diff --git a/arch/cpu/cc2538/lpm.c b/arch/cpu/cc2538/lpm.c
index 9e21fe4dc..7892ff204 100644
--- a/arch/cpu/cc2538/lpm.c
+++ b/arch/cpu/cc2538/lpm.c
@@ -212,10 +212,14 @@ lpm_exit()
   /* Restore system clock to the 32 MHz XOSC */
   select_32_mhz_xosc();
 
+  if((REG(SYS_CTRL_PMCTL) & SYS_CTRL_PMCTL_PM3) == SYS_CTRL_PMCTL_PM1) {
+    ENERGEST_SWITCH(ENERGEST_TYPE_LPM, ENERGEST_TYPE_CPU);
+  } else {
+    ENERGEST_SWITCH(ENERGEST_TYPE_DEEP_LPM, ENERGEST_TYPE_CPU);
+  }
+
   /* Restore PMCTL to PM0 for next pass */
   REG(SYS_CTRL_PMCTL) = SYS_CTRL_PMCTL_PM0;
-
-  ENERGEST_SWITCH(ENERGEST_TYPE_LPM, ENERGEST_TYPE_CPU);
 }
 /*---------------------------------------------------------------------------*/
 void
@@ -286,8 +290,6 @@ lpm_enter()
     REG(SYS_CTRL_PMCTL) = SYS_CTRL_PMCTL_PM1;
   }
 
-  ENERGEST_SWITCH(ENERGEST_TYPE_CPU, ENERGEST_TYPE_LPM);
-
   /* Remember the current time so we can keep stats when we wake up */
   if(LPM_CONF_STATS) {
     sleep_enter_time = RTIMER_NOW();
@@ -310,9 +312,13 @@ lpm_enter()
 
     REG(SYS_CTRL_PMCTL) = SYS_CTRL_PMCTL_PM0;
 
-    ENERGEST_SWITCH(ENERGEST_TYPE_LPM, ENERGEST_TYPE_CPU);
   } else {
     /* All clear. Assert WFI and drop to PM1/2. This is now un-interruptible */
+    if((REG(SYS_CTRL_PMCTL) & SYS_CTRL_PMCTL_PM3) == SYS_CTRL_PMCTL_PM1) {
+      ENERGEST_SWITCH(ENERGEST_TYPE_CPU, ENERGEST_TYPE_LPM);
+    } else {
+      ENERGEST_SWITCH(ENERGEST_TYPE_CPU, ENERGEST_TYPE_DEEP_LPM);
+    }
     assert_wfi();
   }
 
diff --git a/arch/cpu/cc26xx-cc13xx/lpm.c b/arch/cpu/cc26xx-cc13xx/lpm.c
index 48ded636e..a5e746f24 100644
--- a/arch/cpu/cc26xx-cc13xx/lpm.c
+++ b/arch/cpu/cc26xx-cc13xx/lpm.c
@@ -185,7 +185,7 @@ wake_up(void)
 {
   lpm_registered_module_t *module;
 
-  ENERGEST_SWITCH(ENERGEST_TYPE_LPM, ENERGEST_TYPE_CPU);
+  ENERGEST_SWITCH(ENERGEST_TYPE_DEEP_LPM, ENERGEST_TYPE_CPU);
 
   /* Sync so that we get the latest values before adjusting recharge settings */
   ti_lib_sys_ctrl_aon_sync();
@@ -485,7 +485,7 @@ deep_sleep(void)
     ti_lib_pwr_ctrl_source_set(PWRCTRL_PWRSRC_ULDO);
   }
 
-  ENERGEST_SWITCH(ENERGEST_TYPE_CPU, ENERGEST_TYPE_LPM);
+  ENERGEST_SWITCH(ENERGEST_TYPE_CPU, ENERGEST_TYPE_DEEP_LPM);
 
   /* Sync the AON interface to ensure all writes have gone through. */
   ti_lib_sys_ctrl_aon_sync();
diff --git a/arch/platform/cc2538dk/dev/board.h b/arch/platform/cc2538dk/dev/board.h
index 3b3836c58..6e3021ceb 100644
--- a/arch/platform/cc2538dk/dev/board.h
+++ b/arch/platform/cc2538dk/dev/board.h
@@ -71,13 +71,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_YELLOW             2 /**< LED2 (Yellow) -> PC1 */
 #define LEDS_GREEN              4 /**< LED3 (Green)  -> PC2 */
 #define LEDS_ORANGE             8 /**< LED4 (Orange) -> PC3 */
diff --git a/arch/platform/cooja/contiki-conf.h b/arch/platform/cooja/contiki-conf.h
index 638297730..7dea26e17 100644
--- a/arch/platform/cooja/contiki-conf.h
+++ b/arch/platform/cooja/contiki-conf.h
@@ -87,8 +87,6 @@
 #define NBR_TABLE_CONF_MAX_NEIGHBORS 300
 #endif /* NBR_TABLE_CONF_MAX_NEIGHBORS */
 
-#define TCPIP_CONF_ANNOTATE_TRANSMISSIONS 1
-
 #ifndef UIP_CONF_IPV6_QUEUE_PKT
 #define UIP_CONF_IPV6_QUEUE_PKT         1
 #endif /* UIP_CONF_IPV6_QUEUE_PKT */
diff --git a/arch/platform/openmote-cc2538/board.h b/arch/platform/openmote-cc2538/board.h
index e3ce027f2..56724a753 100644
--- a/arch/platform/openmote-cc2538/board.h
+++ b/arch/platform/openmote-cc2538/board.h
@@ -63,13 +63,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       16  /**< LED1 (Red)    -> PC4 */
 #define LEDS_YELLOW    64  /**< LED2 (Yellow) -> PC6 */
 #define LEDS_GREEN     128 /**< LED3 (Green)  -> PC7 */
diff --git a/arch/platform/srf06-cc26xx/launchpad/cc1310/board.h b/arch/platform/srf06-cc26xx/launchpad/cc1310/board.h
index a4b2efbba..1d56d776a 100644
--- a/arch/platform/srf06-cc26xx/launchpad/cc1310/board.h
+++ b/arch/platform/srf06-cc26xx/launchpad/cc1310/board.h
@@ -60,13 +60,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1
 #define LEDS_GREEN     2
 #define LEDS_YELLOW    LEDS_GREEN
diff --git a/arch/platform/srf06-cc26xx/launchpad/cc1350/board.h b/arch/platform/srf06-cc26xx/launchpad/cc1350/board.h
index e645b8b0b..9b5019179 100644
--- a/arch/platform/srf06-cc26xx/launchpad/cc1350/board.h
+++ b/arch/platform/srf06-cc26xx/launchpad/cc1350/board.h
@@ -60,13 +60,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1
 #define LEDS_GREEN     2
 #define LEDS_YELLOW    LEDS_GREEN
diff --git a/arch/platform/srf06-cc26xx/launchpad/cc2650/board.h b/arch/platform/srf06-cc26xx/launchpad/cc2650/board.h
index 9b9d00bf0..65a5bb766 100644
--- a/arch/platform/srf06-cc26xx/launchpad/cc2650/board.h
+++ b/arch/platform/srf06-cc26xx/launchpad/cc2650/board.h
@@ -60,13 +60,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1
 #define LEDS_GREEN     2
 #define LEDS_YELLOW    LEDS_GREEN
diff --git a/arch/platform/srf06-cc26xx/sensortag/cc1350/board.h b/arch/platform/srf06-cc26xx/sensortag/cc1350/board.h
index 7db4c9357..dbd64e538 100644
--- a/arch/platform/srf06-cc26xx/sensortag/cc1350/board.h
+++ b/arch/platform/srf06-cc26xx/sensortag/cc1350/board.h
@@ -63,13 +63,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1
 #define LEDS_GREEN     LEDS_RED
 #define LEDS_YELLOW    LEDS_RED
diff --git a/arch/platform/srf06-cc26xx/sensortag/cc2650/board.h b/arch/platform/srf06-cc26xx/sensortag/cc2650/board.h
index 0cf828850..977712ef2 100644
--- a/arch/platform/srf06-cc26xx/sensortag/cc2650/board.h
+++ b/arch/platform/srf06-cc26xx/sensortag/cc2650/board.h
@@ -63,13 +63,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1
 #define LEDS_GREEN     2
 #define LEDS_YELLOW    LEDS_GREEN
diff --git a/arch/platform/srf06-cc26xx/srf06/cc13xx/board.h b/arch/platform/srf06-cc26xx/srf06/cc13xx/board.h
index 831c2ee33..e210d82d8 100644
--- a/arch/platform/srf06-cc26xx/srf06/cc13xx/board.h
+++ b/arch/platform/srf06-cc26xx/srf06/cc13xx/board.h
@@ -63,13 +63,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1 /**< LED1 (Red)    */
 #define LEDS_YELLOW    2 /**< LED2 (Yellow) */
 #define LEDS_GREEN     4 /**< LED3 (Green)  */
diff --git a/arch/platform/srf06-cc26xx/srf06/cc26xx/board.h b/arch/platform/srf06-cc26xx/srf06/cc26xx/board.h
index 35080aea9..99f97fbf2 100644
--- a/arch/platform/srf06-cc26xx/srf06/cc26xx/board.h
+++ b/arch/platform/srf06-cc26xx/srf06/cc26xx/board.h
@@ -63,13 +63,6 @@
  * Those values are not meant to be modified by the user
  * @{
  */
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED       1 /**< LED1 (Red)    */
 #define LEDS_YELLOW    2 /**< LED2 (Yellow) */
 #define LEDS_GREEN     4 /**< LED3 (Green)  */
diff --git a/arch/platform/zoul/firefly-reva/board.h b/arch/platform/zoul/firefly-reva/board.h
index fb72796c0..bea1fc746 100644
--- a/arch/platform/zoul/firefly-reva/board.h
+++ b/arch/platform/zoul/firefly-reva/board.h
@@ -98,14 +98,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_BLUE
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 /* In leds.h the LEDS_BLUE is defined by LED_YELLOW definition */
 #define LEDS_GREEN    (1 << 4) /**< LED1 (Green) -> PD4 */
 #define LEDS_BLUE     (1 << 3) /**< LED2 (Blue)  -> PD3 */
diff --git a/arch/platform/zoul/firefly/board.h b/arch/platform/zoul/firefly/board.h
index 0d90e4369..4a58fc0cc 100644
--- a/arch/platform/zoul/firefly/board.h
+++ b/arch/platform/zoul/firefly/board.h
@@ -98,14 +98,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_BLUE
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 /* In leds.h the LEDS_BLUE is defined by LED_YELLOW definition */
 #define LEDS_GREEN    (1 << 4) /**< LED1 (Green) -> PD4 */
 #define LEDS_BLUE     (1 << 3) /**< LED2 (Blue)  -> PD3 */
diff --git a/arch/platform/zoul/orion/board.h b/arch/platform/zoul/orion/board.h
index f0e7ba452..494d79372 100644
--- a/arch/platform/zoul/orion/board.h
+++ b/arch/platform/zoul/orion/board.h
@@ -67,14 +67,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_BLUE
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 /* In leds.h the LEDS_BLUE is defined by LED_YELLOW definition */
 #define LEDS_GREEN    (1 << 4) /**< LED1 (Green) -> PD4 */
 #define LEDS_BLUE     (1 << 3) /**< LED2 (Blue)  -> PD3 */
diff --git a/arch/platform/zoul/remote-reva/board.h b/arch/platform/zoul/remote-reva/board.h
index efb516c31..70a8ffdab 100644
--- a/arch/platform/zoul/remote-reva/board.h
+++ b/arch/platform/zoul/remote-reva/board.h
@@ -102,14 +102,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-/* Some files include leds.h before us, so we need to get rid of defaults in
- * leds.h before we provide correct definitions */
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_BLUE
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 /* In leds.h the LEDS_BLUE is defined by LED_YELLOW definition */
 #define LEDS_GREEN    (1 << 4) /**< LED1 (Green) -> PD4 */
 #define LEDS_BLUE     (1 << 3) /**< LED2 (Blue)  -> PD3 */
diff --git a/arch/platform/zoul/remote-revb/board.h b/arch/platform/zoul/remote-revb/board.h
index fb50f13dc..432b4b062 100644
--- a/arch/platform/zoul/remote-revb/board.h
+++ b/arch/platform/zoul/remote-revb/board.h
@@ -105,12 +105,6 @@
  * @{
  */
 /*---------------------------------------------------------------------------*/
-#undef LEDS_GREEN
-#undef LEDS_YELLOW
-#undef LEDS_BLUE
-#undef LEDS_RED
-#undef LEDS_CONF_ALL
-
 #define LEDS_RED              1           /**< LED1 (Red)   -> PD4 */
 #define LEDS_RED_PIN_MASK     (1 << 4)
 #define LEDS_RED_PORT_BASE    GPIO_D_BASE
diff --git a/examples/6tisch/etsi-plugtest-2017/project-conf.h b/examples/6tisch/etsi-plugtest-2017/project-conf.h
index 751ccf977..7cb8158f0 100644
--- a/examples/6tisch/etsi-plugtest-2017/project-conf.h
+++ b/examples/6tisch/etsi-plugtest-2017/project-conf.h
@@ -121,6 +121,4 @@
 #define LOG_CONF_LEVEL_6TOP                        LOG_LEVEL_DBG
 #define TSCH_LOG_CONF_PER_SLOT                     1
 
-#define TCPIP_CONF_ANNOTATE_TRANSMISSIONS          0
-
 #endif /* __PROJECT_CONF_H__ */
diff --git a/os/dev/leds.c b/os/dev/leds.c
index 9273ad9ca..f7028f0c2 100644
--- a/os/dev/leds.c
+++ b/os/dev/leds.c
@@ -33,19 +33,11 @@
 #include "dev/leds.h"
 #include "sys/clock.h"
 
-static unsigned char leds;
-/*---------------------------------------------------------------------------*/
-static inline void
-show_leds(unsigned char new_leds)
-{
-  leds_arch_set(new_leds);
-}
 /*---------------------------------------------------------------------------*/
 void
 leds_init(void)
 {
   leds_arch_init();
-  leds = 0;
 }
 /*---------------------------------------------------------------------------*/
 void
@@ -53,7 +45,7 @@ leds_blink(void)
 {
   /* Blink all leds that were initially off. */
   unsigned char blink;
-  blink = ~leds;
+  blink = ~leds_arch_get();
   leds_toggle(blink);
 
   clock_delay(400);
@@ -69,24 +61,24 @@ leds_get(void) {
 void
 leds_set(unsigned char ledv)
 {
-  show_leds(ledv);
+  leds_arch_set(ledv);
 }
 /*---------------------------------------------------------------------------*/
 void
 leds_on(unsigned char ledv)
 {
-  show_leds(leds | ledv);
+  leds_arch_set(leds_arch_get() | ledv);
 }
 /*---------------------------------------------------------------------------*/
 void
 leds_off(unsigned char ledv)
 {
-  show_leds(leds & ~ledv);
+  leds_arch_set(leds_arch_get() & ~ledv);
 }
 /*---------------------------------------------------------------------------*/
 void
 leds_toggle(unsigned char ledv)
 {
-  show_leds(leds ^ ledv);
+  leds_arch_set(leds_arch_get() ^ ledv);
 }
 /*---------------------------------------------------------------------------*/
diff --git a/os/net/ipv6/sicslowpan.c b/os/net/ipv6/sicslowpan.c
index 2f239f77e..492dfe444 100644
--- a/os/net/ipv6/sicslowpan.c
+++ b/os/net/ipv6/sicslowpan.c
@@ -1504,6 +1504,17 @@ output(const linkaddr_t *localdest)
     set_packet_attrs();
   }
 
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  {
+    uint8_t traffic_class = (UIP_IP_BUF->vtc << 4) | (UIP_IP_BUF->tcflow >> 4);
+    if(traffic_class & UIP_TC_MAC_TRANSMISSION_COUNTER_BIT) {
+      uint8_t max_mac_transmissions = traffic_class & UIP_TC_MAC_TRANSMISSION_COUNTER_MASK;
+      /* propagate the MAC transmission limit to lower layers */
+      packetbuf_set_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS, max_mac_transmissions);
+    }
+  }
+#endif /* UIP_WITH_VARIABLE_RETRANSMISSIONS */
+
   /*
    * The destination address will be tagged to each outbound
    * packet. If the argument localdest is NULL, we are sending a
diff --git a/os/net/ipv6/uip.h b/os/net/ipv6/uip.h
index 809f4b4bc..69888445e 100755
--- a/os/net/ipv6/uip.h
+++ b/os/net/ipv6/uip.h
@@ -820,6 +820,18 @@ CCIF void uip_send(const void *data, int len);
  */
 #define uip_mss()             (uip_conn->mss)
 
+/**
+ * Set the maximal number of MAC transmissions.
+ *
+ * \hideinitializer
+ */
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+#define uip_set_max_mac_transmissions(conn, value)   ((conn)->max_mac_transmissions = (value))
+#else
+#define uip_set_max_mac_transmissions(conn, value)
+#endif
+
+
 /**
  * Set up a new UDP connection.
  *
@@ -883,6 +895,7 @@ struct uip_udp_conn *uip_udp_new(const uip_ipaddr_t *ripaddr, uint16_t rport);
  */
 #define uip_udp_send(len) uip_send((char *)uip_appdata, len)
 
+
 /** @} */
 
 /* uIP convenience and converting functions. */
@@ -1352,6 +1365,9 @@ struct uip_conn {
   uint8_t timer;         /**< The retransmission timer. */
   uint8_t nrtx;          /**< The number of retransmissions for the last
                               segment sent. */
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  uint8_t max_mac_transmissions; /**< Number of max MAC-layer transmissions. */
+#endif
 
   uip_tcp_appstate_t appstate; /** The application state. */
 };
@@ -1389,6 +1405,9 @@ struct uip_udp_conn {
   uint16_t lport;        /**< The local port number in network byte order. */
   uint16_t rport;        /**< The remote port number in network byte order. */
   uint8_t  ttl;          /**< Default time-to-live. */
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  uint8_t  max_mac_transmissions; /**< Number of max MAC-layer transmissions. */
+#endif
 
   /** The application state. */
   uip_udp_appstate_t appstate;
diff --git a/os/net/ipv6/uip6.c b/os/net/ipv6/uip6.c
index b0cab3ebd..d3df05b7f 100644
--- a/os/net/ipv6/uip6.c
+++ b/os/net/ipv6/uip6.c
@@ -508,6 +508,9 @@ uip_connect(const uip_ipaddr_t *ripaddr, uint16_t rport)
   conn->rto = UIP_RTO;
   conn->sa = 0;
   conn->sv = 16;   /* Initial value of the RTT variance. */
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  conn->max_mac_transmissions = UIP_MAX_MAC_TRANSMISSIONS_UNDEFINED;
+#endif
   conn->lport = uip_htons(lastport);
   conn->rport = rport;
   uip_ipaddr_copy(&conn->ripaddr, ripaddr);
@@ -581,6 +584,9 @@ uip_udp_new(const uip_ipaddr_t *ripaddr, uint16_t rport)
     uip_ipaddr_copy(&conn->ripaddr, ripaddr);
   }
   conn->ttl = uip_ds6_if.cur_hop_limit;
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  conn->max_mac_transmissions = UIP_MAX_MAC_TRANSMISSIONS_UNDEFINED;
+#endif
 
   return conn;
 }
@@ -1545,6 +1551,16 @@ uip_process(uint8_t flag)
   UIP_IP_BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
   UIP_IP_BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
 
+  UIP_IP_BUF->vtc = 0x60;
+  UIP_IP_BUF->tcflow = 0x00;
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  if(uip_udp_conn->max_mac_transmissions != UIP_MAX_MAC_TRANSMISSIONS_UNDEFINED) {
+    /* Encapsulate the MAC transmission limit in the Traffic Class field */
+    UIP_IP_BUF->vtc = 0x60 | (UIP_TC_MAC_TRANSMISSION_COUNTER_BIT >> 4);
+    UIP_IP_BUF->tcflow = uip_udp_conn->max_mac_transmissions << 4;
+  }
+#endif /* UIP_WITH_VARIABLE_RETRANSMISSIONS */
+
   UIP_IP_BUF->ttl = uip_udp_conn->ttl;
   UIP_IP_BUF->proto = UIP_PROTO_UDP;
 
@@ -2249,6 +2265,16 @@ uip_process(uint8_t flag)
   UIP_TCP_BUF->srcport  = uip_connr->lport;
   UIP_TCP_BUF->destport = uip_connr->rport;
 
+  UIP_IP_BUF->vtc = 0x60;
+  UIP_IP_BUF->tcflow = 0x00;
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  if(uip_connr->max_mac_transmissions != UIP_MAX_MAC_TRANSMISSIONS_UNDEFINED) {
+    /* Encapsulate the MAC transmission limit in the Traffic Class field */
+    UIP_IP_BUF->vtc = 0x60 | (UIP_TC_MAC_TRANSMISSION_COUNTER_BIT >> 4);
+    UIP_IP_BUF->tcflow = uip_connr->max_mac_transmissions << 4;
+  }
+#endif /* UIP_WITH_VARIABLE_RETRANSMISSIONS */
+
   uip_ipaddr_copy(&UIP_IP_BUF->destipaddr, &uip_connr->ripaddr);
   uip_ds6_select_src(&UIP_IP_BUF->srcipaddr, &UIP_IP_BUF->destipaddr);
   LOG_INFO("Sending TCP packet to ");
@@ -2284,8 +2310,6 @@ uip_process(uint8_t flag)
 #if UIP_UDP
   ip_send_nolen:
 #endif
-  UIP_IP_BUF->vtc = 0x60;
-  UIP_IP_BUF->tcflow = 0x00;
   UIP_IP_BUF->flow = 0x00;
   send:
   LOG_INFO("Sending packet with length %d (%d)\n", uip_len,
diff --git a/os/net/ipv6/uipopt.h b/os/net/ipv6/uipopt.h
index 84b7fd023..d668133a8 100644
--- a/os/net/ipv6/uipopt.h
+++ b/os/net/ipv6/uipopt.h
@@ -518,6 +518,35 @@ void uip_log(char *msg);
 
 #define UIP_DEFAULT_PREFIX_LEN 64
 
+/**
+ * Enables selection of maximal MAC-layer transmission count at application layer
+ */
+#ifdef UIP_CONF_WITH_VARIABLE_RETRANSMISSIONS
+#define UIP_WITH_VARIABLE_RETRANSMISSIONS UIP_CONF_WITH_VARIABLE_RETRANSMISSIONS
+#else
+#define UIP_WITH_VARIABLE_RETRANSMISSIONS 0
+#endif
+
+/**
+ * This is the default value of MAC-layer transmissons for uIPv6
+ *
+ * It means that the limit is selected by the MAC protocol instead of uIPv6.
+ */
+#define UIP_MAX_MAC_TRANSMISSIONS_UNDEFINED 0
+
+/**
+ * The MAC-layer transmissons limit is encapslated in "Traffic Class" field
+ *
+ * In Contiki, if the Traffic Class field in the IPv6 header has this bit set,
+ * the low-order bits are used as the MAC-layer transmissons limit.
+ */
+#define UIP_TC_MAC_TRANSMISSION_COUNTER_BIT  0x40
+
+/**
+ * The bits in the "Traffic Class" field that describe the MAC transmission limit
+ */
+#define UIP_TC_MAC_TRANSMISSION_COUNTER_MASK 0x3F
+
 /** @} */
 
 /*------------------------------------------------------------------------------*/
diff --git a/os/net/mac/csma/csma-output.c b/os/net/mac/csma/csma-output.c
index 167d4374c..532b4ae7a 100644
--- a/os/net/mac/csma/csma-output.c
+++ b/os/net/mac/csma/csma-output.c
@@ -85,9 +85,9 @@
 
 /* macMaxFrameRetries: Maximum number of re-transmissions attampts. Range 0--7 */
 #ifdef CSMA_CONF_MAX_FRAME_RETRIES
-#define CSMA_MAX_MAX_FRAME_RETRIES CSMA_CONF_MAX_FRAME_RETRIES
+#define CSMA_MAX_FRAME_RETRIES CSMA_MAX_FRAME_RETRIES
 #else
-#define CSMA_MAX_MAX_FRAME_RETRIES 7
+#define CSMA_MAX_FRAME_RETRIES 7
 #endif
 
 /* Packet metadata */
@@ -506,7 +506,15 @@ csma_output_packet(mac_callback_t sent, void *ptr)
           if(q->buf != NULL) {
             struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
             /* Neighbor and packet successfully allocated */
-            metadata->max_transmissions = CSMA_MAX_MAX_FRAME_RETRIES + 1;
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+            metadata->max_transmissions = packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
+            if(metadata->max_transmissions == 0) {
+              /* If not set by the application, use the default CSMA value */
+              metadata->max_transmissions = CSMA_MAX_FRAME_RETRIES + 1;
+            }
+#else
+            metadata->max_transmissions = CSMA_MAX_FRAME_RETRIES + 1;
+#endif
             metadata->sent = sent;
             metadata->cptr = ptr;
             list_add(n->packet_queue, q);
diff --git a/os/net/mac/tsch/tsch-queue.c b/os/net/mac/tsch/tsch-queue.c
index 388953a60..7aee0d66a 100644
--- a/os/net/mac/tsch/tsch-queue.c
+++ b/os/net/mac/tsch/tsch-queue.c
@@ -230,7 +230,8 @@ tsch_queue_remove_nbr(struct tsch_neighbor *n)
 /*---------------------------------------------------------------------------*/
 /* Add packet to neighbor queue. Use same lockfree implementation as ringbuf.c (put is atomic) */
 struct tsch_packet *
-tsch_queue_add_packet(const linkaddr_t *addr, mac_callback_t sent, void *ptr)
+tsch_queue_add_packet(const linkaddr_t *addr, uint8_t max_transmissions,
+                      mac_callback_t sent, void *ptr)
 {
   struct tsch_neighbor *n = NULL;
   int16_t put_index = -1;
@@ -252,6 +253,7 @@ tsch_queue_add_packet(const linkaddr_t *addr, mac_callback_t sent, void *ptr)
             p->ptr = ptr;
             p->ret = MAC_TX_DEFERRED;
             p->transmissions = 0;
+            p->max_transmissions = max_transmissions;
             /* Add to ringbuf (actual add committed through atomic operation) */
             n->tx_array[put_index] = p;
             ringbufindex_put(&n->tx_ringbuf);
@@ -342,7 +344,7 @@ tsch_queue_packet_sent(struct tsch_neighbor *n, struct tsch_packet *p,
     }
   } else {
     /* Failed transmission */
-    if(p->transmissions >= TSCH_MAC_MAX_FRAME_RETRIES + 1) {
+    if(p->transmissions >= p->max_transmissions) {
       /* Drop packet */
       tsch_queue_remove_packet_from_queue(n);
       in_queue = 0;
diff --git a/os/net/mac/tsch/tsch-queue.h b/os/net/mac/tsch/tsch-queue.h
index 037461e7d..0d77a6105 100644
--- a/os/net/mac/tsch/tsch-queue.h
+++ b/os/net/mac/tsch/tsch-queue.h
@@ -135,6 +135,7 @@ struct tsch_packet {
   mac_callback_t sent; /* callback for this packet */
   void *ptr; /* MAC callback parameter */
   uint8_t transmissions; /* #transmissions performed for this packet */
+  uint8_t max_transmissions; /* maximal number of Tx before dropping the packet */
   uint8_t ret; /* status -- MAC return code */
   uint8_t header_len; /* length of header and header IEs (needed for link-layer security) */
   uint8_t tsch_sync_ie_offset; /* Offset within the frame used for quick update of EB ASN and join priority */
@@ -176,7 +177,8 @@ struct tsch_neighbor *tsch_queue_get_time_source(void);
 /* Update TSCH time source */
 int tsch_queue_update_time_source(const linkaddr_t *new_addr);
 /* Add packet to neighbor queue. Use same lockfree implementation as ringbuf.c (put is atomic) */
-struct tsch_packet *tsch_queue_add_packet(const linkaddr_t *addr, mac_callback_t sent, void *ptr);
+struct tsch_packet *tsch_queue_add_packet(const linkaddr_t *addr, uint8_t max_transmissions,
+                                          mac_callback_t sent, void *ptr);
 /* Returns the number of packets currently in any TSCH queue */
 int tsch_queue_global_packet_count(void);
 /* Returns the number of packets currently a given neighbor queue */
diff --git a/os/net/mac/tsch/tsch.c b/os/net/mac/tsch/tsch.c
index 017f6542c..bbaed827a 100644
--- a/os/net/mac/tsch/tsch.c
+++ b/os/net/mac/tsch/tsch.c
@@ -832,8 +832,8 @@ PROCESS_THREAD(tsch_send_eb_process, ev, data)
         /* Prepare the EB packet and schedule it to be sent */
         if(tsch_packet_create_eb(&hdr_len, &tsch_sync_ie_offset) > 0) {
           struct tsch_packet *p;
-          /* Enqueue EB packet */
-          if(!(p = tsch_queue_add_packet(&tsch_eb_address, NULL, NULL))) {
+          /* Enqueue EB packet, for a single transmission only */
+          if(!(p = tsch_queue_add_packet(&tsch_eb_address, 1, NULL, NULL))) {
             LOG_ERR("! could not enqueue EB packet\n");
           } else {
               LOG_INFO("TSCH: enqueue EB packet %u %u\n",
@@ -958,6 +958,7 @@ send_packet(mac_callback_t sent, void *ptr)
   int ret = MAC_TX_DEFERRED;
   int hdr_len = 0;
   const linkaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
+  uint8_t max_transmissions = 0;
 
   if(!tsch_is_associated) {
     if(!tsch_is_initialized) {
@@ -1006,13 +1007,21 @@ send_packet(mac_callback_t sent, void *ptr)
   packetbuf_set_addr(PACKETBUF_ADDR_SENDER, &linkaddr_node_addr);
 #endif
 
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  max_transmissions = packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
+#endif
+  if(max_transmissions == 0) {
+    /* If not set by the application, use the default TSCH value */
+    max_transmissions = TSCH_MAC_MAX_FRAME_RETRIES + 1;
+  }
+
   if((hdr_len = NETSTACK_FRAMER.create()) < 0) {
     LOG_ERR("! can't send packet due to framer error\n");
     ret = MAC_TX_ERR;
   } else {
     struct tsch_packet *p;
     /* Enqueue packet */
-    p = tsch_queue_add_packet(addr, sent, ptr);
+    p = tsch_queue_add_packet(addr, max_transmissions, sent, ptr);
     if(p == NULL) {
       LOG_ERR("! can't send packet to ");
       LOG_ERR_LLADDR(addr);
diff --git a/os/net/packetbuf.h b/os/net/packetbuf.h
index c16a3f8f1..706fe51d6 100644
--- a/os/net/packetbuf.h
+++ b/os/net/packetbuf.h
@@ -217,6 +217,9 @@ enum {
   PACKETBUF_ATTR_LINK_QUALITY,
   PACKETBUF_ATTR_RSSI,
   PACKETBUF_ATTR_TIMESTAMP,
+#if UIP_WITH_VARIABLE_RETRANSMISSIONS
+  PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS,
+#endif /* UIP_WITH_VARIABLE_RETRANSMISSIONS */
   PACKETBUF_ATTR_MAC_SEQNO,
   PACKETBUF_ATTR_MAC_ACK,
   PACKETBUF_ATTR_MAC_METADATA,
diff --git a/tests/13-ieee802154/code-flush-nbr-queue/test-flush-nbr-queue.c b/tests/13-ieee802154/code-flush-nbr-queue/test-flush-nbr-queue.c
index 9045f77e4..d8be606ac 100644
--- a/tests/13-ieee802154/code-flush-nbr-queue/test-flush-nbr-queue.c
+++ b/tests/13-ieee802154/code-flush-nbr-queue/test-flush-nbr-queue.c
@@ -58,7 +58,7 @@ UNIT_TEST(test)
 
   UNIT_TEST_BEGIN();
 
-  packet = tsch_queue_add_packet(TEST_PEER_ADDR, NULL, NULL);
+  packet = tsch_queue_add_packet(TEST_PEER_ADDR, 1, NULL, NULL);
   UNIT_TEST_ASSERT(packet != NULL);
 
   nbr = tsch_queue_get_nbr(TEST_PEER_ADDR);
@@ -68,14 +68,14 @@ UNIT_TEST(test)
    * QUEUEBUF_CONF_NUM is set with 1; so another addition should fail due to
    * lack of memory.
    */
-  packet = tsch_queue_add_packet(TEST_PEER_ADDR, NULL, NULL);
+  packet = tsch_queue_add_packet(TEST_PEER_ADDR, 1, NULL, NULL);
   UNIT_TEST_ASSERT(packet == NULL);
 
   /* tsch_queue_flush_nbr_queue() is called inside of tsch_queue_reset(). */
   tsch_queue_reset();
 
   /* After flushing the nbr queue, we should be able to add a new packet */
-  packet = tsch_queue_add_packet(TEST_PEER_ADDR, NULL, NULL);
+  packet = tsch_queue_add_packet(TEST_PEER_ADDR, 1, NULL, NULL);
   UNIT_TEST_ASSERT(packet != NULL);
 
   UNIT_TEST_END();