diff --git a/netmap/attributes.go b/netmap/attributes.go
new file mode 100644
index 0000000..07ce268
--- /dev/null
+++ b/netmap/attributes.go
@@ -0,0 +1,208 @@
+package netmap
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/refs"
+)
+
+// prefix of keys to subnet attributes.
+const attrSubnetPrefix = "__NEOFS__SUBNET_"
+
+const (
+	// subnet attribute's value denoting subnet entry
+	attrSubnetValEntry = "True"
+
+	// subnet attribute's value denoting subnet exit
+	attrSubnetValExit = "False"
+)
+
+// NodeSubnetInfo groups information about subnet which can be written to NodeInfo.
+//
+// Zero value represents entry to zero subnet.
+type NodeSubnetInfo struct {
+	exit bool
+
+	id *refs.SubnetID
+}
+
+// Enters returns true iff node enters the subnet.
+func (x NodeSubnetInfo) Enters() bool {
+	return !x.exit
+}
+
+// SetEntryFlag sets the subnet entry flag.
+func (x *NodeSubnetInfo) SetEntryFlag(enters bool) {
+	x.exit = !enters
+}
+
+// ID returns identifier of the subnet.
+func (x NodeSubnetInfo) ID() *refs.SubnetID {
+	return x.id
+}
+
+// SetID sets identifier of the subnet.
+func (x *NodeSubnetInfo) SetID(id *refs.SubnetID) {
+	x.id = id
+}
+
+func subnetAttributeKey(id *refs.SubnetID) string {
+	txt, _ := id.MarshalText() // never returns an error
+
+	return attrSubnetPrefix + string(txt)
+}
+
+// WriteSubnetInfo writes NodeSubnetInfo to NodeInfo via attributes. NodeInfo must not be nil.
+//
+// Does not add (removes existing) attribute if node:
+//   * exists non-zero subnet;
+//   * enters zero subnet.
+//
+// Attribute key is calculated from ID using format `__NEOFS__SUBNET_%s`.
+// Attribute Value is:
+//   * `True` if node enters the subnet;
+//   * `False`, otherwise.
+func WriteSubnetInfo(node *NodeInfo, info NodeSubnetInfo) {
+	attrs := node.GetAttributes()
+
+	id := info.ID()
+	enters := info.Enters()
+
+	// calculate attribute key
+	key := subnetAttributeKey(id)
+
+	if refs.IsZeroSubnet(id) == enters {
+		for i := range attrs {
+			if attrs[i].GetKey() == key {
+				attrs = append(attrs[:i], attrs[i+1:]...)
+			}
+		}
+	} else {
+		var val string
+
+		if enters {
+			val = attrSubnetValEntry
+		} else {
+			val = attrSubnetValExit
+		}
+
+		presented := false
+
+		for i := range attrs {
+			if attrs[i].GetKey() == key {
+				attrs[i].SetValue(val)
+				presented = true
+			}
+		}
+
+		if !presented {
+			var attr Attribute
+
+			attr.SetKey(key)
+			attr.SetValue(val)
+
+			attrs = append(attrs, &attr)
+		}
+	}
+
+	node.SetAttributes(attrs)
+}
+
+// ErrRemoveSubnet is returned when a node needs to leave the subnet.
+var ErrRemoveSubnet = errors.New("remove subnet")
+
+// IterateSubnets iterates over all subnets the node belongs to and passes the IDs to f.
+// Handler must not be nil.
+//
+// If f returns ErrRemoveSubnet, then removes subnet entry. Breaks on any other non-nil error and returns it.
+//
+// Returns an error if any subnet attribute has wrong format.
+func IterateSubnets(node *NodeInfo, f func(refs.SubnetID) error) error {
+	attrs := node.GetAttributes()
+
+	var (
+		err     error
+		id      refs.SubnetID
+		metZero bool // if zero subnet's attribute was met in for-loop
+	)
+
+	for i := 0; i < len(attrs); i++ { // range must not be used because of attrs mutation in body
+		key := attrs[i].GetKey()
+
+		// cut subnet ID string
+		idTxt := strings.TrimPrefix(key, attrSubnetPrefix)
+		if idTxt == key {
+			// not a subnet attribute
+			continue
+		}
+
+		// check value
+		switch val := attrs[i].GetValue(); val {
+		default:
+			return fmt.Errorf("invalid attribute value: %s", val)
+		case attrSubnetValExit:
+			// node is outside the subnet
+			continue
+		case attrSubnetValEntry:
+			// required to avoid default case
+		}
+
+		// decode subnet ID
+		if err = id.UnmarshalText([]byte(idTxt)); err != nil {
+			return fmt.Errorf("invalid ID text: %w", err)
+		}
+
+		// pass ID to the handler
+		err = f(id)
+
+		isRemoveErr := errors.Is(err, ErrRemoveSubnet)
+
+		if err != nil && !isRemoveErr {
+			return err
+		}
+
+		if !metZero { // in order to not reset if has been already set
+			metZero = refs.IsZeroSubnet(&id)
+
+			if !isRemoveErr {
+				// no handler's error and non-zero subnet
+				continue
+			} else if metZero {
+				// removal error and zero subnet.
+				// we don't remove attribute of zero subnet because it means entry
+				attrs[i].SetValue(attrSubnetValExit)
+
+				continue
+			}
+		}
+
+		if isRemoveErr {
+			// removal error and non-zero subnet.
+			// we can set False or remove attribute, latter is more memory/network efficient.
+			attrs = append(attrs[:i], attrs[i+1:]...)
+			i--
+		}
+	}
+
+	if !metZero {
+		// missing attribute of zero subnet equivalent to entry
+		refs.MakeZeroSubnet(&id)
+
+		err = f(id)
+		if errors.Is(err, ErrRemoveSubnet) {
+			// zero subnet should be clearly removed with False value
+			var attr Attribute
+
+			attr.SetKey(subnetAttributeKey(&id))
+			attr.SetValue(attrSubnetValExit)
+
+			attrs = append(attrs, &attr)
+		}
+	}
+
+	node.SetAttributes(attrs)
+
+	return nil
+}
diff --git a/netmap/attributes_test.go b/netmap/attributes_test.go
new file mode 100644
index 0000000..5cee47e
--- /dev/null
+++ b/netmap/attributes_test.go
@@ -0,0 +1,226 @@
+package netmap_test
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/netmap"
+	"github.com/nspcc-dev/neofs-api-go/v2/refs"
+	"github.com/stretchr/testify/require"
+)
+
+func subnetAttrKey(val string) string {
+	return "__NEOFS__SUBNET_" + val
+}
+
+func assertSubnetAttrKey(t *testing.T, attr *netmap.Attribute, num uint32) {
+	require.Equal(t, subnetAttrKey(strconv.FormatUint(uint64(num), 10)), attr.GetKey())
+}
+
+func TestWriteSubnetInfo(t *testing.T) {
+	t.Run("entry", func(t *testing.T) {
+		t.Run("zero subnet", func(t *testing.T) {
+			var (
+				node netmap.NodeInfo
+				info netmap.NodeSubnetInfo
+			)
+
+			netmap.WriteSubnetInfo(&node, info)
+
+			// entry to zero subnet does not require an attribute
+			attrs := node.GetAttributes()
+			require.Empty(t, attrs)
+
+			// exit the subnet
+			info.SetEntryFlag(false)
+
+			netmap.WriteSubnetInfo(&node, info)
+
+			// exit from zero subnet should be clearly reflected in attributes
+			attrs = node.GetAttributes()
+			require.Len(t, attrs, 1)
+
+			attr := attrs[0]
+			assertSubnetAttrKey(t, attr, 0)
+			require.Equal(t, "False", attr.GetValue())
+
+			// again enter to zero subnet
+			info.SetEntryFlag(true)
+
+			netmap.WriteSubnetInfo(&node, info)
+
+			// attribute should be removed
+			attrs = node.GetAttributes()
+			require.Empty(t, attrs)
+		})
+
+		t.Run("non-zero subnet", func(t *testing.T) {
+			var (
+				node netmap.NodeInfo
+				info netmap.NodeSubnetInfo
+				id   refs.SubnetID
+			)
+
+			// create non-zero subnet ID
+			const num = 15
+
+			id.SetValue(num)
+
+			// enter to the subnet
+			info.SetID(&id)
+			info.SetEntryFlag(true)
+
+			netmap.WriteSubnetInfo(&node, info)
+
+			// check attribute format
+			attrs := node.GetAttributes()
+			require.Len(t, attrs, 1)
+
+			attr := attrs[0]
+			assertSubnetAttrKey(t, attr, num)
+			require.Equal(t, "True", attr.GetValue())
+
+			// again exit the subnet
+			info.SetEntryFlag(false)
+
+			netmap.WriteSubnetInfo(&node, info)
+
+			// attribute should be removed
+			attrs = node.GetAttributes()
+			require.Empty(t, attrs)
+		})
+	})
+}
+
+func TestSubnets(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		var node netmap.NodeInfo
+
+		called := 0
+
+		err := netmap.IterateSubnets(&node, func(id refs.SubnetID) error {
+			called++
+
+			require.True(t, refs.IsZeroSubnet(&id))
+
+			return nil
+		})
+
+		require.NoError(t, err)
+		require.EqualValues(t, 1, called)
+	})
+
+	t.Run("with correct attribute", func(t *testing.T) {
+		var (
+			node netmap.NodeInfo
+			attr netmap.Attribute
+		)
+
+		attr.SetKey(subnetAttrKey("13"))
+		attr.SetValue("True")
+
+		attrs := []*netmap.Attribute{&attr}
+
+		node.SetAttributes(attrs)
+
+		called := 0
+
+		err := netmap.IterateSubnets(&node, func(id refs.SubnetID) error {
+			if !refs.IsZeroSubnet(&id) {
+				called++
+				require.EqualValues(t, 13, id.GetValue())
+			}
+
+			return nil
+		})
+
+		require.NoError(t, err)
+		require.EqualValues(t, 1, called)
+	})
+
+	t.Run("with incorrect attribute", func(t *testing.T) {
+		assertErr := func(attr netmap.Attribute) {
+			var node netmap.NodeInfo
+
+			node.SetAttributes([]*netmap.Attribute{&attr})
+
+			require.Error(t, netmap.IterateSubnets(&node, func(refs.SubnetID) error {
+				return nil
+			}))
+		}
+
+		t.Run("incorrect key", func(t *testing.T) {
+			var attr netmap.Attribute
+
+			attr.SetKey(subnetAttrKey("one-two-three"))
+
+			assertErr(attr)
+		})
+
+		t.Run("incorrect value", func(t *testing.T) {
+			var attr netmap.Attribute
+
+			attr.SetKey(subnetAttrKey("1"))
+
+			for _, invalidVal := range []string{
+				"",
+				"Troo",
+				"Fols",
+			} {
+				attr.SetValue(invalidVal)
+				assertErr(attr)
+			}
+
+			assertErr(attr)
+		})
+	})
+
+	t.Run("remove entry", func(t *testing.T) {
+		t.Run("zero", func(t *testing.T) {
+			var node netmap.NodeInfo
+
+			err := netmap.IterateSubnets(&node, func(id refs.SubnetID) error {
+				if refs.IsZeroSubnet(&id) {
+					return netmap.ErrRemoveSubnet
+				}
+
+				return nil
+			})
+
+			require.NoError(t, err)
+
+			attrs := node.GetAttributes()
+			require.Len(t, attrs, 1)
+
+			attr := attrs[0]
+			assertSubnetAttrKey(t, attr, 0)
+			require.Equal(t, "False", attr.GetValue())
+		})
+
+		t.Run("non-zero", func(t *testing.T) {
+			var (
+				node netmap.NodeInfo
+				attr netmap.Attribute
+			)
+
+			attr.SetKey(subnetAttrKey("99"))
+			attr.SetValue("True")
+
+			attrs := []*netmap.Attribute{&attr}
+			node.SetAttributes(attrs)
+
+			err := netmap.IterateSubnets(&node, func(id refs.SubnetID) error {
+				if !refs.IsZeroSubnet(&id) {
+					return netmap.ErrRemoveSubnet
+				}
+
+				return nil
+			})
+
+			require.NoError(t, err)
+
+			attrs = node.GetAttributes()
+			require.Empty(t, attrs)
+		})
+	})
+}