diff --git a/ie/flow-information.go b/ie/flow-information.go
index cad599e8..21c4ce0e 100644
--- a/ie/flow-information.go
+++ b/ie/flow-information.go
@@ -95,7 +95,7 @@ func (i *IE) FlowDescription() (string, error) {
 			return "", io.ErrUnexpectedEOF
 		}
 
-		return string(i.Payload[4:l]), nil
+		return string(i.Payload[3 : 3+l]), nil
 	case ApplicationDetectionInformation:
 		ies, err := i.ApplicationDetectionInformation()
 		if err != nil {
diff --git a/ie/forwarding-policy.go b/ie/forwarding-policy.go
index c71ce157..45032054 100644
--- a/ie/forwarding-policy.go
+++ b/ie/forwarding-policy.go
@@ -88,5 +88,5 @@ func (i *IE) ForwardingPolicyIdentifier() (string, error) {
 		return "", io.ErrUnexpectedEOF
 	}
 
-	return string(v[1:idlen]), nil
+	return string(v[1 : idlen+1]), nil
 }
diff --git a/ie/ie_string_test.go b/ie/ie_string_test.go
new file mode 100644
index 00000000..3a5a5540
--- /dev/null
+++ b/ie/ie_string_test.go
@@ -0,0 +1,121 @@
+// Copyright 2019-2020 go-pfcp authors. All rights reserved.
+// Use of this source code is governed by a MIT-style license that can be
+// found in the LICENSE file.
+
+package ie_test
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/wmnsk/go-pfcp/ie"
+)
+
+func TestStringIEs(t *testing.T) {
+	cases := []struct {
+		description string
+		structured  *ie.IE
+		decoded     string
+		decoderFunc func(*ie.IE) (string, error)
+	}{
+		{
+			description: "ActivatePredefinedRules",
+			structured:  ie.NewActivatePredefinedRules("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.ActivatePredefinedRules() },
+		}, {
+			description: "APNDNN",
+			structured:  ie.NewAPNDNN("some.apn.example"),
+			decoded:     "some.apn.example",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.APNDNN() },
+		}, {
+			description: "ApplicationID",
+			structured:  ie.NewApplicationID("https://github.com/wmnsk/go-pfcp/"),
+			decoded:     "https://github.com/wmnsk/go-pfcp/",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.ApplicationID() },
+		}, {
+			description: "ApplicationInstanceID",
+			structured:  ie.NewApplicationInstanceID("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.ApplicationInstanceID() },
+		}, {
+			description: "DataNetworkAccessIdentifier",
+			structured:  ie.NewDataNetworkAccessIdentifier("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.DataNetworkAccessIdentifier() },
+		}, {
+			description: "DeactivatePredefinedRules",
+			structured:  ie.NewDeactivatePredefinedRules("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.DeactivatePredefinedRules() },
+		}, {
+			description: "FlowInformation/FlowDescription",
+			structured:  ie.NewFlowInformation(ie.FlowDirectionDownlink, "go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.FlowDescription() },
+		}, {
+			description: "ForwardingPolicyIdentifier",
+			structured:  ie.NewForwardingPolicy("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.ForwardingPolicyIdentifier() },
+		}, {
+			description: "FramedIPv6Route",
+			structured:  ie.NewFramedIPv6Route("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.FramedIPv6Route() },
+		}, {
+			description: "FramedRoute",
+			structured:  ie.NewFramedRoute("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.FramedRoute() },
+		}, {
+			description: "NetworkInstance",
+			structured:  ie.NewNetworkInstance("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.NetworkInstance() },
+		}, {
+			description: "NodeID/IPv4",
+			structured:  ie.NewNodeID("127.0.0.1", "", ""),
+			decoded:     "127.0.0.1",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.NodeID() },
+		}, {
+			description: "NodeID/IPv6",
+			structured:  ie.NewNodeID("", "2001::1", ""),
+			decoded:     "2001::1",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.NodeID() },
+		}, {
+			description: "NodeID/FQDN",
+			structured:  ie.NewNodeID("", "", "go-pfcp.epc.3gppnetwork.org"),
+			decoded:     "go-pfcp.epc.3gppnetwork.org",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.NodeID() },
+		}, {
+			description: "PortManagementInformationContainer",
+			structured:  ie.NewPortManagementInformationContainer("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.PortManagementInformationContainer() },
+		}, {
+			description: "SMFSetID",
+			structured:  ie.NewSMFSetID("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.SMFSetIDString() },
+		}, {
+			description: "UEIPAddressPoolIdentity",
+			structured:  ie.NewUEIPAddressPoolIdentity("go-pfcp"),
+			decoded:     "go-pfcp",
+			decoderFunc: func(i *ie.IE) (string, error) { return i.UEIPAddressPoolIdentityString() },
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.description, func(t *testing.T) {
+			got, err := c.decoderFunc(c.structured)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if diff := cmp.Diff(got, c.decoded); diff != "" {
+				t.Error(diff)
+			}
+		})
+	}
+}
diff --git a/ie/node-id.go b/ie/node-id.go
index 66245df8..b2026d17 100644
--- a/ie/node-id.go
+++ b/ie/node-id.go
@@ -67,7 +67,25 @@ func (i *IE) NodeID() (string, error) {
 	case NodeIDIPv6Address:
 		return net.IP(i.Payload[1:]).To16().String(), nil
 	case NodeIDFQDN:
-		return string(i.Payload[1:]), nil
+		b := i.Payload[1:]
+		var (
+			nodeID []string
+			offset int
+		)
+		max := len(b)
+		for {
+			if offset >= max {
+				break
+			}
+			l := int(b[offset])
+			if offset+l+1 > max {
+				break
+			}
+			nodeID = append(nodeID, string(b[offset+1:offset+l+1]))
+			offset += l + 1
+		}
+
+		return strings.Join(nodeID, "."), nil
 	default:
 		return "", &InvalidNodeIDError{ID: i.Payload[0]}
 	}
diff --git a/ie/smf-set-id.go b/ie/smf-set-id.go
index 8dca4fdc..0a8e3e51 100644
--- a/ie/smf-set-id.go
+++ b/ie/smf-set-id.go
@@ -26,7 +26,7 @@ func (i *IE) SMFSetID() ([]byte, error) {
 	return i.Payload, nil
 }
 
-// SMFSetIDString returns SMFSetIDString in string if the type of IE matches.
+// SMFSetIDString returns SMFSetID in string if the type of IE matches.
 func (i *IE) SMFSetIDString() (string, error) {
 	v, err := i.SMFSetID()
 	if err != nil {
diff --git a/ie/ue-ip-address-pool-identity.go b/ie/ue-ip-address-pool-identity.go
index 9bc6aa07..5c939947 100644
--- a/ie/ue-ip-address-pool-identity.go
+++ b/ie/ue-ip-address-pool-identity.go
@@ -53,7 +53,7 @@ func (i *IE) UEIPAddressPoolIdentity() ([]byte, error) {
 	}
 }
 
-// UEIPAddressPoolIdentityString returns UEIPAddressPoolIdentityString in string if the type of IE matches.
+// UEIPAddressPoolIdentityString returns UEIPAddressPoolIdentity in string if the type of IE matches.
 func (i *IE) UEIPAddressPoolIdentityString() (string, error) {
 	v, err := i.UEIPAddressPoolIdentity()
 	if err != nil {
@@ -65,5 +65,5 @@ func (i *IE) UEIPAddressPoolIdentityString() (string, error) {
 		return "", io.ErrUnexpectedEOF
 	}
 
-	return string(v[1:idlen]), nil
+	return string(v[1 : idlen+1]), nil
 }