diff --git a/default.cfg b/default.cfg
index b46c0f6..dead280 100644
--- a/default.cfg
+++ b/default.cfg
@@ -60,6 +60,7 @@ ntpshm_segment		0
 transportSpecific	0x0
 ptp_dst_mac		01:1B:19:00:00:00
 p2p_dst_mac		01:80:C2:00:00:0E
+udp_ttl			1
 udp6_scope		0x0E
 uds_address		/var/run/ptp4l
 #
diff --git a/ptp4l.8 b/ptp4l.8
index 14830c5..ff7041b 100644
--- a/ptp4l.8
+++ b/ptp4l.8
@@ -243,6 +243,13 @@ devices" that are not synchronized to each other. For this mode, the
 collection of clocks must be synchronized by an external program, for
 example phc2sys(8) in "automatic" mode.
 The default is 0 (disabled).
+.TP
+.B udp_ttl
+Specifies the Time to live (TTL) value for IPv4 multicast messages and the hop
+limit for IPv6 multicast messages. This option is only relevant with the IPv4
+and IPv6 UDP transports. The default is 1 to restrict the messages sent by
+.B ptp4l
+to the same subnet.
 
 .SH PROGRAM AND CLOCK OPTIONS
 
diff --git a/udp6.c b/udp6.c
index fdf5799..b67809f 100644
--- a/udp6.c
+++ b/udp6.c
@@ -99,7 +99,7 @@ static int udp6_close(struct transport *t, struct fdarray *fda)
 }
 
 static int open_socket_ipv6(const char *name, struct in6_addr mc_addr[2], short port,
-			    int *interface_index)
+			    int *interface_index, int hop_limit)
 {
 	struct sockaddr_in6 addr;
 	int fd, index, on = 1;
@@ -132,6 +132,11 @@ static int open_socket_ipv6(const char *name, struct in6_addr mc_addr[2], short
 		pr_err("setsockopt SO_BINDTODEVICE failed: %m");
 		goto no_option;
 	}
+	if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hop_limit,
+		       sizeof(hop_limit))) {
+		pr_err("setsockopt IPV6_MULTICAST_HOPS failed: %m");
+		goto no_option;
+	}
 	addr.sin6_addr = mc_addr[0];
 	if (mc_join(fd, index, (struct sockaddr *) &addr, sizeof(addr))) {
 		pr_err("mcast_join failed");
@@ -160,8 +165,9 @@ static int udp6_open(struct transport *t, const char *name, struct fdarray *fda,
 		    enum timestamp_type ts_type)
 {
 	struct udp6 *udp6 = container_of(t, struct udp6, t);
-	int efd, gfd;
+	int efd, gfd, hop_limit;
 
+	hop_limit = config_get_int(t->cfg, name, "udp_ttl");
 	udp6->mac.len = 0;
 	sk_interface_macaddr(name, &udp6->mac);
 
@@ -176,11 +182,11 @@ static int udp6_open(struct transport *t, const char *name, struct fdarray *fda,
 	if (1 != inet_pton(AF_INET6, PTP_PDELAY_MCAST_IP6ADDR, &mc6_addr[MC_PDELAY]))
 		return -1;
 
-	efd = open_socket_ipv6(name, mc6_addr, EVENT_PORT, &udp6->index);
+	efd = open_socket_ipv6(name, mc6_addr, EVENT_PORT, &udp6->index, hop_limit);
 	if (efd < 0)
 		goto no_event;
 
-	gfd = open_socket_ipv6(name, mc6_addr, GENERAL_PORT, &udp6->index);
+	gfd = open_socket_ipv6(name, mc6_addr, GENERAL_PORT, &udp6->index, hop_limit);
 	if (gfd < 0)
 		goto no_general;