change the prtocol string to const (#1887)

pkg/controller/service_lb.go

@@ -313,11 +313,11 @@ func (c *Controller) updatePodAttachNets(pod *corev1.Pod, svc *corev1.Service) e
 		var protocol string
 		switch port.Protocol {
 		case corev1.ProtocolTCP:
-			protocol = "tcp"
+			protocol = util.ProtocolTCP
 		case corev1.ProtocolUDP:
-			protocol = "udp"
+			protocol = util.ProtocolTCP
 		case corev1.ProtocolSCTP:
-			protocol = "sctp"
+			protocol = util.ProtocolSCTP
 		}
 
 		var rules []string

pkg/util/const.go

@@ -90,8 +90,9 @@ const (
 	VpcDnsNameLabel            = "ovn.kubernetes.io/vpc-dns"
 	NetworkPolicyLogAnnotation = "ovn.kubernetes.io/enable_log"
 
-	ProtocolTCP = "tcp"
-	ProtocolUDP = "udp"
+	ProtocolTCP  = "tcp"
+	ProtocolUDP  = "udp"
+	ProtocolSCTP = "sctp"
 
 	NetworkTypeVlan   = "vlan"
 	NetworkTypeGeneve = "geneve"