diff --git a/bgpd/bgp_nht.c b/bgpd/bgp_nht.c
new file mode 100644
index 0000000..21e1411
--- /dev/null
+++ b/bgpd/bgp_nht.c
@@ -0,0 +1,477 @@
+/* BGP Nexthop tracking
+ * Copyright (C) 2013 Cumulus Networks, Inc.
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING.  If not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <zebra.h>
+
+#include "command.h"
+#include "thread.h"
+#include "prefix.h"
+#include "zclient.h"
+#include "stream.h"
+#include "network.h"
+#include "log.h"
+#include "memory.h"
+#include "nexthop.h"
+#include "filter.h"
+
+#include "bgpd/bgpd.h"
+#include "bgpd/bgp_table.h"
+#include "bgpd/bgp_route.h"
+#include "bgpd/bgp_attr.h"
+#include "bgpd/bgp_nexthop.h"
+#include "bgpd/bgp_debug.h"
+#include "bgpd/bgp_nht.h"
+
+extern struct zclient *zclient;
+extern struct bgp_table *bgp_nexthop_cache_table[AFI_MAX];
+
+static void register_nexthop(struct bgp_nexthop_cache *bnc);
+static void unregister_nexthop (struct bgp_nexthop_cache *bnc);
+static void evaluate_paths(struct bgp_nexthop_cache *bnc);
+static int make_prefix(int afi, struct bgp_info *ri, struct prefix *p);
+static void path_nh_map(struct bgp_info *path, struct bgp_nexthop_cache *bnc,
+			int keep);
+
+int
+bgp_find_nexthop (struct bgp_info *path, int *changed, int *metricchanged)
+{
+  struct bgp_nexthop_cache *bnc = path->nexthop;
+
+  if (!bnc)
+    return 0;
+
+  if (changed)
+    *changed = CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
+
+  if (metricchanged)
+    *metricchanged = CHECK_FLAG(bnc->change_flags,
+				BGP_NEXTHOP_METRIC_CHANGED);
+
+  return (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID));
+}
+
+void
+bgp_unlink_nexthop (struct bgp_info *path)
+{
+  struct bgp_nexthop_cache *bnc = path->nexthop;
+
+  if (!bnc)
+    return;
+
+  path_nh_map(path, NULL, 0);
+
+  if (LIST_EMPTY(&(bnc->paths)))
+    {
+      if (BGP_DEBUG(nht, NHT))
+	{
+	  char buf[INET6_ADDRSTRLEN];
+	  zlog_debug("bgp_unlink_nexthop: freeing bnc %s",
+		     bnc_str(bnc, buf, INET6_ADDRSTRLEN));
+	}
+      unregister_nexthop(bnc);
+      bnc->node->info = NULL;
+      bgp_unlock_node(bnc->node);
+      bnc_free(bnc);
+    }
+}
+
+int
+bgp_find_or_add_nexthop (afi_t afi, struct bgp_info *ri, int *changed,
+			 int *metricchanged)
+{
+  struct bgp_node *rn;
+  struct bgp_nexthop_cache *bnc;
+  struct prefix p;
+
+  if (make_prefix(afi, ri, &p) < 0)
+    return 1;
+  rn = bgp_node_get (bgp_nexthop_cache_table[afi], &p);
+
+  if (!rn->info)
+    {
+      bnc = bnc_new();
+      rn->info = bnc;
+      bnc->node = rn;
+      bgp_lock_node(rn);
+      register_nexthop(bnc);
+    }
+  bnc = rn->info;
+  bgp_unlock_node (rn);
+  path_nh_map(ri, bnc, 1);
+
+  if (changed)
+    *changed = CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
+
+  if (metricchanged)
+    *metricchanged = CHECK_FLAG(bnc->change_flags,
+				BGP_NEXTHOP_METRIC_CHANGED);
+
+  if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
+    (bgp_info_extra_get(ri))->igpmetric = bnc->metric;
+  else if (ri->extra)
+    ri->extra->igpmetric = 0;
+
+  return (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID));
+}
+
+void
+bgp_parse_nexthop_update (void)
+{
+  struct stream *s;
+  struct bgp_node *rn;
+  struct bgp_nexthop_cache *bnc;
+  struct nexthop *nexthop;
+  struct nexthop *oldnh;
+  struct nexthop *nhlist_head = NULL;
+  struct nexthop *nhlist_tail = NULL;
+  uint32_t metric;
+  u_char nexthop_num;
+  struct prefix p;
+  int i;
+
+  s = zclient->ibuf;
+
+  memset(&p, 0, sizeof(struct prefix));
+  p.family = stream_getw(s);
+  p.prefixlen = stream_getc(s);
+  switch (p.family)
+    {
+    case AF_INET:
+      p.u.prefix4.s_addr = stream_get_ipv4 (s);
+      break;
+    case AF_INET6:
+      stream_get(&p.u.prefix6, s, 16);
+      break;
+    default:
+      break;
+    }
+
+  rn = bgp_node_lookup(bgp_nexthop_cache_table[family2afi(p.family)], &p);
+  if (!rn || !rn->info)
+    {
+      if (BGP_DEBUG(nht, NHT))
+	{
+	  char buf[INET6_ADDRSTRLEN];
+	  prefix2str(&p, buf, INET6_ADDRSTRLEN);
+	  zlog_debug("parse nexthop update(%s): rn not found", buf);
+	}
+      if (rn)
+        bgp_unlock_node (rn);
+      return;
+    }
+
+  bnc = rn->info;
+  bgp_unlock_node (rn);
+  bnc->last_update = bgp_clock();
+  bnc->change_flags = 0;
+  metric = stream_getl (s);
+  nexthop_num = stream_getc (s);
+
+  /* debug print the input */
+  if (BGP_DEBUG(nht, NHT))
+    {
+      char buf[INET6_ADDRSTRLEN];
+      prefix2str(&p, buf, INET6_ADDRSTRLEN);
+      zlog_debug("parse nexthop update(%s): metric=%d, #nexthop=%d", buf,
+		 metric, nexthop_num);
+    }
+
+  if (metric != bnc->metric)
+    bnc->change_flags |= BGP_NEXTHOP_METRIC_CHANGED;
+
+  if(nexthop_num != bnc->nexthop_num)
+    bnc->change_flags |= BGP_NEXTHOP_CHANGED;
+
+  if (nexthop_num)
+    {
+      bnc->flags |= BGP_NEXTHOP_VALID;
+      bnc->metric = metric;
+      bnc->nexthop_num = nexthop_num;
+
+      for (i = 0; i < nexthop_num; i++)
+	{
+	  nexthop = nexthop_new();
+	  nexthop->type = stream_getc (s);
+	  switch (nexthop->type)
+	    {
+	    case ZEBRA_NEXTHOP_IPV4:
+	      nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
+	      break;
+	    case ZEBRA_NEXTHOP_IFINDEX:
+	    case ZEBRA_NEXTHOP_IFNAME:
+	      nexthop->ifindex = stream_getl (s);
+	      break;
+            case ZEBRA_NEXTHOP_IPV4_IFINDEX:
+	    case ZEBRA_NEXTHOP_IPV4_IFNAME:
+	      nexthop->gate.ipv4.s_addr = stream_get_ipv4 (s);
+	      nexthop->ifindex = stream_getl (s);
+	      break;
+#ifdef HAVE_IPV6
+            case ZEBRA_NEXTHOP_IPV6:
+	      stream_get (&nexthop->gate.ipv6, s, 16);
+	      break;
+            case ZEBRA_NEXTHOP_IPV6_IFINDEX:
+	    case ZEBRA_NEXTHOP_IPV6_IFNAME:
+	      stream_get (&nexthop->gate.ipv6, s, 16);
+	      nexthop->ifindex = stream_getl (s);
+	      break;
+#endif
+            default:
+              /* do nothing */
+              break;
+	    }
+
+	  if (nhlist_tail)
+	    {
+	      nhlist_tail->next = nexthop;
+	      nhlist_tail = nexthop;
+	    }
+	  else
+	    {
+	      nhlist_tail = nexthop;
+	      nhlist_head = nexthop;
+	    }
+
+	  /* No need to evaluate the nexthop if we have already determined
+	   * that there has been a change.
+	   */
+	  if (bnc->change_flags & BGP_NEXTHOP_CHANGED)
+	    continue;
+
+	  for (oldnh = bnc->nexthop; oldnh; oldnh = oldnh->next)
+	      if (nexthop_same_no_recurse(oldnh, nexthop))
+		  break;
+
+	  if (!oldnh)
+	    bnc->change_flags |= BGP_NEXTHOP_CHANGED;
+	}
+      bnc_nexthop_free(bnc);
+      bnc->nexthop = nhlist_head;
+    }
+  else
+    {
+      bnc->flags &= ~BGP_NEXTHOP_VALID;
+      bnc_nexthop_free(bnc);
+      bnc->nexthop = NULL;
+    }
+
+  evaluate_paths(bnc);
+}
+
+/**
+ * make_prefix - make a prefix structure from the path (essentially
+ * path's node.
+ */
+static int
+make_prefix (int afi, struct bgp_info *ri, struct prefix *p)
+{
+  memset (p, 0, sizeof (struct prefix));
+  switch (afi)
+    {
+    case AFI_IP:
+      p->family = AF_INET;
+      p->prefixlen = IPV4_MAX_BITLEN;
+      p->u.prefix4 = ri->attr->nexthop;
+      break;
+#ifdef HAVE_IPV6
+    case AFI_IP6:
+      if (ri->attr->extra->mp_nexthop_len != 16
+	  || IN6_IS_ADDR_LINKLOCAL (&ri->attr->extra->mp_nexthop_global))
+	return -1;
+
+      p->family = AF_INET6;
+      p->prefixlen = IPV6_MAX_BITLEN;
+      p->u.prefix6 = ri->attr->extra->mp_nexthop_global;
+      break;
+#endif
+    default:
+      break;
+    }
+  return 0;
+}
+
+/**
+ * sendmsg_nexthop -- Format and send a nexthop register/Unregister
+ *   command to Zebra.
+ * ARGUMENTS:
+ *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
+ *   int command -- either ZEBRA_NEXTHOP_REGISTER or ZEBRA_NEXTHOP_UNREGISTER
+ * RETURNS:
+ *   void.
+ */
+static void
+sendmsg_nexthop (struct bgp_nexthop_cache *bnc, int command)
+{
+  struct stream *s;
+  struct prefix *p;
+  int ret;
+
+  /* Check socket. */
+  if (!zclient || zclient->sock < 0)
+    return;
+
+  p = &(bnc->node->p);
+  s = zclient->obuf;
+  stream_reset (s);
+  zclient_create_header (s, command, VRF_DEFAULT);
+  stream_putw(s, PREFIX_FAMILY(p));
+  stream_putc(s, p->prefixlen);
+  switch (PREFIX_FAMILY(p))
+    {
+    case AF_INET:
+      stream_put_in_addr (s, &p->u.prefix4);
+      break;
+#ifdef HAVE_IPV6
+    case AF_INET6:
+      stream_put(s, &(p->u.prefix6), 16);
+      break;
+#endif
+    default:
+      break;
+    }
+  stream_putw_at (s, 0, stream_get_endp (s));
+
+  ret = zclient_send_message(zclient);
+  /* TBD: handle the failure */
+  if (ret < 0)
+    zlog_warn("sendmsg_nexthop: zclient_send_message() failed");
+  return;
+}
+
+/**
+ * register_nexthop - register a nexthop with Zebra for notification
+ *    when the route to the nexthop changes.
+ * ARGUMENTS:
+ *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
+ * RETURNS:
+ *   void.
+ */
+static void
+register_nexthop (struct bgp_nexthop_cache *bnc)
+{
+  /* Check if we have already registered */
+  if (bnc->flags & BGP_NEXTHOP_REGISTERED)
+    return;
+  sendmsg_nexthop(bnc, ZEBRA_NEXTHOP_REGISTER);
+  SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
+}
+
+/**
+ * unregister_nexthop -- Unregister the nexthop from Zebra.
+ * ARGUMENTS:
+ *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
+ * RETURNS:
+ *   void.
+ */
+static void
+unregister_nexthop (struct bgp_nexthop_cache *bnc)
+{
+  /* Check if we have already registered */
+  if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
+    return;
+
+  sendmsg_nexthop(bnc, ZEBRA_NEXTHOP_UNREGISTER);
+  UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
+}
+
+/**
+ * evaluate_paths - Evaluate the paths/nets associated with a nexthop.
+ * ARGUMENTS:
+ *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
+ * RETURNS:
+ *   void.
+ */
+static void
+evaluate_paths (struct bgp_nexthop_cache *bnc)
+{
+  struct bgp_node *rn;
+  struct bgp_info *path;
+  struct bgp *bgp = bgp_get_default();
+  int afi;
+
+  LIST_FOREACH(path, &(bnc->paths), nh_thread)
+    {
+      if (!(path->type == ZEBRA_ROUTE_BGP &&
+	    path->sub_type == BGP_ROUTE_NORMAL))
+	continue;
+
+      rn = path->net;
+      afi = family2afi(rn->p.family);
+
+      /* Path becomes valid/invalid depending on whether the nexthop
+       * reachable/unreachable.
+       */
+      if ((CHECK_FLAG(path->flags, BGP_INFO_VALID) ? 1 : 0) !=
+	  (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) ? 1 : 0))
+	{
+	  if (CHECK_FLAG (path->flags, BGP_INFO_VALID))
+	    {
+	      bgp_aggregate_decrement (bgp, &rn->p, path,
+				       afi, SAFI_UNICAST);
+	      bgp_info_unset_flag (rn, path, BGP_INFO_VALID);
+	    }
+	  else
+	    {
+	      bgp_info_set_flag (rn, path, BGP_INFO_VALID);
+	      bgp_aggregate_increment (bgp, &rn->p, path,
+				       afi, SAFI_UNICAST);
+	    }
+	}
+
+      /* Copy the metric to the path. Will be used for bestpath computation */
+      if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
+	(bgp_info_extra_get(path))->igpmetric = bnc->metric;
+      else if (path->extra)
+	path->extra->igpmetric = 0;
+
+      if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_METRIC_CHANGED) ||
+	  CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CHANGED))
+	SET_FLAG(path->flags, BGP_INFO_IGP_CHANGED);
+
+      bgp_process(bgp, rn, afi, SAFI_UNICAST);
+    }
+  RESET_FLAG(bnc->change_flags);
+}
+
+/**
+ * path_nh_map - make or break path-to-nexthop association.
+ * ARGUMENTS:
+ *   path - pointer to the path structure
+ *   bnc - pointer to the nexthop structure
+ *   make - if set, make the association. if unset, just break the existing
+ *          association.
+ */
+static void
+path_nh_map (struct bgp_info *path, struct bgp_nexthop_cache *bnc, int make)
+{
+  if (path->nexthop)
+    {
+      LIST_REMOVE(path, nh_thread);
+      path->nexthop->path_count--;
+      path->nexthop = NULL;
+    }
+  if (make)
+    {
+      LIST_INSERT_HEAD(&(bnc->paths), path, nh_thread);
+      path->nexthop = bnc;
+      path->nexthop->path_count++;
+    }
+}