diff --git a/xds/internal/resolver/serviceconfig.go b/xds/internal/resolver/serviceconfig.go
index 6a55217e7a87..84c5753adf61 100644
--- a/xds/internal/resolver/serviceconfig.go
+++ b/xds/internal/resolver/serviceconfig.go
@@ -22,12 +22,14 @@ import (
 	"encoding/json"
 	"fmt"
 
+	wrapperspb "github.com/golang/protobuf/ptypes/wrappers"
 	xdsclient "google.golang.org/grpc/xds/internal/client"
 )
 
 const (
 	cdsName            = "cds_experimental"
 	weightedTargetName = "weighted_target_experimental"
+	xdsRoutingName     = "xds_routing_experimental"
 )
 
 type serviceConfig struct {
@@ -53,24 +55,91 @@ type cdsBalancerConfig struct {
 	Cluster string `json:"cluster"`
 }
 
-func serviceUpdateToJSON(su xdsclient.ServiceUpdate) (string, error) {
+type route struct {
+	Path     *string                    `json:"path,omitempty"`
+	Prefix   *string                    `json:"prefix,omitempty"`
+	Regex    *string                    `json:"regex,omitempty"`
+	Headers  []*xdsclient.HeaderMatcher `json:"headers,omitempty"`
+	Fraction *wrapperspb.UInt32Value    `json:"matchFraction,omitempty"`
+	Action   string                     `json:"action"`
+}
+
+type xdsActionConfig struct {
+	ChildPolicy balancerConfig `json:"childPolicy"`
+}
+
+type xdsRoutingBalancerConfig struct {
+	Action map[string]xdsActionConfig `json:"action"`
+	Route  []*route                   `json:"route"`
+}
+
+func (r *xdsResolver) routesToJSON(routes []*xdsclient.Route) (string, error) {
+	r.updateActions(newActionsFromRoutes(routes))
+
+	// Generate routes.
+	var rts []*route
+	for _, rt := range routes {
+		t := &route{
+			Path:    rt.Path,
+			Prefix:  rt.Prefix,
+			Regex:   rt.Regex,
+			Headers: rt.Headers,
+		}
+
+		if f := rt.Fraction; f != nil {
+			t.Fraction = &wrapperspb.UInt32Value{Value: *f}
+		}
+
+		t.Action = r.getActionAssignedName(rt.Action)
+		rts = append(rts, t)
+	}
+
+	// Generate actions.
+	action := make(map[string]xdsActionConfig)
+	for _, act := range r.actions {
+		action[act.assignedName] = xdsActionConfig{
+			ChildPolicy: weightedClusterToBalancerConfig(act.clustersWithWeights),
+		}
+	}
+
+	sc := serviceConfig{
+		LoadBalancingConfig: newBalancerConfig(
+			xdsRoutingName, xdsRoutingBalancerConfig{
+				Route:  rts,
+				Action: action,
+			},
+		),
+	}
+
+	bs, err := json.Marshal(sc)
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal json: %v", err)
+	}
+	return string(bs), nil
+}
+
+func weightedClusterToBalancerConfig(wc map[string]uint32) balancerConfig {
 	// Even if WeightedCluster has only one entry, we still use weighted_target
 	// as top level balancer, to avoid switching top policy between CDS and
 	// weighted_target, causing TCP connection to be recreated.
 	targets := make(map[string]cdsWithWeight)
-	for name, weight := range su.WeightedCluster {
+	for name, weight := range wc {
 		targets[name] = cdsWithWeight{
 			Weight:      weight,
 			ChildPolicy: newBalancerConfig(cdsName, cdsBalancerConfig{Cluster: name}),
 		}
 	}
+	bc := newBalancerConfig(
+		weightedTargetName, weightedCDSBalancerConfig{
+			Targets: targets,
+		},
+	)
+	return bc
+}
 
+func weightedClusterToJSON(wc map[string]uint32) (string, error) {
 	sc := serviceConfig{
-		LoadBalancingConfig: newBalancerConfig(
-			weightedTargetName, weightedCDSBalancerConfig{
-				Targets: targets,
-			},
-		),
+		LoadBalancingConfig: weightedClusterToBalancerConfig(wc),
 	}
 	bs, err := json.Marshal(sc)
 	if err != nil {
@@ -78,3 +147,13 @@ func serviceUpdateToJSON(su xdsclient.ServiceUpdate) (string, error) {
 	}
 	return string(bs), nil
 }
+
+func (r *xdsResolver) serviceUpdateToJSON(su xdsclient.ServiceUpdate) (string, error) {
+	// If WeightedClusters is set, routing is disabled (by env variable). Use
+	// weighted target only.
+	if su.WeightedCluster != nil {
+		return weightedClusterToJSON(su.WeightedCluster)
+	}
+
+	return r.routesToJSON(su.Routes)
+}
diff --git a/xds/internal/resolver/serviceconfig_action.go b/xds/internal/resolver/serviceconfig_action.go
new file mode 100644
index 000000000000..d582048fda09
--- /dev/null
+++ b/xds/internal/resolver/serviceconfig_action.go
@@ -0,0 +1,186 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package resolver
+
+import (
+	"fmt"
+	"math"
+	"sort"
+	"strconv"
+
+	"google.golang.org/grpc/internal/grpcrand"
+	xdsclient "google.golang.org/grpc/xds/internal/client"
+)
+
+type actionWithAssignedName struct {
+	// cluster:weight, "A":40, "B":60
+	clustersWithWeights map[string]uint32
+	// clusterNames, without weights, sorted and hashed, "A_B_"
+	clusterNames string
+	// The assigned name, clusters plus a random number, "A_B_1"
+	assignedName string
+	// randomNumber is the number appended to assignedName.
+	randomNumber int64
+}
+
+// newActionsFromRoutes gets actions from the routes, and turns them into a map
+// keyed by the hash of the clusters.
+//
+// In the returned map, all actions don't have assignedName. The assignedName
+// will be filled in after comparing the new actions with the existing actions,
+// so when a new and old action only diff in weights, the new action can reuse
+// the old action's name.
+//
+// from
+//   {B:60, A:40}, {A:30, B:70}, {B:90, C:10}
+//
+// to
+//   A40_B60_: {{A:40, B:60}, "A_B_", ""}
+//   A30_B70_: {{A:30, B:70}, "A_B_", ""}
+//   B90_C10_: {{B:90, C:10}, "B_C_", ""}
+func newActionsFromRoutes(routes []*xdsclient.Route) map[string]actionWithAssignedName {
+	newActions := make(map[string]actionWithAssignedName)
+	for _, route := range routes {
+		var clusterNames []string
+		for n := range route.Action {
+			clusterNames = append(clusterNames, n)
+		}
+
+		// Sort names to be consistent.
+		sort.Strings(clusterNames)
+		clustersOnly := ""
+		clustersWithWeight := ""
+		for _, c := range clusterNames {
+			// Generates A_B_
+			clustersOnly = clustersOnly + c + "_"
+			// Generates A40_B60_
+			clustersWithWeight = clustersWithWeight + c + strconv.FormatUint(uint64(route.Action[c]), 10) + "_"
+		}
+
+		if _, ok := newActions[clustersWithWeight]; !ok {
+			newActions[clustersWithWeight] = actionWithAssignedName{
+				clustersWithWeights: route.Action,
+				clusterNames:        clustersOnly,
+			}
+		}
+	}
+	return newActions
+}
+
+// updateActions takes a new map of actions, and updates the existing action map in the resolver.
+//
+// In the old map, all actions have assignedName set.
+// In the new map, all actions have no assignedName.
+//
+// After the update, the action map is updated to have all actions from the new
+// map, with assignedName:
+// - if the new action exists in old, get the old name
+// - if the new action doesn't exist in old
+//   - if there is an old action that will be removed, and has the same set of
+//   clusters, reuse the old action's name
+//   - otherwise, generate a new name
+func (r *xdsResolver) updateActions(newActions map[string]actionWithAssignedName) {
+	if r.actions == nil {
+		r.actions = make(map[string]actionWithAssignedName)
+	}
+
+	// Delete actions from existingActions if they are not in newActions. Keep
+	// the removed actions in a map, with key as clusterNames without weights,
+	// so their assigned names can be reused.
+	existingActions := r.actions
+	actionsRemoved := make(map[string][]string)
+	for actionHash, act := range existingActions {
+		if _, ok := newActions[actionHash]; !ok {
+			actionsRemoved[act.clusterNames] = append(actionsRemoved[act.clusterNames], act.assignedName)
+			delete(existingActions, actionHash)
+		}
+	}
+
+	// Find actions in newActions but not in oldActions. Add them, and try to
+	// reuse assigned names from actionsRemoved.
+	if r.usedActionNameRandomNumber == nil {
+		r.usedActionNameRandomNumber = make(map[int64]bool)
+	}
+	for actionHash, act := range newActions {
+		if _, ok := existingActions[actionHash]; !ok {
+			if assignedNamed, ok := actionsRemoved[act.clusterNames]; ok {
+				// Reuse the first assigned name from actionsRemoved.
+				act.assignedName = assignedNamed[0]
+				// If there are more names to reuse after this, update the slice
+				// in the map. Otherwise, remove the entry from the map.
+				if len(assignedNamed) > 1 {
+					actionsRemoved[act.clusterNames] = assignedNamed[1:]
+				} else {
+					delete(actionsRemoved, act.clusterNames)
+				}
+				existingActions[actionHash] = act
+				continue
+			}
+			// Generate a new name.
+			act.randomNumber = r.nextAssignedNameRandomNumber()
+			act.assignedName = fmt.Sprintf("%s%d", act.clusterNames, act.randomNumber)
+			existingActions[actionHash] = act
+		}
+	}
+
+	// Delete entry from nextIndex if all actions with the clusters are removed.
+	remainingRandomNumbers := make(map[int64]bool)
+	for _, act := range existingActions {
+		remainingRandomNumbers[act.randomNumber] = true
+	}
+	r.usedActionNameRandomNumber = remainingRandomNumbers
+}
+
+var grpcrandInt63n = grpcrand.Int63n
+
+func (r *xdsResolver) nextAssignedNameRandomNumber() int64 {
+	for {
+		t := grpcrandInt63n(math.MaxInt32)
+		if !r.usedActionNameRandomNumber[t] {
+			return t
+		}
+	}
+}
+
+// getActionAssignedName hashes the clusters from the action, and find the
+// assigned action name. The assigned action names are kept in r.actions, with
+// the clusters name hash as map key.
+//
+// The assigned action name is not simply the hash. For example, the hash can be
+// "A40_B60_", but the assigned name can be "A_B_0". It's this way so the action
+// can be reused if only weights are changing.
+func (r *xdsResolver) getActionAssignedName(action map[string]uint32) string {
+	var clusterNames []string
+	for n := range action {
+		clusterNames = append(clusterNames, n)
+	}
+	// Hash cluster names. Sort names to be consistent.
+	sort.Strings(clusterNames)
+	clustersWithWeight := ""
+	for _, c := range clusterNames {
+		// Generates hash "A40_B60_".
+		clustersWithWeight = clustersWithWeight + c + strconv.FormatUint(uint64(action[c]), 10) + "_"
+	}
+	// Look in r.actions for the assigned action name.
+	if act, ok := r.actions[clustersWithWeight]; ok {
+		return act.assignedName
+	}
+	r.logger.Warningf("no assigned name found for action %v", action)
+	return ""
+}
diff --git a/xds/internal/resolver/serviceconfig_action_test.go b/xds/internal/resolver/serviceconfig_action_test.go
new file mode 100644
index 000000000000..bfc0e6830155
--- /dev/null
+++ b/xds/internal/resolver/serviceconfig_action_test.go
@@ -0,0 +1,356 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package resolver
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	xdsclient "google.golang.org/grpc/xds/internal/client"
+)
+
+func TestNewActionsFromRoutes(t *testing.T) {
+	tests := []struct {
+		name   string
+		routes []*xdsclient.Route
+		want   map[string]actionWithAssignedName
+	}{
+		{
+			name: "temp",
+			routes: []*xdsclient.Route{
+				{Action: map[string]uint32{"B": 60, "A": 40}},
+				{Action: map[string]uint32{"A": 30, "B": 70}},
+				{Action: map[string]uint32{"B": 90, "C": 10}},
+			},
+			want: map[string]actionWithAssignedName{
+				"A40_B60_": {map[string]uint32{"A": 40, "B": 60}, "A_B_", "", 0},
+				"A30_B70_": {map[string]uint32{"A": 30, "B": 70}, "A_B_", "", 0},
+				"B90_C10_": {map[string]uint32{"B": 90, "C": 10}, "B_C_", "", 0},
+			},
+		},
+	}
+
+	cmpOpts := []cmp.Option{cmp.AllowUnexported(actionWithAssignedName{})}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := newActionsFromRoutes(tt.routes); !cmp.Equal(got, tt.want, cmpOpts...) {
+				t.Errorf("newActionsFromRoutes() got unexpected result, diff %v", cmp.Diff(got, tt.want, cmpOpts...))
+			}
+		})
+	}
+}
+
+func TestRemoveOrReuseName(t *testing.T) {
+	tests := []struct {
+		name         string
+		oldActions   map[string]actionWithAssignedName
+		oldRandNums  map[int64]bool
+		newActions   map[string]actionWithAssignedName
+		wantActions  map[string]actionWithAssignedName
+		wantRandNums map[int64]bool
+	}{
+		{
+			name: "add same cluster",
+			oldActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+			},
+			oldRandNums: map[int64]bool{
+				0: true,
+			},
+			newActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+				},
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+				},
+			},
+			wantActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_1000",
+					randomNumber:        1000,
+				},
+			},
+			wantRandNums: map[int64]bool{
+				0:    true,
+				1000: true,
+			},
+		},
+		{
+			name: "delete same cluster",
+			oldActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_1",
+					randomNumber:        1,
+				},
+			},
+			oldRandNums: map[int64]bool{
+				0: true,
+				1: true,
+			},
+			newActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+				},
+			},
+			wantActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+			},
+			wantRandNums: map[int64]bool{
+				0: true,
+			},
+		},
+		{
+			name: "add new clusters",
+			oldActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+			},
+			oldRandNums: map[int64]bool{
+				0: true,
+			},
+			newActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+				},
+				"a50_b50_": {
+					clustersWithWeights: map[string]uint32{"a": 50, "b": 50},
+					clusterNames:        "a_b_",
+				},
+			},
+			wantActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+				"a50_b50_": {
+					clustersWithWeights: map[string]uint32{"a": 50, "b": 50},
+					clusterNames:        "a_b_",
+					assignedName:        "a_b_1000",
+					randomNumber:        1000,
+				},
+			},
+			wantRandNums: map[int64]bool{
+				0:    true,
+				1000: true,
+			},
+		},
+		{
+			name: "reuse",
+			oldActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+			},
+			oldRandNums: map[int64]bool{
+				0: true,
+			},
+			newActions: map[string]actionWithAssignedName{
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+				},
+			},
+			wantActions: map[string]actionWithAssignedName{
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+			},
+			wantRandNums: map[int64]bool{
+				0: true,
+			},
+		},
+		{
+			name: "add and reuse",
+			oldActions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_1",
+					randomNumber:        1,
+				},
+				"a50_b50_": {
+					clustersWithWeights: map[string]uint32{"a": 50, "b": 50},
+					clusterNames:        "a_b_",
+					assignedName:        "a_b_2",
+					randomNumber:        2,
+				},
+			},
+			oldRandNums: map[int64]bool{
+				0: true,
+				1: true,
+				2: true,
+			},
+			newActions: map[string]actionWithAssignedName{
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+				},
+				"a30_b30_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 30, "b": 30, "c": 40},
+					clusterNames:        "a_b_c_",
+				},
+				"c50_d50_": {
+					clustersWithWeights: map[string]uint32{"c": 50, "d": 50},
+					clusterNames:        "c_d_",
+				},
+			},
+			wantActions: map[string]actionWithAssignedName{
+				"a10_b50_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 10, "b": 50, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_1",
+					randomNumber:        1,
+				},
+				"a30_b30_c40_": {
+					clustersWithWeights: map[string]uint32{"a": 30, "b": 30, "c": 40},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+					randomNumber:        0,
+				},
+				"c50_d50_": {
+					clustersWithWeights: map[string]uint32{"c": 50, "d": 50},
+					clusterNames:        "c_d_",
+					assignedName:        "c_d_1000",
+					randomNumber:        1000,
+				},
+			},
+			wantRandNums: map[int64]bool{
+				0:    true,
+				1:    true,
+				1000: true,
+			},
+		},
+	}
+	cmpOpts := []cmp.Option{cmp.AllowUnexported(actionWithAssignedName{})}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer replaceRandNumGenerator(1000)()
+			r := &xdsResolver{
+				actions:                    tt.oldActions,
+				usedActionNameRandomNumber: tt.oldRandNums,
+			}
+			r.updateActions(tt.newActions)
+			if !cmp.Equal(r.actions, tt.wantActions, cmpOpts...) {
+				t.Errorf("removeOrReuseName() got unexpected actions, diff %v", cmp.Diff(r.actions, tt.wantActions, cmpOpts...))
+			}
+			if !cmp.Equal(r.usedActionNameRandomNumber, tt.wantRandNums) {
+				t.Errorf("removeOrReuseName() got unexpected nextIndex, diff %v", cmp.Diff(r.usedActionNameRandomNumber, tt.wantRandNums))
+			}
+		})
+	}
+}
+
+func TestGetActionAssignedName(t *testing.T) {
+	tests := []struct {
+		name    string
+		actions map[string]actionWithAssignedName
+		action  map[string]uint32
+		want    string
+	}{
+		{
+			name: "good",
+			actions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+				},
+			},
+			action: map[string]uint32{"a": 20, "b": 30, "c": 50},
+			want:   "a_b_c_0",
+		},
+		{
+			name: "two",
+			actions: map[string]actionWithAssignedName{
+				"a20_b30_c50_": {
+					clustersWithWeights: map[string]uint32{"a": 20, "b": 30, "c": 50},
+					clusterNames:        "a_b_c_",
+					assignedName:        "a_b_c_0",
+				},
+				"c50_d50_": {
+					clustersWithWeights: map[string]uint32{"c": 50, "d": 50},
+					clusterNames:        "c_d_",
+					assignedName:        "c_d_0",
+				},
+			},
+			action: map[string]uint32{"c": 50, "d": 50},
+			want:   "c_d_0",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := &xdsResolver{
+				actions: tt.actions,
+			}
+			if got := r.getActionAssignedName(tt.action); got != tt.want {
+				t.Errorf("getActionAssignedName() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/xds/internal/resolver/serviceconfig_test.go b/xds/internal/resolver/serviceconfig_test.go
index 6e83a23cdd5d..4e149893ee70 100644
--- a/xds/internal/resolver/serviceconfig_test.go
+++ b/xds/internal/resolver/serviceconfig_test.go
@@ -23,9 +23,12 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/serviceconfig"
 	_ "google.golang.org/grpc/xds/internal/balancer/weightedtarget"
+	_ "google.golang.org/grpc/xds/internal/balancer/xdsrouting"
 	"google.golang.org/grpc/xds/internal/client"
+	xdsclient "google.golang.org/grpc/xds/internal/client"
 )
 
 const (
@@ -34,7 +37,7 @@ const (
     "weighted_target_experimental": {
 	  "targets": { "test-cluster-1" : { "weight":1, "childPolicy":[{"cds_experimental":{"cluster":"test-cluster-1"}}] } }
 	}
-}]}`
+    }]}`
 	testWeightedCDSJSON = `{"loadBalancingConfig":[{
     "weighted_target_experimental": {
 	  "targets": {
@@ -48,30 +51,303 @@ const (
 		}
 	  }
 	}
-}]}`
+    }]}`
 	testWeightedCDSNoChildJSON = `{"loadBalancingConfig":[{
     "weighted_target_experimental": {
 	  "targets": {}
 	}
-}]}`
+    }]}`
+	testRoutingJSON = `{"loadBalancingConfig":[{
+    "xds_routing_experimental": {
+      "action":{
+        "cluster_1_cluster_2_0":{
+          "childPolicy":[{
+			"weighted_target_experimental": {
+			  "targets": {
+				"cluster_1" : {
+				  "weight":75,
+				  "childPolicy":[{"cds_experimental":{"cluster":"cluster_1"}}]
+				},
+				"cluster_2" : {
+				  "weight":25,
+				  "childPolicy":[{"cds_experimental":{"cluster":"cluster_2"}}]
+				}
+			  }
+			}
+          }]
+        }
+      },
+
+      "route":[{
+        "path":"/service_1/method_1",
+        "action":"cluster_1_cluster_2_0"
+      }]
+    }
+    }]}
+`
+	testRoutingAllMatchersJSON = `{"loadBalancingConfig":[{
+    "xds_routing_experimental": {
+      "action":{
+        "cluster_1_0":{
+          "childPolicy":[{
+			"weighted_target_experimental": {
+			  "targets": {
+				"cluster_1" : {
+				  "weight":1,
+				  "childPolicy":[{"cds_experimental":{"cluster":"cluster_1"}}]
+				}
+			  }
+			}
+          }]
+        },
+        "cluster_2_0":{
+          "childPolicy":[{
+			"weighted_target_experimental": {
+			  "targets": {
+				"cluster_2" : {
+				  "weight":1,
+				  "childPolicy":[{"cds_experimental":{"cluster":"cluster_2"}}]
+				}
+			  }
+			}
+          }]
+        },
+        "cluster_3_0":{
+          "childPolicy":[{
+			"weighted_target_experimental": {
+			  "targets": {
+				"cluster_3" : {
+				  "weight":1,
+				  "childPolicy":[{"cds_experimental":{"cluster":"cluster_3"}}]
+				}
+			  }
+			}
+          }]
+        }
+      },
+
+      "route":[{
+        "path":"/service_1/method_1",
+        "action":"cluster_1_0"
+      },
+      {
+        "prefix":"/service_2/method_1",
+        "action":"cluster_1_0"
+      },
+      {
+        "regex":"^/service_2/method_3$",
+        "action":"cluster_1_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "exactMatch":"value-1", "invertMatch":true}],
+        "action":"cluster_2_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "regexMatch":"^value-1$"}],
+        "action":"cluster_2_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "rangeMatch":{"start":-1, "end":7}}],
+        "action":"cluster_3_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "presentMatch":true}],
+        "action":"cluster_3_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "prefixMatch":"value-1"}],
+        "action":"cluster_2_0"
+      },
+      {
+        "prefix":"",
+        "headers":[{"name":"header-1", "suffixMatch":"value-1"}],
+        "action":"cluster_2_0"
+      },
+      {
+        "prefix":"",
+        "matchFraction":{"value": 31415},
+        "action":"cluster_3_0"
+      }]
+    }
+    }]}
+`
 )
 
-func TestServiceUpdateToJSON(t *testing.T) {
+func TestWeightedClusterToJSON(t *testing.T) {
 	tests := []struct {
 		name     string
-		su       client.ServiceUpdate
+		wc       map[string]uint32
 		wantJSON string // wantJSON is not to be compared verbatim.
 	}{
 		{
 			name:     "one cluster only",
-			su:       client.ServiceUpdate{WeightedCluster: map[string]uint32{testCluster1: 1}},
+			wc:       map[string]uint32{testCluster1: 1},
 			wantJSON: testClusterOnlyJSON,
 		},
 		{
 			name:     "empty weighted clusters",
-			su:       client.ServiceUpdate{WeightedCluster: nil},
+			wc:       nil,
 			wantJSON: testWeightedCDSNoChildJSON,
 		},
+		{
+			name: "weighted clusters",
+			wc: map[string]uint32{
+				"cluster_1": 75,
+				"cluster_2": 25,
+			},
+			wantJSON: testWeightedCDSJSON,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotJSON, err := weightedClusterToJSON(tt.wc)
+			if err != nil {
+				t.Errorf("serviceUpdateToJSON returned error: %v", err)
+				return
+			}
+
+			gotParsed := internal.ParseServiceConfigForTesting.(func(string) *serviceconfig.ParseResult)(gotJSON)
+			wantParsed := internal.ParseServiceConfigForTesting.(func(string) *serviceconfig.ParseResult)(tt.wantJSON)
+
+			if !internal.EqualServiceConfigForTesting(gotParsed.Config, wantParsed.Config) {
+				t.Errorf("serviceUpdateToJSON() = %v, want %v", gotJSON, tt.wantJSON)
+				t.Error("gotParsed: ", cmp.Diff(nil, gotParsed))
+				t.Error("wantParsed: ", cmp.Diff(nil, wantParsed))
+			}
+		})
+	}
+}
+
+func TestRoutesToJSON(t *testing.T) {
+	tests := []struct {
+		name     string
+		routes   []*xdsclient.Route
+		wantJSON string
+		wantErr  bool
+	}{
+		{
+			name: "one route",
+			routes: []*xdsclient.Route{{
+				Path:   newStringP("/service_1/method_1"),
+				Action: map[string]uint32{"cluster_1": 75, "cluster_2": 25},
+			}},
+			wantJSON: testRoutingJSON,
+			wantErr:  false,
+		},
+		{
+			name: "all matchers",
+			routes: []*xdsclient.Route{
+				{
+					Path:   newStringP("/service_1/method_1"),
+					Action: map[string]uint32{"cluster_1": 1},
+				},
+				{
+					Prefix: newStringP("/service_2/method_1"),
+					Action: map[string]uint32{"cluster_1": 1},
+				},
+				{
+					Regex:  newStringP("^/service_2/method_3$"),
+					Action: map[string]uint32{"cluster_1": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:        "header-1",
+						InvertMatch: newBoolP(true),
+						ExactMatch:  newStringP("value-1"),
+					}},
+					Action: map[string]uint32{"cluster_2": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:       "header-1",
+						RegexMatch: newStringP("^value-1$"),
+					}},
+					Action: map[string]uint32{"cluster_2": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:       "header-1",
+						RangeMatch: &xdsclient.Int64Range{Start: -1, End: 7},
+					}},
+					Action: map[string]uint32{"cluster_3": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:         "header-1",
+						PresentMatch: newBoolP(true),
+					}},
+					Action: map[string]uint32{"cluster_3": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:        "header-1",
+						PrefixMatch: newStringP("value-1"),
+					}},
+					Action: map[string]uint32{"cluster_2": 1},
+				},
+				{
+					Prefix: newStringP(""),
+					Headers: []*xdsclient.HeaderMatcher{{
+						Name:        "header-1",
+						SuffixMatch: newStringP("value-1"),
+					}},
+					Action: map[string]uint32{"cluster_2": 1},
+				},
+				{
+					Prefix:   newStringP(""),
+					Fraction: newUint32P(31415),
+					Action:   map[string]uint32{"cluster_3": 1},
+				},
+			},
+			wantJSON: testRoutingAllMatchersJSON,
+			wantErr:  false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Note this random number function only generates 0. This is
+			// because the test doesn't handle action update, and there's only
+			// one action for each cluster bundle.
+			//
+			// This is necessary so the output is deterministic.
+			grpcrandInt63n = func(int64) int64 { return 0 }
+			defer func() { grpcrandInt63n = grpcrand.Int63n }()
+
+			gotJSON, err := (&xdsResolver{}).routesToJSON(tt.routes)
+			if err != nil {
+				t.Errorf("routesToJSON returned error: %v", err)
+				return
+			}
+
+			gotParsed := internal.ParseServiceConfigForTesting.(func(string) *serviceconfig.ParseResult)(gotJSON)
+			wantParsed := internal.ParseServiceConfigForTesting.(func(string) *serviceconfig.ParseResult)(tt.wantJSON)
+
+			if !internal.EqualServiceConfigForTesting(gotParsed.Config, wantParsed.Config) {
+				t.Errorf("serviceUpdateToJSON() = %v, want %v", gotJSON, tt.wantJSON)
+				t.Error("gotParsed: ", cmp.Diff(nil, gotParsed))
+				t.Error("wantParsed: ", cmp.Diff(nil, wantParsed))
+			}
+		})
+	}
+}
+
+func TestServiceUpdateToJSON(t *testing.T) {
+	tests := []struct {
+		name     string
+		su       client.ServiceUpdate
+		wantJSON string
+		wantErr  bool
+	}{
 		{
 			name: "weighted clusters",
 			su: client.ServiceUpdate{WeightedCluster: map[string]uint32{
@@ -79,11 +355,24 @@ func TestServiceUpdateToJSON(t *testing.T) {
 				"cluster_2": 25,
 			}},
 			wantJSON: testWeightedCDSJSON,
+			wantErr:  false,
+		},
+		{
+			name: "routing",
+			su: client.ServiceUpdate{
+				Routes: []*xdsclient.Route{{
+					Path:   newStringP("/service_1/method_1"),
+					Action: map[string]uint32{"cluster_1": 75, "cluster_2": 25},
+				}},
+			},
+			wantJSON: testRoutingJSON,
+			wantErr:  false,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotJSON, err := serviceUpdateToJSON(tt.su)
+			defer replaceRandNumGenerator(0)()
+			gotJSON, err := (&xdsResolver{}).serviceUpdateToJSON(tt.su)
 			if err != nil {
 				t.Errorf("serviceUpdateToJSON returned error: %v", err)
 				return
@@ -100,3 +389,19 @@ func TestServiceUpdateToJSON(t *testing.T) {
 		})
 	}
 }
+
+// Two updates to the same resolver, test that action names are reused.
+func TestServiceUpdateToJSON_TwoConfig_UpdateActions(t *testing.T) {
+}
+
+func newStringP(s string) *string {
+	return &s
+}
+
+func newBoolP(b bool) *bool {
+	return &b
+}
+
+func newUint32P(i uint32) *uint32 {
+	return &i
+}
diff --git a/xds/internal/resolver/xds_resolver.go b/xds/internal/resolver/xds_resolver.go
index fb46a91603c2..cdd103ef7dc3 100644
--- a/xds/internal/resolver/xds_resolver.go
+++ b/xds/internal/resolver/xds_resolver.go
@@ -159,6 +159,16 @@ type xdsResolver struct {
 	updateCh chan suWithError
 	// cancelWatch is the function to cancel the watcher.
 	cancelWatch func()
+
+	// actions is a map from hash of weighted cluster, to the weighted cluster
+	// map, and it's assigned name. E.g.
+	//   "A40_B60_": {{A:40, B:60}, "A_B_", "A_B_0"}
+	//   "A30_B70_": {{A:30, B:70}, "A_B_", "A_B_1"}
+	//   "B90_C10_": {{B:90, C:10}, "B_C_", "B_C_0"}
+	actions map[string]actionWithAssignedName
+	// usedActionNameRandomNumber contains random numbers that have been used in
+	// assigned names, to avoid collision.
+	usedActionNameRandomNumber map[int64]bool
 }
 
 // run is a long running goroutine which blocks on receiving service updates
@@ -185,7 +195,7 @@ func (r *xdsResolver) run() {
 				r.cc.ReportError(update.err)
 				continue
 			}
-			sc, err := serviceUpdateToJSON(update.su)
+			sc, err := r.serviceUpdateToJSON(update.su)
 			if err != nil {
 				r.logger.Warningf("failed to convert update to service config: %v", err)
 				r.cc.ReportError(err)
diff --git a/xds/internal/resolver/xds_resolver_test.go b/xds/internal/resolver/xds_resolver_test.go
index 025a8b2dbc1a..d84ec44eb8c0 100644
--- a/xds/internal/resolver/xds_resolver_test.go
+++ b/xds/internal/resolver/xds_resolver_test.go
@@ -28,6 +28,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/internal"
+	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/resolver"
 	"google.golang.org/grpc/serviceconfig"
 	xdsinternal "google.golang.org/grpc/xds/internal"
@@ -446,3 +447,15 @@ func TestXDSResolverResourceNotFoundError(t *testing.T) {
 		t.Fatalf("ClientConn.UpdateState received error in service config: %v", rState.ServiceConfig.Err)
 	}
 }
+
+func replaceRandNumGenerator(start int64) func() {
+	nextInt := start
+	grpcrandInt63n = func(int64) (ret int64) {
+		ret = nextInt
+		nextInt++
+		return
+	}
+	return func() {
+		grpcrandInt63n = grpcrand.Int63n
+	}
+}