendu br-vms, obtenu %q", iface)
+	}
+}
+
+func TestCreateSubnetCommand_Prepare_BridgeMode_NoVxlanID(t *testing.T) {
+	_, db := newTestDispatcher(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	cmd := CreateSubnetCommand{
+		Name: "sn-1", VPC: "vpc-1", Mode: "bridge",
+		IfaceType: "vms", GatewayIP: "10.0.0.1", CIDR: "10.0.0.0/24",
+	}
+	cmd.Prepare(db, testCfg())
+	if _, err := kv.GetFromDB(db, "subnet/sn-1/vxlan_id"); err == nil {
+		t.Error("vxlan_id ne devrait pas être écrit en mode bridge")
+	}
+}
+
+func TestCreateSubnetCommand_Prepare_UnknownMode(t *testing.T) {
+	_, db := newTestDispatcher(t)
+	kv.AddInDB(db, "vpc/vpc-1/state", "created")
+	cmd := CreateSubnetCommand{
+		Name: "sn-1", VPC: "vpc-1", Mode: "vlan",
+		IfaceType: "vms", GatewayIP: "10.0.0.1", CIDR: "10.0.0.0/24",
+	}
+	if err := cmd.Prepare(db, testCfg()); err == nil {
+		t.Error("Prepare devrait échouer pour un mode inconnu")
+	}
+}
+
 // --- DeleteSubnetCommand.Prepare ---
 
 func TestDeleteSubnetCommand_Prepare_Success(t *testing.T) {