ospf6d: ospfv3-abr-ecmp-support.patch

OSPFv3: Add ABR support and make ECMP > 4.

Signed-off-by: Dinesh G Dutt <ddutt at cumulusnetworks.com>
Signed-off-by: Pradosh Mohapatra <pmohapat at cumulusnetworks.com>

24 files changed, 1062 insertions, 304 deletions

diff --git a/lib/bitfield.h b/lib/bitfield.h
new file mode 100644
index 0000000000..b3f40a948b
--- /dev/null
+++ b/lib/bitfield.h
@@ -0,0 +1,102 @@
+/**
+ * A simple bit array implementation to allocate and free IDs. An example
+ * of its usage is in allocating link state IDs for OSPFv3 as OSPFv3 has
+ * removed all address semantics from LS ID. Another usage can be in
+ * allocating IDs for BGP neighbors (and dynamic update groups) for
+ * efficient storage of adj-rib-out.
+ *
+ * An example:
+ * #include "bitfield.h"
+ *
+ * bitfield_t bitfield;
+ *
+ * bf_init(bitfield, 32);
+ * ...
+ * bf_assign_index(bitfield, id1);
+ * bf_assign_index(bitfield, id2);
+ * ...
+ * bf_release_index(bitfield, id1);
+ */
+
+#ifndef _BITFIELD_H
+#define _BITFIELD_H
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+typedef unsigned int word_t;
+#define WORD_MAX 0xFFFFFFFF
+#define WORD_SIZE (sizeof(word_t) * 8)
+
+/**
+ * The bitfield structure.
+ * @data: the bits to manage.
+ * @n: The current word number that is being used.
+ * @m: total number of words in 'data'
+ */
+#define bitfield_t struct { word_t *data; size_t n, m; }
+
+/**
+ * Initialize the bits.
+ * @v: an instance of bitfield_t struct.
+ * @N: number of bits to start with, which equates to how many
+ *     IDs can be allocated.
+ */
+#define bf_init(v, N)				    \
+  do {						    \
+    (v).n = 0;					    \
+    (v).m = ((N) / WORD_SIZE + 1);		    \
+    (v).data = calloc(1, ((v).m * sizeof(word_t))); \
+  } while (0)
+
+/**
+ * allocate and assign an id from bitfield v.
+ */
+#define bf_assign_index(v, id)				\
+  do {							\
+    bf_find_bit(v, id);					\
+    bf_set_bit(v, id);					\
+  } while (0)
+
+/**
+ * return an id to bitfield v
+ */
+#define bf_release_index(v, id)			\
+  (v).data[bf_index(id)] &= ~(1 << (bf_offset(id)))
+
+#define bf_index(b) ((b) / WORD_SIZE)
+#define bf_offset(b) ((b) % WORD_SIZE)
+
+/**
+ * Set a bit in the array. If it fills up that word and we are
+ * out of words, extend it by one more word.
+ */
+#define bf_set_bit(v, b)					\
+  do {								\
+    size_t w = bf_index(b);					\
+    (v).data[w] |= 1 << (bf_offset(b));				\
+    (v).n += ((v).data[w] == WORD_MAX);				\
+    if ((v).n == (v).m) {					\
+      (v).m = (v).m + 1;					\
+      (v).data = realloc((v).data, (v).m * sizeof(word_t));	\
+    }								\
+  } while (0)
+
+/* Find a clear bit in v and assign it to b. */
+#define bf_find_bit(v, b)					\
+  do {								\
+    word_t word;						\
+    unsigned int w, sh;						\
+    for (w = 0; w <= (v).n; w++) {				\
+      if ((word = (v).data[w]) != WORD_MAX) break;		\
+    }								\
+    (b) = ((word & 0xFFFF) == 0xFFFF) << 4; word >>= (b);	\
+    sh = ((word & 0xFF) == 0xFF) << 3; word >>= sh; (b) |= sh;	\
+    sh = ((word & 0xF) == 0xF) << 2; word >>= sh; (b) |= sh;	\
+    sh = ((word & 0x3) == 0x3) << 1; word >>= sh; (b) |= sh;	\
+    sh = ((word & 0x1) == 0x1) << 0; word >>= sh; (b) |= sh;	\
+    (b) += (w * WORD_SIZE);					\
+  } while (0)
+
+#endif
diff --git a/lib/libospf.h b/lib/libospf.h
index 856c76df55..ade774db6d 100644
--- a/lib/libospf.h
+++ b/lib/libospf.h
@@ -80,6 +80,7 @@
 #define OSPF_FAST_HELLO_DEFAULT             0
 
 #define OSPF_AREA_BACKBONE              0x00000000      /* 0.0.0.0 */
+#define OSPF_AREA_RANGE_COST_UNSPEC	-1U
 
 /* SPF Throttling timer values. */
 #define OSPF_SPF_DELAY_DEFAULT              200
diff --git a/lib/zclient.c b/lib/zclient.c
index d8ef0e8536..24962bac34 100644
--- a/lib/zclient.c
+++ b/lib/zclient.c
@@ -584,7 +584,15 @@ zapi_ipv6_route (u_char cmd, struct zclient *zclient, struct prefix_ipv6 *p,
   /* Nexthop, ifindex, distance and metric information. */
   if (CHECK_FLAG (api->message, ZAPI_MESSAGE_NEXTHOP))
     {
-      stream_putc (s, api->nexthop_num + api->ifindex_num);
+      if (CHECK_FLAG (api->flags, ZEBRA_FLAG_BLACKHOLE))
+        {
+          stream_putc (s, 1);
+          stream_putc (s, ZEBRA_NEXTHOP_BLACKHOLE);
+          /* XXX assert(api->nexthop_num == 0); */
+          /* XXX assert(api->ifindex_num == 0); */
+        }
+      else
+	stream_putc (s, api->nexthop_num + api->ifindex_num);
 
       for (i = 0; i < api->nexthop_num; i++)
 	{
diff --git a/ospf6d/ospf6_abr.c b/ospf6d/ospf6_abr.c
index bb79900e5d..f975ce8427 100644
--- a/ospf6d/ospf6_abr.c
+++ b/ospf6d/ospf6_abr.c
@@ -38,6 +38,7 @@
 #include "ospf6_route.h"
 #include "ospf6_lsdb.h"
 #include "ospf6_message.h"
+#include "ospf6_zebra.h"
 
 #include "ospf6_top.h"
 #include "ospf6_area.h"
@@ -67,6 +68,33 @@ ospf6_is_router_abr (struct ospf6 *o)
   return 0;
 }
 
+static int
+ospf6_abr_nexthops_belong_to_area (struct ospf6_route *route,
+				   struct ospf6_area *area)
+{
+  struct ospf6_interface *oi;
+
+  oi = ospf6_interface_lookup_by_ifindex (ospf6_route_get_first_nh_index(route));
+  if (oi && oi->area && oi->area == area)
+    return 1;
+  else
+    return 0;
+}
+
+static void
+ospf6_abr_delete_route (struct ospf6_route *range, struct ospf6_route *summary,
+			struct ospf6_route_table *summary_table,
+			struct ospf6_lsa *old)
+{
+  if (summary)
+    {
+      ospf6_route_remove (summary, summary_table);
+    }
+
+  if (old)
+    ospf6_lsa_purge (old);
+}
+
 void
 ospf6_abr_enable_area (struct ospf6_area *area)
 {
@@ -139,12 +167,11 @@ ospf6_abr_disable_area (struct ospf6_area *area)
 }
 
 /* RFC 2328 12.4.3. Summary-LSAs */
-void
+int
 ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
                                      struct ospf6_area *area)
 {
   struct ospf6_lsa *lsa, *old = NULL;
-  struct ospf6_interface *oi;
   struct ospf6_route *summary, *range = NULL;
   struct ospf6_area *route_area;
   char buffer[OSPF6_MAX_LSASIZE];
@@ -157,6 +184,54 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
   char buf[64];
   int is_debug = 0;
 
+  /* Only destination type network, range or ASBR are considered */
+  if (route->type != OSPF6_DEST_TYPE_NETWORK &&
+      route->type != OSPF6_DEST_TYPE_RANGE &&
+      ((route->type != OSPF6_DEST_TYPE_ROUTER) ||
+       !CHECK_FLAG (route->path.router_bits, OSPF6_ROUTER_BIT_E)))
+    {
+      if (is_debug)
+        zlog_debug ("Route type is none of network, range nor ASBR, ignore");
+      return 0;
+    }
+
+  /* AS External routes are never considered */
+  if (route->path.type == OSPF6_PATH_TYPE_EXTERNAL1 ||
+      route->path.type == OSPF6_PATH_TYPE_EXTERNAL2)
+    {
+      if (is_debug)
+        zlog_debug ("Path type is external, skip");
+      return 0;
+    }
+
+  /* do not generate if the path's area is the same as target area */
+  if (route->path.area_id == area->area_id)
+    {
+      if (is_debug)
+        zlog_debug ("The route is in the area itself, ignore");
+      return 0;
+    }
+
+  /* do not generate if the nexthops belongs to the target area */
+  if (ospf6_abr_nexthops_belong_to_area (route, area))
+    {
+      if (is_debug)
+        zlog_debug ("The route's nexthop is in the same area, ignore");
+      return 0;
+    }
+
+  if (route->type == OSPF6_DEST_TYPE_ROUTER)
+    {
+      if (ADV_ROUTER_IN_PREFIX (&route->prefix) == area->ospf6->router_id)
+	{
+          inet_ntop (AF_INET, &(ADV_ROUTER_IN_PREFIX (&route->prefix)), buf,
+		     sizeof (buf));
+	  zlog_debug ("%s: Skipping ASBR announcement for ABR (%s)", __func__,
+		      buf);
+	  return 0;
+	}
+    }
+
   if (route->type == OSPF6_DEST_TYPE_ROUTER)
     {
       if (IS_OSPF6_DEBUG_ABR || IS_OSPF6_DEBUG_ORIGINATE (INTER_ROUTER))
@@ -192,76 +267,53 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
     {
       if (is_debug)
         zlog_debug ("The route has just removed, purge previous LSA");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
-    }
 
-  /* Only destination type network, range or ASBR are considered */
-  if (route->type != OSPF6_DEST_TYPE_NETWORK &&
-      route->type != OSPF6_DEST_TYPE_RANGE &&
-      (route->type != OSPF6_DEST_TYPE_ROUTER ||
-       ! CHECK_FLAG (route->path.router_bits, OSPF6_ROUTER_BIT_E)))
-    {
-      if (is_debug)
-        zlog_debug ("Route type is none of network, range nor ASBR, withdraw");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
-    }
+      if (route->type == OSPF6_DEST_TYPE_RANGE)
+	{
+	  /* Whether the route have active longer prefix */
+	  if (! CHECK_FLAG (route->flag, OSPF6_ROUTE_ACTIVE_SUMMARY))
+	    {
+	      if (is_debug)
+		zlog_debug ("The range is not active. withdraw");
+
+	      ospf6_abr_delete_route (route, summary, summary_table, old);
+	    }
+	}
+      else
+	if (old)
+	  ospf6_lsa_purge (old);
 
-  /* AS External routes are never considered */
-  if (route->path.type == OSPF6_PATH_TYPE_EXTERNAL1 ||
-      route->path.type == OSPF6_PATH_TYPE_EXTERNAL2)
-    {
-      if (is_debug)
-        zlog_debug ("Path type is external, withdraw");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
+      return 0;
     }
 
-  /* do not generate if the path's area is the same as target area */
-  if (route->path.area_id == area->area_id)
+  if ((route->type == OSPF6_DEST_TYPE_ROUTER) && IS_AREA_STUB(area))
     {
       if (is_debug)
-        zlog_debug ("The route is in the area itself, ignore");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
-    }
+        zlog_debug ("Area has been stubbed, purge Inter-Router LSA");
 
-  /* do not generate if the nexthops belongs to the target area */
-  oi = ospf6_interface_lookup_by_ifindex (route->nexthop[0].ifindex);
-  if (oi && oi->area && oi->area == area)
-    {
-      if (is_debug)
-        zlog_debug ("The route's nexthop is in the same area, ignore");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
+      ospf6_abr_delete_route (route, summary, summary_table, old);
+      return 0;
     }
 
   /* do not generate if the route cost is greater or equal to LSInfinity */
   if (route->path.cost >= OSPF_LS_INFINITY)
     {
-      if (is_debug)
-        zlog_debug ("The cost exceeds LSInfinity, withdraw");
-      if (summary)
-        ospf6_route_remove (summary, summary_table);
-      if (old)
-        ospf6_lsa_purge (old);
-      return;
+      /* When we're clearing the range route because all active prefixes
+       * under the range are gone, we set the range's cost to
+       * OSPF_AREA_RANGE_COST_UNSPEC, which is > OSPF_LS_INFINITY. We
+       * don't want to trigger the code here for that. This code is for
+       * handling routes that have gone to infinity. The range removal happens
+       * elsewhere.
+       */
+      if ((route->type != OSPF6_DEST_TYPE_RANGE) &&
+	  (route->path.cost != OSPF_AREA_RANGE_COST_UNSPEC))
+	{
+	  if (is_debug)
+	    zlog_debug ("The cost exceeds LSInfinity, withdraw");
+	  if (old)
+	    ospf6_lsa_purge (old);
+	  return 0;
+	}
     }
 
   /* if this is a route to ASBR */
@@ -272,11 +324,8 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
         {
           if (is_debug)
             zlog_debug ("This is the secondary path to the ASBR, ignore");
-          if (summary)
-            ospf6_route_remove (summary, summary_table);
-          if (old)
-            ospf6_lsa_purge (old);
-          return;
+	  ospf6_abr_delete_route (route, summary, summary_table, old);
+          return 0;
         }
 
       /* Do not generate if the area is stub */
@@ -305,12 +354,8 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
               zlog_debug ("Suppressed by range %s of area %s",
                          buf, route_area->name);
             }
-
-          if (summary)
-            ospf6_route_remove (summary, summary_table);
-          if (old)
-            ospf6_lsa_purge (old);
-          return;
+	  ospf6_abr_delete_route (route, summary, summary_table, old);
+          return 0;
         }
     }
 
@@ -322,23 +367,17 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
         {
           if (is_debug)
             zlog_debug ("This is the range with DoNotAdvertise set. ignore");
-          if (summary)
-            ospf6_route_remove (summary, summary_table);
-          if (old)
-            ospf6_lsa_purge (old);
-          return;
+	  ospf6_abr_delete_route (route, summary, summary_table, old);
+	  return 0;
         }
 
-      /* Whether the route have active longer prefix */
+      /* If there are no active prefixes in this range, remove */
       if (! CHECK_FLAG (route->flag, OSPF6_ROUTE_ACTIVE_SUMMARY))
         {
           if (is_debug)
             zlog_debug ("The range is not active. withdraw");
-          if (summary)
-            ospf6_route_remove (summary, summary_table);
-          if (old)
-            ospf6_lsa_purge (old);
-          return;
+	  ospf6_abr_delete_route (route, summary, summary_table, old);
+          return 0;
         }
     }
 
@@ -359,7 +398,7 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
                            buf, sizeof(buf));
                 zlog_debug ("prefix %s was denied by export list", buf);
               }
-            return;
+            return 0;
           }
     }
 
@@ -380,7 +419,7 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
                             buf, sizeof (buf));
                  zlog_debug ("prefix %s was denied by filter-list out", buf);
                }
-             return;
+             return 0;
            }
     }
 
@@ -388,16 +427,25 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
   if (summary == NULL)
     {
       summary = ospf6_route_copy (route);
-      if (route->type == OSPF6_DEST_TYPE_NETWORK ||
-          route->type == OSPF6_DEST_TYPE_RANGE)
-        summary->path.origin.type = htons (OSPF6_LSTYPE_INTER_PREFIX);
-      else
-        summary->path.origin.type = htons (OSPF6_LSTYPE_INTER_ROUTER);
       summary->path.origin.adv_router = area->ospf6->router_id;
-      summary->path.origin.id =
-        ospf6_new_ls_id (summary->path.origin.type,
-                         summary->path.origin.adv_router, area->lsdb);
+
+      if (route->type == OSPF6_DEST_TYPE_ROUTER)
+	{
+	  summary->path.origin.type = htons (OSPF6_LSTYPE_INTER_ROUTER);
+	  summary->path.origin.id = ADV_ROUTER_IN_PREFIX (&route->prefix);
+	}
+      else
+	{
+	  summary->path.origin.type = htons (OSPF6_LSTYPE_INTER_PREFIX);
+	  if (route->type == OSPF6_DEST_TYPE_RANGE)
+	    summary->path.origin.id  = route->linkstate_id;
+	  else
+	    summary->path.origin.id =
+	      ospf6_new_ls_id (summary->path.origin.type,
+			       summary->path.origin.adv_router, area->lsdb);
+	}
       summary = ospf6_route_add (summary, summary_table);
+
     }
   else
     {
@@ -413,7 +461,7 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
   summary->path.area_id = area->area_id;
   summary->path.type = OSPF6_PATH_TYPE_INTER;
   summary->path.cost = route->path.cost;
-  summary->nexthop[0] = route->nexthop[0];
+    /* summary->nexthop[0] = route->nexthop[0]; */
 
   /* prepare buffer */
   memset (buffer, 0, sizeof (buffer));
@@ -470,35 +518,100 @@ ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
 
   /* Originate */
   ospf6_lsa_originate_area (lsa, area);
+
+  return 1;
 }
 
-static void
+void
 ospf6_abr_range_update (struct ospf6_route *range)
 {
   u_int32_t cost = 0;
   struct ospf6_route *ro;
+  int gen_range_summary = 0;
+  char buf[INET6_ADDRSTRLEN];
 
   assert (range->type == OSPF6_DEST_TYPE_RANGE);
+  prefix2str (&range->prefix, buf, sizeof (buf));
 
-  /* update range's cost and active flag */
-  for (ro = ospf6_route_match_head (&range->prefix, ospf6->route_table);
-       ro; ro = ospf6_route_match_next (&range->prefix, ro))
+  if (CHECK_FLAG(range->flag, OSPF6_ROUTE_REMOVE))
     {
-      if (ro->path.area_id == range->path.area_id &&
-          ! CHECK_FLAG (ro->flag, OSPF6_ROUTE_REMOVE))
-        cost = MAX (cost, ro->path.cost);
+      UNSET_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY);
+      gen_range_summary = 1;
     }
-
-  if (range->path.cost != cost)
+  else
     {
-      range->path.cost = cost;
+      /* update range's cost and active flag */
+      for (ro = ospf6_route_match_head (&range->prefix, ospf6->route_table);
+	   ro; ro = ospf6_route_match_next (&range->prefix, ro))
+	{
+	  if (ro->path.area_id == range->path.area_id &&
+	      (ro->path.type == OSPF6_PATH_TYPE_INTRA) &&
+	      ! CHECK_FLAG (ro->flag, OSPF6_ROUTE_REMOVE))
+	    cost = MAX (cost, ro->path.cost);
+	}
+    }
 
-      if (range->path.cost)
-        SET_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY);
+  /* Non-zero cost is a proxy for active longer prefixes in this range.
+   * If there are active routes covered by this range AND either the configured
+   * cost has changed or the summarized cost has changed then redo summaries.
+   * Alternately, if there are no longer active prefixes and there are
+   * summary announcements, withdraw those announcements.
+   *
+   * The don't advertise code relies on the path.cost being set to UNSPEC to
+   * work the first time. Subsequent times the path.cost is not 0 anyway if there
+   * were active ranges.
+   */
+  if (CHECK_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE))
+    {
+      if (range->path.cost != 0)
+	{
+	  range->path.cost = 0;
+	  gen_range_summary = 1;
+	}
+    }
+  else if (cost &&
+	   (((range->path.u.cost_config != OSPF_AREA_RANGE_COST_UNSPEC) &&
+	     (range->path.cost != range->path.u.cost_config)) ||
+	    ((range->path.u.cost_config == OSPF_AREA_RANGE_COST_UNSPEC) &&
+	     (range->path.cost != cost))))
+    {
+      if (range->path.u.cost_config == OSPF_AREA_RANGE_COST_UNSPEC)
+	{
+	  range->path.cost = cost;
+	}
       else
-        UNSET_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY);
+	{
+	  range->path.cost = range->path.u.cost_config;
+	}
 
+      SET_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY);
+      gen_range_summary = 1;
+    }
+  else if (!cost && CHECK_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY))
+    {
+      UNSET_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY);
+      range->path.cost = OSPF_AREA_RANGE_COST_UNSPEC;
+      gen_range_summary = 1;
+    }
+
+  if (gen_range_summary)
+    {
       ospf6_abr_originate_summary (range);
+
+      if (CHECK_FLAG (range->flag, OSPF6_ROUTE_ACTIVE_SUMMARY))
+	{
+	  if (IS_OSPF6_DEBUG_ABR)
+	    zlog_debug ("Add discard route");
+
+	  ospf6_zebra_add_discard (range);
+	}
+      else
+	{
+	  if (IS_OSPF6_DEBUG_ABR)
+	    zlog_debug ("Delete discard route");
+
+	  ospf6_zebra_delete_discard (range);
+	}
     }
 }
 
@@ -514,7 +627,9 @@ ospf6_abr_originate_summary (struct ospf6_route *route)
       oa = ospf6_area_lookup (route->path.area_id, ospf6);
       range = ospf6_route_lookup_bestmatch (&route->prefix, oa->range_table);
       if (range)
-        ospf6_abr_range_update (range);
+	{
+	  ospf6_abr_range_update (range);
+	}
     }
 
   for (ALL_LIST_ELEMENTS (ospf6->area_list, node, nnode, oa))
@@ -534,7 +649,6 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
   u_int8_t prefix_options = 0;
   u_int32_t cost = 0;
   u_char router_bits = 0;
-  int i;
   char buf[64];
   int is_debug = 0;
   struct ospf6_inter_prefix_lsa *prefix_lsa = NULL;
@@ -575,6 +689,7 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
       ospf6_linkstate_prefix (router_lsa->router_id, htonl (0), &prefix);
       if (is_debug)
         inet_ntop (AF_INET, &router_lsa->router_id, buf, sizeof (buf));
+
       table = oa->ospf6->brouter_table;
       type = OSPF6_DEST_TYPE_ROUTER;
       options[0] = router_lsa->options[0];
@@ -600,6 +715,8 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
         old = route;
       route = ospf6_route_next (route);
     }
+  if (route)
+    ospf6_route_unlock (route);
 
   /* (1) if cost == LSInfinity or if the LSA is MaxAge */
   if (cost == OSPF_LS_INFINITY)
@@ -666,8 +783,22 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
             zlog_debug ("Prefix has NU/LA bit set, ignore");
           if (old)
             ospf6_route_remove (old, table);
+
           return;
 	}
+      /* Avoid infinite recursion if someone has maliciously announced an
+	 Inter-Router LSA for an ABR
+      */
+      if (lsa->header->adv_router == router_lsa->router_id)
+	{
+	  if (is_debug)
+	    zlog_debug ("Ignorning Inter-Router LSA for an ABR (%s)",
+			buf);
+	  if (old)
+	    ospf6_route_remove (old, table);
+
+	  return;
+	}
     }
 
   /* (4) if the routing table entry for the ABR does not exist */
@@ -718,7 +849,7 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
           }
     }
 
-  /* (5),(6),(7) the path preference is handled by the sorting
+  /* (5),(6): the path preference is handled by the sorting
      in the routing table. Always install the path by substituting
      old route (if any). */
   if (old)
@@ -739,12 +870,33 @@ ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa)
   route->path.area_id = oa->area_id;
   route->path.type = OSPF6_PATH_TYPE_INTER;
   route->path.cost = abr_entry->path.cost + cost;
-  for (i = 0; i < OSPF6_MULTI_PATH_LIMIT; i++)
-    route->nexthop[i] = abr_entry->nexthop[i];
 
-  if (is_debug)
-    zlog_debug ("Install route: %s", buf);
-  ospf6_route_add (route, table);
+  ospf6_route_copy_nexthops (route, abr_entry);
+
+  /* (7) If the routes are identical, copy the next hops over to existing
+     route. ospf6's route table implementation will otherwise string both
+     routes, but keep the older one as the best route since the routes
+     are identical.
+  */
+  old = ospf6_route_lookup (&prefix, table);
+
+  if (old && (ospf6_route_cmp (route, old) == 0))
+    {
+      ospf6_route_merge_nexthops (old, route);
+      /* Update RIB/FIB */
+      if (table->hook_add)
+	(*table->hook_add) (old);
+
+      /* Delete new route */
+      ospf6_route_delete (route);
+    }
+  else
+    {
+      if (is_debug)
+	zlog_debug ("Install route: %s", buf);
+      /* ospf6_ia_add_nw_route (table, &prefix, route); */
+      ospf6_route_add (route, table);
+    }
 }
 
 void
@@ -752,21 +904,22 @@ ospf6_abr_examin_brouter (u_int32_t router_id)
 {
   struct ospf6_lsa *lsa;
   struct ospf6_area *oa;
-  struct listnode *node, *nnode;
   u_int16_t type;
 
-  for (ALL_LIST_ELEMENTS (ospf6->area_list, node, nnode, oa))
-    {
-      type = htons (OSPF6_LSTYPE_INTER_ROUTER);
-      for (lsa = ospf6_lsdb_type_router_head (type, router_id, oa->lsdb); lsa;
-           lsa = ospf6_lsdb_type_router_next (type, router_id, lsa))
-        ospf6_abr_examin_summary (lsa, oa);
+  if (ospf6_is_router_abr (ospf6))
+    oa = ospf6->backbone;
+  else
+    oa = listgetdata(listhead(ospf6->area_list));
 
-      type = htons (OSPF6_LSTYPE_INTER_PREFIX);
-      for (lsa = ospf6_lsdb_type_router_head (type, router_id, oa->lsdb); lsa;
-           lsa = ospf6_lsdb_type_router_next (type, router_id, lsa))
-        ospf6_abr_examin_summary (lsa, oa);
-    }
+  type = htons (OSPF6_LSTYPE_INTER_ROUTER);
+  for (lsa = ospf6_lsdb_type_router_head (type, router_id, oa->lsdb); lsa;
+       lsa = ospf6_lsdb_type_router_next (type, router_id, lsa))
+      ospf6_abr_examin_summary (lsa, oa);
+
+  type = htons (OSPF6_LSTYPE_INTER_PREFIX);
+  for (lsa = ospf6_lsdb_type_router_head (type, router_id, oa->lsdb); lsa;
+       lsa = ospf6_lsdb_type_router_next (type, router_id, lsa))
+    ospf6_abr_examin_summary (lsa, oa);
 }
 
 void
diff --git a/ospf6d/ospf6_abr.h b/ospf6d/ospf6_abr.h
index 816f596451..09b1d87c45 100644
--- a/ospf6d/ospf6_abr.h
+++ b/ospf6d/ospf6_abr.h
@@ -62,12 +62,13 @@ extern int ospf6_is_router_abr (struct ospf6 *o);
 extern void ospf6_abr_enable_area (struct ospf6_area *oa);
 extern void ospf6_abr_disable_area (struct ospf6_area *oa);
 
-extern void ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
+extern int ospf6_abr_originate_summary_to_area (struct ospf6_route *route,
                                                 struct ospf6_area *area);
 extern void ospf6_abr_originate_summary (struct ospf6_route *route);
 extern void ospf6_abr_examin_summary (struct ospf6_lsa *lsa, struct ospf6_area *oa);
 extern void ospf6_abr_examin_brouter (u_int32_t router_id);
 extern void ospf6_abr_reimport (struct ospf6_area *oa);
+extern void ospf6_abr_range_update (struct ospf6_route *range);
 
 extern int config_write_ospf6_debug_abr (struct vty *vty);
 extern void install_element_ospf6_debug_abr (void);
diff --git a/ospf6d/ospf6_area.c b/ospf6d/ospf6_area.c
index 4b4ca1304a..12ab7ce033 100644
--- a/ospf6d/ospf6_area.c
+++ b/ospf6d/ospf6_area.c
@@ -160,6 +160,7 @@ ospf6_area_create (u_int32_t area_id, struct ospf6 *o)
 
   oa->range_table = OSPF6_ROUTE_TABLE_CREATE (AREA, PREFIX_RANGES);
   oa->range_table->scope = oa;
+  bf_init(oa->range_table->idspace, 32);
   oa->summary_prefix = OSPF6_ROUTE_TABLE_CREATE (AREA, SUMMARY_PREFIXES);
   oa->summary_prefix->scope = oa;
   oa->summary_router = OSPF6_ROUTE_TABLE_CREATE (AREA, SUMMARY_ROUTERS);
@@ -182,6 +183,11 @@ ospf6_area_create (u_int32_t area_id, struct ospf6 *o)
   oa->ospf6 = o;
   listnode_add_sort (o->area_list, oa);
 
+  if (area_id == OSPF_AREA_BACKBONE)
+    {
+      o->backbone = oa;
+    }
+
   /* import athoer area's routes as inter-area routes */
   for (route = ospf6_route_head (o->route_table); route;
        route = ospf6_route_next (route))
@@ -196,10 +202,6 @@ ospf6_area_delete (struct ospf6_area *oa)
   struct listnode *n;
   struct ospf6_interface *oi;
 
-  ospf6_route_table_delete (oa->range_table);
-  ospf6_route_table_delete (oa->summary_prefix);
-  ospf6_route_table_delete (oa->summary_router);
-
   /* The ospf6_interface structs store configuration
    * information which should not be lost/reset when
    * deleting an area.
@@ -217,8 +219,9 @@ ospf6_area_delete (struct ospf6_area *oa)
   ospf6_route_table_delete (oa->spf_table);
   ospf6_route_table_delete (oa->route_table);
 
-  THREAD_OFF (oa->thread_spf_calculation);
-  THREAD_OFF (oa->thread_route_calculation);
+  ospf6_route_table_delete (oa->range_table);
+  ospf6_route_table_delete (oa->summary_prefix);
+  ospf6_route_table_delete (oa->summary_router);
 
   listnode_delete (oa->ospf6->area_list, oa);
   oa->ospf6 = NULL;
@@ -281,9 +284,6 @@ ospf6_area_disable (struct ospf6_area *oa)
   ospf6_spf_table_finish(oa->spf_table);
   ospf6_route_remove_all(oa->route_table);
 
-  THREAD_OFF (oa->thread_spf_calculation);
-  THREAD_OFF (oa->thread_route_calculation);
-
   THREAD_OFF (oa->thread_router_lsa);
   THREAD_OFF (oa->thread_intra_prefix_lsa);
 }
@@ -346,20 +346,17 @@ DEFUN (area_range,
   int ret;
   struct ospf6_area *oa;
   struct prefix prefix;
-  struct ospf6_route *range;
+  struct ospf6_route *range, *route;
+  u_int32_t cost = OSPF_AREA_RANGE_COST_UNSPEC;
 
   OSPF6_CMD_AREA_GET (argv[0], oa);
-  argc--;
-  argv++;
 
-  ret = str2prefix (argv[0], &prefix);
+  ret = str2prefix (argv[1], &prefix);
   if (ret != 1 || prefix.family != AF_INET6)
     {
-      vty_out (vty, "Malformed argument: %s%s", argv[0], VNL);
+      vty_out (vty, "Malformed argument: %s%s", argv[1], VNL);
       return CMD_SUCCESS;
     }
-  argc--;
-  argv++;
 
   range = ospf6_route_lookup (&prefix, oa->range_table);
   if (range == NULL)
@@ -367,23 +364,45 @@ DEFUN (area_range,
       range = ospf6_route_create ();
       range->type = OSPF6_DEST_TYPE_RANGE;
       range->prefix = prefix;
+      range->path.area_id = oa->area_id;
+      range->path.cost = OSPF_AREA_RANGE_COST_UNSPEC;
+      range->linkstate_id =
+	(u_int32_t) htonl(ospf6_new_range_ls_id (oa->range_table));
     }
 
-  if (argc)
+  if (argc > 2)
     {
-      if (! strcmp (argv[0], "not-advertise"))
-        SET_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE);
-      else if (! strcmp (argv[0], "advertise"))
-        UNSET_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE);
+      if (strcmp (argv[2], "not-advertise") == 0)
+	{
+	  SET_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE);
+	}
+      else if (strcmp (argv[2], "advertise") == 0)
+	{
+	  UNSET_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE);
+	}
+      else
+	{
+	  VTY_GET_INTEGER_RANGE ("cost", cost, argv[2], 0, OSPF_LS_INFINITY);
+	  UNSET_FLAG (range->flag, OSPF6_ROUTE_DO_NOT_ADVERTISE);
+	}
     }
 
-  if (range->rnode)
+  range->path.u.cost_config = cost;
+
+  zlog_debug ("%s: for prefix %s, flag = %x\n", __func__, argv[1], range->flag);
+  if (range->rnode == NULL)
     {
-      vty_out (vty, "Range already defined: %s%s", argv[-1], VNL);
-      return CMD_WARNING;
+      ospf6_route_add (range, oa->range_table);
+    }
+
+  if (ospf6_is_router_abr (ospf6))
+    {
+      /* Redo summaries if required */
+      for (route = ospf6_route_head (ospf6->route_table); route;
+	   route = ospf6_route_next (route))
+	ospf6_abr_originate_summary(route);
     }
 
-  ospf6_route_add (range, oa->range_table);
   return CMD_SUCCESS;
 }
 
@@ -396,6 +415,26 @@ ALIAS (area_range,
        "Specify IPv6 prefix\n"
        )
 
+ALIAS (area_range,
+       area_range_cost_cmd,
+       "area (A.B.C.D|<0-4294967295>) range X:X::X:X/M cost <0-16777215>",
+       "OSPF area parameters\n"
+       OSPF6_AREA_ID_STR
+       "Summarize routes matching address/mask (border routers only)\n"
+       "Area range prefix\n"
+       "User specified metric for this range\n"
+       "Advertised metric for this range\n")
+
+ALIAS (area_range,
+       area_range_advertise_cost_cmd,
+       "area (A.B.C.D|<0-4294967295>) range X:X::X:X/M advertise cost <0-16777215>",
+       "OSPF area parameters\n"
+       OSPF6_AREA_ID_STR
+       "Summarize routes matching address/mask (border routers only)\n"
+       "Area range prefix\n"
+       "User specified metric for this range\n"
+       "Advertised metric for this range\n")
+
 DEFUN (no_area_range,
        no_area_range_cmd,
        "no area A.B.C.D range X:X::X:X/M",
@@ -408,7 +447,7 @@ DEFUN (no_area_range,
   int ret;
   struct ospf6_area *oa;
   struct prefix prefix;
-  struct ospf6_route *range;
+  struct ospf6_route *range, *route;
 
   OSPF6_CMD_AREA_GET (argv[0], oa);
   argc--;
@@ -428,6 +467,21 @@ DEFUN (no_area_range,
       return CMD_SUCCESS;
     }
 
+  if (ospf6_is_router_abr(oa->ospf6))
+    {
+      /* Blow away the aggregated LSA and route */
+      SET_FLAG (range->flag, OSPF6_ROUTE_REMOVE);
+
+      /* Redo summaries if required */
+      for (route = ospf6_route_head (ospf6->route_table); route;
+	   route = ospf6_route_next (route))
+	ospf6_abr_originate_summary(route);
+
+      /* purge the old aggregated summary LSA */
+      ospf6_abr_originate_summary(range);
+    }
+  ospf6_release_range_ls_id(oa->range_table,
+			    (u_int32_t) ntohl(range->linkstate_id));
   ospf6_route_remove (range, oa->range_table);
 
   return CMD_SUCCESS;
@@ -801,6 +855,8 @@ ospf6_area_init (void)
 
   install_element (OSPF6_NODE, &area_range_cmd);
   install_element (OSPF6_NODE, &area_range_advertise_cmd);
+  install_element (OSPF6_NODE, &area_range_cost_cmd);
+  install_element (OSPF6_NODE, &area_range_advertise_cost_cmd);
   install_element (OSPF6_NODE, &no_area_range_cmd);
 
   install_element (OSPF6_NODE, &area_import_list_cmd);
diff --git a/ospf6d/ospf6_area.h b/ospf6d/ospf6_area.h
index 655967a9a3..6911869069 100644
--- a/ospf6d/ospf6_area.h
+++ b/ospf6d/ospf6_area.h
@@ -55,8 +55,6 @@ struct ospf6_area
   struct ospf6_route_table *spf_table;
   struct ospf6_route_table *route_table;
 
-  struct thread  *thread_spf_calculation;
-  struct thread  *thread_route_calculation;
   u_int32_t spf_calculation;	/* SPF calculation count */
 
   struct thread *thread_router_lsa;
@@ -98,6 +96,8 @@ struct ospf6_area
 #define PREFIX_NAME_OUT(A)  (A)->plist_out.name
 #define PREFIX_LIST_OUT(A)  (A)->plist_out.list
 
+  /* Time stamps. */
+  struct timeval ts_spf;		/* SPF calculation time stamp. */
 };
 
 #define OSPF6_AREA_ENABLE     0x01
diff --git a/ospf6d/ospf6_asbr.c b/ospf6d/ospf6_asbr.c
index 4d86c31e46..880e10ed68 100644
--- a/ospf6d/ospf6_asbr.c
+++ b/ospf6d/ospf6_asbr.c
@@ -159,7 +159,6 @@ ospf6_asbr_lsa_add (struct ospf6_lsa *lsa)
   struct prefix asbr_id;
   struct ospf6_route *asbr_entry, *route;
   char buf[64];
-  int i;
 
   external = (struct ospf6_as_external_lsa *)
     OSPF6_LSA_HEADER_END (lsa->header);
@@ -218,18 +217,17 @@ ospf6_asbr_lsa_add (struct ospf6_lsa *lsa)
       route->path.type = OSPF6_PATH_TYPE_EXTERNAL2;
       route->path.metric_type = 2;
       route->path.cost = asbr_entry->path.cost;
-      route->path.cost_e2 = OSPF6_ASBR_METRIC (external);
+      route->path.u.cost_e2 = OSPF6_ASBR_METRIC (external);
     }
   else
     {
       route->path.type = OSPF6_PATH_TYPE_EXTERNAL1;
       route->path.metric_type = 1;
       route->path.cost = asbr_entry->path.cost + OSPF6_ASBR_METRIC (external);
-      route->path.cost_e2 = 0;
+      route->path.u.cost_e2 = 0;
     }
 
-  for (i = 0; i < OSPF6_MULTI_PATH_LIMIT; i++)
-    ospf6_nexthop_copy (&route->nexthop[i], &asbr_entry->nexthop[i]);
+  ospf6_route_copy_nexthops (route, asbr_entry);
 
   if (IS_OSPF6_DEBUG_EXAMIN (AS_EXTERNAL))
     {
@@ -408,8 +406,7 @@ ospf6_asbr_redistribute_unset (int type)
       if (info->type != type)
         continue;
 
-      ospf6_asbr_redistribute_remove (info->type, route->nexthop[0].ifindex,
-                                      &route->prefix);
+      ospf6_asbr_redistribute_remove (info->type, 0, &route->prefix);
     }
 
   ospf6_asbr_routemap_unset (type);
@@ -488,9 +485,11 @@ ospf6_asbr_redistribute_add (int type, int ifindex, struct prefix *prefix,
         }
 
       info->type = type;
-      match->nexthop[0].ifindex = ifindex;
+
       if (nexthop_num && nexthop)
-        memcpy (&match->nexthop[0].address, nexthop, sizeof (struct in6_addr));
+	ospf6_route_add_nexthop (match, ifindex, nexthop);
+      else
+	ospf6_route_add_nexthop (match, ifindex, NULL);
 
       /* create/update binding in external_id_table */
       prefix_id.family = AF_INET;
@@ -533,9 +532,10 @@ ospf6_asbr_redistribute_add (int type, int ifindex, struct prefix *prefix,
     }
 
   info->type = type;
-  route->nexthop[0].ifindex = ifindex;
   if (nexthop_num && nexthop)
-    memcpy (&route->nexthop[0].address, nexthop, sizeof (struct in6_addr));
+    ospf6_route_add_nexthop (route, ifindex, nexthop);
+  else
+    ospf6_route_add_nexthop (route, ifindex, NULL);
 
   /* create/update binding in external_id_table */
   prefix_id.family = AF_INET;
@@ -1274,13 +1274,13 @@ ospf6_asbr_external_route_show (struct vty *vty, struct ospf6_route *route)
     inet_ntop (AF_INET6, &info->forwarding, forwarding, sizeof (forwarding));
   else
     snprintf (forwarding, sizeof (forwarding), ":: (ifindex %d)",
-              route->nexthop[0].ifindex);
+              ospf6_route_get_first_nh_index (route));
 
   vty_out (vty, "%c %-32s %-15s type-%d %5lu %s%s",
            zebra_route_char(info->type),
            prefix, id, route->path.metric_type,
            (u_long) (route->path.metric_type == 2 ?
-                     route->path.cost_e2 : route->path.cost),
+                     route->path.u.cost_e2 : route->path.cost),
            forwarding, VNL);
 }
 
diff --git a/ospf6d/ospf6_flood.c b/ospf6d/ospf6_flood.c
index 49ed6e265e..4d537f6eda 100644
--- a/ospf6d/ospf6_flood.c
+++ b/ospf6d/ospf6_flood.c
@@ -892,6 +892,9 @@ ospf6_receive_lsa (struct ospf6_neighbor *from,
               table calculation (replacing database copy) */
       ospf6_install_lsa (new);
 
+      if (OSPF6_LSA_IS_MAXAGE (new))
+	ospf6_maxage_remove (from->ospf6_if->area->ospf6);
+
       /* (e) possibly acknowledge */
       ospf6_acknowledge_lsa (new, ismore_recent, from);
 
diff --git a/ospf6d/ospf6_interface.c b/ospf6d/ospf6_interface.c
index f0ef790933..cdea9c4a24 100644
--- a/ospf6d/ospf6_interface.c
+++ b/ospf6d/ospf6_interface.c
@@ -391,6 +391,7 @@ ospf6_interface_connected_route_update (struct interface *ifp)
   struct ospf6_route *route;
   struct connected *c;
   struct listnode *node, *nnode;
+  struct in6_addr nh_addr;
 
   oi = (struct ospf6_interface *) ifp->info;
   if (oi == NULL)
@@ -446,8 +447,8 @@ ospf6_interface_connected_route_update (struct interface *ifp)
       route->path.area_id = oi->area->area_id;
       route->path.type = OSPF6_PATH_TYPE_INTRA;
       route->path.cost = oi->cost;
-      route->nexthop[0].ifindex = oi->interface->ifindex;
-      inet_pton (AF_INET6, "::1", &route->nexthop[0].address);
+      inet_pton (AF_INET6, "::1", &nh_addr);
+      ospf6_route_add_nexthop (route, oi->interface->ifindex, &nh_addr);
       ospf6_route_add (route, oi->route_connected);
     }
 
diff --git a/ospf6d/ospf6_intra.c b/ospf6d/ospf6_intra.c
index 4ad7521e93..a220437af3 100644
--- a/ospf6d/ospf6_intra.c
+++ b/ospf6d/ospf6_intra.c
@@ -228,7 +228,7 @@ ospf6_router_lsa_originate (struct thread *thread)
       for (ALL_LIST_ELEMENTS_RO (oi->neighbor_list, j, on))
         if (on->state == OSPF6_NEIGHBOR_FULL)
           count++;
-      
+
       if (count == 0)
         continue;
 
@@ -355,14 +355,25 @@ ospf6_router_lsa_originate (struct thread *thread)
   /* Do premature-aging of rest, undesired Router-LSAs */
   type = ntohs (OSPF6_LSTYPE_ROUTER);
   router = oa->ospf6->router_id;
+  count = 0;
   for (lsa = ospf6_lsdb_type_router_head (type, router, oa->lsdb); lsa;
        lsa = ospf6_lsdb_type_router_next (type, router, lsa))
     {
       if (ntohl (lsa->header->id) < link_state_id)
         continue;
       ospf6_lsa_purge (lsa);
+      count++;
     }
 
+  /*
+   * Waiting till the LSA is actually removed from the database to trigger
+   * SPF delays network convergence. Unlike IPv4, for an ABR, when all
+   * interfaces associated with an area are gone, triggering an SPF right away
+   * helps convergence with inter-area routes.
+   */
+  if (count && !link_state_id)
+    ospf6_spf_schedule (oa->ospf6, OSPF6_SPF_FLAGS_ROUTER_LSA_ORIGINATED);
+
   return 0;
 }
 
@@ -459,7 +470,15 @@ ospf6_network_lsa_originate (struct thread *thread)
   if (oi->state != OSPF6_INTERFACE_DR)
     {
       if (old)
-        ospf6_lsa_purge (old);
+	{
+	  ospf6_lsa_purge (old);
+	    /*
+	     * Waiting till the LSA is actually removed from the database to
+	     * trigger SPF delays network convergence.
+	     */
+	  ospf6_spf_schedule (oi->area->ospf6,
+			      OSPF6_SPF_FLAGS_NETWORK_LSA_ORIGINATED);
+	}
       return 0;
     }
 
@@ -468,11 +487,11 @@ ospf6_network_lsa_originate (struct thread *thread)
 
   /* If none of neighbor is adjacent to us */
   count = 0;
-  
+
   for (ALL_LIST_ELEMENTS_RO (oi->neighbor_list, i, on))
     if (on->state == OSPF6_NEIGHBOR_FULL)
       count++;
-  
+
   if (count == 0)
     {
       if (IS_OSPF6_DEBUG_ORIGINATE (NETWORK))
@@ -1078,7 +1097,7 @@ ospf6_intra_prefix_lsa_originate_transit (struct thread *thread)
   for (ALL_LIST_ELEMENTS_RO (oi->neighbor_list, i, on))
     if (on->state == OSPF6_NEIGHBOR_FULL)
       full_count++;
-  
+
   if (full_count == 0)
     {
       if (IS_OSPF6_DEBUG_ORIGINATE (INTRA_PREFIX))
@@ -1214,7 +1233,7 @@ ospf6_intra_prefix_lsa_add (struct ospf6_lsa *lsa)
   struct ospf6_intra_prefix_lsa *intra_prefix_lsa;
   struct prefix ls_prefix;
   struct ospf6_route *route, *ls_entry;
-  int i, prefix_num;
+  int prefix_num;
   struct ospf6_prefix *op;
   char *start, *current, *end;
   char buf[64];
@@ -1310,13 +1329,11 @@ ospf6_intra_prefix_lsa_add (struct ospf6_lsa *lsa)
         {
           ifp = if_lookup_prefix(&route->prefix);
           if (ifp)
-            route->nexthop[0].ifindex = ifp->ifindex;
+	    ospf6_route_add_nexthop (route, ifp->ifindex, NULL);
         }
       else
         {
-          for (i = 0; ospf6_nexthop_is_set (&ls_entry->nexthop[i]) &&
-               i < OSPF6_MULTI_PATH_LIMIT; i++)
-            ospf6_nexthop_copy (&route->nexthop[i], &ls_entry->nexthop[i]);
+	  ospf6_route_copy_nexthops (route, ls_entry);
         }
 
       if (IS_OSPF6_DEBUG_EXAMIN (INTRA_PREFIX))
@@ -1509,7 +1526,7 @@ ospf6_brouter_debug_print (struct ospf6_route *brouter)
              id, adv_router);
   zlog_info ("  options: %s router-bits: %s metric-type: %d metric: %d/%d",
              options, capa, brouter->path.metric_type,
-             brouter->path.cost, brouter->path.cost_e2);
+             brouter->path.cost, brouter->path.u.cost_e2);
 }
 
 void
diff --git a/ospf6d/ospf6_lsdb.c b/ospf6d/ospf6_lsdb.c
index 707afc67eb..37259d6c7c 100644
--- a/ospf6d/ospf6_lsdb.c
+++ b/ospf6d/ospf6_lsdb.c
@@ -31,7 +31,9 @@
 #include "ospf6_proto.h"
 #include "ospf6_lsa.h"
 #include "ospf6_lsdb.h"
+#include "ospf6_route.h"
 #include "ospf6d.h"
+#include "bitfield.h"
 
 struct ospf6_lsdb *
 ospf6_lsdb_create (void *data)
@@ -538,21 +540,42 @@ ospf6_lsdb_show (struct vty *vty, int level,
     }
 }
 
-/* Decide new Link State ID to originate.
-   note return value is network byte order */
+/* Decide new Link State ID to originate for the range. */
+u_int32_t
+ospf6_new_range_ls_id (struct ospf6_route_table *range_table)
+{
+  u_int32_t id;
+
+  bf_assign_index(range_table->idspace, id);
+  return (id);
+}
+
+/* Release the LS ID back to the ID pool */
+void
+ospf6_release_range_ls_id (struct ospf6_route_table *range_table,
+			   u_int32_t id)
+{
+  bf_release_index(range_table->idspace, id);
+}
+
 u_int32_t
 ospf6_new_ls_id (u_int16_t type, u_int32_t adv_router,
                  struct ospf6_lsdb *lsdb)
 {
   struct ospf6_lsa *lsa;
-  u_int32_t id = 1;
+  u_int32_t id = 1, tmp_id;
 
+  /* This routine is curently invoked only for Inter-Prefix LSAs for
+   * non-summarized routes (no area/range).
+   */
   for (lsa = ospf6_lsdb_type_router_head (type, adv_router, lsdb); lsa;
        lsa = ospf6_lsdb_type_router_next (type, adv_router, lsa))
     {
-      if (ntohl (lsa->header->id) < id)
-        continue;
-      if (ntohl (lsa->header->id) > id)
+      tmp_id = ntohl (lsa->header->id);
+      if (tmp_id < id)
+	continue;
+
+      if (tmp_id > id)
       {
 	ospf6_lsdb_lsa_unlock (lsa);
         break;
diff --git a/ospf6d/ospf6_lsdb.h b/ospf6d/ospf6_lsdb.h
index a124adbf05..ba4218ae56 100644
--- a/ospf6d/ospf6_lsdb.h
+++ b/ospf6d/ospf6_lsdb.h
@@ -24,6 +24,7 @@
 
 #include "prefix.h"
 #include "table.h"
+#include "ospf6_route.h"
 
 struct ospf6_lsdb
 {
@@ -77,6 +78,9 @@ extern void ospf6_lsdb_show (struct vty *vty, int level, u_int16_t *type,
 
 extern u_int32_t ospf6_new_ls_id (u_int16_t type, u_int32_t adv_router,
                                   struct ospf6_lsdb *lsdb);
+extern u_int32_t ospf6_new_range_ls_id (struct ospf6_route_table *range_table);
+extern void ospf6_release_range_ls_id (struct ospf6_route_table *range_table,
+				       u_int32_t id);
 extern u_int32_t ospf6_new_ls_seqnum (u_int16_t type, u_int32_t id,
                                       u_int32_t adv_router,
                                       struct ospf6_lsdb *lsdb);
diff --git a/ospf6d/ospf6_main.c b/ospf6d/ospf6_main.c
index 4f6d9e5140..8272d4733d 100644
--- a/ospf6d/ospf6_main.c
+++ b/ospf6d/ospf6_main.c
@@ -21,6 +21,7 @@
 
 #include <zebra.h>
 #include <lib/version.h>
+#include <stdlib.h>
 
 #include "getopt.h"
 #include "thread.h"
@@ -237,6 +238,9 @@ main (int argc, char *argv[], char *envp[])
   /* Preserve name of myself. */
   progname = ((p = strrchr (argv[0], '/')) ? ++p : argv[0]);
 
+  /* Seed random number for LSA ID */
+  srand (time(NULL));
+
   /* Command line argument treatment. */
   while (1) 
     {
diff --git a/ospf6d/ospf6_route.c b/ospf6d/ospf6_route.c
index 9e6b33e546..0493e77760 100644
--- a/ospf6d/ospf6_route.c
+++ b/ospf6d/ospf6_route.c
@@ -37,6 +37,7 @@
 #include "ospf6_area.h"
 #include "ospf6_interface.h"
 #include "ospf6d.h"
+#include "ospf6_zebra.h"
 
 unsigned char conf_debug_ospf6_route = 0;
 
@@ -173,18 +174,232 @@ const char *ospf6_path_type_substr[OSPF6_PATH_TYPE_MAX] =
 { "??", "IA", "IE", "E1", "E2", };
 
 
+struct ospf6_nexthop *
+ospf6_nexthop_create (void)
+{
+  struct ospf6_nexthop *nh;
+
+  nh = XCALLOC (MTYPE_OSPF6_NEXTHOP, sizeof (struct ospf6_nexthop));
+  return nh;
+}
+
+void
+ospf6_nexthop_delete (struct ospf6_nexthop *nh)
+{
+  if (nh)
+    XFREE (MTYPE_OSPF6_NEXTHOP, nh);
+}
+
+void
+ospf6_free_nexthops (struct list *nh_list)
+{
+  struct ospf6_nexthop *nh;
+  struct listnode *node, *nnode;
+
+  if (nh_list)
+    {
+      for (ALL_LIST_ELEMENTS (nh_list, node, nnode, nh))
+	ospf6_nexthop_delete (nh);
+    }
+}
+
+void
+ospf6_clear_nexthops (struct list *nh_list)
+{
+  struct listnode *node;
+  struct ospf6_nexthop *nh;
+
+  if (nh_list)
+    {
+      for (ALL_LIST_ELEMENTS_RO (nh_list, node, nh))
+	ospf6_nexthop_clear (nh);
+    }
+}
+
+static struct ospf6_nexthop *
+ospf6_route_find_nexthop (struct list *nh_list, struct ospf6_nexthop *nh_match)
+{
+  struct listnode *node;
+  struct ospf6_nexthop *nh;
+
+  if (nh_list && nh_match)
+    {
+      for (ALL_LIST_ELEMENTS_RO (nh_list, node, nh))
+	{
+	  if (ospf6_nexthop_is_same (nh, nh_match))
+	    return (nh);
+	}
+    }
+
+  return (NULL);
+}
+
+void
+ospf6_copy_nexthops (struct list *dst, struct list *src)
+{
+  struct ospf6_nexthop *nh_new, *nh;
+  struct listnode *node;
+
+  if (dst && src)
+    {
+      for (ALL_LIST_ELEMENTS_RO (src, node, nh))
+	{
+	  if (ospf6_nexthop_is_set (nh))
+	    {
+	      nh_new = ospf6_nexthop_create ();
+	      ospf6_nexthop_copy (nh_new, nh);
+	      listnode_add (dst, nh_new);
+	    }
+	}
+    }
+}
+
+void
+ospf6_merge_nexthops (struct list *dst, struct list *src)
+{
+  struct listnode *node;
+  struct ospf6_nexthop *nh, *nh_new;
+
+  if (src && dst)
+    {
+      for (ALL_LIST_ELEMENTS_RO (src, node, nh))
+	{
+	  if (!ospf6_route_find_nexthop (dst, nh))
+	    {
+	      nh_new = ospf6_nexthop_create ();
+	      ospf6_nexthop_copy (nh_new, nh);
+	      listnode_add (dst, nh_new);
+	    }
+	}
+    }
+}
+
+int
+ospf6_route_cmp_nexthops (struct ospf6_route *a, struct ospf6_route *b)
+{
+  struct listnode *anode, *bnode;
+  struct ospf6_nexthop *anh, *bnh;
+
+  if (a && b)
+    {
+      if (listcount(a->nh_list) == listcount(b->nh_list))
+	{
+	  for (ALL_LIST_ELEMENTS_RO (a->nh_list, anode, anh))
+	    {
+	      for (ALL_LIST_ELEMENTS_RO (b->nh_list, bnode, bnh))
+		if (!ospf6_nexthop_is_same (anh, bnh))
+		  return (1);
+	    }
+	  return (0);
+	}
+      else
+	return (1);
+    }
+  /* One of the routes doesn't exist ? */
+  return (1);
+}
+
+int
+ospf6_num_nexthops (struct list *nh_list)
+{
+  return (listcount(nh_list));
+}
+
+void
+ospf6_add_nexthop (struct list *nh_list, int ifindex,
+		   struct in6_addr *addr)
+{
+  struct ospf6_nexthop *nh;
+  struct ospf6_nexthop nh_match;
+
+  if (nh_list)
+    {
+      nh_match.ifindex = ifindex;
+      if (addr != NULL)
+	memcpy (&nh_match.address, addr, sizeof (struct in6_addr));
+      else
+	memset (&nh_match.address, 0, sizeof (struct in6_addr));
+
+      if (!ospf6_route_find_nexthop (nh_list, &nh_match))
+	{
+	  nh = ospf6_nexthop_create();
+	  ospf6_nexthop_copy (nh, &nh_match);
+	  listnode_add (nh_list, nh);
+	}
+    }
+}
+
+void
+ospf6_route_zebra_copy_nexthops (struct ospf6_route *route,
+				 unsigned int *ifindexes,
+				 struct in6_addr **nexthop_addr,
+				 int entries)
+{
+  struct ospf6_nexthop *nh;
+  struct listnode *node;
+  char buf[64];
+  int i;
+
+  if (route)
+    {
+      i = 0;
+      for (ALL_LIST_ELEMENTS_RO (route->nh_list, node, nh))
+	{
+	  if (IS_OSPF6_DEBUG_ZEBRA (SEND))
+	    {
+	      char ifname[IFNAMSIZ];
+	      inet_ntop (AF_INET6, &nh->address, buf, sizeof (buf));
+	      if (!if_indextoname(nh->ifindex, ifname))
+		strlcpy(ifname, "unknown", sizeof(ifname));
+	      zlog_debug ("  nexthop: %s%%%.*s(%d)", buf, IFNAMSIZ, ifname,
+			  nh->ifindex);
+	    }
+	  if (i < entries)
+	    {
+	      nexthop_addr[i] = &nh->address;
+	      ifindexes[i] = nh->ifindex;
+	      i++;
+	    }
+	  else
+	    {
+	      return;
+	    }
+	}
+    }
+}
+
+int
+ospf6_route_get_first_nh_index (struct ospf6_route *route)
+{
+  struct ospf6_nexthop *nh;
+
+  if (route)
+    {
+      if (nh = (struct ospf6_nexthop *)listhead (route->nh_list))
+	return (nh->ifindex);
+    }
+
+  return (-1);
+}
+
 struct ospf6_route *
 ospf6_route_create (void)
 {
   struct ospf6_route *route;
   route = XCALLOC (MTYPE_OSPF6_ROUTE, sizeof (struct ospf6_route));
+  route->nh_list = list_new();
   return route;
 }
 
 void
 ospf6_route_delete (struct ospf6_route *route)
 {
-  XFREE (MTYPE_OSPF6_ROUTE, route);
+  if (route)
+    {
+      ospf6_free_nexthops (route->nh_list);
+      list_free (route->nh_list);
+      XFREE (MTYPE_OSPF6_ROUTE, route);
+    }
 }
 
 struct ospf6_route *
@@ -193,7 +408,15 @@ ospf6_route_copy (struct ospf6_route *route)
   struct ospf6_route *new;
 
   new = ospf6_route_create ();
-  memcpy (new, route, sizeof (struct ospf6_route));
+  new->type = route->type;
+  memcpy (&new->prefix, &route->prefix, sizeof (struct prefix));
+  new->installed = route->installed;
+  new->changed = route->changed;
+  new->flag = route->flag;
+  new->route_option = route->route_option;
+  new->linkstate_id = route->linkstate_id;
+  new->path = route->path;
+  ospf6_copy_nexthops (new->nh_list, route->nh_list);
   new->rnode = NULL;
   new->prev = NULL;
   new->next = NULL;
@@ -226,7 +449,7 @@ ospf6_route_unlock (struct ospf6_route *route)
 /* Route compare function. If ra is more preferred, it returns
    less than 0. If rb is more preferred returns greater than 0.
    Otherwise (neither one is preferred), returns 0 */
-static int
+int
 ospf6_route_cmp (struct ospf6_route *ra, struct ospf6_route *rb)
 {
   assert (ospf6_route_is_same (ra, rb));
@@ -246,8 +469,8 @@ ospf6_route_cmp (struct ospf6_route *ra, struct ospf6_route *rb)
 
   if (ra->path.type == OSPF6_PATH_TYPE_EXTERNAL2)
     {
-      if (ra->path.cost_e2 != rb->path.cost_e2)
-        return (ra->path.cost_e2 - rb->path.cost_e2);
+      if (ra->path.u.cost_e2 != rb->path.u.cost_e2)
+        return (ra->path.u.cost_e2 - rb->path.u.cost_e2);
     }
   else
     {
@@ -789,6 +1012,8 @@ ospf6_route_show (struct vty *vty, struct ospf6_route *route)
   char destination[64], nexthop[64];
   char duration[16], ifname[IFNAMSIZ];
   struct timeval now, res;
+  struct listnode *node;
+  struct ospf6_nexthop *nh;
 
   quagga_gettime (QUAGGA_CLK_MONOTONIC, &now);
   timersub (&now, &route->changed, &res);
@@ -804,29 +1029,28 @@ ospf6_route_show (struct vty *vty, struct ospf6_route *route)
   else
     prefix2str (&route->prefix, destination, sizeof (destination));
 
-  /* nexthop */
-  inet_ntop (AF_INET6, &route->nexthop[0].address, nexthop,
-             sizeof (nexthop));
-  if (! if_indextoname (route->nexthop[0].ifindex, ifname))
-    snprintf (ifname, sizeof (ifname), "%d", route->nexthop[0].ifindex);
 
-  vty_out (vty, "%c%1s %2s %-30s %-25s %6.*s %s%s",
-           (ospf6_route_is_best (route) ? '*' : ' '),
-           OSPF6_DEST_TYPE_SUBSTR (route->type),
-           OSPF6_PATH_TYPE_SUBSTR (route->path.type),
-           destination, nexthop, IFNAMSIZ, ifname, duration, VNL);
-
-  for (i = 1; ospf6_nexthop_is_set (&route->nexthop[i]) &&
-       i < OSPF6_MULTI_PATH_LIMIT; i++)
+  i = 0;
+  for (ALL_LIST_ELEMENTS_RO (route->nh_list, node, nh))
     {
       /* nexthop */
-      inet_ntop (AF_INET6, &route->nexthop[i].address, nexthop,
+      inet_ntop (AF_INET6, &nh->address, nexthop,
                  sizeof (nexthop));
-      if (! if_indextoname (route->nexthop[i].ifindex, ifname))
-        snprintf (ifname, sizeof (ifname), "%d", route->nexthop[i].ifindex);
-
-      vty_out (vty, "%c%1s %2s %-30s %-25s %6.*s %s%s",
-               ' ', "", "", "", nexthop, IFNAMSIZ, ifname, "", VNL);
+      if (! if_indextoname (nh->ifindex, ifname))
+        snprintf (ifname, sizeof (ifname), "%d", nh->ifindex);
+
+      if (!i)
+	{
+	  vty_out (vty, "%c%1s %2s %-30s %-25s %6.*s %s%s",
+		   (ospf6_route_is_best (route) ? '*' : ' '),
+		   OSPF6_DEST_TYPE_SUBSTR (route->type),
+		   OSPF6_PATH_TYPE_SUBSTR (route->path.type),
+		   destination, nexthop, IFNAMSIZ, ifname, duration, VNL);
+	  i++;
+	}
+      else
+	vty_out (vty, "%c%1s %2s %-30s %-25s %6.*s %s%s",
+		 ' ', "", "", "", nexthop, IFNAMSIZ, ifname, "", VNL);
     }
 }
 
@@ -837,7 +1061,8 @@ ospf6_route_show_detail (struct vty *vty, struct ospf6_route *route)
   char area_id[16], id[16], adv_router[16], capa[16], options[16];
   struct timeval now, res;
   char duration[16];
-  int i;
+  struct listnode *node;
+  struct ospf6_nexthop *nh;
 
   quagga_gettime (QUAGGA_CLK_MONOTONIC, &now);
 
@@ -909,18 +1134,16 @@ ospf6_route_show_detail (struct vty *vty, struct ospf6_route *route)
   vty_out (vty, "Metric Type: %d%s", route->path.metric_type,
            VNL);
   vty_out (vty, "Metric: %d (%d)%s",
-           route->path.cost, route->path.cost_e2, VNL);
+           route->path.cost, route->path.u.cost_e2, VNL);
 
   /* Nexthops */
   vty_out (vty, "Nexthop:%s", VNL);
-  for (i = 0; ospf6_nexthop_is_set (&route->nexthop[i]) &&
-       i < OSPF6_MULTI_PATH_LIMIT; i++)
+  for (ALL_LIST_ELEMENTS_RO (route->nh_list, node, nh))
     {
       /* nexthop */
-      inet_ntop (AF_INET6, &route->nexthop[i].address, nexthop,
-                 sizeof (nexthop));
-      if (! if_indextoname (route->nexthop[i].ifindex, ifname))
-        snprintf (ifname, sizeof (ifname), "%d", route->nexthop[i].ifindex);
+      inet_ntop (AF_INET6, &nh->address, nexthop, sizeof (nexthop));
+      if (! if_indextoname (nh->ifindex, ifname))
+        snprintf (ifname, sizeof (ifname), "%d", nh->ifindex);
       vty_out (vty, "  %s %.*s%s", nexthop, IFNAMSIZ, ifname, VNL);
     }
   vty_out (vty, "%s", VNL);
@@ -933,7 +1156,7 @@ ospf6_route_show_table_summary (struct vty *vty,
   struct ospf6_route *route, *prev = NULL;
   int i, pathtype[OSPF6_PATH_TYPE_MAX];
   unsigned int number = 0;
-  int nhinval = 0, ecmp = 0;
+  int nh_count =0 , nhinval = 0, ecmp = 0;
   int alternative = 0, destination = 0;
 
   for (i = 0; i < OSPF6_PATH_TYPE_MAX; i++)
@@ -946,9 +1169,10 @@ ospf6_route_show_table_summary (struct vty *vty,
         destination++;
       else
         alternative++;
-      if (! ospf6_nexthop_is_set (&route->nexthop[0]))
+      nh_count = ospf6_num_nexthops (route->nh_list);
+      if (!nh_count)
         nhinval++;
-      else if (ospf6_nexthop_is_set (&route->nexthop[1]))
+      else if (nh_count > 1)
         ecmp++;
       pathtype[route->path.type]++;
       number++;
diff --git a/ospf6d/ospf6_route.h b/ospf6d/ospf6_route.h
index b384824cb0..0f71595111 100644
--- a/ospf6d/ospf6_route.h
+++ b/ospf6d/ospf6_route.h
@@ -96,7 +96,10 @@ struct ospf6_path
   /* Cost */
   u_int8_t metric_type;
   u_int32_t cost;
-  u_int32_t cost_e2;
+  union {
+    u_int32_t cost_e2;
+    u_int32_t cost_config;
+  } u;
 };
 
 #define OSPF6_PATH_TYPE_NONE         0
@@ -109,6 +112,7 @@ struct ospf6_path
 
 #include "prefix.h"
 #include "table.h"
+#include "bitfield.h"
 
 struct ospf6_route
 {
@@ -132,17 +136,18 @@ struct ospf6_route
   /* flag */
   u_char flag;
 
-  /* path */
-  struct ospf6_path path;
-
-  /* nexthop */
-  struct ospf6_nexthop nexthop[OSPF6_MULTI_PATH_LIMIT];
-
   /* route option */
   void *route_option;
 
   /* link state id for advertising */
   u_int32_t linkstate_id;
+
+  /* path */
+  struct ospf6_path path;
+
+  /* nexthop */
+  struct list *nh_list;
+
 };
 
 #define OSPF6_DEST_TYPE_NONE       0
@@ -160,6 +165,7 @@ struct ospf6_route
 #define OSPF6_ROUTE_ACTIVE_SUMMARY   0x10
 #define OSPF6_ROUTE_DO_NOT_ADVERTISE 0x20
 #define OSPF6_ROUTE_WAS_REMOVED      0x40
+#define OSPF6_ROUTE_BLACKHOLE_ADDED  0x80
 
 struct ospf6_route_table
 {
@@ -172,6 +178,8 @@ struct ospf6_route_table
 
   u_int32_t count;
 
+  bitfield_t idspace;
+
   /* hooks */
   void (*hook_add) (struct ospf6_route *);
   void (*hook_change) (struct ospf6_route *);
@@ -231,8 +239,8 @@ extern const char *ospf6_path_type_substr[OSPF6_PATH_TYPE_MAX];
   ((ra)->type == (rb)->type && \
    memcmp (&(ra)->prefix, &(rb)->prefix, sizeof (struct prefix)) == 0 && \
    memcmp (&(ra)->path, &(rb)->path, sizeof (struct ospf6_path)) == 0 && \
-   memcmp (&(ra)->nexthop, &(rb)->nexthop,                               \
-           sizeof (struct ospf6_nexthop) * OSPF6_MULTI_PATH_LIMIT) == 0)
+   ospf6_route_cmp_nexthops (ra, rb) == 0)
+
 #define ospf6_route_is_best(r) (CHECK_FLAG ((r)->flag, OSPF6_ROUTE_BEST))
 
 #define ospf6_linkstate_prefix_adv_router(x) \
@@ -251,9 +259,35 @@ extern void ospf6_linkstate_prefix (u_int32_t adv_router, u_int32_t id,
 extern void ospf6_linkstate_prefix2str (struct prefix *prefix, char *buf,
                                         int size);
 
+extern struct ospf6_nexthop *ospf6_nexthop_create (void);
+extern void ospf6_nexthop_delete (struct ospf6_nexthop *nh);
+extern void ospf6_free_nexthops (struct list *nh_list);
+extern void ospf6_clear_nexthops (struct list *nh_list);
+extern int ospf6_num_nexthops (struct list *nh_list);
+extern void ospf6_copy_nexthops (struct list *dst, struct list *src);
+extern void ospf6_merge_nexthops (struct list *dst, struct list *src);
+extern void ospf6_add_nexthop (struct list *nh_list, int ifindex,
+			       struct in6_addr *addr);
+extern int ospf6_num_nexthops (struct list *nh_list);
+extern int ospf6_route_cmp_nexthops (struct ospf6_route *a,
+				     struct ospf6_route *b);
+extern void ospf6_route_zebra_copy_nexthops (struct ospf6_route *route,
+					     unsigned int *ifindices,
+					     struct in6_addr **addr,
+					     int entries);
+extern int ospf6_route_get_first_nh_index (struct ospf6_route *route);
+
+/* Hide abstraction of nexthop implementation in route from outsiders */
+#define ospf6_route_copy_nexthops(dst, src) ospf6_copy_nexthops(dst->nh_list, src->nh_list)
+#define ospf6_route_merge_nexthops(dst, src) ospf6_merge_nexthops(dst->nh_list, src->nh_list)
+#define ospf6_route_num_nexthops(route) ospf6_num_nexthops(route->nh_list)
+#define ospf6_route_add_nexthop(route, ifindex, addr) \
+  ospf6_add_nexthop(route->nh_list, ifindex, addr)
+
 extern struct ospf6_route *ospf6_route_create (void);
 extern void ospf6_route_delete (struct ospf6_route *);
 extern struct ospf6_route *ospf6_route_copy (struct ospf6_route *route);
+extern int ospf6_route_cmp (struct ospf6_route *ra, struct ospf6_route *rb);
 
 extern void ospf6_route_lock (struct ospf6_route *route);
 extern void ospf6_route_unlock (struct ospf6_route *route);
diff --git a/ospf6d/ospf6_spf.c b/ospf6d/ospf6_spf.c
index 3ef5485fde..20ec3721da 100644
--- a/ospf6d/ospf6_spf.c
+++ b/ospf6d/ospf6_spf.c
@@ -43,6 +43,41 @@
 
 unsigned char conf_debug_ospf6_spf = 0;
 
+static void
+ospf6_spf_copy_nexthops_to_route (struct ospf6_route *rt,
+				  struct ospf6_vertex *v)
+{
+  if (rt && v)
+    ospf6_copy_nexthops (rt->nh_list, v->nh_list);
+}
+
+static void
+ospf6_spf_merge_nexthops_to_route (struct ospf6_route *rt,
+				   struct ospf6_vertex *v)
+{
+  if (rt && v)
+    ospf6_merge_nexthops (rt->nh_list, v->nh_list);
+}
+
+static int
+ospf6_spf_get_ifindex_from_nh (struct ospf6_vertex *v)
+{
+  struct ospf6_nexthop *nh;
+  struct listnode *node;
+
+  if (v)
+    {
+      node = listhead(v->nh_list);
+      if (node)
+	{
+	  nh = listgetdata (node);
+	  if (nh)
+	    return (nh->ifindex);
+	}
+    }
+  return -1;
+}
+
 static int
 ospf6_vertex_cmp (void *a, void *b)
 {
@@ -76,7 +111,6 @@ static struct ospf6_vertex *
 ospf6_vertex_create (struct ospf6_lsa *lsa)
 {
   struct ospf6_vertex *v;
-  int i;
 
   v = (struct ospf6_vertex *)
     XMALLOC (MTYPE_OSPF6_VERTEX, sizeof (struct ospf6_vertex));
@@ -96,6 +130,10 @@ ospf6_vertex_create (struct ospf6_lsa *lsa)
   /* name */
   ospf6_linkstate_prefix2str (&v->vertex_id, v->name, sizeof (v->name));
 
+  if (IS_OSPF6_DEBUG_SPF (PROCESS))
+    zlog_debug ("%s: Creating vertex %s of type %s", __func__, v->name,
+		((ntohs (lsa->header->type) == OSPF6_LSTYPE_ROUTER) ? "Router" : "N/W"));
+
   /* Associated LSA */
   v->lsa = lsa;
 
@@ -105,8 +143,7 @@ ospf6_vertex_create (struct ospf6_lsa *lsa)
   v->options[1] = *(u_char *)(OSPF6_LSA_HEADER_END (lsa->header) + 2);
   v->options[2] = *(u_char *)(OSPF6_LSA_HEADER_END (lsa->header) + 3);
 
-  for (i = 0; i < OSPF6_MULTI_PATH_LIMIT; i++)
-    ospf6_nexthop_clear (&v->nexthop[i]);
+  v->nh_list =  list_new();
 
   v->parent = NULL;
   v->child_list = list_new ();
@@ -224,7 +261,8 @@ static void
 ospf6_nexthop_calc (struct ospf6_vertex *w, struct ospf6_vertex *v,
                     caddr_t lsdesc)
 {
-  int i, ifindex;
+  int i;
+  int ifindex;
   struct ospf6_interface *oi;
   u_int16_t type;
   u_int32_t adv_router;
@@ -233,8 +271,14 @@ ospf6_nexthop_calc (struct ospf6_vertex *w, struct ospf6_vertex *v,
   char buf[64];
 
   assert (VERTEX_IS_TYPE (ROUTER, w));
-  ifindex = (VERTEX_IS_TYPE (NETWORK, v) ? v->nexthop[0].ifindex :
+  ifindex = (VERTEX_IS_TYPE (NETWORK, v) ? ospf6_spf_get_ifindex_from_nh (v) :
              ROUTER_LSDESC_GET_IFID (lsdesc));
+  if (ifindex == -1)
+    {
+      zlog_err ("No nexthop ifindex at vertex %s", v->name);
+      return;
+    }
+
   oi = ospf6_interface_lookup_by_ifindex (ifindex);
   if (oi == NULL)
     {
@@ -263,13 +307,8 @@ ospf6_nexthop_calc (struct ospf6_vertex *w, struct ospf6_vertex *v,
           zlog_debug ("  nexthop %s from %s", buf, lsa->name);
         }
 
-      if (i < OSPF6_MULTI_PATH_LIMIT)
-        {
-          memcpy (&w->nexthop[i].address, &link_lsa->linklocal_addr,
-                  sizeof (struct in6_addr));
-          w->nexthop[i].ifindex = ifindex;
-          i++;
-        }
+      ospf6_add_nexthop (w->nh_list, ifindex, &link_lsa->linklocal_addr);
+      i++;
     }
 
   if (i == 0 && IS_OSPF6_DEBUG_SPF (PROCESS))
@@ -280,8 +319,7 @@ static int
 ospf6_spf_install (struct ospf6_vertex *v,
                    struct ospf6_route_table *result_table)
 {
-  struct ospf6_route *route;
-  int i, j;
+  struct ospf6_route *route, *parent_route;
   struct ospf6_vertex *prev;
 
   if (IS_OSPF6_DEBUG_SPF (PROCESS))
@@ -302,23 +340,7 @@ ospf6_spf_install (struct ospf6_vertex *v,
       if (IS_OSPF6_DEBUG_SPF (PROCESS))
         zlog_debug ("  another path found, merge");
 
-      for (i = 0; ospf6_nexthop_is_set (&v->nexthop[i]) &&
-           i < OSPF6_MULTI_PATH_LIMIT; i++)
-        {
-          for (j = 0; j < OSPF6_MULTI_PATH_LIMIT; j++)
-            {
-              if (ospf6_nexthop_is_set (&route->nexthop[j]))
-                {
-                  if (ospf6_nexthop_is_same (&route->nexthop[j],
-                                             &v->nexthop[i]))
-                    break;
-                  else
-                    continue;
-                }
-              ospf6_nexthop_copy (&route->nexthop[j], &v->nexthop[i]);
-              break;
-            }
-        }
+      ospf6_spf_merge_nexthops_to_route (route, v);
 
       prev = (struct ospf6_vertex *) route->route_option;
       assert (prev->hops <= v->hops);
@@ -345,15 +367,35 @@ ospf6_spf_install (struct ospf6_vertex *v,
   route->path.origin.adv_router = v->lsa->header->adv_router;
   route->path.metric_type = 1;
   route->path.cost = v->cost;
-  route->path.cost_e2 = v->hops;
+  route->path.u.cost_e2 = v->hops;
   route->path.router_bits = v->capability;
   route->path.options[0] = v->options[0];
   route->path.options[1] = v->options[1];
   route->path.options[2] = v->options[2];
 
-  for (i = 0; ospf6_nexthop_is_set (&v->nexthop[i]) &&
-       i < OSPF6_MULTI_PATH_LIMIT; i++)
-    ospf6_nexthop_copy (&route->nexthop[i], &v->nexthop[i]);
+  ospf6_spf_copy_nexthops_to_route (route, v);
+
+  /*
+   * The SPF logic implementation does not transfer the multipathing properties
+   * of a parent to a child node. Thus if there was a 3-way multipath to a
+   * node's parent and a single hop from the parent to the child, the logic of
+   * creating new vertices and computing next hops prevents there from being 3
+   * paths to the child node. This is primarily because the resolution of
+   * multipath is done in this routine, not in the main spf loop.
+   *
+   * The following logic addresses that problem by merging the parent's nexthop
+   * information with the child's, if the parent is not the root of the tree.
+   * This is based on the assumption that before a node's route is installed,
+   * its parent's route's nexthops have already been installed.
+   */
+  if (v->parent && v->parent->hops)
+    {
+      parent_route = ospf6_route_lookup (&v->parent->vertex_id, result_table);
+      if (parent_route)
+	{
+	  ospf6_route_merge_nexthops (route, parent_route);
+	}
+    }
 
   if (v->parent)
     listnode_add_sort (v->parent->child_list, v);
@@ -416,19 +458,24 @@ ospf6_spf_calculation (u_int32_t router_id,
 {
   struct pqueue *candidate_list;
   struct ospf6_vertex *root, *v, *w;
-  int i;
   int size;
   caddr_t lsdesc;
   struct ospf6_lsa *lsa;
+  struct in6_addr address;
 
   ospf6_spf_table_finish (result_table);
 
   /* Install the calculating router itself as the root of the SPF tree */
   /* construct root vertex */
   lsa = ospf6_lsdb_lookup (htons (OSPF6_LSTYPE_ROUTER), htonl (0),
-                           router_id, oa->lsdb);
+                           router_id, oa->lsdb_self);
   if (lsa == NULL)
-    return;
+    {
+      if (IS_OSPF6_DEBUG_SPF (PROCESS))
+	zlog_debug ("%s: No router LSA for area %s\n",
+		    __func__, oa->name);
+      return;
+    }
 
   /* initialize */
   candidate_list = pqueue_create ();
@@ -438,8 +485,7 @@ ospf6_spf_calculation (u_int32_t router_id,
   root->area = oa;
   root->cost = 0;
   root->hops = 0;
-  root->nexthop[0].ifindex = 0; /* loopbak I/F is better ... */
-  inet_pton (AF_INET6, "::1", &root->nexthop[0].address);
+  inet_pton (AF_INET6, "::1", &address);
 
   /* Actually insert root to the candidate-list as the only candidate */
   pqueue_enqueue (root, candidate_list);
@@ -470,6 +516,9 @@ ospf6_spf_calculation (u_int32_t router_id,
           if (lsa == NULL)
             continue;
 
+	  if (OSPF6_LSA_IS_MAXAGE (lsa))
+	    continue;
+
           if (! ospf6_lsdesc_backlink (lsa, lsdesc, v))
             continue;
 
@@ -489,14 +538,12 @@ ospf6_spf_calculation (u_int32_t router_id,
 
           /* nexthop calculation */
           if (w->hops == 0)
-            w->nexthop[0].ifindex = ROUTER_LSDESC_GET_IFID (lsdesc);
+	    ospf6_add_nexthop (w->nh_list, ROUTER_LSDESC_GET_IFID (lsdesc), NULL);
           else if (w->hops == 1 && v->hops == 0)
             ospf6_nexthop_calc (w, v, lsdesc);
           else
             {
-              for (i = 0; ospf6_nexthop_is_set (&v->nexthop[i]) &&
-                   i < OSPF6_MULTI_PATH_LIMIT; i++)
-                ospf6_nexthop_copy (&w->nexthop[i], &v->nexthop[i]);
+	      ospf6_copy_nexthops (w->nh_list, v->nh_list);
             }
 
           /* add new candidate to the candidate_list */
diff --git a/ospf6d/ospf6_spf.h b/ospf6d/ospf6_spf.h
index b3481dc379..7bf525d6fe 100644
--- a/ospf6d/ospf6_spf.h
+++ b/ospf6d/ospf6_spf.h
@@ -60,9 +60,6 @@ struct ospf6_vertex
   /* Router hops to this node */
   u_char hops;
 
-  /* nexthops to this node */
-  struct ospf6_nexthop nexthop[OSPF6_MULTI_PATH_LIMIT];
-
   /* capability bits */
   u_char capability;
 
@@ -72,6 +69,9 @@ struct ospf6_vertex
   /* For tree display */
   struct ospf6_vertex *parent;
   struct list *child_list;
+
+  /* nexthops to this node */
+  struct list *nh_list;
 };
 
 #define OSPF6_VERTEX_TYPE_ROUTER  0x01
diff --git a/ospf6d/ospf6_top.c b/ospf6d/ospf6_top.c
index 7191270143..a08826d630 100644
--- a/ospf6d/ospf6_top.c
+++ b/ospf6d/ospf6_top.c
@@ -92,6 +92,7 @@ ospf6_top_route_hook_add (struct ospf6_route *route)
 static void
 ospf6_top_route_hook_remove (struct ospf6_route *route)
 {
+  route->flag |= OSPF6_ROUTE_REMOVE;
   ospf6_abr_originate_summary (route);
   ospf6_zebra_route_update_remove (route);
 }
@@ -107,6 +108,7 @@ ospf6_top_brouter_hook_add (struct ospf6_route *route)
 static void
 ospf6_top_brouter_hook_remove (struct ospf6_route *route)
 {
+  route->flag |= OSPF6_ROUTE_REMOVE;
   ospf6_abr_examin_brouter (ADV_ROUTER_IN_PREFIX (&route->prefix));
   ospf6_asbr_lsentry_remove (route);
   ospf6_abr_originate_summary (route);
diff --git a/ospf6d/ospf6_zebra.c b/ospf6d/ospf6_zebra.c
index 85f70647f9..04a1fd6488 100644
--- a/ospf6d/ospf6_zebra.c
+++ b/ospf6d/ospf6_zebra.c
@@ -362,7 +362,7 @@ ospf6_zebra_route_update (int type, struct ospf6_route *request)
   int nhcount;
   struct in6_addr **nexthops;
   unsigned int *ifindexes;
-  int i, ret = 0;
+  int ret = 0;
   struct prefix_ipv6 *dest;
 
   if (IS_OSPF6_DEBUG_ZEBRA (SEND))
@@ -408,11 +408,7 @@ ospf6_zebra_route_update (int type, struct ospf6_route *request)
       return;
     }
 
-  nhcount = 0;
-  for (i = 0; i < OSPF6_MULTI_PATH_LIMIT; i++)
-    if (ospf6_nexthop_is_set (&request->nexthop[i]))
-      nhcount++;
-
+  nhcount = ospf6_route_num_nexthops (request);
   if (nhcount == 0)
     {
       if (IS_OSPF6_DEBUG_ZEBRA (SEND))
@@ -439,21 +435,7 @@ ospf6_zebra_route_update (int type, struct ospf6_route *request)
       return;
     }
 
-  for (i = 0; i < nhcount; i++)
-    {
-      if (IS_OSPF6_DEBUG_ZEBRA (SEND))
-	{
-	  char ifname[IFNAMSIZ];
-	  inet_ntop (AF_INET6, &request->nexthop[i].address,
-		     buf, sizeof (buf));
-	  if (!if_indextoname(request->nexthop[i].ifindex, ifname))
-	    strlcpy(ifname, "unknown", sizeof(ifname));
-	  zlog_debug ("  nexthop: %s%%%.*s(%d)", buf, IFNAMSIZ, ifname,
-		      request->nexthop[i].ifindex);
-	}
-      nexthops[i] = &request->nexthop[i].address;
-      ifindexes[i] = request->nexthop[i].ifindex;
-    }
+  ospf6_route_zebra_copy_nexthops (request, ifindexes, nexthops, nhcount);
 
   api.type = ZEBRA_ROUTE_OSPF6;
   api.flags = 0;
@@ -467,7 +449,7 @@ ospf6_zebra_route_update (int type, struct ospf6_route *request)
   api.ifindex = ifindexes;
   SET_FLAG (api.message, ZAPI_MESSAGE_METRIC);
   api.metric = (request->path.metric_type == 2 ?
-                request->path.cost_e2 : request->path.cost);
+                request->path.u.cost_e2 : request->path.cost);
 
   dest = (struct prefix_ipv6 *) &request->prefix;
   if (type == REM)
@@ -509,6 +491,90 @@ ospf6_zebra_route_update_remove (struct ospf6_route *request)
   ospf6_zebra_route_update (REM, request);
 }
 
+void
+ospf6_zebra_add_discard (struct ospf6_route *request)
+{
+  struct zapi_ipv6 api;
+  char buf[INET6_ADDRSTRLEN];
+  struct prefix_ipv6 *dest;
+
+  if (zclient->redist[ZEBRA_ROUTE_OSPF6])
+    {
+      if (!CHECK_FLAG (request->flag, OSPF6_ROUTE_BLACKHOLE_ADDED))
+	{
+	  api.type = ZEBRA_ROUTE_OSPF6;
+	  api.flags = ZEBRA_FLAG_BLACKHOLE;
+	  api.message = 0;
+	  api.safi = SAFI_UNICAST;
+	  SET_FLAG (api.message, ZAPI_MESSAGE_NEXTHOP);
+	  api.nexthop_num = 0;
+	  api.ifindex_num = 0;
+
+	  dest = (struct prefix_ipv6 *) &request->prefix;
+
+	  zapi_ipv6_route (ZEBRA_IPV6_ROUTE_ADD, zclient, dest, &api);
+
+	  if (IS_OSPF6_DEBUG_ZEBRA (SEND))
+	    zlog_debug ("Zebra: Route add discard %s/%d",
+			inet_ntop (AF_INET6, &dest->prefix,
+				   buf, INET6_ADDRSTRLEN),
+			dest->prefixlen);
+	  SET_FLAG (request->flag, OSPF6_ROUTE_BLACKHOLE_ADDED);
+	}
+      else
+	{
+	  dest = (struct prefix_ipv6 *) &request->prefix;
+
+	  if (IS_OSPF6_DEBUG_ZEBRA (SEND))
+	    zlog_debug ("Zebra: Blackhole route present already %s/%d",
+			inet_ntop (AF_INET6, &dest->prefix,
+				   buf, INET6_ADDRSTRLEN),
+			dest->prefixlen);
+	}
+    }
+}
+
+void
+ospf6_zebra_delete_discard (struct ospf6_route *request)
+{
+  struct zapi_ipv6 api;
+  char buf[INET6_ADDRSTRLEN];
+  struct prefix_ipv6 *dest;
+
+  if (zclient->redist[ZEBRA_ROUTE_OSPF6])
+    {
+      if (CHECK_FLAG (request->flag, OSPF6_ROUTE_BLACKHOLE_ADDED))
+	{
+
+	  api.type = ZEBRA_ROUTE_OSPF6;
+	  api.flags = ZEBRA_FLAG_BLACKHOLE;
+	  api.message = 0;
+	  api.safi = SAFI_UNICAST;
+	  SET_FLAG (api.message, ZAPI_MESSAGE_NEXTHOP);
+	  api.nexthop_num = 0;
+	  api.ifindex_num = 0;
+
+	  dest = (struct prefix_ipv6 *) &request->prefix;
+
+	  zapi_ipv6_route (ZEBRA_IPV6_ROUTE_DELETE, zclient, dest, &api);
+
+	  if (IS_OSPF6_DEBUG_ZEBRA (SEND))
+	    zlog_debug ("Zebra: Route delete discard %s/%d",
+			inet_ntop (AF_INET6, &dest->prefix, buf,
+				   INET6_ADDRSTRLEN), dest->prefixlen);
+	  UNSET_FLAG (request->flag, OSPF6_ROUTE_BLACKHOLE_ADDED);
+	}
+      else
+	{
+	  dest = (struct prefix_ipv6 *) &request->prefix;
+	  if (IS_OSPF6_DEBUG_ZEBRA (SEND))
+	    zlog_debug ("Zebra: Blackhole route already deleted %s/%d",
+			inet_ntop (AF_INET6, &dest->prefix, buf,
+				   INET6_ADDRSTRLEN), dest->prefixlen);
+	}
+    }
+}
+
 DEFUN (redistribute_ospf6,
        redistribute_ospf6_cmd,
        "redistribute ospf6",
diff --git a/ospf6d/ospf6_zebra.h b/ospf6d/ospf6_zebra.h
index 24a4ae6396..753b8edc94 100644
--- a/ospf6d/ospf6_zebra.h
+++ b/ospf6d/ospf6_zebra.h
@@ -44,6 +44,8 @@ extern void ospf6_zebra_redistribute (int);
 extern void ospf6_zebra_no_redistribute (int);
 #define ospf6_zebra_is_redistribute(type) (zclient->redist[type])
 extern void ospf6_zebra_init (void);
+extern void ospf6_zebra_add_discard (struct ospf6_route *request);
+extern void ospf6_zebra_delete_discard (struct ospf6_route *request);
 
 extern int config_write_ospf6_debug_zebra (struct vty *vty);
 extern void install_element_ospf6_debug_zebra (void);
diff --git a/ospfd/ospf_abr.h b/ospfd/ospf_abr.h
index e367e44772..2a728936d3 100644
--- a/ospfd/ospf_abr.h
+++ b/ospfd/ospf_abr.h
@@ -52,7 +52,6 @@ struct ospf_area_range
 
   /* Configured range cost. */
   u_int32_t cost_config;
-#define OSPF_AREA_RANGE_COST_UNSPEC	-1U
 };
 
 /* Prototypes. */
diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index 7c6b3782a5..5e8eb7b9f1 100644
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -1420,6 +1420,10 @@ netlink_route (int cmd, int family, void *dest, int length, void *gate,
             req.r.rtm_type = RTN_UNREACHABLE;
           else
             assert (RTN_BLACKHOLE != RTN_UNREACHABLE);  /* false */
+
+	  if (IS_ZEBRA_DEBUG_KERNEL)
+	    zlog_debug ("%s: Adding discard route for family %s\n",
+			__FUNCTION__, family == AF_INET ? "IPv4" : "IPv6");
         }
       else
         req.r.rtm_type = RTN_UNICAST;
@@ -1912,13 +1916,17 @@ kernel_delete_ipv4 (struct prefix *p, struct rib *rib)
 int
 kernel_add_ipv6 (struct prefix *p, struct rib *rib)
 {
-  return netlink_route_multipath (RTM_NEWROUTE, p, rib, AF_INET6);
+    {
+      return netlink_route_multipath (RTM_NEWROUTE, p, rib, AF_INET6);
+    }
 }
 
 int
 kernel_delete_ipv6 (struct prefix *p, struct rib *rib)
 {
-  return netlink_route_multipath (RTM_DELROUTE, p, rib, AF_INET6);
+    {
+      return netlink_route_multipath (RTM_DELROUTE, p, rib, AF_INET6);
+    }
 }
 
 /* Delete IPv6 route from the kernel. */
diff --git a/zebra/zserv.c b/zebra/zserv.c
index 3c850e4259..d745a43d5f 100644
--- a/zebra/zserv.c
+++ b/zebra/zserv.c
@@ -1298,6 +1298,9 @@ zread_ipv6_add (struct zserv *client, u_short length)
 	        ifindices[if_count++] = stream_getl (s);
               }
 	      break;
+            case ZEBRA_NEXTHOP_BLACKHOLE:
+              nexthop_blackhole_add (rib);
+              break;
 	    }
 	}