diff --git a/Makefile.dep b/Makefile.dep
index 1aff898994da4e0c59572888fa8f16ae6cb95618..6e6551f0032d0ad9f5c88f29fb45472e8f3fbc87 100644
--- a/Makefile.dep
+++ b/Makefile.dep
@@ -48,6 +48,10 @@ ifneq (,$(filter sixlowpan,$(USEMODULE)))
USEMODULE += vtimer
endif
+ifneq (,$(filter ng_ipv6_nc,$(USEMODULE)))
+ USEMODULE += ng_ipv6_addr
+endif
+
ifneq (,$(filter aodvv2,$(USEMODULE)))
USEMODULE += vtimer
USEMODULE += sixlowpan
diff --git a/sys/Makefile b/sys/Makefile
index f91df0d1afe5fbb7a31edcb91c9836140587a715..230a0296acebaa48cdb22602f06620ec849542c4 100644
--- a/sys/Makefile
+++ b/sys/Makefile
@@ -65,6 +65,9 @@ endif
ifneq (,$(filter ng_ipv6_addr,$(USEMODULE)))
DIRS += net/network_layer/ng_ipv6/addr
endif
+ifneq (,$(filter ng_ipv6_nc,$(USEMODULE)))
+ DIRS += net/network_layer/ng_ipv6/nc
+endif
ifneq (,$(filter ng_netapi,$(USEMODULE)))
DIRS += net/crosslayer/ng_netapi
endif
diff --git a/sys/include/net/ng_ipv6/nc.h b/sys/include/net/ng_ipv6/nc.h
new file mode 100644
index 0000000000000000000000000000000000000000..0421705bfe1810779b8639b3b6b69ee24686d943
--- /dev/null
+++ b/sys/include/net/ng_ipv6/nc.h
@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for
+ * more details.
+ */
+
+/**
+ * @defgroup net_ng_ipv6_nc IPv6 neighbor cache
+ * @ingroup net_ng_ipv6
+ * @brief Translates IPv6 addresses to link layer addresses.
+ * @{
+ *
+ * @file
+ * @brief Neighbor cache definitions.
+ *
+ * @author Martine Lenders <mlenders@inf.fu-berlin.de>
+ */
+
+#ifndef NG_IPV6_NC_H_
+#define NG_IPV6_NC_H_
+
+#include <stdint.h>
+
+#include "kernel_types.h"
+#include "net/ng_ipv6/addr.h"
+#include "net/ng_netif.h"
+#include "net/ng_pktqueue.h"
+#include "timex.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef NG_IPV6_NC_SIZE
+/**
+ * @brief The size of the neighbor cache
+ */
+#define NG_IPV6_NC_SIZE (NG_NETIF_NUMOF * 8)
+#endif
+
+#ifndef NG_IPV6_NC_L2_ADDR_MAX
+/**
+ * @brief The maximum size of a link layer address
+ */
+#define NG_IPV6_NC_L2_ADDR_MAX (8)
+#endif
+
+/**
+ * @{
+ * @name Flag definitions for ng_ipv6_nc_t
+ */
+/**
+ * @{
+ * @brief States of a neighbor cache entry.
+ *
+ * @see <a href="http://tools.ietf.org/html/rfc4861#section-7.3.2">
+ * RFC 4861, section 7.3.2
+ * </a>
+ */
+#define NG_IPV6_NC_STATE_MASK (0x07) /**< Mask for neighbor cache state */
+#define NG_IPV6_NC_STATE_POS (0) /**< Shift of neighbor cache state */
+
+#define NG_IPV6_NC_STATE_UNMANAGED (0x00) /**< The entry is not manage by NDP */
+
+/**
+ * @brief The entry is unreachable
+ *
+ * @see <a href="http://tools.ietf.org/html/rfc7048#section-3">
+ * RFC 7048, section 3
+ * </a>
+ */
+#define NG_IPV6_NC_STATE_UNREACHABLE (0x01)
+#define NG_IPV6_NC_STATE_INCOMPLETE (0x02) /**< Address resolution is performed */
+#define NG_IPV6_NC_STATE_STALE (0x03) /**< The entry is stale */
+#define NG_IPV6_NC_STATE_DELAY (0x04) /**< The entry was stale but packet was sent out */
+#define NG_IPV6_NC_STATE_PROBE (0x05) /**< Periodic reachabality confirmation */
+#define NG_IPV6_NC_STATE_REACHABLE (0x07) /**< The entry is reachable */
+/**
+ * @}
+ */
+
+#define NG_IPV6_NC_IS_ROUTER (0x08) /**< The neighbor is a router */
+
+#define NG_IPV6_NC_TYPE_MASK (0x30) /**< Mask for neighbor cache state */
+#define NG_IPV6_NC_TYPE_POS (4) /**< Shift of neighbor cache state */
+
+/**
+ * @{
+ * @brief States of a neighbor cache entry.
+ *
+ * @see <a href="http://tools.ietf.org/html/rfc6775#section-3.5">
+ * RFC 6775, section 3.5
+ * </a>
+ */
+/**
+ * @brief The entry has no type
+ *
+ * @details The node sents multicast Neighbor Solicitations for hosts.
+ */
+#define NG_IPV6_NC_TYPE_NONE (0x00)
+#define NG_IPV6_NC_TYPE_GC (0x10) /**< The entry is marked for removal */
+#define NG_IPV6_NC_TYPE_TENTATIVE (0x20) /**< The entry is temporary */
+#define NG_IPV6_NC_TYPE_REGISTERED (0x30) /**< The entry is registered */
+/**
+ * @}
+ */
+/**
+ * @}
+ */
+
+/**
+ * @brief Neighbor cache entry as defined in
+ * <a href="http://tools.ietf.org/html/rfc4861#section-5.1">
+ * RFC 4861, section 5.1
+ * </a>.
+ */
+typedef struct {
+ ng_pktqueue_t pkts; /**< Packets waiting for address resolution */
+ ng_ipv6_addr_t ipv6_addr; /**< IPv6 address of the neighbor */
+ uint8_t l2_addr[NG_IPV6_NC_L2_ADDR_MAX];/**< Link layer address of the neighbor */
+ uint8_t l2_addr_len; /**< Length of ng_ipv6_nc_t::l2_addr */
+ uint8_t flags; /**< Flags as defined above */
+ kernel_pid_t iface; /**< PID to the interface where the neighbor is */
+} ng_ipv6_nc_t;
+
+/**
+ * @brief Initializes neighbor cache
+ */
+void ng_ipv6_nc_init(void);
+
+/**
+ * @brief Adds a neighbor to the neighbor cache
+ *
+ * @param[in] iface PID to the interface where the neighbor is.
+ * Must not be KERNEL_PID_UNDEF.
+ * @param[in] ipv6_addr IPv6 address of the neighbor. Must not be NULL.
+ * @param[in] l2_addr Link layer address of the neighbor. NULL if unknown.
+ * @param[in] l2_addr_len Length of @p l2_addr, must be lesser than or equal
+ * to NG_IPV6_L2_ADDR_MAX. 0 if unknown.
+ * @param[in] flags Flags for the entry
+ *
+ * @return 0 on success
+ * @return -EADDRINUSE, if @p ipv6_addr is already registered to the neighbor
+ * cache.
+ * @return -EFAULT, if @p ipv6_addr was NULL.
+ * @return -EINVAL, if @p l2_addr_len is greater then @ref NG_IPV6_NC_L2_ADDR_MAX,
+ * @p ipv6_addr is unspecified or @p iface is KERNEL_PID_UNDEF.
+ * @return -ENOMEM, if no space is left to store entry.
+ */
+int ng_ipv6_nc_add(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr,
+ const void *l2_addr, size_t l2_addr_len, uint8_t flags);
+
+/**
+ * @brief Removes a neighbor from the neighbor cache
+ *
+ * @param[in] iface PID to the interface where the neighbor is. If it
+ * is KERNEL_PID_UNDEF it will be removed for all
+ * interfaces.
+ * @param[in] ipv6_addr IPv6 address of the neighbor
+ */
+void ng_ipv6_nc_remove(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr);
+
+/**
+ * @brief Searches for any neighbor cache entry fitting the @p ipv6_addr.
+ *
+ * @param[in] iface PID to the interface where the neighbor is. If it
+ * is KERNEL_PID_UNDEF it will be searched on all
+ * interfaces.
+ * @param[in] ipv6_addr An IPv6 address
+ *
+ * @return The neighbor cache entry, if one is found.
+ * @return NULL, if none is found.
+ */
+ng_ipv6_nc_t *ng_ipv6_nc_get(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr);
+
+/**
+ * @brief Searches for any neighbor cache entry fitting the @p ipv6_addr,
+ * where you currently can send a packet to (do not confuse with
+ * NG_IPV6_NC_STATE_REACHABLE).
+ *
+ * @param[in] iface PID to the interface where the neighbor is. If it
+ * is KERNEL_PID_UNDEF it will be searched on all
+ * interfaces.
+ * @param[in] ipv6_addr An IPv6 address
+ *
+ * @return The neighbor cache entry, if one is found.
+ * @return NULL, if none is found.
+ */
+ng_ipv6_nc_t *ng_ipv6_nc_get_reachable(kernel_pid_t iface,
+ const ng_ipv6_addr_t *ipv6_addr);
+
+/**
+ * @brief Marks an entry as still reachable, if one with a fitting @p ipv6_addr
+ * can be found.
+ *
+ * @details This function can be used by upper layer protocols for neighbor
+ * discovery optimization to confirm that there was a reachability
+ * confirmation (e. g. an ACK in TCP) from the neighbor.
+ *
+ * @see <a href="http://tools.ietf.org/html/rfc4861#section-7.3.1">
+ * RFC 4861, section 7.3.1
+ * </a>
+ *
+ * @param[in] ipv6_addr An IPv6 address
+ *
+ * @return The neighbor cache entry, if one is found.
+ * @return NULL, if none is found.
+ */
+ng_ipv6_nc_t *ng_ipv6_nc_still_reachable(const ng_ipv6_addr_t *ipv6_addr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NG_IPV6_NC_H_ */
+/**
+ * @}
+ */
diff --git a/sys/net/network_layer/ng_ipv6/nc/Makefile b/sys/net/network_layer/ng_ipv6/nc/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..9349ccc16f426f40838e51cdb32d20bab630e76c
--- /dev/null
+++ b/sys/net/network_layer/ng_ipv6/nc/Makefile
@@ -0,0 +1,3 @@
+MODULE = ng_ipv6_nc
+
+include $(RIOTBASE)/Makefile.base
diff --git a/sys/net/network_layer/ng_ipv6/nc/ng_ipv6_nc.c b/sys/net/network_layer/ng_ipv6/nc/ng_ipv6_nc.c
new file mode 100644
index 0000000000000000000000000000000000000000..6aeb5fec0b78ae3e61f03479688b891d54aaf8bd
--- /dev/null
+++ b/sys/net/network_layer/ng_ipv6/nc/ng_ipv6_nc.c
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @{
+ *
+ * @file
+ */
+
+#include <errno.h>
+#include <string.h>
+
+#include "net/ng_ipv6/addr.h"
+#include "net/ng_ipv6/nc.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+#if ENABLE_DEBUG
+static char addr_str[NG_IPV6_ADDR_MAX_STR_LEN];
+#endif
+
+static ng_ipv6_nc_t ncache[NG_IPV6_NC_SIZE];
+
+void ng_ipv6_nc_init(void)
+{
+ memset(ncache, 0, sizeof(ncache));
+}
+
+ng_ipv6_nc_t *_find_free_entry(void)
+{
+ for (int i = 0; i < NG_IPV6_NC_SIZE; i++) {
+ if (ng_ipv6_addr_is_unspecified(&(ncache[i].ipv6_addr))) {
+ return ncache + i;
+ }
+ }
+
+ return NULL;
+}
+
+int ng_ipv6_nc_add(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr,
+ const void *l2_addr, size_t l2_addr_len, uint8_t flags)
+{
+ if (ipv6_addr == NULL) {
+ DEBUG("ipv6_nc: address was NULL\n");
+ return -EFAULT;
+ }
+
+ if ((l2_addr_len > NG_IPV6_NC_L2_ADDR_MAX) || (iface == KERNEL_PID_UNDEF) ||
+ ng_ipv6_addr_is_unspecified(ipv6_addr)) {
+ return -EINVAL;
+ }
+
+ for (int i = 0; i < NG_IPV6_NC_SIZE; i++) {
+ if (ng_ipv6_addr_equal(&(ncache[i].ipv6_addr), ipv6_addr)) {
+ DEBUG("ipv6_nc: Address %s already registered\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)));
+ return -EADDRINUSE;
+ }
+
+ if (ncache[i].iface == KERNEL_PID_UNDEF) {
+ ncache[i].iface = iface;
+
+ ng_pktqueue_init(&(ncache[i].pkts));
+ memcpy(&(ncache[i].ipv6_addr), ipv6_addr, sizeof(ng_ipv6_addr_t));
+ DEBUG("ipv6_nc: Register %s for interface %" PRIkernel_pid,
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)),
+ iface);
+
+ if ((l2_addr != NULL) && (l2_addr_len > 0)) {
+#if ENABLE_DEBUG
+ DEBUG(" to L2 address ");
+
+ for (size_t i = 0; i < l2_addr_len; i++) {
+ if (i > 0) {
+ putchar(':');
+ }
+
+ DEBUG("%02x", ((uint8_t *)l2_addr)[i]);
+ }
+
+#endif
+ memcpy(&(ncache[i].l2_addr), l2_addr, l2_addr_len);
+ ncache[i].l2_addr_len = l2_addr_len;
+ }
+
+ ncache[i].flags = flags;
+ DEBUG(" with flags = 0x%0x\n", flags);
+
+ return 0;
+ }
+ }
+
+ return -ENOMEM;
+}
+
+void ng_ipv6_nc_remove(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr)
+{
+ ng_ipv6_nc_t *entry = ng_ipv6_nc_get(iface, ipv6_addr);
+
+ if (entry != NULL) {
+ DEBUG("ipv6_nc: Remove %s for interface %" PRIkernel_pid "\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)),
+ iface);
+
+ ng_ipv6_addr_set_unspecified(&(entry->ipv6_addr));
+ entry->iface = KERNEL_PID_UNDEF;
+ entry->flags = 0;
+ }
+}
+
+ng_ipv6_nc_t *ng_ipv6_nc_get(kernel_pid_t iface, const ng_ipv6_addr_t *ipv6_addr)
+{
+ if (ipv6_addr == NULL) {
+ DEBUG("ipv6_nc: address was NULL\n");
+ return NULL;
+ }
+
+ for (int i = 0; i < NG_IPV6_NC_SIZE; i++) {
+ if (((iface == KERNEL_PID_UNDEF) || (iface == ncache[i].iface)) &&
+ ng_ipv6_addr_equal(&(ncache[i].ipv6_addr), ipv6_addr)) {
+ DEBUG("ipv6_nc: Found entry for %s on interface %" PRIkernel_pid
+ " (0 = all interfaces) [%p]\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)),
+ iface, (void *)(ncache + i));
+
+ return ncache + i;
+ }
+ }
+
+ return NULL;
+}
+
+ng_ipv6_nc_t *ng_ipv6_nc_get_reachable(kernel_pid_t iface,
+ const ng_ipv6_addr_t *ipv6_addr)
+{
+ ng_ipv6_nc_t *entry = ng_ipv6_nc_get(iface, ipv6_addr);
+
+ if (entry == NULL) {
+ DEBUG("ipv6_nc: No entry found for %s on interface %" PRIkernel_pid "\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)),
+ iface);
+ return NULL;
+ }
+
+ switch ((entry->flags & NG_IPV6_NC_STATE_MASK) >> NG_IPV6_NC_STATE_POS) {
+ case NG_IPV6_NC_STATE_UNREACHABLE:
+ case NG_IPV6_NC_STATE_INCOMPLETE:
+ DEBUG("ipv6_nc: Entry %s is unreachable (flags = 0x%02x)\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)),
+ entry->flags);
+ return NULL;
+
+ default:
+ return entry;
+ }
+}
+
+ng_ipv6_nc_t *ng_ipv6_nc_still_reachable(const ng_ipv6_addr_t *ipv6_addr)
+{
+ ng_ipv6_nc_t *entry = ng_ipv6_nc_get(KERNEL_PID_UNDEF, ipv6_addr);
+
+ if (entry == NULL) {
+ DEBUG("ipv6_nc: No entry found for %s\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)));
+ return NULL;
+ }
+
+ if (((entry->flags & NG_IPV6_NC_STATE_MASK) >> NG_IPV6_NC_STATE_POS) !=
+ NG_IPV6_NC_STATE_INCOMPLETE) {
+ DEBUG("ipv6_nc: Marking entry %s as reachable\n",
+ ng_ipv6_addr_to_str(addr_str, ipv6_addr, sizeof(addr_str)));
+ entry->flags &= ~(NG_IPV6_NC_STATE_MASK >> NG_IPV6_NC_STATE_POS);
+ entry->flags |= (NG_IPV6_NC_STATE_REACHABLE >> NG_IPV6_NC_STATE_POS);
+ }
+
+ return entry;
+}
+
+/** @} */