diff --git a/resolver/map.go b/resolver/map.go
index 804be887de0a..ada5b9bb79ba 100644
--- a/resolver/map.go
+++ b/resolver/map.go
@@ -136,3 +136,116 @@ func (a *AddressMap) Values() []any {
 	}
 	return ret
 }
+
+type endpointNode struct {
+	addrs map[string]struct{}
+}
+
+// Equal returns whether the unordered set of addrs are the same between the
+// endpoint nodes.
+func (en *endpointNode) Equal(en2 *endpointNode) bool {
+	if len(en.addrs) != len(en2.addrs) {
+		return false
+	}
+	for addr := range en.addrs {
+		if _, ok := en2.addrs[addr]; !ok {
+			return false
+		}
+	}
+	return true
+}
+
+func toEndpointNode(endpoint Endpoint) endpointNode {
+	en := make(map[string]struct{})
+	for _, addr := range endpoint.Addresses {
+		en[addr.Addr] = struct{}{}
+	}
+	return endpointNode{
+		addrs: en,
+	}
+}
+
+// EndpointMap is a map of endpoints to arbitrary values keyed on only the
+// unordered set of address strings within an endpoint. This map is not thread
+// safe, thus it is unsafe to access concurrently. Must be created via
+// NewEndpointMap; do not construct directly.
+type EndpointMap struct {
+	endpoints map[*endpointNode]any
+}
+
+// NewEndpointMap creates a new EndpointMap.
+func NewEndpointMap() *EndpointMap {
+	return &EndpointMap{
+		endpoints: make(map[*endpointNode]any),
+	}
+}
+
+// Get returns the value for the address in the map, if present.
+func (em *EndpointMap) Get(e Endpoint) (value any, ok bool) {
+	en := toEndpointNode(e)
+	if endpoint := em.find(en); endpoint != nil {
+		return em.endpoints[endpoint], true
+	}
+	return nil, false
+}
+
+// Set updates or adds the value to the address in the map.
+func (em *EndpointMap) Set(e Endpoint, value any) {
+	en := toEndpointNode(e)
+	if endpoint := em.find(en); endpoint != nil {
+		em.endpoints[endpoint] = value
+		return
+	}
+	em.endpoints[&en] = value
+}
+
+// Len returns the number of entries in the map.
+func (em *EndpointMap) Len() int {
+	return len(em.endpoints)
+}
+
+// Keys returns a slice of all current map keys, as endpoints specifying the
+// addresses present in the endpoint keys, in which uniqueness is determined by
+// the unordered set of addresses. Thus, endpoint information returned is not
+// the full endpoint data (drops duplicated addresses and attributes) but can be
+// used for EndpointMap accesses.
+func (em *EndpointMap) Keys() []Endpoint {
+	ret := make([]Endpoint, 0, len(em.endpoints))
+	for en := range em.endpoints {
+		var endpoint Endpoint
+		for addr := range en.addrs {
+			endpoint.Addresses = append(endpoint.Addresses, Address{Addr: addr})
+		}
+		ret = append(ret, endpoint)
+	}
+	return ret
+}
+
+// Values returns a slice of all current map values.
+func (em *EndpointMap) Values() []any {
+	ret := make([]any, 0, len(em.endpoints))
+	for _, val := range em.endpoints {
+		ret = append(ret, val)
+	}
+	return ret
+}
+
+// find returns a pointer to the endpoint node in em if the endpoint node is
+// already present. If not found, nil is returned. The comparisons are done on
+// the unordered set of addresses within an endpoint.
+func (em EndpointMap) find(e endpointNode) *endpointNode {
+	for endpoint := range em.endpoints {
+		if e.Equal(endpoint) {
+			return endpoint
+		}
+	}
+	return nil
+}
+
+// Delete removes the specified endpoint from the map.
+func (em *EndpointMap) Delete(e Endpoint) {
+	en := toEndpointNode(e)
+	if entry := em.find(en); entry != nil {
+		delete(em.endpoints, entry)
+	}
+}
diff --git a/resolver/map_test.go b/resolver/map_test.go
index 0b0ac1667902..c14f3eb3c690 100644
--- a/resolver/map_test.go
+++ b/resolver/map_test.go
@@ -38,6 +38,17 @@ var (
 	addr5 = Address{Addr: "a1", Attributes: attributes.New("a1", "3"), ServerName: "s1"}
 	addr6 = Address{Addr: "a1", Attributes: attributes.New("a1", 3), ServerName: "s2"}
 	addr7 = Address{Addr: "a1", Attributes: attributes.New("a1", 3), ServerName: "s1", BalancerAttributes: attributes.New("xx", 3)}
+
+	endpoint1   = Endpoint{Addresses: []Address{{Addr: "addr1"}}}
+	endpoint2   = Endpoint{Addresses: []Address{{Addr: "addr2"}}}
+	endpoint3   = Endpoint{Addresses: []Address{{Addr: "addr3"}}}
+	endpoint4   = Endpoint{Addresses: []Address{{Addr: "addr4"}}}
+	endpoint5   = Endpoint{Addresses: []Address{{Addr: "addr5"}}}
+	endpoint6   = Endpoint{Addresses: []Address{{Addr: "addr6"}}}
+	endpoint7   = Endpoint{Addresses: []Address{{Addr: "addr7"}}}
+	endpoint12  = Endpoint{Addresses: []Address{{Addr: "addr1"}, {Addr: "addr2"}}}
+	endpoint21  = Endpoint{Addresses: []Address{{Addr: "addr2"}, {Addr: "addr1"}}}
+	endpoint123 = Endpoint{Addresses: []Address{{Addr: "addr1"}, {Addr: "addr2"}, {Addr: "addr3"}}}
 )
 
 func (s) TestAddressMap_Length(t *testing.T) {
@@ -161,3 +172,118 @@ func (s) TestAddressMap_Values(t *testing.T) {
 		t.Fatalf("addrMap.Values returned unexpected elements (-want, +got):\n%v", diff)
 	}
 }
+
+func (s) TestEndpointMap_Length(t *testing.T) {
+	em := NewEndpointMap()
+	// Should be empty at creation time.
+	if got := em.Len(); got != 0 {
+		t.Fatalf("em.Len() = %v; want 0", got)
+	}
+	// Add two endpoints with the same unordered set of addresses. This should
+	// amount to one endpoint. It should also not take into account attributes.
+	em.Set(endpoint12, struct{}{})
+	em.Set(endpoint21, struct{}{})
+
+	if got := em.Len(); got != 1 {
+		t.Fatalf("em.Len() = %v; want 1", got)
+	}
+
+	// Add another unique endpoint. This should cause the length to be 2.
+	em.Set(endpoint123, struct{}{})
+	if got := em.Len(); got != 2 {
+		t.Fatalf("em.Len() = %v; want 2", got)
+	}
+}
+
+func (s) TestEndpointMap_Get(t *testing.T) {
+	em := NewEndpointMap()
+	em.Set(endpoint1, 1)
+	// The second endpoint endpoint21 should override.
+	em.Set(endpoint12, 1)
+	em.Set(endpoint21, 2)
+	em.Set(endpoint3, 3)
+	em.Set(endpoint4, 4)
+	em.Set(endpoint5, 5)
+	em.Set(endpoint6, 6)
+	em.Set(endpoint7, 7)
+
+	if got, ok := em.Get(endpoint1); !ok || got.(int) != 1 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 1)
+	}
+	if got, ok := em.Get(endpoint12); !ok || got.(int) != 2 {
+		t.Fatalf("em.Get(endpoint12) = %v, %v; want %v, true", got, ok, 2)
+	}
+	if got, ok := em.Get(endpoint21); !ok || got.(int) != 2 {
+		t.Fatalf("em.Get(endpoint21) = %v, %v; want %v, true", got, ok, 2)
+	}
+	if got, ok := em.Get(endpoint3); !ok || got.(int) != 3 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 3)
+	}
+	if got, ok := em.Get(endpoint4); !ok || got.(int) != 4 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 4)
+	}
+	if got, ok := em.Get(endpoint5); !ok || got.(int) != 5 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 5)
+	}
+	if got, ok := em.Get(endpoint6); !ok || got.(int) != 6 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 6)
+	}
+	if got, ok := em.Get(endpoint7); !ok || got.(int) != 7 {
+		t.Fatalf("em.Get(endpoint1) = %v, %v; want %v, true", got, ok, 7)
+	}
+	if _, ok := em.Get(endpoint123); ok {
+		t.Fatalf("em.Get(endpoint123) = _, %v; want _, false", ok)
+	}
+}
+
+func (s) TestEndpointMap_Delete(t *testing.T) {
+	em := NewEndpointMap()
+	// Initial state of system: [1, 2, 3, 12]
+	em.Set(endpoint1, struct{}{})
+	em.Set(endpoint2, struct{}{})
+	em.Set(endpoint3, struct{}{})
+	em.Set(endpoint12, struct{}{})
+	// Delete: [2, 21]
+	em.Delete(endpoint2)
+	em.Delete(endpoint21)
+
+	// [1, 3] should be present:
+	if _, ok := em.Get(endpoint1); !ok {
+		t.Fatalf("em.Get(endpoint1) = %v, want true", ok)
+	}
+	if _, ok := em.Get(endpoint3); !ok {
+		t.Fatalf("em.Get(endpoint3) = %v, want true", ok)
+	}
+	// [2, 12] should not be present:
+	if _, ok := em.Get(endpoint2); ok {
+		t.Fatalf("em.Get(endpoint2) = %v, want false", ok)
+	}
+	if _, ok := em.Get(endpoint12); ok {
+		t.Fatalf("em.Get(endpoint12) = %v, want false", ok)
+	}
+	if _, ok := em.Get(endpoint21); ok {
+		t.Fatalf("em.Get(endpoint21) = %v, want false", ok)
+	}
+}
+
+func (s) TestEndpointMap_Values(t *testing.T) {
+	em := NewEndpointMap()
+	em.Set(endpoint1, 1)
+	// The second endpoint endpoint21 should override.
+	em.Set(endpoint12, 1)
+	em.Set(endpoint21, 2)
+	em.Set(endpoint3, 3)
+	em.Set(endpoint4, 4)
+	em.Set(endpoint5, 5)
+	em.Set(endpoint6, 6)
+	em.Set(endpoint7, 7)
+	want := []int{1, 2, 3, 4, 5, 6, 7}
+	var got []int
+	for _, v := range em.Values() {
+		got = append(got, v.(int))
+	}
+	sort.Ints(got)
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Fatalf("em.Values() returned unexpected elements (-want, +got):\n%v", diff)
+	}
+}