diff --git a/tlv/aetype_string.go b/tlv/aetype_string.go
new file mode 100644
index 0000000..6eab6d9
--- /dev/null
+++ b/tlv/aetype_string.go
@@ -0,0 +1,27 @@
+// Code generated by "stringer -type=AEType -trimprefix AE"; DO NOT EDIT.
+
+package tlv
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[AEWildcard-0]
+	_ = x[AEIPv4-1]
+	_ = x[AEIPv6-2]
+	_ = x[AEIPv6LL-3]
+	_ = x[AEIPv4oIPv6-4]
+}
+
+const _AEType_name = "WildcardIPv4IPv6IPv6LLIPv4oIPv6"
+
+var _AEType_index = [...]uint8{0, 8, 12, 16, 22, 31}
+
+func (i AEType) String() string {
+	if i >= AEType(len(_AEType_index)-1) {
+		return "AEType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _AEType_name[_AEType_index[i]:_AEType_index[i+1]]
+}
diff --git a/tlv/tlv.go b/tlv/tlv.go
index 5c19e88..0b0a845 100644
--- a/tlv/tlv.go
+++ b/tlv/tlv.go
@@ -1,5 +1,6 @@
 //go:generate stringer -type=Type -trimprefix Type
 //go:generate stringer -type=SubType -trimprefix SubType
+//go:generate stringer -type=AEType -trimprefix AE
 package tlv
 
 import (
@@ -48,6 +49,33 @@ type SubTLV interface {
 	L() uint8
 }
 
+type AEType uint8
+
+const (
+	AEWildcard  = AEType(0)
+	AEIPv4      = AEType(1)
+	AEIPv6      = AEType(2)
+	AEIPv6LL    = AEType(3)
+	AEIPv4oIPv6 = AEType(4)
+)
+
+func AEFromPrefix(p netaddr.IPPrefix) AEType {
+	return AEFromIP(p.IP())
+}
+func AEFromIP(p netaddr.IP) AEType {
+	switch {
+	case p.IsZero():
+		return AEWildcard
+	case p.Is4():
+		return AEIPv4
+	case p.IsLinkLocalUnicast():
+		return AEIPv6LL
+	case p.Is6():
+		return AEIPv6
+	}
+	panic("unknown AE")
+}
+
 type Scanner struct {
 	buf []byte
 	err error
@@ -340,11 +368,9 @@ type Ack struct {
 func (Ack) T() Type {
 	return TypeAck
 }
-
 func (Ack) L() uint8 {
 	return 4
 }
-
 func AckFromBytes(b []byte) (Ack, []byte, error) {
 	if err := assertLengthGreater(b, TypeAck, 2); err != nil {
 		return Ack{}, b, err
@@ -389,7 +415,7 @@ type IHU struct {
 func (IHU) T() Type {
 	return TypeIHU
 }
-func (i IHU) AE() uint8 {
+func (i IHU) AE() AEType {
 	return AEFromIP(i.Address)
 }
 func (i IHU) L() uint8 {
@@ -413,7 +439,7 @@ func IHUFromBytes(b []byte) (IHU, []byte, error) {
 	var ihu IHU
 	var err error
 
-	ae := b[0]
+	ae := AEType(b[0])
 	ihu.Rxcost = uint16(b[2])<<8 | uint16(b[3])
 	ihu.Interval = uint16(b[4])<<8 | uint16(b[5])
 	ihu.Address, b, err = ipFromBytes(ae, b[6:])
@@ -447,15 +473,12 @@ func RouterIDFromBytes(b []byte) (RouterID, []byte, error) {
 
 	return rid, b, nil
 }
-
 func (RouterID) T() Type {
 	return TypeRouterID
 }
-
 func (RouterID) L() uint8 {
 	return 8
 }
-
 func (r RouterID) String() string {
 	var buf bytes.Buffer
 	buf.Grow(8*3 - 1)
@@ -495,7 +518,7 @@ func NextHopFromBytes(b []byte) (NextHop, []byte, error) {
 
 	var nh NextHop
 	var err error
-	ae := b[0]
+	ae := AEType(b[0])
 	nh.Address, b, err = ipFromBytes(ae, b[2:])
 	return nh, b, err
 }
@@ -516,17 +539,14 @@ type Update struct {
 func (Update) T() Type {
 	return TypeUpdate
 }
-
 func (u Update) L() uint8 {
 	return 10 + psizeFromPlen(u.Prefix.Bits())
 }
-
 func (u Update) FormatHeader() string {
 	return fmt.Sprintf("Flags 0x%02x Omitted %2d Interval %4d Seqno %5d Metric %5d RouterID %s",
 		u.Flags, u.Omitted, u.Interval, u.Seqno, u.Metric, u.RouterID,
 	)
 }
-
 func (s *PacketDecoder) UpdateFromBytes(b []byte) (Update, []byte, error) {
 	if err := assertLengthGreater(b, TypeUpdate, 10); err != nil {
 		return Update{}, b, err
@@ -580,32 +600,13 @@ func (s *PacketDecoder) UpdateFromBytes(b []byte) (Update, []byte, error) {
 	return u, b, err
 }
 
-func AEFromPrefix(p netaddr.IPPrefix) uint8 {
-	return AEFromIP(p.IP())
-}
-func AEFromIP(p netaddr.IP) uint8 {
-	if p.IsZero() {
-		return 0
-	}
-	if p.Is4() {
-		return 1
-	}
-	if p.IsLinkLocalUnicast() {
-		return 3
-	}
-	if p.Is6() {
-		return 2
-	}
-	panic("unknown AE")
-}
-
 type RouteRequest struct {
 	// AE     uint8
 	// plen   uint8
 	Prefix netaddr.IPPrefix
 }
 
-func (r RouteRequest) AE() uint8 {
+func (r RouteRequest) AE() AEType {
 	return AEFromPrefix(r.Prefix)
 }
 func (RouteRequest) T() Type {
@@ -734,25 +735,25 @@ func prefixV6LL(b []byte) (netaddr.IPPrefix, []byte, error) {
 	copy(ip6ll[8:], b[:8])
 	return netaddr.IPPrefixFrom(netaddr.IPv6Raw(ip6ll), 8), b[8:], nil
 }
-func ipFromBytes(ae uint8, b []byte) (netaddr.IP, []byte, error) {
+func ipFromBytes(ae AEType, b []byte) (netaddr.IP, []byte, error) {
 	switch ae {
-	case 0:
+	case AEWildcard:
 		return netaddr.IP{}, b, nil
-	case 1:
+	case AEIPv4:
 		if len(b) < 4 {
 			return netaddr.IP{}, b, fmt.Errorf("Not enough bytes for v4 address: %d", len(b))
 		}
 		var ip4 [4]byte
 		copy(ip4[:], b[:4])
 		return netaddr.IPFrom4(ip4), b[4:], nil
-	case 2:
+	case AEIPv6:
 		if len(b) < 16 {
 			return netaddr.IP{}, b, fmt.Errorf("Not enough bytes for v6 address: %d", len(b))
 		}
 		var ip6 [16]byte
 		copy(ip6[:], b[:16])
 		return netaddr.IPv6Raw(ip6), b[16:], nil
-	case 3:
+	case AEIPv6LL:
 		if len(b) < 8 {
 			return netaddr.IP{}, b, fmt.Errorf("Not enough bytes for v6ll address: %d", len(b))
 		}
@@ -761,6 +762,8 @@ func ipFromBytes(ae uint8, b []byte) (netaddr.IP, []byte, error) {
 		ip6ll[1] = 0x80
 		copy(ip6ll[8:], b[:8])
 		return netaddr.IPv6Raw(ip6ll), b[8:], nil
+	case AEIPv4oIPv6:
+		return netaddr.IP{}, b, fmt.Errorf("Not implemented AE Type %s", ae)
 	default:
 		return netaddr.IP{}, b, fmt.Errorf("Invalid AE %d", ae)
 	}