Index: sys/sys/sockio.h
===================================================================
RCS file: /cvs/src/sys/sys/sockio.h,v
retrieving revision 1.74
diff -u -p -r1.74 sockio.h
--- sys/sys/sockio.h	19 Feb 2018 00:21:31 -0000	1.74
+++ sys/sys/sockio.h	19 Feb 2018 04:37:57 -0000
@@ -194,6 +194,9 @@
 #define	SIOCSLIFPHYDF	_IOW('i', 193, struct ifreq)	/* set tunnel df/nodf */
 #define	SIOCGLIFPHYDF	_IOWR('i', 194, struct ifreq)	/* set tunnel df/nodf */
 
+#define	SIOCSVNENTROPY	_IOW('i', 195, struct ifreq)	/* set vnetid entropy */
+#define	SIOCGVNENTROPY	_IOWR('i', 196, struct ifreq)	/* get vnetid entropy */
+
 #define	SIOCSVH		_IOWR('i', 245, struct ifreq)	/* set carp param */
 #define	SIOCGVH		_IOWR('i', 246, struct ifreq)	/* get carp param */
 
Index: sys/net/if.c
===================================================================
RCS file: /cvs/src/sys/net/if.c,v
retrieving revision 1.545
diff -u -p -r1.545 if.c
--- sys/net/if.c	19 Feb 2018 00:24:48 -0000	1.545
+++ sys/net/if.c	19 Feb 2018 04:37:57 -0000
@@ -2119,6 +2119,7 @@ ifioctl(struct socket *so, u_long cmd, c
 	case SIOCDELMULTI:
 	case SIOCSIFMEDIA:
 	case SIOCSVNETID:
+	case SIOCSVNENTROPY:
 	case SIOCSIFPAIR:
 	case SIOCSIFPARENT:
 	case SIOCDIFPARENT:
Index: sys/net/if_gre.c
===================================================================
RCS file: /cvs/src/sys/net/if_gre.c,v
retrieving revision 1.105
diff -u -p -r1.105 if_gre.c
--- sys/net/if_gre.c	19 Feb 2018 00:46:27 -0000	1.105
+++ sys/net/if_gre.c	19 Feb 2018 04:37:57 -0000
@@ -142,6 +142,14 @@ union gre_addr {
 	struct in6_addr		in6;
 };
 
+#define GRE_KEY_MIN		0x00000000U
+#define GRE_KEY_MAX		0xffffffffU
+#define GRE_KEY_SHIFT		0
+
+#define GRE_KEY_ENTROPY_MIN	0x00000000U
+#define GRE_KEY_ENTROPY_MAX	0x00ffffffU
+#define GRE_KEY_ENTROPY_SHIFT	8
+
 struct gre_tunnel {
 	uint32_t		t_key_mask;
 #define GRE_KEY_NONE			htonl(0x00000000U)
@@ -172,6 +180,9 @@ static int	gre_set_vnetid(struct gre_tun
 static int	gre_get_vnetid(struct gre_tunnel *, struct ifreq *);
 static int	gre_del_vnetid(struct gre_tunnel *);
 
+static int	gre_set_vnentropy(struct gre_tunnel *, struct ifreq *);
+static int	gre_get_vnentropy(struct gre_tunnel *, struct ifreq *);
+
 static struct mbuf *
 		gre_encap(const struct gre_tunnel *, struct mbuf *, uint16_t,
 		    uint8_t, uint8_t);
@@ -649,6 +660,11 @@ gre_input_key(struct mbuf **mp, int *off
 	pf_pkt_addr_changed(m);
 #endif
 
+	if (sc->sc_tunnel.t_key_mask == GRE_KEY_ENTROPY) {
+		m->m_pkthdr.ph_flowid = M_FLOWID_VALID |
+		    (bemtoh32(&key->t_key) & ~GRE_KEY_ENTROPY);
+	}
+
 	ifp->if_ipackets++;
 	ifp->if_ibytes += m->m_pkthdr.len;
 
@@ -709,6 +725,11 @@ egre_input(const struct gre_tunnel *key,
 	pf_pkt_addr_changed(m);
 #endif
 
+	if (sc->sc_tunnel.t_key_mask == GRE_KEY_ENTROPY) {
+		m->m_pkthdr.ph_flowid = M_FLOWID_VALID |
+		    (bemtoh32(&key->t_key) & ~GRE_KEY_ENTROPY);
+	}
+
 	ml_enqueue(&ml, m);
 	if_input(&sc->sc_ac.ac_if, &ml);
 
@@ -991,6 +1012,12 @@ gre_encap(const struct gre_tunnel *tunne
 
 		gkh = (struct gre_h_key *)(gh + 1);
 		gkh->gre_key = tunnel->t_key;
+
+		if (tunnel->t_key_mask == GRE_KEY_ENTROPY &&
+		    ISSET(m->m_pkthdr.ph_flowid, M_FLOWID_VALID)) {
+			gkh->gre_key |= htonl(~GRE_KEY_ENTROPY &
+			    (m->m_pkthdr.ph_flowid & M_FLOWID_MASK));
+		}
 	}
 
 	switch (tunnel->t_af) {
@@ -1101,6 +1128,14 @@ gre_tunnel_ioctl(struct ifnet *ifp, stru
 		error = gre_del_vnetid(tunnel);
 		break;
 
+	case SIOCSVNENTROPY:
+		error = gre_set_vnentropy(tunnel, ifr);
+		break;
+
+	case SIOCGVNENTROPY:
+		error = gre_get_vnentropy(tunnel, ifr);
+		break;
+
 	case SIOCSLIFPHYADDR:
 		error = gre_set_tunnel(tunnel, (struct if_laddrreq *)data);
 		break;
@@ -1248,6 +1283,7 @@ egre_ioctl(struct ifnet *ifp, u_long cmd
 
 	case SIOCSVNETID:
 	case SIOCDVNETID:
+	case SIOCSVNENTROPY:
 	case SIOCSLIFPHYADDR:
 	case SIOCDIFPHYADDR:
 	case SIOCSLIFPHYRTABLE:
@@ -1576,17 +1612,25 @@ static int
 gre_set_vnetid(struct gre_tunnel *tunnel, struct ifreq *ifr)
 {
 	uint32_t key;
+	uint32_t min = GRE_KEY_MIN;
+	uint32_t max = GRE_KEY_MAX;
+	unsigned int shift = GRE_KEY_SHIFT;
+	uint32_t mask = GRE_KEY_MASK;
+
+	if (tunnel->t_key_mask == GRE_KEY_ENTROPY) {
+		min = GRE_KEY_ENTROPY_MIN;
+		max = GRE_KEY_ENTROPY_MAX;
+		shift = GRE_KEY_ENTROPY_SHIFT;
+		mask = GRE_KEY_ENTROPY;
+	}
 
-	if (ifr->ifr_vnetid < 0 || ifr->ifr_vnetid > 0xffffffff)
-		return EINVAL;
-
-	key = htonl(ifr->ifr_vnetid);
+	if (ifr->ifr_vnetid < min || ifr->ifr_vnetid > max)
+		return (EINVAL);
 
-	if (tunnel->t_key_mask == GRE_KEY_MASK && tunnel->t_key == key)
-		return (0);
+	key = htonl(ifr->ifr_vnetid << shift);
 
 	/* commit */
-	tunnel->t_key_mask = GRE_KEY_MASK;
+	tunnel->t_key_mask = mask;
 	tunnel->t_key = key;
 
 	return (0);
@@ -1595,10 +1639,20 @@ gre_set_vnetid(struct gre_tunnel *tunnel
 static int
 gre_get_vnetid(struct gre_tunnel *tunnel, struct ifreq *ifr)
 {
-	if (tunnel->t_key_mask == GRE_KEY_NONE)
+	int shift;
+
+	switch (tunnel->t_key_mask) {
+	case GRE_KEY_NONE:
 		return (EADDRNOTAVAIL);
+	case GRE_KEY_ENTROPY:
+		shift = GRE_KEY_ENTROPY_SHIFT;
+		break;
+	case GRE_KEY_MASK:
+		shift = GRE_KEY_SHIFT;
+		break;
+	}
 
-	ifr->ifr_vnetid = (int64_t)ntohl(tunnel->t_key);
+	ifr->ifr_vnetid = ntohl(tunnel->t_key) >> shift;
 
 	return (0);
 }
@@ -1607,6 +1661,47 @@ static int
 gre_del_vnetid(struct gre_tunnel *tunnel)
 {
 	tunnel->t_key_mask = GRE_KEY_NONE;
+
+	return (0);
+}
+
+static int
+gre_set_vnentropy(struct gre_tunnel *tunnel, struct ifreq *ifr)
+{
+	uint32_t mask, key;
+
+	if (tunnel->t_key_mask == GRE_KEY_NONE)
+		return (EADDRNOTAVAIL);
+
+	mask = ifr->ifr_vnetid ? GRE_KEY_ENTROPY : GRE_KEY_MASK;
+	if (tunnel->t_key_mask == mask) {
+		/* nop */
+		return (0);
+	}
+
+	key = ntohl(tunnel->t_key);
+	if (mask == GRE_KEY_ENTROPY) {
+		if (key > GRE_KEY_ENTROPY_MAX)
+			return (ERANGE);
+
+		key = htonl(key << GRE_KEY_ENTROPY_SHIFT);
+	} else
+		key = htonl(key >> GRE_KEY_ENTROPY_SHIFT);
+
+	/* commit */
+	tunnel->t_key_mask = mask;
+	tunnel->t_key = key;
+
+	return (0);
+}
+
+static int
+gre_get_vnentropy(struct gre_tunnel *tunnel, struct ifreq *ifr)
+{
+	if (tunnel->t_key_mask == GRE_KEY_NONE)
+		return (EADDRNOTAVAIL);
+
+	ifr->ifr_vnetid = tunnel->t_key_mask == GRE_KEY_ENTROPY;
 
 	return (0);
 }
Index: sbin/ifconfig/ifconfig.8
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.8,v
retrieving revision 1.300
diff -u -p -r1.300 ifconfig.8
--- sbin/ifconfig/ifconfig.8	19 Feb 2018 00:23:57 -0000	1.300
+++ sbin/ifconfig/ifconfig.8	19 Feb 2018 04:37:57 -0000
@@ -1606,6 +1606,7 @@ for a complete list of the available pro
 .Op Oo Fl Oc Ns Cm tunneldf
 .Op Cm tunnelttl Ar ttl
 .Op Oo Fl Oc Ns Cm vnetid Ar network-id
+.Op Oo Fl Oc Ns Cm vnentropy
 .Ek
 .nr nS 0
 .Pp
@@ -1681,6 +1682,14 @@ to accept packets with arbitrary network
 multipoint-to-multipoint modes).
 .It Cm -vnetid
 Clear the virtual network identifier.
+.It Cm vnentropy
+Enable splitting of the virtual network identifier space into a
+network identifier and a flow identifier.
+This may allow load balancing of the encapsulated traffic over
+multiple links.
+.It Cm -vnentropy
+Enable splitting of the virtual network identifier space into a
+network identifier and a flow identifier.
 .El
 .Sh UMB
 .nr nS 1
Index: sbin/ifconfig/ifconfig.c
===================================================================
RCS file: /cvs/src/sbin/ifconfig/ifconfig.c,v
retrieving revision 1.358
diff -u -p -r1.358 ifconfig.c
--- sbin/ifconfig/ifconfig.c	19 Feb 2018 00:23:57 -0000	1.358
+++ sbin/ifconfig/ifconfig.c	19 Feb 2018 04:37:57 -0000
@@ -121,6 +121,23 @@
 	"\5VLAN_MTU\6VLAN_HWTAGGING\10CSUM_TCPv6"			\
 	"\11CSUM_UDPv6\20WOL"
 
+struct ifencap {
+	unsigned int	 ife_flags;
+#define IFE_VNETID_MASK		0xf
+#define IFE_VNETID_NOPE		0x0
+#define IFE_VNETID_NONE		0x1
+#define IFE_VNETID_ANY		0x2
+#define IFE_VNETID_SET		0x3
+	int64_t		 ife_vnetid;
+#define IFE_VNETID_ENTROPY	0x10
+
+#define IFE_PARENT_MASK		0xf00
+#define IFE_PARENT_NOPE		0x000
+#define IFE_PARENT_NONE		0x100
+#define IFE_PARENT_SET		0x200
+	char		ife_parent[IFNAMSIZ];
+};
+
 struct	ifreq		ifr, ridreq;
 struct	in_aliasreq	in_addreq;
 struct	in6_ifreq	ifr6;
@@ -252,6 +269,9 @@ void	setpfsync_syncpeer(const char *, in
 void	unsetpfsync_syncpeer(const char *, int);
 void	setpfsync_defer(const char *, int);
 void	pfsync_status(void);
+void	setvnentropy(const char *, int);
+void	delvnentropy(const char *, int);
+void	getvnentropy(struct ifencap *);
 void	settunneldf(const char *, int);
 void	settunnelnodf(const char *, int);
 void	setpppoe_dev(const char *,int);
@@ -438,6 +458,8 @@ const struct	cmd {
 	{ "tunnelttl",	NEXTARG,	0,		settunnelttl },
 	{ "tunneldf",	0,		0,		settunneldf },
 	{ "-tunneldf",	0,		0,		settunnelnodf },
+	{ "vnentropy",	0,		0,		setvnentropy },
+	{ "-vnentropy",	0,		0,		delvnentropy },
 	{ "pppoedev",	NEXTARG,	0,		setpppoe_dev },
 	{ "pppoesvc",	NEXTARG,	0,		setpppoe_svc },
 	{ "-pppoesvc",	1,		0,		setpppoe_svc },
@@ -3312,6 +3334,40 @@ settunnelnodf(const char *ignored, int a
 }
 
 void
+setvnentropy(const char *ignored, int alsoignored)
+{
+	strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
+
+	ifr.ifr_vnetid = 1;
+	if (ioctl(s, SIOCSVNENTROPY, &ifr) < 0)
+		warn("SIOCSVNENTROPY");
+}
+
+/* ARGSUSED */
+void
+delvnentropy(const char *ignored, int alsoignored)
+{
+	ifr.ifr_vnetid = 0;
+	if (ioctl(s, SIOCSVNENTROPY, &ifr) < 0)
+		warn("SIOCSVNENTROPY");
+}
+
+void
+getvnentropy(struct ifencap *ife)
+{
+	if (strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)) >=
+	    sizeof(ifr.ifr_name))
+		errx(1, "vnentropy: name is too long");
+
+	if (ioctl(s, SIOCGVNENTROPY, &ifr) == -1)
+		return;
+
+	if (ifr.ifr_vnetid)
+		ife->ife_flags |= IFE_VNETID_ENTROPY;
+}
+
+
+void
 mpe_status(void)
 {
 	struct shim_hdr	shim;
@@ -3497,22 +3553,6 @@ setmpwcontrolword(const char *value, int
 }
 #endif /* SMALL */
 
-struct ifencap {
-	unsigned int	 ife_flags;
-#define IFE_VNETID_MASK		0xf
-#define IFE_VNETID_NOPE		0x0
-#define IFE_VNETID_NONE		0x1
-#define IFE_VNETID_ANY		0x2
-#define IFE_VNETID_SET		0x3
-	int64_t		 ife_vnetid;
-
-#define IFE_PARENT_MASK		0xf0
-#define IFE_PARENT_NOPE		0x00
-#define IFE_PARENT_NONE		0x10
-#define IFE_PARENT_SET		0x20
-	char		ife_parent[IFNAMSIZ];
-};
-
 void
 setvnetid(const char *id, int param)
 {
@@ -3564,6 +3604,12 @@ getvnetid(struct ifencap *ife)
 
 	ife->ife_flags |= IFE_VNETID_SET;
 	ife->ife_vnetid = ifr.ifr_vnetid;
+
+	if (ioctl(s, SIOCGVNENTROPY, &ifr) == -1)
+		return;
+
+	if (ifr.ifr_vnetid)
+		ife->ife_flags |= IFE_VNETID_ENTROPY;
 }
 
 void
@@ -3619,6 +3665,7 @@ getencap(void)
 	struct ifencap ife = { .ife_flags = 0 };
 
 	getvnetid(&ife);
+	getvnentropy(&ife);
 	getifparent(&ife);
 
 	if (ife.ife_flags == 0)
@@ -3635,6 +3682,8 @@ getencap(void)
 		break;
 	case IFE_VNETID_SET:
 		printf(" vnetid %lld", ife.ife_vnetid);
+		if (ife.ife_flags & IFE_VNETID_ENTROPY)
+			printf("+");
 		break;
 	}