diff --git a/go.mod b/go.mod
index f0bf674..fe65aee 100644
--- a/go.mod
+++ b/go.mod
@@ -10,7 +10,7 @@ require (
 	github.com/lib/pq v1.10.9
 	github.com/nextmn/gopacket-gtp v0.0.8
 	github.com/nextmn/gopacket-srv6 v0.0.8
-	github.com/nextmn/json-api v0.0.16
+	github.com/nextmn/json-api v0.0.17
 	github.com/nextmn/logrus-formatter v0.0.1
 	github.com/nextmn/rfc9433 v0.0.2
 	github.com/sirupsen/logrus v1.9.3
@@ -21,14 +21,14 @@ require (
 
 require (
 	github.com/bytedance/sonic v1.12.7 // indirect
-	github.com/bytedance/sonic/loader v0.2.2 // indirect
+	github.com/bytedance/sonic/loader v0.2.3 // indirect
 	github.com/cloudwego/base64x v0.1.4 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.6 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
 	github.com/gin-contrib/sse v1.0.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/go-playground/validator/v10 v10.23.0 // indirect
+	github.com/go-playground/validator/v10 v10.24.0 // indirect
 	github.com/goccy/go-json v0.10.4 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.9 // indirect
@@ -46,5 +46,5 @@ require (
 	golang.org/x/net v0.34.0 // indirect
 	golang.org/x/sys v0.29.0 // indirect
 	golang.org/x/text v0.21.0 // indirect
-	google.golang.org/protobuf v1.36.2 // indirect
+	google.golang.org/protobuf v1.36.3 // indirect
 )
diff --git a/go.sum b/go.sum
index cdc83f5..227880c 100644
--- a/go.sum
+++ b/go.sum
@@ -3,8 +3,8 @@ github.com/adrg/xdg v0.5.3/go.mod h1:nlTsY+NNiCBGCK2tpm09vRqfVzrc2fLmXGpBLF0zlTQ
 github.com/bytedance/sonic v1.12.7 h1:CQU8pxOy9HToxhndH0Kx/S1qU/CuS9GnKYrGioDcU1Q=
 github.com/bytedance/sonic v1.12.7/go.mod h1:tnbal4mxOMju17EGfknm2XyYcpyCnIROYOEYuemj13I=
 github.com/bytedance/sonic/loader v0.1.1/go.mod h1:ncP89zfokxS5LZrJxl5z0UJcsk4M4yY2JpfqGeCtNLU=
-github.com/bytedance/sonic/loader v0.2.2 h1:jxAJuN9fOot/cyz5Q6dUuMJF5OqQ6+5GfA8FjjQ0R4o=
-github.com/bytedance/sonic/loader v0.2.2/go.mod h1:N8A3vUdtUebEY2/VQC0MyhYeKUFosQU6FxH2JmUe6VI=
+github.com/bytedance/sonic/loader v0.2.3 h1:yctD0Q3v2NOGfSWPLPvG2ggA2kV6TS6s4wioyEqssH0=
+github.com/bytedance/sonic/loader v0.2.3/go.mod h1:N8A3vUdtUebEY2/VQC0MyhYeKUFosQU6FxH2JmUe6VI=
 github.com/cloudwego/base64x v0.1.4 h1:jwCgWpFanWmN8xoIUHa2rtzmkd5J2plF/dnLS6Xd/0Y=
 github.com/cloudwego/base64x v0.1.4/go.mod h1:0zlkT4Wn5C6NdauXdJRhSKRlJvmclQ1hhJgA0rcu/8w=
 github.com/cloudwego/iasm v0.2.0/go.mod h1:8rXZaNYT2n95jn+zTI1sDr+IgcD2GVs0nlbbQPiEFhY=
@@ -25,8 +25,8 @@ github.com/go-playground/locales v0.14.1 h1:EWaQ/wswjilfKLTECiXz7Rh+3BjFhfDFKv/o
 github.com/go-playground/locales v0.14.1/go.mod h1:hxrqLVvrK65+Rwrd5Fc6F2O76J/NuW9t0sjnWqG1slY=
 github.com/go-playground/universal-translator v0.18.1 h1:Bcnm0ZwsGyWbCzImXv+pAJnYK9S473LQFuzCbDbfSFY=
 github.com/go-playground/universal-translator v0.18.1/go.mod h1:xekY+UJKNuX9WP91TpwSH2VMlDf28Uj24BCp08ZFTUY=
-github.com/go-playground/validator/v10 v10.23.0 h1:/PwmTwZhS0dPkav3cdK9kV1FsAmrL8sThn8IHr/sO+o=
-github.com/go-playground/validator/v10 v10.23.0/go.mod h1:dbuPbCMFw/DrkbEynArYaCwl3amGuJotoKCe95atGMM=
+github.com/go-playground/validator/v10 v10.24.0 h1:KHQckvo8G6hlWnrPX4NJJ+aBfWNAE/HH+qdL2cBpCmg=
+github.com/go-playground/validator/v10 v10.24.0/go.mod h1:GGzBIJMuE98Ic/kJsBXbz1x/7cByt++cQ+YOuDM5wus=
 github.com/goccy/go-json v0.10.4 h1:JSwxQzIqKfmFX1swYPpUThQZp/Ka4wzJdK0LWVytLPM=
 github.com/goccy/go-json v0.10.4/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/gofrs/uuid v4.4.0+incompatible h1:3qXRTX8/NbyulANqlc0lchS1gqAVxRgsuW1YrTJupqA=
@@ -57,8 +57,8 @@ github.com/nextmn/gopacket-gtp v0.0.8 h1:NF3GRPSdDjmoTeyN584NwbJJJ3tHwPZysZE2ma/
 github.com/nextmn/gopacket-gtp v0.0.8/go.mod h1:94jLjLU04IOVTKBXUP09MXZCgmlizqmflU2ion1ht6E=
 github.com/nextmn/gopacket-srv6 v0.0.8 h1:oP4wuJ7dOiV/gWmX3zoFcdp2dKdSWLUaxH2fJ3TYAwA=
 github.com/nextmn/gopacket-srv6 v0.0.8/go.mod h1:2Tyuo9zsG0bP2IhC4tVRgPRuyUqOgrvEEH9seJSZTlU=
-github.com/nextmn/json-api v0.0.16 h1:RU5eTVvnwrYK0Zmh/EhdO7Q3A+hUWjavg9ytJknaYTU=
-github.com/nextmn/json-api v0.0.16/go.mod h1:CQXeNPj9MDGsEExtnqJFIGjLgZAKsmOoO2fy+mep7Ak=
+github.com/nextmn/json-api v0.0.17 h1:u8Q32fxy7xh1XCGG/QrtZIN/8NVDU6Q9W8CnaMZdZq0=
+github.com/nextmn/json-api v0.0.17/go.mod h1:CQXeNPj9MDGsEExtnqJFIGjLgZAKsmOoO2fy+mep7Ak=
 github.com/nextmn/logrus-formatter v0.0.1 h1:Bsf78jjiEESc+rV8xE6IyKj4frDPGMwXFNrLQzm6A1E=
 github.com/nextmn/logrus-formatter v0.0.1/go.mod h1:vdSZ+sIcSna8vjbXkSFxsnsKHqRwaUEed4JCPcXoGyM=
 github.com/nextmn/rfc9433 v0.0.2 h1:6FjMY+Qy8MNXQ0PPxezUsyXDxJiCbTp5j3OcXQgIQh8=
@@ -117,8 +117,8 @@ golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
 golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-google.golang.org/protobuf v1.36.2 h1:R8FeyR1/eLmkutZOM5CWghmo5itiG9z0ktFlTVLuTmU=
-google.golang.org/protobuf v1.36.2/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
+google.golang.org/protobuf v1.36.3 h1:82DV7MYdb8anAVi3qge1wSnMDrnKK7ebr+I0hHRN1BU=
+google.golang.org/protobuf v1.36.3/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/database/database.go b/internal/database/database.go
index 5c7c3e2..7e7cc55 100644
--- a/internal/database/database.go
+++ b/internal/database/database.go
@@ -125,7 +125,14 @@ func (db *Database) InsertRule(ctx context.Context, r n4tosrv6.Rule) (*uuid.UUID
 			} else {
 				dst = r.Match.Payload.Dst.String() + "/32"
 			}
-			err := stmt.QueryRowContext(ctx, r.Enabled, dst, pq.Array(srh)).Scan(&id)
+			src_ipv6 := "::"
+			if r.Action.SourceGtp4 != nil {
+				src_ipv6 = r.Action.SourceGtp4.String()
+			} else {
+				return nil, fmt.Errorf("Empty SourceGtp4 for downlink Action")
+			}
+
+			err := stmt.QueryRowContext(ctx, r.Enabled, dst, pq.Array(srh), src_ipv6).Scan(&id)
 			return &id, err
 		} else {
 			return nil, fmt.Errorf("Procedure not registered")
@@ -139,13 +146,14 @@ func (db *Database) GetRule(ctx context.Context, uuid uuid.UUID) (n4tosrv6.Rule,
 	var type_uplink bool
 	var enabled bool
 	var action_srh []string
+	var action_source_gtp4 *string
 	var match_ue_ip string
 	var match_gnb_ip []string
 	var match_service_ip *string
 	var match_uplink_teid *uint32
 	var match_uplink_upf *string
 	if stmt, ok := db.stmt["get_rule"]; ok {
-		err := stmt.QueryRowContext(ctx, uuid.String()).Scan(&type_uplink, &enabled, pq.Array(&action_srh), &match_ue_ip, pq.Array(&match_gnb_ip), &match_uplink_teid, &match_uplink_upf, &match_service_ip)
+		err := stmt.QueryRowContext(ctx, uuid.String()).Scan(&type_uplink, &enabled, pq.Array(&action_srh), &action_source_gtp4, &match_ue_ip, pq.Array(&match_gnb_ip), &match_uplink_teid, &match_uplink_upf, &match_service_ip)
 		if err != nil {
 			return n4tosrv6.Rule{}, err
 		}
@@ -202,8 +210,18 @@ func (db *Database) GetRule(ctx context.Context, uuid uuid.UUID) (n4tosrv6.Rule,
 			return n4tosrv6.Rule{}, err
 		}
 
+		if action_source_gtp4 == nil {
+			return n4tosrv6.Rule{}, fmt.Errorf("Empty SourceGtp4 for downlink rule")
+		}
+
+		source_gtp4, err := netip.ParseAddr(*action_source_gtp4)
+		if err != nil {
+			return n4tosrv6.Rule{}, err
+		}
+
 		rule.Action = n4tosrv6.Action{
-			SRH: *srh,
+			SRH:        *srh,
+			SourceGtp4: &source_gtp4,
 		}
 
 		return rule, err
@@ -217,6 +235,7 @@ func (db *Database) GetRules(ctx context.Context) (n4tosrv6.RuleMap, error) {
 	var type_uplink bool
 	var enabled bool
 	var action_srh []string
+	var action_source_gtp4 *string
 	var match_ue_ip string
 	var match_gnb_ip []string
 	var match_uplink_teid *uint32
@@ -234,7 +253,7 @@ func (db *Database) GetRules(ctx context.Context) (n4tosrv6.RuleMap, error) {
 				// avoid looping if no longer necessary
 				return n4tosrv6.RuleMap{}, ctx.Err()
 			default:
-				err := rows.Scan(&uuid, &type_uplink, &enabled, pq.Array(&action_srh), &match_ue_ip, pq.Array(&match_gnb_ip), &match_uplink_teid, &match_uplink_upf, &match_service_ip)
+				err := rows.Scan(&uuid, &type_uplink, &enabled, pq.Array(&action_srh), &action_source_gtp4, &match_ue_ip, pq.Array(&match_gnb_ip), &match_uplink_teid, &match_uplink_upf, &match_service_ip)
 				if err != nil {
 					return m, err
 				}
@@ -285,6 +304,14 @@ func (db *Database) GetRules(ctx context.Context) (n4tosrv6.RuleMap, error) {
 						}
 					}
 				}
+				if action_source_gtp4 == nil {
+					return n4tosrv6.RuleMap{}, fmt.Errorf("Empty SourceGtp4 for downlink rule")
+				}
+
+				source_gtp4, err := netip.ParseAddr(*action_source_gtp4)
+				if err != nil {
+					return n4tosrv6.RuleMap{}, err
+				}
 
 				srh, err := n4tosrv6.NewSRH(action_srh)
 				if err != nil {
@@ -292,7 +319,8 @@ func (db *Database) GetRules(ctx context.Context) (n4tosrv6.RuleMap, error) {
 				}
 
 				rule.Action = n4tosrv6.Action{
-					SRH: *srh,
+					SRH:        *srh,
+					SourceGtp4: &source_gtp4,
 				}
 				m[uuid] = rule
 			}
@@ -351,7 +379,9 @@ func (db *Database) GetUplinkAction(ctx context.Context, uplinkFTeid jsonapi.Fte
 		if err != nil {
 			return n4tosrv6.Action{}, err
 		}
-		return n4tosrv6.Action{SRH: *srh}, err
+		return n4tosrv6.Action{
+			SRH: *srh,
+		}, err
 	} else {
 		return n4tosrv6.Action{}, fmt.Errorf("Procedure not registered")
 	}
@@ -359,8 +389,9 @@ func (db *Database) GetUplinkAction(ctx context.Context, uplinkFTeid jsonapi.Fte
 
 func (db *Database) GetDownlinkAction(ctx context.Context, ueIp netip.Addr) (n4tosrv6.Action, error) {
 	var action_srh []string
+	var action_source_gtp4 *string
 	if stmt, ok := db.stmt["get_downlink_action"]; ok {
-		err := stmt.QueryRowContext(ctx, ueIp.String()).Scan(pq.Array(&action_srh))
+		err := stmt.QueryRowContext(ctx, ueIp.String()).Scan(pq.Array(&action_srh), &action_source_gtp4)
 		if err != nil {
 			return n4tosrv6.Action{}, err
 		}
@@ -368,7 +399,17 @@ func (db *Database) GetDownlinkAction(ctx context.Context, ueIp netip.Addr) (n4t
 		if err != nil {
 			return n4tosrv6.Action{}, err
 		}
-		return n4tosrv6.Action{SRH: *srh}, err
+		if action_source_gtp4 == nil {
+			return n4tosrv6.Action{}, fmt.Errorf("Empty SourceGtp4 for downlink rule")
+		}
+		source_gtp4, err := netip.ParseAddr(*action_source_gtp4)
+		if err != nil {
+			return n4tosrv6.Action{}, err
+		}
+		return n4tosrv6.Action{
+			SRH:        *srh,
+			SourceGtp4: &source_gtp4,
+		}, err
 	} else {
 		return n4tosrv6.Action{}, fmt.Errorf("Procedure not registered")
 	}
@@ -376,11 +417,17 @@ func (db *Database) GetDownlinkAction(ctx context.Context, ueIp netip.Addr) (n4t
 
 func (db *Database) UpdateAction(ctx context.Context, uuidRule uuid.UUID, action n4tosrv6.Action) error {
 	srh := []string{}
+	source_gtp4 := "::"
+	if action.SourceGtp4 != nil {
+		source_gtp4 = action.SourceGtp4.String()
+	} else {
+		return fmt.Errorf("Empty SourceGtp4 for downlink rule")
+	}
 	for _, ip := range action.SRH {
 		srh = append(srh, ip.String())
 	}
 	if stmt, ok := db.stmt["update_action"]; ok {
-		_, err := stmt.ExecContext(ctx, uuidRule.String(), pq.Array(srh))
+		_, err := stmt.ExecContext(ctx, uuidRule.String(), pq.Array(srh), source_gtp4)
 		return err
 	} else {
 		return fmt.Errorf("Procedure not registered")
diff --git a/internal/database/database.sql b/internal/database/database.sql
index 29efab3..1417a36 100644
--- a/internal/database/database.sql
+++ b/internal/database/database.sql
@@ -8,6 +8,7 @@ CREATE TABLE IF NOT EXISTS rule (
 	type_uplink BOOL NOT NULL,
 	enabled BOOL NOT NULL,
 	action_srh INET ARRAY NOT NULL,
+	action_source_gtp4 INET,
 	match_ue_ip CIDR NOT NULL,
 	match_gnb_ip CIDR ARRAY,
 	match_service_ip CIDR,
@@ -33,12 +34,13 @@ END;$$;
 CREATE OR REPLACE PROCEDURE insert_downlink_rule(
 	IN in_enabled BOOL, IN in_ue_ip CIDR,
 	IN in_srh INET ARRAY,
+	IN in_source_gtp4 INET,
 	OUT out_uuid UUID
 )
 LANGUAGE plpgsql AS $$
 BEGIN
-	INSERT INTO rule(type_uplink, enabled, match_ue_ip, action_srh)
-		VALUES(FALSE, in_enabled, in_ue_ip, in_srh) RETURNING rule.uuid INTO out_uuid;
+	INSERT INTO rule(type_uplink, enabled, match_ue_ip, action_srh, action_source_gtp4)
+		VALUES(FALSE, in_enabled, in_ue_ip, in_srh, in_source_gtp4) RETURNING rule.uuid INTO out_uuid;
 END;$$;
 
 
@@ -78,11 +80,13 @@ END;$$;
 
 CREATE OR REPLACE PROCEDURE update_action(
 	IN in_uuid UUID,
-	IN in_srh INET ARRAY
+	IN in_srh INET ARRAY,
+	IN in_source_gtp4 INET
 )
 LANGUAGE plpgsql AS $$
 BEGIN
 	UPDATE rule SET action_srh = in_srh WHERE rule.uuid = in_uuid;
+	UPDATE rule SET action_source_gtp4 = in_source_gtp4 WHERE rule.uuid = in_uuid;
 END;$$;
 
 CREATE OR REPLACE FUNCTION get_uplink_action(
@@ -111,11 +115,12 @@ CREATE OR REPLACE FUNCTION get_downlink_action(
 	IN in_ue_ip_address INET
 )
 RETURNS TABLE (
-	t_action_srh INET ARRAY
+	t_action_srh INET ARRAY,
+	t_action_source_gtp4 INET
 )
 AS $$
 BEGIN
-	RETURN QUERY SELECT rule.action_srh AS "t_action_srh"
+	RETURN QUERY SELECT rule.action_srh AS "t_action_srh", rule.action_source_gtp4 AS "t_action_source_gtp4"
 		FROM rule
 		WHERE (rule.type_uplink = FALSE AND rule.enabled = TRUE
 			AND match_ue_ip && in_ue_ip_address);
@@ -128,6 +133,7 @@ RETURNS TABLE (
 	t_type_uplink BOOL,
 	t_enabled BOOL,
 	t_action_srh INET ARRAY,
+	t_action_source_gtp4 INET,
 	t_match_ue_ip CIDR,
 	t_match_gnb_ip CIDR ARRAY,
 	t_match_uplink_teid BIGINT,
@@ -137,7 +143,8 @@ RETURNS TABLE (
 AS $$
 BEGIN
 	RETURN QUERY SELECT type_uplink AS "t_type_uplink", enabled AS "t_enabled",
-		action_srh AS "t_action_srh", match_ue_ip AS "t_match_ue_ip", match_gnb_ip AS "t_match_gnb_ip",
+		action_srh AS "t_action_srh", action_source_gtp4 AS "t_action_source_gtp4",
+		match_ue_ip AS "t_match_ue_ip", match_gnb_ip AS "t_match_gnb_ip",
 		match_uplink_teid AS "t_match_uplink_teid", match_uplink_upf AS "t_match_uplink_upf",
 		match_service_ip AS "t_match_service_ip"
 		FROM rule
@@ -150,6 +157,7 @@ RETURNS TABLE (
 	t_type_uplink BOOL,
 	t_enabled BOOL,
 	t_action_srh INET ARRAY,
+	t_action_source_gtp4 INET,
 	t_match_ue_ip CIDR,
 	t_match_gnb_ip CIDR ARRAY,
 	t_match_uplink_teid BIGINT,
@@ -160,7 +168,8 @@ AS $$
 BEGIN
 	RETURN QUERY SELECT uuid AS "t_uuid", type_uplink AS "t_type_uplink",
 		enabled AS "t_enabled",
-		action_srh AS "t_action_srh", match_ue_ip AS "t_match_ue_ip", match_gnb_ip AS "t_match_gnb_ip",
+		action_srh AS "t_action_srh", action_source_gtp4 AS "t_action_source_gtp4",
+		match_ue_ip AS "t_match_ue_ip", match_gnb_ip AS "t_match_gnb_ip",
 		match_uplink_teid AS "t_match_uplink_teid", match_uplink_upf AS "t_match_uplink_upf",
 		match_service_ip AS "t_match_service_ip"
 		FROM rule;
diff --git a/internal/database/database_gen.go b/internal/database/database_gen.go
index 4bf7ebe..1faf4f2 100644
--- a/internal/database/database_gen.go
+++ b/internal/database/database_gen.go
@@ -14,12 +14,12 @@ type procedureOrFunction struct {
 
 var procedures = map[string]procedureOrFunction{
 	"insert_uplink_rule":   {is_procedure: true, num_in: 7, num_out: 1},
-	"insert_downlink_rule": {is_procedure: true, num_in: 3, num_out: 1},
+	"insert_downlink_rule": {is_procedure: true, num_in: 4, num_out: 1},
 	"enable_rule":          {is_procedure: true, num_in: 1, num_out: 0},
 	"disable_rule":         {is_procedure: true, num_in: 1, num_out: 0},
 	"switch_rule":          {is_procedure: true, num_in: 2, num_out: 0},
 	"delete_rule":          {is_procedure: true, num_in: 1, num_out: 0},
-	"update_action":        {is_procedure: true, num_in: 2, num_out: 0},
+	"update_action":        {is_procedure: true, num_in: 3, num_out: 0},
 	"get_uplink_action":    {is_procedure: false, num_in: 5, num_out: 0},
 	"get_downlink_action":  {is_procedure: false, num_in: 1, num_out: 0},
 	"get_rule":             {is_procedure: false, num_in: 1, num_out: 0},
diff --git a/internal/netfunc/headend-encaps-ctrl.go b/internal/netfunc/headend-encaps-ctrl.go
index 71b2f8f..1c89793 100644
--- a/internal/netfunc/headend-encaps-ctrl.go
+++ b/internal/netfunc/headend-encaps-ctrl.go
@@ -45,7 +45,10 @@ func (h HeadendEncapsWithCtrl) Handle(ctx context.Context, packet []byte) ([]byt
 	if err != nil {
 		return nil, err
 	}
-	srgw_gtp_ip := netip.MustParseAddr("10.3.0.1")                            // FIXME: dont hardcode
+	if action.SourceGtp4 == nil {
+		return nil, fmt.Errorf("Empty SourceGtp4 for downlink Action")
+	}
+	srgw_gtp_ip := *action.SourceGtp4
 	ipv6Src := encoding.NewMGTP4IPv6Src(h.srcPrefix, srgw_gtp_ip.As4(), 2152) // FIXME:dont hardcode udp port number to 2152
 	src, err := ipv6Src.Marshal()
 	if err != nil {