Reorganize source tree to use single autotools instance

Change-Id: I7b51f88292e057c6443b12224486f2d0c9f8ae23
Signed-off-by: Damjan Marion <damarion@cisco.com>

1 files changed, 2001 insertions, 0 deletions

diff --git a/src/vnet/fib/fib_path.c b/src/vnet/fib/fib_path.c
new file mode 100644
index 00000000000..809e3e166da
--- /dev/null
+++ b/src/vnet/fib/fib_path.c
@@ -0,0 +1,2001 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+#include <vnet/ip/format.h>
+#include <vnet/ip/ip.h>
+#include <vnet/dpo/drop_dpo.h>
+#include <vnet/dpo/receive_dpo.h>
+#include <vnet/dpo/load_balance_map.h>
+#include <vnet/dpo/lookup_dpo.h>
+
+#include <vnet/adj/adj.h>
+
+#include <vnet/fib/fib_path.h>
+#include <vnet/fib/fib_node.h>
+#include <vnet/fib/fib_table.h>
+#include <vnet/fib/fib_entry.h>
+#include <vnet/fib/fib_path_list.h>
+#include <vnet/fib/fib_internal.h>
+#include <vnet/fib/fib_urpf_list.h>
+
+/**
+ * Enurmeration of path types
+ */
+typedef enum fib_path_type_t_ {
+    /**
+     * Marker. Add new types after this one.
+     */
+    FIB_PATH_TYPE_FIRST = 0,
+    /**
+     * Attached-nexthop. An interface and a nexthop are known.
+     */
+    FIB_PATH_TYPE_ATTACHED_NEXT_HOP = FIB_PATH_TYPE_FIRST,
+    /**
+     * attached. Only the interface is known.
+     */
+    FIB_PATH_TYPE_ATTACHED,
+    /**
+     * recursive. Only the next-hop is known.
+     */
+    FIB_PATH_TYPE_RECURSIVE,
+    /**
+     * special. nothing is known. so we drop.
+     */
+    FIB_PATH_TYPE_SPECIAL,
+    /**
+     * exclusive. user provided adj.
+     */
+    FIB_PATH_TYPE_EXCLUSIVE,
+    /**
+     * deag. Link to a lookup adj in the next table
+     */
+    FIB_PATH_TYPE_DEAG,
+    /**
+     * receive. it's for-us.
+     */
+    FIB_PATH_TYPE_RECEIVE,
+    /**
+     * Marker. Add new types before this one, then update it.
+     */
+    FIB_PATH_TYPE_LAST = FIB_PATH_TYPE_RECEIVE,
+} __attribute__ ((packed)) fib_path_type_t;
+
+/**
+ * The maximum number of path_types
+ */
+#define FIB_PATH_TYPE_MAX (FIB_PATH_TYPE_LAST + 1)
+
+#define FIB_PATH_TYPES {					\
+    [FIB_PATH_TYPE_ATTACHED_NEXT_HOP] = "attached-nexthop",	\
+    [FIB_PATH_TYPE_ATTACHED]          = "attached",		\
+    [FIB_PATH_TYPE_RECURSIVE]         = "recursive",	        \
+    [FIB_PATH_TYPE_SPECIAL]           = "special",	        \
+    [FIB_PATH_TYPE_EXCLUSIVE]         = "exclusive",	        \
+    [FIB_PATH_TYPE_DEAG]              = "deag",	                \
+    [FIB_PATH_TYPE_RECEIVE]           = "receive",	        \
+}
+
+#define FOR_EACH_FIB_PATH_TYPE(_item) \
+    for (_item = FIB_PATH_TYPE_FIRST; _item <= FIB_PATH_TYPE_LAST; _item++)
+
+/**
+ * Enurmeration of path operational (i.e. derived) attributes
+ */
+typedef enum fib_path_oper_attribute_t_ {
+    /**
+     * Marker. Add new types after this one.
+     */
+    FIB_PATH_OPER_ATTRIBUTE_FIRST = 0,
+    /**
+     * The path forms part of a recursive loop.
+     */
+    FIB_PATH_OPER_ATTRIBUTE_RECURSIVE_LOOP = FIB_PATH_OPER_ATTRIBUTE_FIRST,
+    /**
+     * The path is resolved
+     */
+    FIB_PATH_OPER_ATTRIBUTE_RESOLVED,
+    /**
+     * The path has become a permanent drop.
+     */
+    FIB_PATH_OPER_ATTRIBUTE_DROP,
+    /**
+     * Marker. Add new types before this one, then update it.
+     */
+    FIB_PATH_OPER_ATTRIBUTE_LAST = FIB_PATH_OPER_ATTRIBUTE_DROP,
+} __attribute__ ((packed)) fib_path_oper_attribute_t;
+
+/**
+ * The maximum number of path operational attributes
+ */
+#define FIB_PATH_OPER_ATTRIBUTE_MAX (FIB_PATH_OPER_ATTRIBUTE_LAST + 1)
+
+#define FIB_PATH_OPER_ATTRIBUTES {					\
+    [FIB_PATH_OPER_ATTRIBUTE_RECURSIVE_LOOP] = "recursive-loop",	\
+    [FIB_PATH_OPER_ATTRIBUTE_RESOLVED]       = "resolved",	        \
+    [FIB_PATH_OPER_ATTRIBUTE_DROP]           = "drop",		        \
+}
+
+#define FOR_EACH_FIB_PATH_OPER_ATTRIBUTE(_item) \
+    for (_item = FIB_PATH_OPER_ATTRIBUTE_FIRST; \
+	 _item <= FIB_PATH_OPER_ATTRIBUTE_LAST; \
+	 _item++)
+
+/**
+ * Path flags from the attributes
+ */
+typedef enum fib_path_oper_flags_t_ {
+    FIB_PATH_OPER_FLAG_NONE = 0,
+    FIB_PATH_OPER_FLAG_RECURSIVE_LOOP = (1 << FIB_PATH_OPER_ATTRIBUTE_RECURSIVE_LOOP),
+    FIB_PATH_OPER_FLAG_DROP = (1 << FIB_PATH_OPER_ATTRIBUTE_DROP),
+    FIB_PATH_OPER_FLAG_RESOLVED = (1 << FIB_PATH_OPER_ATTRIBUTE_RESOLVED),
+} __attribute__ ((packed)) fib_path_oper_flags_t;
+
+/**
+ * A FIB path
+ */
+typedef struct fib_path_t_ {
+    /**
+     * A path is a node in the FIB graph.
+     */
+    fib_node_t fp_node;
+
+    /**
+     * The index of the path-list to which this path belongs
+     */
+    u32 fp_pl_index;
+
+    /**
+     * This marks the start of the memory area used to hash
+     * the path
+     */
+    STRUCT_MARK(path_hash_start);
+
+    /**
+     * Configuration Flags
+     */
+    fib_path_cfg_flags_t fp_cfg_flags;
+
+    /**
+     * The type of the path. This is the selector for the union
+     */
+    fib_path_type_t fp_type;
+
+    /**
+     * The protocol of the next-hop, i.e. the address family of the
+     * next-hop's address. We can't derive this from the address itself
+     * since the address can be all zeros
+     */
+    fib_protocol_t fp_nh_proto;
+
+    /**
+     * UCMP [unnormalised] weigt
+     */
+    u32 fp_weight;
+
+    /**
+     * per-type union of the data required to resolve the path
+     */
+    union {
+	struct {
+	    /**
+	     * The next-hop
+	     */
+	    ip46_address_t fp_nh;
+	    /**
+	     * The interface
+	     */
+	    u32 fp_interface;
+	} attached_next_hop;
+	struct {
+	    /**
+	     * The interface
+	     */
+	    u32 fp_interface;
+	} attached;
+	struct {
+	    union
+	    {
+		/**
+		 * The next-hop
+		 */
+		ip46_address_t fp_ip;
+		/**
+		 * The local label to resolve through.
+		 */
+		mpls_label_t fp_local_label;
+	    } fp_nh;
+	    /**
+	     * The FIB table index in which to find the next-hop.
+	     * This needs to be fixed. We should lookup the adjacencies in
+	     * a separate table of adjacencies, rather than from the FIB.
+	     * Two reasons I can think of:
+	     *   - consider:
+	     *       int ip addr Gig0 10.0.0.1/24
+	     *       ip route 10.0.0.2/32 via Gig1 192.168.1.2
+	     *       ip route 1.1.1.1/32 via Gig0 10.0.0.2
+	     *     this is perfectly valid.
+	     *     Packets addressed to 10.0.0.2 should be sent via Gig1.
+	     *     Packets address to 1.1.1.1 should be sent via Gig0.
+	     *    when we perform the adj resolution from the FIB for the path
+	     *    "via Gig0 10.0.0.2" the lookup will result in the route via Gig1
+	     *    and so we will pick up the adj via Gig1 - which was not what the
+	     *    operator wanted.
+	     *  - we can only return link-type IPv4 and so not the link-type MPLS.
+	     *    more on this in a later commit.
+	     *
+	     * The table ID should only belong to a recursive path and indicate
+	     * which FIB should be used to resolve the next-hop.
+	     */
+	    fib_node_index_t fp_tbl_id;
+	} recursive;
+	struct {
+	    /**
+	     * The FIB index in which to perfom the next lookup
+	     */
+	    fib_node_index_t fp_tbl_id;
+	} deag;
+	struct {
+	} special;
+	struct {
+	    /**
+	     * The user provided 'exclusive' DPO
+	     */
+	    dpo_id_t fp_ex_dpo;
+	} exclusive;
+	struct {
+	    /**
+	     * The interface on which the local address is configured
+	     */
+	    u32 fp_interface;
+	    /**
+	     * The next-hop
+	     */
+	    ip46_address_t fp_addr;
+	} receive;
+    };
+    STRUCT_MARK(path_hash_end);
+
+    /**
+     * Memebers in this last section represent information that is
+     * dervied during resolution. It should not be copied to new paths
+     * nor compared.
+     */
+
+    /**
+     * Operational Flags
+     */
+    fib_path_oper_flags_t fp_oper_flags;
+
+    /**
+     * the resolving via fib. not part of the union, since it it not part
+     * of the path's hash.
+     */
+    fib_node_index_t fp_via_fib;
+
+    /**
+     * The Data-path objects through which this path resolves for IP.
+     */
+    dpo_id_t fp_dpo;
+
+    /**
+     * the index of this path in the parent's child list.
+     */
+    u32 fp_sibling;
+} fib_path_t;
+
+/*
+ * Array of strings/names for the path types and attributes
+ */
+static const char *fib_path_type_names[] = FIB_PATH_TYPES;
+static const char *fib_path_oper_attribute_names[] = FIB_PATH_OPER_ATTRIBUTES;
+static const char *fib_path_cfg_attribute_names[]  = FIB_PATH_CFG_ATTRIBUTES;
+
+/*
+ * The memory pool from which we allocate all the paths
+ */
+static fib_path_t *fib_path_pool;
+
+/*
+ * Debug macro
+ */
+#ifdef FIB_DEBUG
+#define FIB_PATH_DBG(_p, _fmt, _args...)			\
+{       		          				\
+    u8 *_tmp = NULL;						\
+    _tmp = fib_path_format(fib_path_get_index(_p), _tmp);	\
+    clib_warning("path:[%d:%s]:" _fmt,				\
+		 fib_path_get_index(_p), _tmp,			\
+		 ##_args);					\
+    vec_free(_tmp);						\
+}
+#else
+#define FIB_PATH_DBG(_p, _fmt, _args...)
+#endif
+
+static fib_path_t *
+fib_path_get (fib_node_index_t index)
+{
+    return (pool_elt_at_index(fib_path_pool, index));
+}
+
+static fib_node_index_t 
+fib_path_get_index (fib_path_t *path)
+{
+    return (path - fib_path_pool);
+}
+
+static fib_node_t *
+fib_path_get_node (fib_node_index_t index)
+{
+    return ((fib_node_t*)fib_path_get(index));
+}
+
+static fib_path_t*
+fib_path_from_fib_node (fib_node_t *node)
+{
+#if CLIB_DEBUG > 0
+    ASSERT(FIB_NODE_TYPE_PATH == node->fn_type);
+#endif
+    return ((fib_path_t*)node);
+}
+
+u8 *
+format_fib_path (u8 * s, va_list * args)
+{
+    fib_path_t *path = va_arg (*args, fib_path_t *);
+    vnet_main_t * vnm = vnet_get_main();
+    fib_path_oper_attribute_t oattr;
+    fib_path_cfg_attribute_t cattr;
+
+    s = format (s, "      index:%d ", fib_path_get_index(path));
+    s = format (s, "pl-index:%d ", path->fp_pl_index);
+    s = format (s, "%U ", format_fib_protocol, path->fp_nh_proto);
+    s = format (s, "weight=%d ", path->fp_weight);
+    s = format (s, "%s: ", fib_path_type_names[path->fp_type]);
+    if (FIB_PATH_OPER_FLAG_NONE != path->fp_oper_flags) {
+	s = format(s, " oper-flags:");
+	FOR_EACH_FIB_PATH_OPER_ATTRIBUTE(oattr) {
+	    if ((1<<oattr) & path->fp_oper_flags) {
+		s = format (s, "%s,", fib_path_oper_attribute_names[oattr]);
+	    }
+	}
+    }
+    if (FIB_PATH_CFG_FLAG_NONE != path->fp_cfg_flags) {
+	s = format(s, " cfg-flags:");
+	FOR_EACH_FIB_PATH_CFG_ATTRIBUTE(cattr) {
+	    if ((1<<cattr) & path->fp_cfg_flags) {
+		s = format (s, "%s,", fib_path_cfg_attribute_names[cattr]);
+	    }
+	}
+    }
+    s = format(s, "\n       ");
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	s = format (s, "%U", format_ip46_address,
+		    &path->attached_next_hop.fp_nh,
+		    IP46_TYPE_ANY);
+	if (path->fp_oper_flags & FIB_PATH_OPER_FLAG_DROP)
+	{
+	    s = format (s, " if_index:%d", path->attached_next_hop.fp_interface);
+	}
+	else
+	{
+	    s = format (s, " %U",
+			format_vnet_sw_interface_name,
+			vnm,
+			vnet_get_sw_interface(
+			    vnm,
+			    path->attached_next_hop.fp_interface));
+	    if (vnet_sw_interface_is_p2p(vnet_get_main(),
+					 path->attached_next_hop.fp_interface))
+	    {
+		s = format (s, " (p2p)");
+	    }
+	}
+	if (!dpo_id_is_valid(&path->fp_dpo))
+	{
+	    s = format(s, "\n          unresolved");
+	}
+	else
+	{
+	    s = format(s, "\n          %U",
+		       format_dpo_id,
+		       &path->fp_dpo, 13);
+	}
+	break;
+    case FIB_PATH_TYPE_ATTACHED:
+	if (path->fp_oper_flags & FIB_PATH_OPER_FLAG_DROP)
+	{
+	    s = format (s, " if_index:%d", path->attached_next_hop.fp_interface);
+	}
+	else
+	{
+	    s = format (s, " %U",
+			format_vnet_sw_interface_name,
+			vnm,
+			vnet_get_sw_interface(
+			    vnm,
+			    path->attached.fp_interface));
+	}
+	break;
+    case FIB_PATH_TYPE_RECURSIVE:
+	if (FIB_PROTOCOL_MPLS == path->fp_nh_proto)
+	{
+	    s = format (s, "via %U",
+			format_mpls_unicast_label,
+			path->recursive.fp_nh.fp_local_label);
+	}
+	else
+	{
+	    s = format (s, "via %U",
+			format_ip46_address,
+			&path->recursive.fp_nh.fp_ip,
+			IP46_TYPE_ANY);
+	}
+	s = format (s, " in fib:%d",
+		    path->recursive.fp_tbl_id,
+		    path->fp_via_fib); 
+	s = format (s, " via-fib:%d", path->fp_via_fib); 
+	s = format (s, " via-dpo:[%U:%d]",
+		    format_dpo_type, path->fp_dpo.dpoi_type, 
+		    path->fp_dpo.dpoi_index);
+
+	break;
+    case FIB_PATH_TYPE_RECEIVE:
+    case FIB_PATH_TYPE_SPECIAL:
+    case FIB_PATH_TYPE_DEAG:
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	if (dpo_id_is_valid(&path->fp_dpo))
+	{
+	    s = format(s, "%U", format_dpo_id,
+		       &path->fp_dpo, 2);
+	}
+	break;
+    }
+    return (s);
+}
+
+u8 *
+fib_path_format (fib_node_index_t pi, u8 *s)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(pi);
+    ASSERT(NULL != path);
+
+    return (format (s, "%U", format_fib_path, path));
+}
+
+u8 *
+fib_path_adj_format (fib_node_index_t pi,
+		     u32 indent,
+		     u8 *s)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(pi);
+    ASSERT(NULL != path);
+
+    if (!dpo_id_is_valid(&path->fp_dpo))
+    {
+	s = format(s, " unresolved");
+    }
+    else
+    {
+	s = format(s, "%U", format_dpo_id,
+		   &path->fp_dpo, 2);
+    }
+
+    return (s);
+}
+
+/*
+ * fib_path_last_lock_gone
+ *
+ * We don't share paths, we share path lists, so the [un]lock functions
+ * are no-ops
+ */
+static void
+fib_path_last_lock_gone (fib_node_t *node)
+{
+    ASSERT(0);
+}
+
+static const adj_index_t
+fib_path_attached_next_hop_get_adj (fib_path_t *path,
+				    vnet_link_t link)
+{
+    if (vnet_sw_interface_is_p2p(vnet_get_main(),
+				 path->attached_next_hop.fp_interface))
+    {
+	/*
+	 * if the interface is p2p then the adj for the specific
+	 * neighbour on that link will never exist. on p2p links
+	 * the subnet address (the attached route) links to the
+	 * auto-adj (see below), we want that adj here too.
+	 */
+	return (adj_nbr_add_or_lock(path->fp_nh_proto,
+				    link,
+				    &zero_addr,
+				    path->attached_next_hop.fp_interface));
+    }
+    else
+    {
+	return (adj_nbr_add_or_lock(path->fp_nh_proto,
+				    link,
+				    &path->attached_next_hop.fp_nh,
+				    path->attached_next_hop.fp_interface));
+    }
+}
+
+static void
+fib_path_attached_next_hop_set (fib_path_t *path)
+{
+    /*
+     * resolve directly via the adjacnecy discribed by the
+     * interface and next-hop
+     */
+    if (!vnet_sw_interface_is_admin_up(vnet_get_main(),
+				      path->attached_next_hop.fp_interface))
+    {
+	path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+    }
+
+    dpo_set(&path->fp_dpo,
+	    DPO_ADJACENCY,
+	    fib_proto_to_dpo(path->fp_nh_proto),
+	    fib_path_attached_next_hop_get_adj(
+		 path,
+		 fib_proto_to_link(path->fp_nh_proto)));
+
+    /*
+     * become a child of the adjacency so we receive updates
+     * when its rewrite changes
+     */
+    path->fp_sibling = adj_child_add(path->fp_dpo.dpoi_index,
+				     FIB_NODE_TYPE_PATH,
+				     fib_path_get_index(path));
+}
+
+/*
+ * create of update the paths recursive adj
+ */
+static void
+fib_path_recursive_adj_update (fib_path_t *path,
+			       fib_forward_chain_type_t fct,
+			       dpo_id_t *dpo)
+{
+    dpo_id_t via_dpo = DPO_INVALID;
+
+    /*
+     * get the DPO to resolve through from the via-entry
+     */
+    fib_entry_contribute_forwarding(path->fp_via_fib,
+				    fct,
+				    &via_dpo);
+
+
+    /*
+     * hope for the best - clear if restrictions apply.
+     */
+    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RESOLVED;
+
+    /*
+     * Validate any recursion constraints and over-ride the via
+     * adj if not met
+     */
+    if (path->fp_oper_flags & FIB_PATH_OPER_FLAG_RECURSIVE_LOOP)
+    {
+	path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+	dpo_copy(&via_dpo, drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+    }
+    else if (path->fp_cfg_flags & FIB_PATH_CFG_FLAG_RESOLVE_HOST)
+    {
+	/*
+	 * the via FIB must be a host route.
+	 * note the via FIB just added will always be a host route
+	 * since it is an RR source added host route. So what we need to
+	 * check is whether the route has other sources. If it does then
+	 * some other source has added it as a host route. If it doesn't
+	 * then it was added only here and inherits forwarding from a cover.
+	 * the cover is not a host route.
+	 * The RR source is the lowest priority source, so we check if it
+	 * is the best. if it is there are no other sources.
+	 */
+	if (fib_entry_get_best_source(path->fp_via_fib) >= FIB_SOURCE_RR)
+	{
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+            dpo_copy(&via_dpo, drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+
+            /*
+             * PIC edge trigger. let the load-balance maps know
+             */
+            load_balance_map_path_state_change(fib_path_get_index(path));
+	}
+    }
+    else if (path->fp_cfg_flags & FIB_PATH_CFG_FLAG_RESOLVE_ATTACHED)
+    {
+	/*
+	 * RR source entries inherit the flags from the cover, so
+	 * we can check the via directly
+	 */
+	if (!(FIB_ENTRY_FLAG_ATTACHED & fib_entry_get_flags(path->fp_via_fib)))
+	{
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+            dpo_copy(&via_dpo, drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+
+            /*
+             * PIC edge trigger. let the load-balance maps know
+             */
+            load_balance_map_path_state_change(fib_path_get_index(path));
+	}
+    }
+
+    /*
+     * update the path's contributed DPO
+     */
+    dpo_copy(dpo, &via_dpo);
+
+    FIB_PATH_DBG(path, "recursive update: %U",
+		 fib_get_lookup_main(path->fp_nh_proto),
+		 &path->fp_dpo, 2);
+
+    dpo_reset(&via_dpo);
+}
+
+/*
+ * fib_path_is_permanent_drop
+ *
+ * Return !0 if the path is configured to permanently drop,
+ * despite other attributes.
+ */
+static int
+fib_path_is_permanent_drop (fib_path_t *path)
+{
+    return ((path->fp_cfg_flags & FIB_PATH_CFG_FLAG_DROP) ||
+	    (path->fp_oper_flags & FIB_PATH_OPER_FLAG_DROP));
+}
+
+/*
+ * fib_path_unresolve
+ *
+ * Remove our dependency on the resolution target
+ */
+static void
+fib_path_unresolve (fib_path_t *path)
+{
+    /*
+     * the forced drop path does not need unresolving
+     */
+    if (fib_path_is_permanent_drop(path))
+    {
+	return;
+    }
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_RECURSIVE:
+	if (FIB_NODE_INDEX_INVALID != path->fp_via_fib)
+	{
+	    fib_prefix_t pfx;
+
+	    fib_entry_get_prefix(path->fp_via_fib, &pfx);
+	    fib_entry_child_remove(path->fp_via_fib,
+				   path->fp_sibling);
+	    fib_table_entry_special_remove(path->recursive.fp_tbl_id,
+					   &pfx,
+					   FIB_SOURCE_RR);
+	    path->fp_via_fib = FIB_NODE_INDEX_INVALID;
+	}
+	break;
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+    case FIB_PATH_TYPE_ATTACHED:
+	adj_child_remove(path->fp_dpo.dpoi_index,
+			 path->fp_sibling);
+        adj_unlock(path->fp_dpo.dpoi_index);
+        break;
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	dpo_reset(&path->exclusive.fp_ex_dpo);
+        break;
+    case FIB_PATH_TYPE_SPECIAL:
+    case FIB_PATH_TYPE_RECEIVE:
+    case FIB_PATH_TYPE_DEAG:
+        /*
+         * these hold only the path's DPO, which is reset below.
+         */
+	break;
+    }
+
+    /*
+     * release the adj we were holding and pick up the
+     * drop just in case.
+     */
+    dpo_reset(&path->fp_dpo);
+    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+
+    return;
+}
+
+static fib_forward_chain_type_t
+fib_path_proto_to_chain_type (fib_protocol_t proto)
+{
+    switch (proto)
+    {
+    case FIB_PROTOCOL_IP4:
+	return (FIB_FORW_CHAIN_TYPE_UNICAST_IP4);
+    case FIB_PROTOCOL_IP6:
+	return (FIB_FORW_CHAIN_TYPE_UNICAST_IP6);
+    case FIB_PROTOCOL_MPLS:
+	return (FIB_FORW_CHAIN_TYPE_MPLS_NON_EOS);
+    }
+    return (FIB_FORW_CHAIN_TYPE_UNICAST_IP4);
+}
+
+/*
+ * fib_path_back_walk_notify
+ *
+ * A back walk has reach this path.
+ */
+static fib_node_back_walk_rc_t
+fib_path_back_walk_notify (fib_node_t *node,
+			   fib_node_back_walk_ctx_t *ctx)
+{
+    fib_path_t *path;
+
+    path = fib_path_from_fib_node(node);
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_RECURSIVE:
+	if (FIB_NODE_BW_REASON_FLAG_EVALUATE & ctx->fnbw_reason)
+	{
+	    /*
+	     * modify the recursive adjacency to use the new forwarding
+	     * of the via-fib.
+	     * this update is visible to packets in flight in the DP.
+	     */
+	    fib_path_recursive_adj_update(
+		path,
+		fib_path_proto_to_chain_type(path->fp_nh_proto),
+		&path->fp_dpo);
+	}
+	if ((FIB_NODE_BW_REASON_FLAG_ADJ_UPDATE & ctx->fnbw_reason) ||
+            (FIB_NODE_BW_REASON_FLAG_ADJ_DOWN   & ctx->fnbw_reason))
+	{
+	    /*
+	     * ADJ updates (complete<->incomplete) do not need to propagate to
+	     * recursive entries.
+	     * The only reason its needed as far back as here, is that the adj
+	     * and the incomplete adj are a different DPO type, so the LBs need
+	     * to re-stack.
+	     * If this walk was quashed in the fib_entry, then any non-fib_path
+	     * children (like tunnels that collapse out the LB when they stack)
+	     * would not see the update.
+	     */
+	    return (FIB_NODE_BACK_WALK_CONTINUE);
+	}
+	break;
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	/*
+FIXME comment
+	 * ADJ_UPDATE backwalk pass silently through here and up to
+	 * the path-list when the multipath adj collapse occurs.
+	 * The reason we do this is that the assumtption is that VPP
+	 * runs in an environment where the Control-Plane is remote
+	 * and hence reacts slowly to link up down. In order to remove
+	 * this down link from the ECMP set quickly, we back-walk.
+	 * VPP also has dedicated CPUs, so we are not stealing resources
+	 * from the CP to do so.
+	 */
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_UP & ctx->fnbw_reason)
+	{
+            if (path->fp_oper_flags & FIB_PATH_OPER_FLAG_RESOLVED)
+            {
+                /*
+                 * alreday resolved. no need to walk back again
+                 */
+                return (FIB_NODE_BACK_WALK_CONTINUE);
+            }
+	    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RESOLVED;
+	}
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_DOWN & ctx->fnbw_reason)
+	{
+            if (!(path->fp_oper_flags & FIB_PATH_OPER_FLAG_RESOLVED))
+            {
+                /*
+                 * alreday unresolved. no need to walk back again
+                 */
+                return (FIB_NODE_BACK_WALK_CONTINUE);
+            }
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+	}
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_DELETE & ctx->fnbw_reason)
+	{
+	    /*
+	     * The interface this path resolves through has been deleted.
+	     * This will leave the path in a permanent drop state. The route
+	     * needs to be removed and readded (and hence the path-list deleted)
+	     * before it can forward again.
+	     */
+	    fib_path_unresolve(path);
+	    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_DROP;
+	}
+        if (FIB_NODE_BW_REASON_FLAG_ADJ_UPDATE & ctx->fnbw_reason)
+	{
+            /*
+             * restack the DPO to pick up the correct DPO sub-type
+             */
+            uword if_is_up;
+            adj_index_t ai;
+
+            if_is_up = vnet_sw_interface_is_admin_up(
+                           vnet_get_main(),
+                           path->attached_next_hop.fp_interface);
+
+            if (if_is_up)
+            {
+                path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RESOLVED;
+            }
+
+            ai = fib_path_attached_next_hop_get_adj(
+                     path,
+                     fib_proto_to_link(path->fp_nh_proto));
+
+            dpo_set(&path->fp_dpo, DPO_ADJACENCY,
+                    fib_proto_to_dpo(path->fp_nh_proto),
+                    ai);
+            adj_unlock(ai);
+
+            if (!if_is_up)
+            {
+                /*
+                 * If the interface is not up there is no reason to walk
+                 * back to children. if we did they would only evalute
+                 * that this path is unresolved and hence it would
+                 * not contribute the adjacency - so it would be wasted
+                 * CPU time.
+                 */
+                return (FIB_NODE_BACK_WALK_CONTINUE);
+            }
+        }
+        if (FIB_NODE_BW_REASON_FLAG_ADJ_DOWN & ctx->fnbw_reason)
+	{
+            if (!(path->fp_oper_flags & FIB_PATH_OPER_FLAG_RESOLVED))
+            {
+                /*
+                 * alreday unresolved. no need to walk back again
+                 */
+                return (FIB_NODE_BACK_WALK_CONTINUE);
+            }
+            /*
+             * the adj has gone down. the path is no longer resolved.
+             */
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+        }
+	break;
+    case FIB_PATH_TYPE_ATTACHED:
+	/*
+	 * FIXME; this could schedule a lower priority walk, since attached
+	 * routes are not usually in ECMP configurations so the backwalk to
+	 * the FIB entry does not need to be high priority
+	 */
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_UP & ctx->fnbw_reason)
+	{
+	    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RESOLVED;
+	}
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_DOWN & ctx->fnbw_reason)
+	{
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+	}
+	if (FIB_NODE_BW_REASON_FLAG_INTERFACE_DELETE & ctx->fnbw_reason)
+	{
+	    fib_path_unresolve(path);
+	    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_DROP;
+	}
+	break;
+    case FIB_PATH_TYPE_DEAG:
+	/*
+	 * FIXME When VRF delete is allowed this will need a poke.
+	 */
+    case FIB_PATH_TYPE_SPECIAL:
+    case FIB_PATH_TYPE_RECEIVE:
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	/*
+	 * these path types have no parents. so to be
+	 * walked from one is unexpected.
+	 */
+	ASSERT(0);
+	break;
+    }
+
+    /*
+     * propagate the backwalk further to the path-list
+     */
+    fib_path_list_back_walk(path->fp_pl_index, ctx);
+
+    return (FIB_NODE_BACK_WALK_CONTINUE);
+}
+
+static void
+fib_path_memory_show (void)
+{
+    fib_show_memory_usage("Path",
+			  pool_elts(fib_path_pool),
+			  pool_len(fib_path_pool),
+			  sizeof(fib_path_t));
+}
+
+/*
+ * The FIB path's graph node virtual function table
+ */
+static const fib_node_vft_t fib_path_vft = {
+    .fnv_get = fib_path_get_node,
+    .fnv_last_lock = fib_path_last_lock_gone,
+    .fnv_back_walk = fib_path_back_walk_notify,
+    .fnv_mem_show = fib_path_memory_show,
+};
+
+static fib_path_cfg_flags_t
+fib_path_route_flags_to_cfg_flags (const fib_route_path_t *rpath)
+{
+    fib_path_cfg_flags_t cfg_flags = FIB_PATH_CFG_FLAG_NONE;
+
+    if (rpath->frp_flags & FIB_ROUTE_PATH_RESOLVE_VIA_HOST)
+	cfg_flags |= FIB_PATH_CFG_FLAG_RESOLVE_HOST;
+    if (rpath->frp_flags & FIB_ROUTE_PATH_RESOLVE_VIA_ATTACHED)
+	cfg_flags |= FIB_PATH_CFG_FLAG_RESOLVE_ATTACHED;
+
+    return (cfg_flags);
+}
+
+/*
+ * fib_path_create
+ *
+ * Create and initialise a new path object.
+ * return the index of the path.
+ */
+fib_node_index_t
+fib_path_create (fib_node_index_t pl_index,
+		 fib_protocol_t nh_proto,
+		 fib_path_cfg_flags_t flags,
+		 const fib_route_path_t *rpath)
+{
+    fib_path_t *path;
+
+    pool_get(fib_path_pool, path);
+    memset(path, 0, sizeof(*path));
+
+    fib_node_init(&path->fp_node,
+		  FIB_NODE_TYPE_PATH);
+
+    dpo_reset(&path->fp_dpo);
+    path->fp_pl_index = pl_index;
+    path->fp_nh_proto = nh_proto;
+    path->fp_via_fib = FIB_NODE_INDEX_INVALID;
+    path->fp_weight = rpath->frp_weight;
+    if (0 == path->fp_weight)
+    {
+        /*
+         * a weight of 0 is a meaningless value. We could either reject it, and thus force
+         * clients to always use 1, or we can accept it and fixup approrpiately.
+         */
+        path->fp_weight = 1;
+    }
+    path->fp_cfg_flags = flags;
+    path->fp_cfg_flags |= fib_path_route_flags_to_cfg_flags(rpath);
+
+    /*
+     * deduce the path's tpye from the parementers and save what is needed.
+     */
+    if (~0 != rpath->frp_sw_if_index)
+    {
+	if (flags & FIB_PATH_CFG_FLAG_LOCAL)
+	{
+	    path->fp_type = FIB_PATH_TYPE_RECEIVE;
+	    path->receive.fp_interface = rpath->frp_sw_if_index;
+            path->receive.fp_addr = rpath->frp_addr;
+	}
+	else
+	{
+	    if (ip46_address_is_zero(&rpath->frp_addr))
+	    {
+		path->fp_type = FIB_PATH_TYPE_ATTACHED;
+		path->attached.fp_interface = rpath->frp_sw_if_index;
+	    }
+	    else
+	    {
+		path->fp_type = FIB_PATH_TYPE_ATTACHED_NEXT_HOP;
+		path->attached_next_hop.fp_interface = rpath->frp_sw_if_index;
+		path->attached_next_hop.fp_nh = rpath->frp_addr;
+	    }
+	}
+    }
+    else
+    {
+	if (ip46_address_is_zero(&rpath->frp_addr))
+	{
+	    if (~0 == rpath->frp_fib_index)
+	    {
+		path->fp_type = FIB_PATH_TYPE_SPECIAL;
+	    }
+	    else
+	    {
+		path->fp_type = FIB_PATH_TYPE_DEAG;
+		path->deag.fp_tbl_id = rpath->frp_fib_index;
+	    }		
+	}
+	else
+	{
+	    path->fp_type = FIB_PATH_TYPE_RECURSIVE;
+	    if (FIB_PROTOCOL_MPLS == path->fp_nh_proto)
+	    {
+		path->recursive.fp_nh.fp_local_label = rpath->frp_local_label;
+	    }
+	    else
+	    {
+		path->recursive.fp_nh.fp_ip = rpath->frp_addr;
+	    }
+	    path->recursive.fp_tbl_id = rpath->frp_fib_index;
+	}
+    }
+
+    FIB_PATH_DBG(path, "create");
+
+    return (fib_path_get_index(path));
+}
+
+/*
+ * fib_path_create_special
+ *
+ * Create and initialise a new path object.
+ * return the index of the path.
+ */
+fib_node_index_t
+fib_path_create_special (fib_node_index_t pl_index,
+			 fib_protocol_t nh_proto,
+			 fib_path_cfg_flags_t flags,
+			 const dpo_id_t *dpo)
+{
+    fib_path_t *path;
+
+    pool_get(fib_path_pool, path);
+    memset(path, 0, sizeof(*path));
+
+    fib_node_init(&path->fp_node,
+		  FIB_NODE_TYPE_PATH);
+    dpo_reset(&path->fp_dpo);
+
+    path->fp_pl_index = pl_index;
+    path->fp_weight = 1;
+    path->fp_nh_proto = nh_proto;
+    path->fp_via_fib = FIB_NODE_INDEX_INVALID;
+    path->fp_cfg_flags = flags;
+
+    if (FIB_PATH_CFG_FLAG_DROP & flags)
+    {
+	path->fp_type = FIB_PATH_TYPE_SPECIAL;
+    }
+    else if (FIB_PATH_CFG_FLAG_LOCAL & flags)
+    {
+	path->fp_type = FIB_PATH_TYPE_RECEIVE;
+	path->attached.fp_interface = FIB_NODE_INDEX_INVALID;
+    }
+    else
+    {
+	path->fp_type = FIB_PATH_TYPE_EXCLUSIVE;
+	ASSERT(NULL != dpo);
+	dpo_copy(&path->exclusive.fp_ex_dpo, dpo);
+    }
+
+    return (fib_path_get_index(path));
+}
+
+/*
+ * fib_path_copy
+ *
+ * Copy a path. return index of new path.
+ */
+fib_node_index_t
+fib_path_copy (fib_node_index_t path_index,
+	       fib_node_index_t path_list_index)
+{
+    fib_path_t *path, *orig_path;
+
+    pool_get(fib_path_pool, path);
+
+    orig_path = fib_path_get(path_index);
+    ASSERT(NULL != orig_path);
+
+    memcpy(path, orig_path, sizeof(*path));
+
+    FIB_PATH_DBG(path, "create-copy:%d", path_index);
+
+    /*
+     * reset the dynamic section
+     */
+    fib_node_init(&path->fp_node, FIB_NODE_TYPE_PATH);
+    path->fp_oper_flags     = FIB_PATH_OPER_FLAG_NONE;
+    path->fp_pl_index  = path_list_index;
+    path->fp_via_fib   = FIB_NODE_INDEX_INVALID;
+    memset(&path->fp_dpo, 0, sizeof(path->fp_dpo));
+    dpo_reset(&path->fp_dpo);
+
+    return (fib_path_get_index(path));
+}
+
+/*
+ * fib_path_destroy
+ *
+ * destroy a path that is no longer required
+ */
+void
+fib_path_destroy (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    ASSERT(NULL != path);
+    FIB_PATH_DBG(path, "destroy");
+
+    fib_path_unresolve(path);
+
+    fib_node_deinit(&path->fp_node);
+    pool_put(fib_path_pool, path);
+}
+
+/*
+ * fib_path_destroy
+ *
+ * destroy a path that is no longer required
+ */
+uword
+fib_path_hash (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (hash_memory(STRUCT_MARK_PTR(path, path_hash_start),
+			(STRUCT_OFFSET_OF(fib_path_t, path_hash_end) -
+			 STRUCT_OFFSET_OF(fib_path_t, path_hash_start)),
+			0));
+}
+
+/*
+ * fib_path_cmp_i
+ *
+ * Compare two paths for equivalence.
+ */
+static int
+fib_path_cmp_i (const fib_path_t *path1,
+		const fib_path_t *path2)
+{
+    int res;
+
+    res = 1;
+
+    /*
+     * paths of different types and protocol are not equal.
+     * different weights only are the same path.
+     */
+    if (path1->fp_type != path2->fp_type)
+    {
+	res = (path1->fp_type - path2->fp_type);
+    }
+    if (path1->fp_nh_proto != path2->fp_nh_proto)
+    {
+	res = (path1->fp_nh_proto - path2->fp_nh_proto);
+    }
+    else
+    {
+	/*
+	 * both paths are of the same type.
+	 * consider each type and its attributes in turn.
+	 */
+	switch (path1->fp_type)
+	{
+	case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	    res = ip46_address_cmp(&path1->attached_next_hop.fp_nh,
+				   &path2->attached_next_hop.fp_nh);
+	    if (0 == res) {
+		res = vnet_sw_interface_compare(
+			  vnet_get_main(),
+			  path1->attached_next_hop.fp_interface,
+			  path2->attached_next_hop.fp_interface);
+	    }
+	    break;
+	case FIB_PATH_TYPE_ATTACHED:
+	    res = vnet_sw_interface_compare(
+		      vnet_get_main(),
+		      path1->attached.fp_interface,
+		      path2->attached.fp_interface);
+	    break;
+	case FIB_PATH_TYPE_RECURSIVE:
+	    res = ip46_address_cmp(&path1->recursive.fp_nh,
+				   &path2->recursive.fp_nh);
+ 
+	    if (0 == res)
+	    {
+		res = (path1->recursive.fp_tbl_id - path2->recursive.fp_tbl_id);
+	    }
+	    break;
+	case FIB_PATH_TYPE_DEAG:
+	    res = (path1->deag.fp_tbl_id - path2->deag.fp_tbl_id);
+	    break;
+	case FIB_PATH_TYPE_SPECIAL:
+	case FIB_PATH_TYPE_RECEIVE:
+	case FIB_PATH_TYPE_EXCLUSIVE:
+	    res = 0;
+	    break;
+	}
+    }
+    return (res);
+}
+
+/*
+ * fib_path_cmp_for_sort
+ *
+ * Compare two paths for equivalence. Used during path sorting.
+ * As usual 0 means equal.
+ */
+int
+fib_path_cmp_for_sort (void * v1,
+		       void * v2)
+{
+    fib_node_index_t *pi1 = v1, *pi2 = v2;
+    fib_path_t *path1, *path2;
+
+    path1 = fib_path_get(*pi1);
+    path2 = fib_path_get(*pi2);
+
+    return (fib_path_cmp_i(path1, path2));
+}
+
+/*
+ * fib_path_cmp
+ *
+ * Compare two paths for equivalence.
+ */
+int
+fib_path_cmp (fib_node_index_t pi1,
+	      fib_node_index_t pi2)
+{
+    fib_path_t *path1, *path2;
+
+    path1 = fib_path_get(pi1);
+    path2 = fib_path_get(pi2);
+
+    return (fib_path_cmp_i(path1, path2));
+}
+
+int
+fib_path_cmp_w_route_path (fib_node_index_t path_index,
+			   const fib_route_path_t *rpath)
+{
+    fib_path_t *path;
+    int res;
+
+    path = fib_path_get(path_index);
+
+    res = 1;
+
+    if (path->fp_weight != rpath->frp_weight)
+    {
+	res = (path->fp_weight - rpath->frp_weight);
+    }
+    else
+    {
+	/*
+	 * both paths are of the same type.
+	 * consider each type and its attributes in turn.
+	 */
+	switch (path->fp_type)
+	{
+	case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	    res = ip46_address_cmp(&path->attached_next_hop.fp_nh,
+				   &rpath->frp_addr);
+	    if (0 == res)
+	    {
+		res = vnet_sw_interface_compare(
+			  vnet_get_main(),
+			  path->attached_next_hop.fp_interface,
+			  rpath->frp_sw_if_index);
+	    }
+	    break;
+	case FIB_PATH_TYPE_ATTACHED:
+	    res = vnet_sw_interface_compare(
+		      vnet_get_main(),
+		      path->attached.fp_interface,
+		      rpath->frp_sw_if_index);
+	    break;
+	case FIB_PATH_TYPE_RECURSIVE:
+            if (FIB_PROTOCOL_MPLS == path->fp_nh_proto)
+            {
+                res = path->recursive.fp_nh.fp_local_label - rpath->frp_local_label;
+            }
+            else
+            {
+                res = ip46_address_cmp(&path->recursive.fp_nh.fp_ip,
+                                       &rpath->frp_addr);
+            }
+
+            if (0 == res)
+            {
+                res = (path->recursive.fp_tbl_id - rpath->frp_fib_index);
+            }
+	    break;
+	case FIB_PATH_TYPE_DEAG:
+	    res = (path->deag.fp_tbl_id - rpath->frp_fib_index);
+	    break;
+	case FIB_PATH_TYPE_SPECIAL:
+	case FIB_PATH_TYPE_RECEIVE:
+	case FIB_PATH_TYPE_EXCLUSIVE:
+	    res = 0;
+	    break;
+	}
+    }
+    return (res);
+}
+
+/*
+ * fib_path_recursive_loop_detect
+ *
+ * A forward walk of the FIB object graph to detect for a cycle/loop. This
+ * walk is initiated when an entry is linking to a new path list or from an old.
+ * The entry vector passed contains all the FIB entrys that are children of this
+ * path (it is all the entries encountered on the walk so far). If this vector
+ * contains the entry this path resolve via, then a loop is about to form.
+ * The loop must be allowed to form, since we need the dependencies in place
+ * so that we can track when the loop breaks.
+ * However, we MUST not produce a loop in the forwarding graph (else packets
+ * would loop around the switch path until the loop breaks), so we mark recursive
+ * paths as looped so that they do not contribute forwarding information.
+ * By marking the path as looped, an etry such as;
+ *    X/Y
+ *     via a.a.a.a (looped)
+ *     via b.b.b.b (not looped)
+ * can still forward using the info provided by b.b.b.b only
+ */
+int
+fib_path_recursive_loop_detect (fib_node_index_t path_index,
+				fib_node_index_t **entry_indicies)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    /*
+     * the forced drop path is never looped, cos it is never resolved.
+     */
+    if (fib_path_is_permanent_drop(path))
+    {
+	return (0);
+    }
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_RECURSIVE:
+    {
+	fib_node_index_t *entry_index, *entries;
+	int looped = 0;
+	entries = *entry_indicies;
+
+	vec_foreach(entry_index, entries) {
+	    if (*entry_index == path->fp_via_fib)
+	    {
+		/*
+		 * the entry that is about to link to this path-list (or
+		 * one of this path-list's children) is the same entry that
+		 * this recursive path resolves through. this is a cycle.
+		 * abort the walk.
+		 */
+		looped = 1;
+		break;
+	    }
+	}
+
+	if (looped)
+	{
+	    FIB_PATH_DBG(path, "recursive loop formed");
+	    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RECURSIVE_LOOP;
+
+	    dpo_copy(&path->fp_dpo,
+                    drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+	}
+	else
+	{
+	    /*
+	     * no loop here yet. keep forward walking the graph.
+	     */	    
+	    if (fib_entry_recursive_loop_detect(path->fp_via_fib, entry_indicies))
+	    {
+		FIB_PATH_DBG(path, "recursive loop formed");
+		path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RECURSIVE_LOOP;
+	    }
+	    else
+	    {
+		FIB_PATH_DBG(path, "recursive loop cleared");
+		path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RECURSIVE_LOOP;
+	    }
+	}
+	break;
+    }
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+    case FIB_PATH_TYPE_ATTACHED:
+    case FIB_PATH_TYPE_SPECIAL:
+    case FIB_PATH_TYPE_DEAG:
+    case FIB_PATH_TYPE_RECEIVE:
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	/*
+	 * these path types cannot be part of a loop, since they are the leaves
+	 * of the graph.
+	 */
+	break;
+    }
+
+    return (fib_path_is_looped(path_index));
+}
+
+int
+fib_path_resolve (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    /*
+     * hope for the best.
+     */
+    path->fp_oper_flags |= FIB_PATH_OPER_FLAG_RESOLVED;
+
+    /*
+     * the forced drop path resolves via the drop adj
+     */
+    if (fib_path_is_permanent_drop(path))
+    {
+	dpo_copy(&path->fp_dpo,
+                 drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+	path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+	return (fib_path_is_resolved(path_index));
+    }
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	fib_path_attached_next_hop_set(path);
+	break;
+    case FIB_PATH_TYPE_ATTACHED:
+	/*
+	 * path->attached.fp_interface
+	 */
+	if (!vnet_sw_interface_is_admin_up(vnet_get_main(),
+					   path->attached.fp_interface))
+	{
+	    path->fp_oper_flags &= ~FIB_PATH_OPER_FLAG_RESOLVED;
+	}
+	if (vnet_sw_interface_is_p2p(vnet_get_main(),
+				     path->attached.fp_interface))
+	{
+	    /*
+	     * point-2-point interfaces do not require a glean, since
+	     * there is nothing to ARP. Install a rewrite/nbr adj instead
+	     */
+	    dpo_set(&path->fp_dpo,
+		    DPO_ADJACENCY,
+		    fib_proto_to_dpo(path->fp_nh_proto),
+		    adj_nbr_add_or_lock(
+			path->fp_nh_proto,
+			fib_proto_to_link(path->fp_nh_proto),
+			&zero_addr,
+			path->attached.fp_interface));
+	}
+	else
+	{
+	    dpo_set(&path->fp_dpo,
+		    DPO_ADJACENCY_GLEAN,
+		    fib_proto_to_dpo(path->fp_nh_proto),
+		    adj_glean_add_or_lock(path->fp_nh_proto,
+					  path->attached.fp_interface,
+					  NULL));
+	}
+	/*
+	 * become a child of the adjacency so we receive updates
+	 * when the interface state changes
+	 */
+	path->fp_sibling = adj_child_add(path->fp_dpo.dpoi_index,
+					 FIB_NODE_TYPE_PATH,
+					 fib_path_get_index(path));
+
+	break;
+    case FIB_PATH_TYPE_RECURSIVE:
+    {
+	/*
+	 * Create a RR source entry in the table for the address
+	 * that this path recurses through.
+	 * This resolve action is recursive, hence we may create
+	 * more paths in the process. more creates mean maybe realloc
+	 * of this path.
+	 */
+	fib_node_index_t fei;
+	fib_prefix_t pfx;
+
+	ASSERT(FIB_NODE_INDEX_INVALID == path->fp_via_fib);
+
+	if (FIB_PROTOCOL_MPLS == path->fp_nh_proto)
+	{
+	    fib_prefix_from_mpls_label(path->recursive.fp_nh.fp_local_label, &pfx);
+	}
+	else
+	{
+	    fib_prefix_from_ip46_addr(&path->recursive.fp_nh.fp_ip, &pfx);
+	}
+
+	fei = fib_table_entry_special_add(path->recursive.fp_tbl_id,
+					  &pfx,
+					  FIB_SOURCE_RR,
+					  FIB_ENTRY_FLAG_NONE,
+					  ADJ_INDEX_INVALID);
+
+	path = fib_path_get(path_index);
+	path->fp_via_fib = fei;
+
+	/*
+	 * become a dependent child of the entry so the path is 
+	 * informed when the forwarding for the entry changes.
+	 */
+	path->fp_sibling = fib_entry_child_add(path->fp_via_fib,
+					       FIB_NODE_TYPE_PATH,
+					       fib_path_get_index(path));
+
+	/*
+	 * create and configure the IP DPO
+	 */
+	fib_path_recursive_adj_update(
+	    path,
+	    fib_path_proto_to_chain_type(path->fp_nh_proto),
+	    &path->fp_dpo);
+
+	break;
+    }
+    case FIB_PATH_TYPE_SPECIAL:
+	/*
+	 * Resolve via the drop
+	 */
+	dpo_copy(&path->fp_dpo,
+                 drop_dpo_get(fib_proto_to_dpo(path->fp_nh_proto)));
+	break;
+    case FIB_PATH_TYPE_DEAG:
+	/*
+	 * Resolve via a lookup DPO.
+         * FIXME. control plane should add routes with a table ID
+	 */
+	lookup_dpo_add_or_lock_w_fib_index(path->deag.fp_tbl_id,
+                                          fib_proto_to_dpo(path->fp_nh_proto),
+                                          LOOKUP_INPUT_DST_ADDR,
+                                          LOOKUP_TABLE_FROM_CONFIG,
+                                          &path->fp_dpo);
+	break;
+    case FIB_PATH_TYPE_RECEIVE:
+	/*
+	 * Resolve via a receive DPO.
+	 */
+	receive_dpo_add_or_lock(fib_proto_to_dpo(path->fp_nh_proto),
+                                path->receive.fp_interface,
+                                &path->receive.fp_addr,
+                                &path->fp_dpo);
+	break;
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	/*
+	 * Resolve via the user provided DPO
+	 */
+	dpo_copy(&path->fp_dpo, &path->exclusive.fp_ex_dpo);
+	break;
+    }
+
+    return (fib_path_is_resolved(path_index));
+}
+
+u32
+fib_path_get_resolving_interface (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	return (path->attached_next_hop.fp_interface);
+    case FIB_PATH_TYPE_ATTACHED:
+	return (path->attached.fp_interface);
+    case FIB_PATH_TYPE_RECEIVE:
+	return (path->receive.fp_interface);
+    case FIB_PATH_TYPE_RECURSIVE:
+	return (fib_entry_get_resolving_interface(path->fp_via_fib));    
+    case FIB_PATH_TYPE_SPECIAL:
+    case FIB_PATH_TYPE_DEAG:
+    case FIB_PATH_TYPE_EXCLUSIVE:
+	break;
+    }
+    return (~0);
+}
+
+adj_index_t
+fib_path_get_adj (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    ASSERT(dpo_is_adj(&path->fp_dpo));
+    if (dpo_is_adj(&path->fp_dpo))
+    {
+	return (path->fp_dpo.dpoi_index);
+    }
+    return (ADJ_INDEX_INVALID);
+}
+
+int
+fib_path_get_weight (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    ASSERT(path);
+
+    return (path->fp_weight);
+}
+
+/**
+ * @brief Contribute the path's adjacency to the list passed.
+ * By calling this function over all paths, recursively, a child
+ * can construct its full set of forwarding adjacencies, and hence its
+ * uRPF list.
+ */
+void
+fib_path_contribute_urpf (fib_node_index_t path_index,
+			  index_t urpf)
+{
+    fib_path_t *path;
+
+    if (!fib_path_is_resolved(path_index))
+	return;
+
+    path = fib_path_get(path_index);
+
+    switch (path->fp_type)
+    {
+    case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	fib_urpf_list_append(urpf, path->attached_next_hop.fp_interface);
+	break;
+
+    case FIB_PATH_TYPE_ATTACHED:
+	fib_urpf_list_append(urpf, path->attached.fp_interface);
+	break;
+
+    case FIB_PATH_TYPE_RECURSIVE:
+	fib_entry_contribute_urpf(path->fp_via_fib, urpf);
+	break;
+
+    case FIB_PATH_TYPE_EXCLUSIVE:
+    case FIB_PATH_TYPE_SPECIAL:
+	/*
+	 * these path types may link to an adj, if that's what
+	 * the clinet gave
+	 */
+	if (dpo_is_adj(&path->fp_dpo))
+	{
+	    ip_adjacency_t *adj;
+
+	    adj = adj_get(path->fp_dpo.dpoi_index);
+
+	    fib_urpf_list_append(urpf, adj->rewrite_header.sw_if_index);
+	}
+	break;
+
+    case FIB_PATH_TYPE_DEAG:
+    case FIB_PATH_TYPE_RECEIVE:
+	/*
+	 * these path types don't link to an adj
+	 */
+	break;
+    }
+}
+
+void
+fib_path_contribute_forwarding (fib_node_index_t path_index,
+				fib_forward_chain_type_t fct,
+				dpo_id_t *dpo)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    ASSERT(path);
+    ASSERT(FIB_FORW_CHAIN_TYPE_MPLS_EOS != fct);
+
+    FIB_PATH_DBG(path, "contribute");
+
+    /*
+     * The DPO stored in the path was created when the path was resolved.
+     * This then represents the path's 'native' protocol; IP.
+     * For all others will need to go find something else.
+     */
+    if (fib_path_proto_to_chain_type(path->fp_nh_proto) == fct)
+    {
+	dpo_copy(dpo, &path->fp_dpo);
+    }
+    else
+    {
+	switch (path->fp_type)
+	{
+	case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+	    switch (fct)
+	    {
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP4:
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP6:
+	    case FIB_FORW_CHAIN_TYPE_MPLS_EOS:
+	    case FIB_FORW_CHAIN_TYPE_MPLS_NON_EOS:
+	    case FIB_FORW_CHAIN_TYPE_ETHERNET:
+	    {
+		adj_index_t ai;
+
+		/*
+		 * get a appropriate link type adj.
+		 */
+		ai = fib_path_attached_next_hop_get_adj(
+		         path,
+			 fib_forw_chain_type_to_link_type(fct));
+		dpo_set(dpo, DPO_ADJACENCY,
+			fib_forw_chain_type_to_dpo_proto(fct), ai);
+		adj_unlock(ai);
+
+		break;
+	    }
+	    }
+	    break;
+	case FIB_PATH_TYPE_RECURSIVE:
+	    switch (fct)
+	    {
+	    case FIB_FORW_CHAIN_TYPE_MPLS_EOS:
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP4:
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP6:
+	    case FIB_FORW_CHAIN_TYPE_MPLS_NON_EOS:
+		fib_path_recursive_adj_update(path, fct, dpo);
+		break;
+	    case FIB_FORW_CHAIN_TYPE_ETHERNET:
+		ASSERT(0);
+		break;
+	    }
+	    break;
+	case FIB_PATH_TYPE_DEAG:
+	    switch (fct)
+	    {
+	    case FIB_FORW_CHAIN_TYPE_MPLS_NON_EOS:
+                lookup_dpo_add_or_lock_w_table_id(MPLS_FIB_DEFAULT_TABLE_ID,
+                                                  DPO_PROTO_MPLS,
+                                                  LOOKUP_INPUT_DST_ADDR,
+                                                  LOOKUP_TABLE_FROM_CONFIG,
+                                                  dpo);
+                break;
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP4:
+	    case FIB_FORW_CHAIN_TYPE_UNICAST_IP6:
+	    case FIB_FORW_CHAIN_TYPE_MPLS_EOS:
+		dpo_copy(dpo, &path->fp_dpo);
+		break;		
+	    case FIB_FORW_CHAIN_TYPE_ETHERNET:
+		ASSERT(0);
+		break;
+            }
+            break;
+	case FIB_PATH_TYPE_EXCLUSIVE:
+	    dpo_copy(dpo, &path->exclusive.fp_ex_dpo);
+	    break;
+        case FIB_PATH_TYPE_ATTACHED:
+	case FIB_PATH_TYPE_RECEIVE:
+	case FIB_PATH_TYPE_SPECIAL:
+	    ASSERT(0);
+            break;
+	}
+
+    }
+}
+
+load_balance_path_t *
+fib_path_append_nh_for_multipath_hash (fib_node_index_t path_index,
+				       fib_forward_chain_type_t fct,
+				       load_balance_path_t *hash_key)
+{
+    load_balance_path_t *mnh;
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    ASSERT(path);
+
+    if (fib_path_is_resolved(path_index))
+    {
+	vec_add2(hash_key, mnh, 1);
+
+	mnh->path_weight = path->fp_weight;
+	mnh->path_index = path_index;
+	fib_path_contribute_forwarding(path_index, fct, &mnh->path_dpo);
+    }
+
+    return (hash_key);
+}
+
+int
+fib_path_is_recursive (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (FIB_PATH_TYPE_RECURSIVE == path->fp_type);
+}
+
+int
+fib_path_is_exclusive (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (FIB_PATH_TYPE_EXCLUSIVE == path->fp_type);
+}
+
+int
+fib_path_is_deag (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (FIB_PATH_TYPE_DEAG == path->fp_type);
+}
+
+int
+fib_path_is_resolved (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (dpo_id_is_valid(&path->fp_dpo) &&
+	    (path->fp_oper_flags & FIB_PATH_OPER_FLAG_RESOLVED) &&
+	    !fib_path_is_looped(path_index) &&
+	    !fib_path_is_permanent_drop(path));
+}
+
+int
+fib_path_is_looped (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (path->fp_oper_flags & FIB_PATH_OPER_FLAG_RECURSIVE_LOOP);
+}
+
+int
+fib_path_encode (fib_node_index_t path_list_index,
+		 fib_node_index_t path_index,
+                 void *ctx)
+{
+    fib_route_path_encode_t **api_rpaths = ctx;
+    fib_route_path_encode_t *api_rpath;
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+    if (!path)
+      return (0);
+    vec_add2(*api_rpaths, api_rpath, 1);
+    api_rpath->rpath.frp_weight = path->fp_weight;
+    api_rpath->rpath.frp_proto = path->fp_nh_proto;
+    api_rpath->rpath.frp_sw_if_index = ~0;
+    api_rpath->dpo = path->exclusive.fp_ex_dpo;
+    switch (path->fp_type)
+      {
+      case FIB_PATH_TYPE_RECEIVE:
+        api_rpath->rpath.frp_addr = path->receive.fp_addr;
+        api_rpath->rpath.frp_sw_if_index = path->receive.fp_interface;
+        break;
+      case FIB_PATH_TYPE_ATTACHED:
+        api_rpath->rpath.frp_sw_if_index = path->attached.fp_interface;
+        break;
+      case FIB_PATH_TYPE_ATTACHED_NEXT_HOP:
+        api_rpath->rpath.frp_sw_if_index = path->attached_next_hop.fp_interface;
+        api_rpath->rpath.frp_addr = path->attached_next_hop.fp_nh;
+        break;
+      case FIB_PATH_TYPE_SPECIAL:
+        break;
+      case FIB_PATH_TYPE_DEAG:
+        break;
+      case FIB_PATH_TYPE_RECURSIVE:
+        api_rpath->rpath.frp_addr = path->recursive.fp_nh.fp_ip;
+        break;
+      default:
+        break;
+      }
+    return (1);
+}
+
+fib_protocol_t
+fib_path_get_proto (fib_node_index_t path_index)
+{
+    fib_path_t *path;
+
+    path = fib_path_get(path_index);
+
+    return (path->fp_nh_proto);
+}
+
+void
+fib_path_module_init (void)
+{
+    fib_node_register_type (FIB_NODE_TYPE_PATH, &fib_path_vft);
+}
+
+static clib_error_t *
+show_fib_path_command (vlib_main_t * vm,
+			unformat_input_t * input,
+			vlib_cli_command_t * cmd)
+{
+    fib_node_index_t pi;
+    fib_path_t *path;
+
+    if (unformat (input, "%d", &pi))
+    {
+	/*
+	 * show one in detail
+	 */
+	if (!pool_is_free_index(fib_path_pool, pi))
+	{
+	    path = fib_path_get(pi);
+	    u8 *s = fib_path_format(pi, NULL);
+	    s = format(s, "children:");
+	    s = fib_node_children_format(path->fp_node.fn_children, s);
+	    vlib_cli_output (vm, "%s", s);
+	    vec_free(s);
+	}
+	else
+	{
+	    vlib_cli_output (vm, "path %d invalid", pi);
+	}
+    }
+    else
+    {
+	vlib_cli_output (vm, "FIB Paths");
+	pool_foreach(path, fib_path_pool,
+	({
+	    vlib_cli_output (vm, "%U", format_fib_path, path);
+	}));
+    }
+
+    return (NULL);
+}
+
+VLIB_CLI_COMMAND (show_fib_path, static) = {
+  .path = "show fib paths",
+  .function = show_fib_path_command,
+  .short_help = "show fib paths",
+};