diff --git a/lib/defaults/defaults.go b/lib/defaults/defaults.go
index 758d7c9251..d8bafb0b6a 100644
--- a/lib/defaults/defaults.go
+++ b/lib/defaults/defaults.go
@@ -1345,6 +1345,9 @@ var (
 
 	// KubeControllerManagerPort specifies the default controller manager healthz port
 	KubeControllerManagerPort = 10257
+
+	// FlannelBackend specifies the default flannel backend
+	FlannelBackend = "vxlan"
 )
 
 // HookSecurityContext returns default securityContext for hook pods
diff --git a/lib/ops/opsservice/configure.go b/lib/ops/opsservice/configure.go
index a6af77a7c5..5082cf35e0 100644
--- a/lib/ops/opsservice/configure.go
+++ b/lib/ops/opsservice/configure.go
@@ -1444,9 +1444,9 @@ func (s *site) addClusterConfig(config clusterconfig.Interface, overrideArgs map
 	if globalConfig.HighAvailability != nil && *globalConfig.HighAvailability {
 		args = append(args, "--high-availability")
 	}
-	if globalConfig.FlannelBackend != "" {
+	if globalConfig.FlannelBackend != nil {
 		args = append(args,
-			fmt.Sprintf("--flannel-backend=%v", globalConfig.FlannelBackend))
+			fmt.Sprintf("--flannel-backend=%v", *globalConfig.FlannelBackend))
 	}
 	return args
 }
diff --git a/lib/ops/resources/gravity/collection.go b/lib/ops/resources/gravity/collection.go
index a411bf957e..1d54031a8f 100644
--- a/lib/ops/resources/gravity/collection.go
+++ b/lib/ops/resources/gravity/collection.go
@@ -664,9 +664,7 @@ func (r configCollection) WriteText(w io.Writer) error {
 		fmt.Fprintf(t, "%v\n", string(config.Config))
 	}
 	config := r.GetGlobalConfig()
-	if len(config.FlannelBackend) != 0 {
-		fmt.Fprintf(t, "Flannel Backend:\t%v\n", config.FlannelBackend)
-	}
+	fmt.Fprintf(t, "Flannel Backend:\t%v\n", utils.FormatStringPtrWithDefault(config.FlannelBackend, defaults.FlannelBackend))
 	if len(config.PodCIDR) != 0 {
 		fmt.Fprintf(t, "Pod IP Range:\t%v\n", config.PodCIDR)
 	}
@@ -685,7 +683,7 @@ func (r configCollection) WriteText(w io.Writer) error {
 	if len(config.FeatureGates) != 0 {
 		fmt.Fprintf(t, "Feature Gates:\t%v\n", formatFeatureGates(config.FeatureGates))
 	}
-	fmt.Fprintf(t, "High Availability:\t%v\n", formatBoolPtr(config.HighAvailability))
+	fmt.Fprintf(t, "High Availability:\t%v\n", utils.FormatBoolPtr(config.HighAvailability))
 	displayCloudConfig := config.CloudProvider != "" || config.CloudConfig != ""
 	if displayCloudConfig {
 		common.PrintCustomTableHeader(t, []string{"Cloud"}, "-")
@@ -742,13 +740,6 @@ func formatFeatureGates(features map[string]bool) string {
 	return strings.Join(result, ",")
 }
 
-func formatBoolPtr(ptr *bool) string {
-	if ptr == nil {
-		return "<unset>"
-	}
-	return fmt.Sprint(*ptr)
-}
-
 type operationsCollection struct {
 	operations []storage.Operation
 }
diff --git a/lib/storage/clusterconfig/clusterconfig.go b/lib/storage/clusterconfig/clusterconfig.go
index 9751df475f..ae10b052b0 100644
--- a/lib/storage/clusterconfig/clusterconfig.go
+++ b/lib/storage/clusterconfig/clusterconfig.go
@@ -140,8 +140,11 @@ func (r Resource) Merge(other Resource) Resource {
 		}
 	}
 	// Changing cloud provider is not supported
-	if other.Spec.Global.FlannelBackend != "" {
-		r.Spec.Global.FlannelBackend = other.Spec.Global.FlannelBackend
+	if other.Spec.Global.FlannelBackend != nil {
+		if r.Spec.Global.FlannelBackend == nil {
+			r.Spec.Global.FlannelBackend = new(string)
+		}
+		*r.Spec.Global.FlannelBackend = *other.Spec.Global.FlannelBackend
 	}
 	if other.Spec.Global.PodCIDR != "" {
 		r.Spec.Global.PodCIDR = other.Spec.Global.PodCIDR
@@ -279,7 +282,7 @@ func (r Global) IsEmpty() bool {
 		r.ServiceNodePortRange == "" &&
 		r.ProxyPortRange == "" &&
 		r.HighAvailability == nil &&
-		r.FlannelBackend == "" &&
+		r.FlannelBackend == nil &&
 		len(r.FeatureGates) == 0
 }
 
@@ -313,8 +316,8 @@ type Global struct {
 	FeatureGates map[string]bool `json:"featureGates,omitempty"`
 	// HighAvailability enables high availability mode for Kubernetes.
 	HighAvailability *bool `json:"highAvailability,omitempty"`
-	// FlannelBackend specifies the backend to pair with flannel.
-	FlannelBackend string `json:"flannelBackend,omitempty"`
+	// FlannelBackend optionally specifies the backend to pair with flannel.
+	FlannelBackend *string `json:"flannelBackend,omitempty"`
 }
 
 // specSchemaTemplate is JSON schema for the cluster configuration resource
diff --git a/lib/storage/clusterconfig/clusterconfig_test.go b/lib/storage/clusterconfig/clusterconfig_test.go
index 0af802a2bb..d3aa6dd86a 100644
--- a/lib/storage/clusterconfig/clusterconfig_test.go
+++ b/lib/storage/clusterconfig/clusterconfig_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/gravitational/gravity/lib/constants"
 	"github.com/gravitational/gravity/lib/defaults"
 	"github.com/gravitational/gravity/lib/storage"
+	"github.com/gravitational/gravity/lib/utils"
 
 	teleservices "github.com/gravitational/teleport/lib/services"
 	"github.com/gravitational/trace"
@@ -187,7 +188,7 @@ spec:
 						},
 						PodSubnetSize:    "26",
 						HighAvailability: newBoolPtr(true),
-						FlannelBackend:   "vxlan",
+						FlannelBackend:   utils.StringPtr("vxlan"),
 					},
 				},
 			},
@@ -246,7 +247,7 @@ func (*S) TestMergesClusterConfiguration(c *C) {
 							"feature2": false,
 						},
 						HighAvailability: newBoolPtr(true),
-						FlannelBackend:   "vxlan",
+						FlannelBackend:   utils.StringPtr("vxlan"),
 					},
 				},
 			},
@@ -266,7 +267,7 @@ func (*S) TestMergesClusterConfiguration(c *C) {
 							"feature2": false,
 						},
 						HighAvailability: newBoolPtr(true),
-						FlannelBackend:   "vxlan",
+						FlannelBackend:   utils.StringPtr("vxlan"),
 					},
 				},
 			},
@@ -294,7 +295,7 @@ address: 10.0.0.1
 							"feature1": true,
 							"feature2": false,
 						},
-						FlannelBackend: "vxlan",
+						FlannelBackend: utils.StringPtr("vxlan"),
 					},
 				},
 			},
@@ -341,7 +342,7 @@ address: 10.0.0.1
 							"feature1": true,
 							"feature3": true,
 						},
-						FlannelBackend: "vxlan",
+						FlannelBackend: utils.StringPtr("vxlan"),
 					},
 				},
 			},
diff --git a/lib/update/clusterconfig/plan.go b/lib/update/clusterconfig/plan.go
index bcc1c9235f..1bd580b766 100644
--- a/lib/update/clusterconfig/plan.go
+++ b/lib/update/clusterconfig/plan.go
@@ -197,7 +197,7 @@ func shouldUpdateNodes(clusterConfig clusterconfig.Interface, numWorkerNodes int
 	config := clusterConfig.GetGlobalConfig()
 	hasComponentUpdate := len(config.FeatureGates) != 0
 	hasCIDRUpdate := len(config.PodCIDR) != 0 || len(config.ServiceCIDR) != 0 || config.PodSubnetSize != ""
-	hasFlannelUpdate := config.FlannelBackend != ""
+	hasFlannelUpdate := config.FlannelBackend != nil
 	return !clusterConfig.GetKubeletConfig().IsEmpty() || hasComponentUpdate || hasCIDRUpdate || hasFlannelUpdate
 }
 
diff --git a/lib/utils/units.go b/lib/utils/units.go
index 25ae672260..653f38eac5 100644
--- a/lib/utils/units.go
+++ b/lib/utils/units.go
@@ -146,13 +146,38 @@ func BoolPtr(v bool) *bool {
 	return &v
 }
 
+// FormatBoolPtr formats the bool pointer value for output
+func FormatBoolPtr(v *bool) string {
+	if v == nil {
+		return "<unset>"
+	}
+	return fmt.Sprint(*v)
+}
+
 // DurationPtr returns a pointer to the provided duration value
 func DurationPtr(v time.Duration) *teleservices.Duration {
 	d := teleservices.NewDuration(v)
 	return &d
 }
 
+// StringValue returns the string value in v or an empty string if it's nil
+func StringValue(v *string) string {
+	if v != nil {
+		return *v
+	}
+	return ""
+}
+
 // StringPtr returns a pointer to the provided string
 func StringPtr(s string) *string {
 	return &s
 }
+
+// FormatStringPtrWithDefault formats the string pointer value for output.
+// If the pointer value is nil, the specified default is used
+func FormatStringPtrWithDefault(v *string, def string) string {
+	if v == nil {
+		return def
+	}
+	return *v
+}
diff --git a/lib/validate/clusterconfig.go b/lib/validate/clusterconfig.go
index 941ca2afa5..ec4c840824 100644
--- a/lib/validate/clusterconfig.go
+++ b/lib/validate/clusterconfig.go
@@ -89,8 +89,13 @@ func ClusterConfiguration(existing, update clusterconfig.Interface) error {
 		return trace.Wrap(err)
 	}
 
-	if !isSupportedBackend(newGlobalConfig.FlannelBackend) {
-		return trace.BadParameter("unsupported flannel backend was specified: %v", newGlobalConfig.FlannelBackend)
+	if newGlobalConfig.FlannelBackend != nil {
+		if *newGlobalConfig.FlannelBackend == "" {
+			return trace.BadParameter("flannel backend cannot be reset")
+		}
+		if !isSupportedBackend(*newGlobalConfig.FlannelBackend) {
+			return trace.BadParameter("unsupported flannel backend was specified: %v", *newGlobalConfig.FlannelBackend)
+		}
 	}
 
 	return nil
diff --git a/tool/gravity/cli/config_test.go b/tool/gravity/cli/config_test.go
index a9b1e95156..0268a65796 100644
--- a/tool/gravity/cli/config_test.go
+++ b/tool/gravity/cli/config_test.go
@@ -23,6 +23,7 @@ import (
 	"github.com/gravitational/gravity/lib/ops/resources"
 	"github.com/gravitational/gravity/lib/storage"
 	"github.com/gravitational/gravity/lib/storage/clusterconfig"
+	"github.com/gravitational/gravity/lib/utils"
 
 	"gopkg.in/check.v1"
 )
@@ -77,7 +78,7 @@ spec:
 				ServiceCIDR:    "100.200.0.0/16",
 				PodCIDR:        "100.96.0.0/16",
 				PodSubnetSize:  "26",
-				FlannelBackend: "vxlan",
+				FlannelBackend: utils.StringPtr("vxlan"),
 				CloudConfig: `[global]
 node-tags=example-cluster
 multizone="true"