Reorganize source tree to use single autotools instance

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

9 files changed, 2243 insertions, 0 deletions

diff --git a/src/vnet/gre/error.def b/src/vnet/gre/error.def
new file mode 100644
index 00000000..161ecc1d
--- /dev/null
+++ b/src/vnet/gre/error.def
@@ -0,0 +1,23 @@
+/*
+ * gre_error.def: gre errors
+ *
+ * Copyright (c) 2012 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.
+ */
+
+gre_error (NONE, "no error")
+gre_error (UNKNOWN_PROTOCOL, "unknown protocol")
+gre_error (UNSUPPORTED_VERSION, "unsupported version")
+gre_error (PKTS_DECAP, "GRE input packets decapsulated")
+gre_error (PKTS_ENCAP, "GRE output packets encapsulated")
+gre_error (NO_SUCH_TUNNEL, "GRE input packets dropped due to missing tunnel")
diff --git a/src/vnet/gre/gre.api b/src/vnet/gre/gre.api
new file mode 100644
index 00000000..28f6dbc9
--- /dev/null
+++ b/src/vnet/gre/gre.api
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2015-2016 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.
+ */
+
+define gre_add_del_tunnel
+{
+  u32 client_index;
+  u32 context;
+  u8 is_add;
+  u8 is_ipv6;
+  u8 teb;
+  u8 src_address[16];
+  u8 dst_address[16];
+  u32 outer_fib_id;
+};
+
+define gre_add_del_tunnel_reply
+{
+  u32 context;
+  i32 retval;
+  u32 sw_if_index;
+};
+
+define gre_tunnel_dump
+{
+  u32 client_index;
+  u32 context;
+  u32 sw_if_index;
+};
+
+define gre_tunnel_details
+{
+  u32 context;
+  u32 sw_if_index;
+  u8 is_ipv6;
+  u8 teb;
+  u8 src_address[16];
+  u8 dst_address[16];
+  u32 outer_fib_id;
+};
+
+/*
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/gre/gre.c b/src/vnet/gre/gre.c
new file mode 100644
index 00000000..0faed13e
--- /dev/null
+++ b/src/vnet/gre/gre.c
@@ -0,0 +1,455 @@
+/*
+ * gre.c: gre
+ *
+ * Copyright (c) 2012 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 <vnet/vnet.h>
+#include <vnet/gre/gre.h>
+#include <vnet/adj/adj_midchain.h>
+
+gre_main_t gre_main;
+
+typedef struct {
+  union {
+    ip4_and_gre_header_t ip4_and_gre;
+    u64 as_u64[3];
+  };
+} ip4_and_gre_union_t;
+
+
+/* Packet trace structure */
+typedef struct {
+  /* Tunnel-id / index in tunnel vector */
+  u32 tunnel_id;
+
+  /* pkt length */
+  u32 length;
+
+  /* tunnel ip4 addresses */
+  ip4_address_t src;
+  ip4_address_t dst;
+} gre_tx_trace_t;
+
+u8 * format_gre_tx_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  gre_tx_trace_t * t = va_arg (*args, gre_tx_trace_t *);
+
+  s = format (s, "GRE: tunnel %d len %d src %U dst %U",
+	      t->tunnel_id, clib_net_to_host_u16 (t->length),
+	      format_ip4_address, &t->src.as_u8,
+	      format_ip4_address, &t->dst.as_u8);
+  return s;
+}
+
+u8 * format_gre_protocol (u8 * s, va_list * args)
+{
+  gre_protocol_t p = va_arg (*args, u32);
+  gre_main_t * gm = &gre_main;
+  gre_protocol_info_t * pi = gre_get_protocol_info (gm, p);
+
+  if (pi)
+    s = format (s, "%s", pi->name);
+  else
+    s = format (s, "0x%04x", p);
+
+  return s;
+}
+
+u8 * format_gre_header_with_length (u8 * s, va_list * args)
+{
+  gre_main_t * gm = &gre_main;
+  gre_header_t * h = va_arg (*args, gre_header_t *);
+  u32 max_header_bytes = va_arg (*args, u32);
+  gre_protocol_t p = clib_net_to_host_u16 (h->protocol);
+  uword indent, header_bytes;
+
+  header_bytes = sizeof (h[0]);
+  if (max_header_bytes != 0 && header_bytes > max_header_bytes)
+    return format (s, "gre header truncated");
+
+  indent = format_get_indent (s);
+
+  s = format (s, "GRE %U", format_gre_protocol, p);
+
+  if (max_header_bytes != 0 && header_bytes > max_header_bytes)
+    {
+      gre_protocol_info_t * pi = gre_get_protocol_info (gm, p);
+      vlib_node_t * node = vlib_get_node (gm->vlib_main, pi->node_index);
+      if (node->format_buffer)
+	s = format (s, "\n%U%U",
+		    format_white_space, indent,
+		    node->format_buffer, (void *) (h + 1),
+		    max_header_bytes - header_bytes);
+    }
+
+  return s;
+}
+
+u8 * format_gre_header (u8 * s, va_list * args)
+{
+  gre_header_t * h = va_arg (*args, gre_header_t *);
+  return format (s, "%U", format_gre_header_with_length, h, 0);
+}
+
+/* Returns gre protocol as an int in host byte order. */
+uword
+unformat_gre_protocol_host_byte_order (unformat_input_t * input,
+				       va_list * args)
+{
+  u16 * result = va_arg (*args, u16 *);
+  gre_main_t * gm = &gre_main;
+  int i;
+
+  /* Named type. */
+  if (unformat_user (input, unformat_vlib_number_by_name,
+		     gm->protocol_info_by_name, &i))
+    {
+      gre_protocol_info_t * pi = vec_elt_at_index (gm->protocol_infos, i);
+      *result = pi->protocol;
+      return 1;
+    }
+
+  return 0;
+}
+
+uword
+unformat_gre_protocol_net_byte_order (unformat_input_t * input,
+				      va_list * args)
+{
+  u16 * result = va_arg (*args, u16 *);
+  if (! unformat_user (input, unformat_gre_protocol_host_byte_order, result))
+    return 0;
+  *result = clib_host_to_net_u16 ((u16) *result);
+  return 1;
+}
+
+uword
+unformat_gre_header (unformat_input_t * input, va_list * args)
+{
+  u8 ** result = va_arg (*args, u8 **);
+  gre_header_t _h, * h = &_h;
+  u16 p;
+
+  if (! unformat (input, "%U",
+		  unformat_gre_protocol_host_byte_order, &p))
+    return 0;
+
+  h->protocol = clib_host_to_net_u16 (p);
+
+  /* Add header to result. */
+  {
+    void * p;
+    u32 n_bytes = sizeof (h[0]);
+
+    vec_add2 (*result, p, n_bytes);
+    clib_memcpy (p, h, n_bytes);
+  }
+
+  return 1;
+}
+
+static int
+gre_proto_from_vnet_link (vnet_link_t link)
+{
+    switch (link)
+    {
+    case VNET_LINK_IP4:
+        return (GRE_PROTOCOL_ip4);
+    case VNET_LINK_IP6:
+        return (GRE_PROTOCOL_ip6);
+    case VNET_LINK_MPLS:
+        return (GRE_PROTOCOL_mpls_unicast);
+    case VNET_LINK_ETHERNET:
+        return (GRE_PROTOCOL_teb);
+    case VNET_LINK_ARP:
+        return (GRE_PROTOCOL_arp);
+    }
+    ASSERT(0);
+    return (GRE_PROTOCOL_ip4);
+}
+
+static u8*
+gre_build_rewrite (vnet_main_t * vnm,
+		   u32 sw_if_index,
+		   vnet_link_t link_type,
+		   const void *dst_address)
+{
+  gre_main_t * gm = &gre_main;
+  ip4_and_gre_header_t * h;
+  u8* rewrite = NULL;
+  gre_tunnel_t *t;
+  u32 ti;
+
+  ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
+
+  if (~0 == ti)
+      /* not one of ours */
+      return (0);
+
+  t = pool_elt_at_index(gm->tunnels, ti);
+
+  vec_validate(rewrite, sizeof(*h)-1);
+  h = (ip4_and_gre_header_t*)rewrite;
+  h->gre.protocol = clib_host_to_net_u16(gre_proto_from_vnet_link(link_type));
+
+  h->ip4.ip_version_and_header_length = 0x45;
+  h->ip4.ttl = 254;
+  h->ip4.protocol = IP_PROTOCOL_GRE;
+  /* fixup ip4 header length and checksum after-the-fact */
+  h->ip4.src_address.as_u32 = t->tunnel_src.as_u32;
+  h->ip4.dst_address.as_u32 = t->tunnel_dst.as_u32;
+  h->ip4.checksum = ip4_header_checksum (&h->ip4);
+
+  return (rewrite);
+}
+
+void
+gre_fixup (vlib_main_t *vm,
+	   ip_adjacency_t *adj,
+	   vlib_buffer_t *b0)
+{
+    ip4_header_t * ip0;
+
+    ip0 = vlib_buffer_get_current (b0);
+
+    /* Fixup the checksum and len fields in the GRE tunnel encap
+     * that was applied at the midchain node */
+    ip0->length = clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
+    ip0->checksum = ip4_header_checksum (ip0);
+}
+
+void
+gre_update_adj (vnet_main_t * vnm,
+		u32 sw_if_index,
+		adj_index_t ai)
+{
+    adj_nbr_midchain_update_rewrite (ai, gre_fixup, 
+				     ADJ_MIDCHAIN_FLAG_NONE,
+				     gre_build_rewrite(vnm, sw_if_index,
+						       adj_get_link_type(ai),
+						       NULL));
+
+    gre_tunnel_stack(ai);
+}
+
+/**
+ * @brief TX function. Only called L2. L3 traffic uses the adj-midchains
+ */
+static uword
+gre_interface_tx_inline (vlib_main_t * vm,
+                         vlib_node_runtime_t * node,
+                         vlib_frame_t * frame)
+{
+  gre_main_t * gm = &gre_main;
+  u32 next_index;
+  u32 * from, * to_next, n_left_from, n_left_to_next;
+  vnet_interface_output_runtime_t * rd = (void *) node->runtime_data;
+  const gre_tunnel_t *gt = pool_elt_at_index (gm->tunnels, rd->dev_instance);
+
+  /* Vector of buffer / pkt indices we're supposed to process */
+  from = vlib_frame_vector_args (frame);
+
+  /* Number of buffers / pkts */
+  n_left_from = frame->n_vectors;
+
+  /* Speculatively send the first buffer to the last disposition we used */
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      /* set up to enqueue to our disposition with index = next_index */
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      /*
+       * FIXME DUAL LOOP
+       */
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t * b0;
+	  u32 bi0;
+
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer(vm, bi0);
+
+	  vnet_buffer(b0)->ip.adj_index[VLIB_TX] = gt->l2_adj_index;
+
+	  if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
+	    {
+	      gre_tx_trace_t *tr = vlib_add_trace (vm, node,
+						   b0, sizeof (*tr));
+	      tr->tunnel_id = gt - gm->tunnels;
+	      tr->length = vlib_buffer_length_in_chain (vm, b0);
+	      tr->src.as_u32 = gt->tunnel_src.as_u32;
+	      tr->dst.as_u32 = gt->tunnel_src.as_u32;
+	    }
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, gt->l2_tx_arc);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, gre_input_node.index,
+			       GRE_ERROR_PKTS_ENCAP, frame->n_vectors);
+
+  return frame->n_vectors;
+}
+
+static uword
+gre_interface_tx (vlib_main_t * vm,
+                  vlib_node_runtime_t * node,
+                  vlib_frame_t * frame)
+{
+    return (gre_interface_tx_inline (vm, node, frame));
+}
+
+static uword
+gre_teb_interface_tx (vlib_main_t * vm,
+                      vlib_node_runtime_t * node,
+                      vlib_frame_t * frame)
+{
+    return (gre_interface_tx_inline (vm, node, frame));
+}
+
+static u8 * format_gre_tunnel_name (u8 * s, va_list * args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  return format (s, "gre%d", dev_instance);
+}
+
+static u8 * format_gre_tunnel_teb_name (u8 * s, va_list * args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  return format (s, "teb-gre%d", dev_instance);
+}
+
+static u8 * format_gre_device (u8 * s, va_list * args)
+{
+  u32 dev_instance = va_arg (*args, u32);
+  CLIB_UNUSED (int verbose) = va_arg (*args, int);
+
+  s = format (s, "GRE tunnel: id %d\n", dev_instance);
+  return s;
+}
+
+VNET_DEVICE_CLASS (gre_device_class) = {
+  .name = "GRE tunnel device",
+  .format_device_name = format_gre_tunnel_name,
+  .format_device = format_gre_device,
+  .format_tx_trace = format_gre_tx_trace,
+  .tx_function = gre_interface_tx,
+  .admin_up_down_function = gre_interface_admin_up_down,
+#ifdef SOON
+  .clear counter = 0;
+#endif
+};
+
+VLIB_DEVICE_TX_FUNCTION_MULTIARCH (gre_device_class,
+				   gre_interface_tx)
+
+VNET_DEVICE_CLASS (gre_device_teb_class) = {
+  .name = "GRE TEB tunnel device",
+  .format_device_name = format_gre_tunnel_teb_name,
+  .format_device = format_gre_device,
+  .format_tx_trace = format_gre_tx_trace,
+  .tx_function = gre_teb_interface_tx,
+  .admin_up_down_function = gre_interface_admin_up_down,
+#ifdef SOON
+  .clear counter = 0;
+#endif
+};
+
+VLIB_DEVICE_TX_FUNCTION_MULTIARCH (gre_device_teb_class,
+				   gre_teb_interface_tx)
+
+VNET_HW_INTERFACE_CLASS (gre_hw_interface_class) = {
+  .name = "GRE",
+  .format_header = format_gre_header_with_length,
+  .unformat_header = unformat_gre_header,
+  .build_rewrite = gre_build_rewrite,
+  .update_adjacency = gre_update_adj,
+  .flags = VNET_HW_INTERFACE_CLASS_FLAG_P2P,
+};
+
+static void add_protocol (gre_main_t * gm,
+			  gre_protocol_t protocol,
+			  char * protocol_name)
+{
+  gre_protocol_info_t * pi;
+  u32 i;
+
+  vec_add2 (gm->protocol_infos, pi, 1);
+  i = pi - gm->protocol_infos;
+
+  pi->name = protocol_name;
+  pi->protocol = protocol;
+  pi->next_index = pi->node_index = ~0;
+
+  hash_set (gm->protocol_info_by_protocol, protocol, i);
+  hash_set_mem (gm->protocol_info_by_name, pi->name, i);
+}
+
+static clib_error_t * gre_init (vlib_main_t * vm)
+{
+  gre_main_t * gm = &gre_main;
+  clib_error_t * error;
+  ip_main_t * im = &ip_main;
+  ip_protocol_info_t * pi;
+
+  memset (gm, 0, sizeof (gm[0]));
+  gm->vlib_main = vm;
+  gm->vnet_main = vnet_get_main();
+
+  if ((error = vlib_call_init_function (vm, ip_main_init)))
+    return error;
+
+  if ((error = vlib_call_init_function (vm, ip4_lookup_init)))
+    return error;
+
+  /* Set up the ip packet generator */
+  pi = ip_get_protocol_info (im, IP_PROTOCOL_GRE);
+  pi->format_header = format_gre_header;
+  pi->unformat_pg_edit = unformat_pg_gre_header;
+
+  gm->protocol_info_by_name = hash_create_string (0, sizeof (uword));
+  gm->protocol_info_by_protocol = hash_create (0, sizeof (uword));
+  gm->tunnel_by_key = hash_create (0, sizeof (uword));
+
+#define _(n,s) add_protocol (gm, GRE_PROTOCOL_##s, #s);
+  foreach_gre_protocol
+#undef _
+
+  return vlib_call_init_function (vm, gre_input_init);
+}
+
+VLIB_INIT_FUNCTION (gre_init);
+
+gre_main_t * gre_get_main (vlib_main_t * vm)
+{
+  vlib_call_init_function (vm, gre_init);
+  return &gre_main;
+}
+
diff --git a/src/vnet/gre/gre.h b/src/vnet/gre/gre.h
new file mode 100644
index 00000000..b6544b9b
--- /dev/null
+++ b/src/vnet/gre/gre.h
@@ -0,0 +1,235 @@
+/*
+ * gre.h: types/functions for gre.
+ *
+ * Copyright (c) 2012 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.
+ */
+
+#ifndef included_gre_h
+#define included_gre_h
+
+#include <vnet/vnet.h>
+#include <vnet/gre/packet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ip/ip4.h>
+#include <vnet/ip/ip4_packet.h>
+#include <vnet/pg/pg.h>
+#include <vnet/ip/format.h>
+#include <vnet/adj/adj_types.h>
+
+extern vnet_hw_interface_class_t gre_hw_interface_class;
+
+typedef enum {
+#define gre_error(n,s) GRE_ERROR_##n,
+#include <vnet/gre/error.def>
+#undef gre_error
+  GRE_N_ERROR,
+} gre_error_t;
+
+/**
+ * A GRE payload protocol registration
+ */
+typedef struct {
+  /** Name (a c string). */
+  char * name;
+
+  /** GRE protocol type in host byte order. */
+  gre_protocol_t protocol;
+
+  /** Node which handles this type. */
+  u32 node_index;
+
+  /** Next index for this type. */
+  u32 next_index;
+} gre_protocol_info_t;
+
+/**
+ * @brief The GRE tunnel type
+ */
+typedef enum gre_tunnel_tyoe_t_
+{
+  /**
+   * L3 GRE (i.e. this tunnel is in L3 mode)
+   */
+  GRE_TUNNEL_TYPE_L3,
+  /**
+   * Transparent Ethernet Bridging - the tunnel is in L2 mode
+   */
+  GRE_TUNNEL_TYPE_TEB,
+} gre_tunnel_type_t;
+
+#define GRE_TUNNEL_TYPE_NAMES {    \
+    [GRE_TUNNEL_TYPE_L3] = "L3",   \
+    [GRE_TUNNEL_TYPE_TEB] = "TEB", \
+}
+
+#define GRE_TUNNEL_N_TYPES ((gre_tunnel_type_t)GRE_TUNNEL_TYPE_TEB+1)
+
+/**
+ * @brief A representation of a GRE tunnel
+ */
+typedef struct {
+  /**
+   * Linkage into the FIB object graph
+   */
+  fib_node_t node;
+
+  /**
+   * The tunnel's source/local address
+   */
+  ip4_address_t tunnel_src;
+  /**
+   * The tunnel's destination/remote address
+   */
+  ip4_address_t tunnel_dst;
+  /**
+   * The FIB in which the src.dst address are present
+   */
+  u32 outer_fib_index;
+  u32 hw_if_index;
+  u32 sw_if_index;
+  gre_tunnel_type_t type;
+
+  /**
+   * The FIB entry sourced by the tunnel for its destination prefix
+   */
+  fib_node_index_t fib_entry_index;
+
+  /**
+   * The tunnel is a child of the FIB entry for its desintion. This is
+   * so it receives updates when the forwarding information for that entry
+   * changes.
+   * The tunnels sibling index on the FIB entry's dependency list.
+   */
+  u32 sibling_index;
+
+  /**
+   * on a L2 tunnel this is the VLIB arc from the L2-tx to the l2-midchain
+   */
+  u32 l2_tx_arc;
+
+  /**
+   * an L2 tunnel always rquires an L2 midchain. cache here for DP.
+   */
+  adj_index_t l2_adj_index;
+} gre_tunnel_t;
+
+/**
+ * @brief GRE related global data
+ */
+typedef struct {
+  /**
+   * pool of tunnel instances
+   */
+  gre_tunnel_t *tunnels;
+
+  /**
+   * GRE payload protocol registrations
+   */
+  gre_protocol_info_t * protocol_infos;
+
+  /**
+   *  Hash tables mapping name/protocol to protocol info index.
+   */
+  uword * protocol_info_by_name, * protocol_info_by_protocol;
+  /**
+   * Hash mapping src/dst addr pair to tunnel
+   */
+  uword * tunnel_by_key;
+
+  /**
+   * Free vlib hw_if_indices.
+   * A free list per-tunnel type since the interfaces ctreated are fo different
+   * types and we cannot change the type.
+   */
+  u32 * free_gre_tunnel_hw_if_indices[GRE_TUNNEL_N_TYPES];
+
+  /**
+   * Mapping from sw_if_index to tunnel index
+   */
+  u32 * tunnel_index_by_sw_if_index;
+
+  /* convenience */
+  vlib_main_t * vlib_main;
+  vnet_main_t * vnet_main;
+} gre_main_t;
+
+/**
+ * @brief IPv4 and GRE header.
+ */
+typedef CLIB_PACKED (struct {
+  ip4_header_t ip4;
+  gre_header_t gre;
+}) ip4_and_gre_header_t;
+
+always_inline gre_protocol_info_t *
+gre_get_protocol_info (gre_main_t * em, gre_protocol_t protocol)
+{
+  uword * p = hash_get (em->protocol_info_by_protocol, protocol);
+  return p ? vec_elt_at_index (em->protocol_infos, p[0]) : 0;
+}
+
+gre_main_t gre_main;
+
+/* Register given node index to take input for given gre type. */
+void
+gre_register_input_type (vlib_main_t * vm,
+			 gre_protocol_t protocol,
+			 u32 node_index);
+
+extern  clib_error_t * gre_interface_admin_up_down (vnet_main_t * vnm,
+						    u32 hw_if_index,
+						    u32 flags);
+
+extern void gre_tunnel_stack (adj_index_t ai);
+extern void gre_update_adj (vnet_main_t * vnm,
+                            u32 sw_if_index,
+                            adj_index_t ai);
+
+format_function_t format_gre_protocol;
+format_function_t format_gre_header;
+format_function_t format_gre_header_with_length;
+
+extern vlib_node_registration_t gre_input_node;
+extern vnet_device_class_t gre_device_class;
+extern vnet_device_class_t gre_device_teb_class;
+
+/* Parse gre protocol as 0xXXXX or protocol name.
+   In either host or network byte order. */
+unformat_function_t unformat_gre_protocol_host_byte_order;
+unformat_function_t unformat_gre_protocol_net_byte_order;
+
+/* Parse gre header. */
+unformat_function_t unformat_gre_header;
+unformat_function_t unformat_pg_gre_header;
+
+void
+gre_register_input_protocol (vlib_main_t * vm,
+			     gre_protocol_t protocol,
+			     u32 node_index);
+
+/* manually added to the interface output node in gre.c */
+#define GRE_OUTPUT_NEXT_LOOKUP	1
+
+typedef struct {
+  u8 is_add;
+
+  ip4_address_t src, dst;
+  u32 outer_fib_id;
+  u8 teb;
+} vnet_gre_add_del_tunnel_args_t;
+
+int vnet_gre_add_del_tunnel
+  (vnet_gre_add_del_tunnel_args_t *a, u32 * sw_if_indexp);
+
+#endif /* included_gre_h */
diff --git a/src/vnet/gre/gre_api.c b/src/vnet/gre/gre_api.c
new file mode 100644
index 00000000..333838c0
--- /dev/null
+++ b/src/vnet/gre/gre_api.c
@@ -0,0 +1,204 @@
+/*
+ *------------------------------------------------------------------
+ * gre_api.c - gre api
+ *
+ * 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 <vnet/vnet.h>
+#include <vlibmemory/api.h>
+
+#include <vnet/interface.h>
+#include <vnet/api_errno.h>
+
+#include <vnet/gre/gre.h>
+#include <vnet/fib/fib_table.h>
+
+#include <vnet/vnet_msg_enum.h>
+
+#define vl_typedefs		/* define message structures */
+#include <vnet/vnet_all_api_h.h>
+#undef vl_typedefs
+
+#define vl_endianfun		/* define message structures */
+#include <vnet/vnet_all_api_h.h>
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+#define vl_printfun
+#include <vnet/vnet_all_api_h.h>
+#undef vl_printfun
+
+#include <vlibapi/api_helper_macros.h>
+
+#define foreach_vpe_api_msg                             \
+_(GRE_ADD_DEL_TUNNEL, gre_add_del_tunnel)               \
+_(GRE_TUNNEL_DUMP, gre_tunnel_dump)
+
+static void vl_api_gre_add_del_tunnel_t_handler
+  (vl_api_gre_add_del_tunnel_t * mp)
+{
+  vl_api_gre_add_del_tunnel_reply_t *rmp;
+  int rv = 0;
+  vnet_gre_add_del_tunnel_args_t _a, *a = &_a;
+  u32 outer_fib_id;
+  uword *p;
+  ip4_main_t *im = &ip4_main;
+  u32 sw_if_index = ~0;
+
+  p = hash_get (im->fib_index_by_table_id, ntohl (mp->outer_fib_id));
+  if (!p)
+    {
+      rv = VNET_API_ERROR_NO_SUCH_FIB;
+      goto out;
+    }
+  outer_fib_id = p[0];
+
+  /* Check src & dst are different */
+  if ((mp->is_ipv6 && memcmp (mp->src_address, mp->dst_address, 16) == 0) ||
+      (!mp->is_ipv6 && memcmp (mp->src_address, mp->dst_address, 4) == 0))
+    {
+      rv = VNET_API_ERROR_SAME_SRC_DST;
+      goto out;
+    }
+  memset (a, 0, sizeof (*a));
+
+  a->is_add = mp->is_add;
+  a->teb = mp->teb;
+
+  /* ip addresses sent in network byte order */
+  clib_memcpy (&(a->src), mp->src_address, 4);
+  clib_memcpy (&(a->dst), mp->dst_address, 4);
+
+  a->outer_fib_id = outer_fib_id;
+  rv = vnet_gre_add_del_tunnel (a, &sw_if_index);
+
+out:
+  /* *INDENT-OFF* */
+  REPLY_MACRO2(VL_API_GRE_ADD_DEL_TUNNEL_REPLY,
+  ({
+    rmp->sw_if_index = ntohl (sw_if_index);
+  }));
+  /* *INDENT-ON* */
+}
+
+static void send_gre_tunnel_details
+  (gre_tunnel_t * t, unix_shared_memory_queue_t * q, u32 context)
+{
+  vl_api_gre_tunnel_details_t *rmp;
+  ip4_main_t *im = &ip4_main;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  memset (rmp, 0, sizeof (*rmp));
+  rmp->_vl_msg_id = ntohs (VL_API_GRE_TUNNEL_DETAILS);
+  clib_memcpy (rmp->src_address, &(t->tunnel_src), 4);
+  clib_memcpy (rmp->dst_address, &(t->tunnel_dst), 4);
+  rmp->outer_fib_id = htonl (im->fibs[t->outer_fib_index].ft_table_id);
+  rmp->teb = (GRE_TUNNEL_TYPE_TEB == t->type);
+  rmp->sw_if_index = htonl (t->sw_if_index);
+  rmp->context = context;
+
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_gre_tunnel_dump_t_handler (vl_api_gre_tunnel_dump_t * mp)
+{
+  unix_shared_memory_queue_t *q;
+  gre_main_t *gm = &gre_main;
+  gre_tunnel_t *t;
+  u32 sw_if_index;
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (q == 0)
+    {
+      return;
+    }
+
+  sw_if_index = ntohl (mp->sw_if_index);
+
+  if (~0 == sw_if_index)
+    {
+      /* *INDENT-OFF* */
+      pool_foreach (t, gm->tunnels,
+      ({
+        send_gre_tunnel_details(t, q, mp->context);
+      }));
+      /* *INDENT-ON* */
+    }
+  else
+    {
+      if ((sw_if_index >= vec_len (gm->tunnel_index_by_sw_if_index)) ||
+	  (~0 == gm->tunnel_index_by_sw_if_index[sw_if_index]))
+	{
+	  return;
+	}
+      t = &gm->tunnels[gm->tunnel_index_by_sw_if_index[sw_if_index]];
+      send_gre_tunnel_details (t, q, mp->context);
+    }
+}
+
+/*
+ * gre_api_hookup
+ * Add vpe's API message handlers to the table.
+ * vlib has alread mapped shared memory and
+ * added the client registration handlers.
+ * See .../vlib-api/vlibmemory/memclnt_vlib.c:memclnt_process()
+ */
+#define vl_msg_name_crc_list
+#include <vnet/vnet_all_api_h.h>
+#undef vl_msg_name_crc_list
+
+static void
+setup_message_id_table (api_main_t * am)
+{
+#define _(id,n,crc) vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id);
+  foreach_vl_msg_name_crc_gre;
+#undef _
+}
+
+static clib_error_t *
+gre_api_hookup (vlib_main_t * vm)
+{
+  api_main_t *am = &api_main;
+
+#define _(N,n)                                                  \
+    vl_msg_api_set_handlers(VL_API_##N, #n,                     \
+                           vl_api_##n##_t_handler,              \
+                           vl_noop_handler,                     \
+                           vl_api_##n##_t_endian,               \
+                           vl_api_##n##_t_print,                \
+                           sizeof(vl_api_##n##_t), 1);
+  foreach_vpe_api_msg;
+#undef _
+
+  /*
+   * Set up the (msg_name, crc, message-id) table
+   */
+  setup_message_id_table (am);
+
+  return 0;
+}
+
+VLIB_API_INIT_FUNCTION (gre_api_hookup);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/gre/interface.c b/src/vnet/gre/interface.c
new file mode 100644
index 00000000..d624587d
--- /dev/null
+++ b/src/vnet/gre/interface.c
@@ -0,0 +1,606 @@
+/*
+ * gre_interface.c: gre interfaces
+ *
+ * Copyright (c) 2012 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 <vnet/vnet.h>
+#include <vnet/pg/pg.h>
+#include <vnet/gre/gre.h>
+#include <vnet/ip/format.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/adj/adj_midchain.h>
+#include <vnet/adj/adj_nbr.h>
+#include <vnet/mpls/mpls.h>
+
+static const char *gre_tunnel_type_names[] = GRE_TUNNEL_TYPE_NAMES;
+
+static inline u64
+gre_mk_key (const ip4_address_t *src,
+            const ip4_address_t *dst,
+            u32 out_fib_index)
+{
+  // FIXME. the fib index should be part of the key
+  return ((u64)src->as_u32 << 32 | (u64)dst->as_u32);
+}
+
+static u8 *
+format_gre_tunnel_type (u8 * s, va_list * args)
+{
+  gre_tunnel_type_t type = va_arg (*args, gre_tunnel_type_t);
+
+  return (format(s, "%s", gre_tunnel_type_names[type]));
+}
+
+static u8 *
+format_gre_tunnel (u8 * s, va_list * args)
+{
+  gre_tunnel_t * t = va_arg (*args, gre_tunnel_t *);
+  gre_main_t * gm = &gre_main;
+
+  s = format (s,
+              "[%d] %U (src) %U (dst) payload %U outer_fib_index %d",
+              t - gm->tunnels,
+              format_ip4_address, &t->tunnel_src,
+              format_ip4_address, &t->tunnel_dst,
+              format_gre_tunnel_type, t->type,
+              t->outer_fib_index);
+
+  return s;
+}
+
+static gre_tunnel_t *
+gre_tunnel_db_find (const ip4_address_t *src,
+                    const ip4_address_t *dst,
+                    u32 out_fib_index)
+{
+  gre_main_t * gm = &gre_main;
+  uword * p;
+  u64 key;
+
+  key = gre_mk_key(src, dst, out_fib_index);
+
+  p = hash_get (gm->tunnel_by_key, key);
+
+  if (NULL == p)
+    return (NULL);
+
+  return (pool_elt_at_index (gm->tunnels, p[0]));
+}
+
+static void
+gre_tunnel_db_add (const gre_tunnel_t *t)
+{
+  gre_main_t * gm = &gre_main;
+  u64 key;
+
+  key = gre_mk_key(&t->tunnel_src, &t->tunnel_dst, t->outer_fib_index);
+  hash_set (gm->tunnel_by_key, key, t - gm->tunnels);
+}
+
+static void
+gre_tunnel_db_remove (const gre_tunnel_t *t)
+{
+  gre_main_t * gm = &gre_main;
+  u64 key;
+
+  key = gre_mk_key(&t->tunnel_src, &t->tunnel_dst, t->outer_fib_index);
+  hash_unset (gm->tunnel_by_key, key);
+}
+
+static gre_tunnel_t *
+gre_tunnel_from_fib_node (fib_node_t *node)
+{
+#if (CLIB_DEBUG > 0)
+    ASSERT(FIB_NODE_TYPE_GRE_TUNNEL == node->fn_type);
+#endif
+    return ((gre_tunnel_t*) (((char*)node) -
+                             STRUCT_OFFSET_OF(gre_tunnel_t, node)));
+}
+
+/**
+ * gre_tunnel_stack
+ *
+ * 'stack' (resolve the recursion for) the tunnel's midchain adjacency
+ */
+void
+gre_tunnel_stack (adj_index_t ai)
+{
+    gre_main_t * gm = &gre_main;
+    ip_adjacency_t *adj;
+    gre_tunnel_t *gt;
+    u32 sw_if_index;
+
+    adj = adj_get(ai);
+    sw_if_index = adj->rewrite_header.sw_if_index;
+
+    if ((vec_len(gm->tunnel_index_by_sw_if_index) < sw_if_index) ||
+	(~0 == gm->tunnel_index_by_sw_if_index[sw_if_index]))
+	return;
+
+    gt = pool_elt_at_index(gm->tunnels,
+			   gm->tunnel_index_by_sw_if_index[sw_if_index]);
+
+    /*
+     * find the adjacency that is contributed by the FIB entry
+     * that this tunnel resovles via, and use it as the next adj
+     * in the midchain
+     */
+    if (vnet_hw_interface_get_flags(vnet_get_main(),
+				    gt->hw_if_index) &
+	VNET_HW_INTERFACE_FLAG_LINK_UP)
+    {
+	adj_nbr_midchain_stack(
+	    ai,
+	    fib_entry_contribute_ip_forwarding(gt->fib_entry_index));
+    }
+    else
+    {
+	adj_nbr_midchain_unstack(ai);
+    }
+}
+
+/**
+ * @brief Call back when restacking all adjacencies on a GRE interface
+ */
+static adj_walk_rc_t
+gre_adj_walk_cb (adj_index_t ai,
+		 void *ctx)
+{
+    gre_tunnel_stack(ai);
+
+    return (ADJ_WALK_RC_CONTINUE);
+}
+
+static void
+gre_tunnel_restack (gre_tunnel_t *gt)
+{
+    fib_protocol_t proto;
+
+    /*
+     * walk all the adjacencies on th GRE interface and restack them
+     */
+    FOR_EACH_FIB_IP_PROTOCOL(proto)
+    {
+	adj_nbr_walk(gt->sw_if_index,
+		     proto,
+		     gre_adj_walk_cb,
+		     NULL);
+    }
+}
+
+/**
+ * Function definition to backwalk a FIB node
+ */
+static fib_node_back_walk_rc_t
+gre_tunnel_back_walk (fib_node_t *node,
+		      fib_node_back_walk_ctx_t *ctx)
+{
+    gre_tunnel_restack(gre_tunnel_from_fib_node(node));
+
+    return (FIB_NODE_BACK_WALK_CONTINUE);
+}
+
+/**
+ * Function definition to get a FIB node from its index
+ */
+static fib_node_t*
+gre_tunnel_fib_node_get (fib_node_index_t index)
+{
+    gre_tunnel_t * gt;
+    gre_main_t * gm;
+
+    gm  = &gre_main;
+    gt = pool_elt_at_index(gm->tunnels, index);
+
+    return (&gt->node);
+}
+
+/**
+ * Function definition to inform the FIB node that its last lock has gone.
+ */
+static void
+gre_tunnel_last_lock_gone (fib_node_t *node)
+{
+    /*
+     * The MPLS GRE tunnel is a root of the graph. As such
+     * it never has children and thus is never locked.
+     */
+    ASSERT(0);
+}
+
+/*
+ * Virtual function table registered by MPLS GRE tunnels
+ * for participation in the FIB object graph.
+ */
+const static fib_node_vft_t gre_vft = {
+    .fnv_get = gre_tunnel_fib_node_get,
+    .fnv_last_lock = gre_tunnel_last_lock_gone,
+    .fnv_back_walk = gre_tunnel_back_walk,
+};
+
+static int 
+vnet_gre_tunnel_add (vnet_gre_add_del_tunnel_args_t *a,
+                     u32 * sw_if_indexp)
+{
+  gre_main_t * gm = &gre_main;
+  vnet_main_t * vnm = gm->vnet_main;
+  ip4_main_t * im = &ip4_main;
+  gre_tunnel_t * t;
+  vnet_hw_interface_t * hi;
+  u32 hw_if_index, sw_if_index;
+  u32 outer_fib_index;
+  u8 address[6];
+  clib_error_t *error;
+
+  outer_fib_index = ip4_fib_index_from_table_id(a->outer_fib_id);
+
+  if (~0 == outer_fib_index)
+    return VNET_API_ERROR_NO_SUCH_FIB;
+
+  t = gre_tunnel_db_find(&a->src, &a->dst, a->outer_fib_id);
+
+  if (NULL != t)
+    return VNET_API_ERROR_INVALID_VALUE;
+
+  pool_get_aligned (gm->tunnels, t, CLIB_CACHE_LINE_BYTES);
+  memset (t, 0, sizeof (*t));
+  fib_node_init(&t->node, FIB_NODE_TYPE_GRE_TUNNEL);
+
+  if (a->teb)
+      t->type = GRE_TUNNEL_TYPE_TEB;
+  else
+      t->type = GRE_TUNNEL_TYPE_L3;
+
+  if (vec_len (gm->free_gre_tunnel_hw_if_indices[t->type]) > 0) {
+      vnet_interface_main_t * im = &vnm->interface_main;
+
+      hw_if_index = gm->free_gre_tunnel_hw_if_indices[t->type]
+          [vec_len (gm->free_gre_tunnel_hw_if_indices[t->type])-1];
+      _vec_len (gm->free_gre_tunnel_hw_if_indices[t->type]) -= 1;
+
+      hi = vnet_get_hw_interface (vnm, hw_if_index);
+      hi->dev_instance = t - gm->tunnels;
+      hi->hw_instance = hi->dev_instance;
+
+      /* clear old stats of freed tunnel before reuse */
+      sw_if_index = hi->sw_if_index;
+      vnet_interface_counter_lock(im);
+      vlib_zero_combined_counter
+          (&im->combined_sw_if_counters[VNET_INTERFACE_COUNTER_TX], sw_if_index);
+      vlib_zero_combined_counter
+          (&im->combined_sw_if_counters[VNET_INTERFACE_COUNTER_RX], sw_if_index);
+      vlib_zero_simple_counter
+          (&im->sw_if_counters[VNET_INTERFACE_COUNTER_DROP], sw_if_index);
+        vnet_interface_counter_unlock(im);
+      if (GRE_TUNNEL_TYPE_TEB == t->type)
+      {
+          t->l2_tx_arc = vlib_node_add_named_next(vlib_get_main(),
+                                                  hi->tx_node_index,
+                                                  "adj-l2-midchain");
+      }
+    } else {
+      if (GRE_TUNNEL_TYPE_TEB == t->type)
+      {
+        /* Default MAC address (d00b:eed0:0000 + sw_if_index) */
+        memset (address, 0, sizeof (address));
+        address[0] = 0xd0;
+        address[1] = 0x0b;
+        address[2] = 0xee;
+        address[3] = 0xd0;
+        address[4] = t - gm->tunnels;
+
+        error = ethernet_register_interface(vnm,
+					    gre_device_teb_class.index,
+					    t - gm->tunnels, address,
+					    &hw_if_index,
+					    0);
+
+        if (error)
+        {
+          clib_error_report (error);
+          return VNET_API_ERROR_INVALID_REGISTRATION;
+        }
+	hi = vnet_get_hw_interface (vnm, hw_if_index);
+
+	t->l2_tx_arc = vlib_node_add_named_next(vlib_get_main(),
+						hi->tx_node_index,
+						"adj-l2-midchain");
+      } else {
+	hw_if_index = vnet_register_interface(vnm,
+					      gre_device_class.index,
+					      t - gm->tunnels,
+					      gre_hw_interface_class.index,
+					      t - gm->tunnels);
+      }
+      hi = vnet_get_hw_interface (vnm, hw_if_index);
+      sw_if_index = hi->sw_if_index;
+    }
+
+  t->hw_if_index = hw_if_index;
+  t->outer_fib_index = outer_fib_index;
+  t->sw_if_index = sw_if_index;
+  t->l2_adj_index = ADJ_INDEX_INVALID;
+
+  vec_validate_init_empty (gm->tunnel_index_by_sw_if_index, sw_if_index, ~0);
+  gm->tunnel_index_by_sw_if_index[sw_if_index] = t - gm->tunnels;
+
+  vec_validate (im->fib_index_by_sw_if_index, sw_if_index);
+
+  hi->min_packet_bytes = 64 + sizeof (gre_header_t) + sizeof (ip4_header_t);
+  hi->per_packet_overhead_bytes =
+      /* preamble */ 8 + /* inter frame gap */ 12;
+
+  /* Standard default gre MTU. */
+  hi->max_l3_packet_bytes[VLIB_RX] = hi->max_l3_packet_bytes[VLIB_TX] = 9000;
+
+  clib_memcpy (&t->tunnel_src, &a->src, sizeof (t->tunnel_src));
+  clib_memcpy (&t->tunnel_dst, &a->dst, sizeof (t->tunnel_dst));
+
+  gre_tunnel_db_add(t);
+
+  /*
+   * source the FIB entry for the tunnel's destination
+   * and become a child thereof. The tunnel will then get poked
+   * when the forwarding for the entry updates, and the tunnel can
+   * re-stack accordingly
+   */
+  const fib_prefix_t tun_dst_pfx = {
+      .fp_len = 32,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr = {
+          .ip4 = t->tunnel_dst,
+      }
+  };
+
+  t->fib_entry_index =
+      fib_table_entry_special_add(outer_fib_index,
+                                  &tun_dst_pfx,
+                                  FIB_SOURCE_RR,
+                                  FIB_ENTRY_FLAG_NONE,
+                                  ADJ_INDEX_INVALID);
+  t->sibling_index =
+      fib_entry_child_add(t->fib_entry_index,
+                          FIB_NODE_TYPE_GRE_TUNNEL,
+                          t - gm->tunnels);
+
+  clib_memcpy (&t->tunnel_src, &a->src, sizeof (t->tunnel_src));
+  clib_memcpy (&t->tunnel_dst, &a->dst, sizeof (t->tunnel_dst));
+
+  if (GRE_TUNNEL_TYPE_TEB == t->type)
+  {
+      t->l2_adj_index = adj_nbr_add_or_lock(FIB_PROTOCOL_IP4,
+					    VNET_LINK_ETHERNET,
+					    &zero_addr,
+					    sw_if_index);
+      gre_update_adj(vnm, t->sw_if_index, t->l2_adj_index);
+  }
+
+  if (sw_if_indexp)
+    *sw_if_indexp = sw_if_index;
+
+  return 0;
+}
+
+static int 
+vnet_gre_tunnel_delete (vnet_gre_add_del_tunnel_args_t *a,
+                        u32 * sw_if_indexp)
+{
+  gre_main_t * gm = &gre_main;
+  vnet_main_t * vnm = gm->vnet_main;
+  gre_tunnel_t * t;
+  u32 sw_if_index;
+
+  t = gre_tunnel_db_find(&a->src, &a->dst, a->outer_fib_id);
+
+  if (NULL == t)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  sw_if_index = t->sw_if_index;
+  vnet_sw_interface_set_flags (vnm, sw_if_index, 0 /* down */);
+  /* make sure tunnel is removed from l2 bd or xconnect */
+  set_int_l2_mode(gm->vlib_main, vnm, MODE_L3, sw_if_index, 0, 0, 0, 0);
+  vec_add1 (gm->free_gre_tunnel_hw_if_indices[t->type], t->hw_if_index);
+  gm->tunnel_index_by_sw_if_index[sw_if_index] = ~0;
+
+  if (GRE_TUNNEL_TYPE_TEB == t->type)
+    adj_unlock(t->l2_adj_index);
+
+  if (t->l2_adj_index != ADJ_INDEX_INVALID)
+      adj_unlock(t->l2_adj_index);
+
+  fib_entry_child_remove(t->fib_entry_index,
+                         t->sibling_index);
+  fib_table_entry_delete_index(t->fib_entry_index,
+                               FIB_SOURCE_RR);
+
+  gre_tunnel_db_remove(t);
+  fib_node_deinit(&t->node);
+  pool_put (gm->tunnels, t);
+
+  if (sw_if_indexp)
+    *sw_if_indexp = sw_if_index;
+
+  return 0;
+}
+
+int
+vnet_gre_add_del_tunnel (vnet_gre_add_del_tunnel_args_t *a,
+                         u32 * sw_if_indexp)
+{
+  if (a->is_add)
+    return (vnet_gre_tunnel_add(a, sw_if_indexp));
+  else
+    return (vnet_gre_tunnel_delete(a, sw_if_indexp));
+}
+
+clib_error_t *
+gre_interface_admin_up_down (vnet_main_t * vnm, u32 hw_if_index, u32 flags)
+{
+  gre_main_t * gm = &gre_main;
+  vnet_hw_interface_t * hi;
+  gre_tunnel_t *t;
+  u32 ti;
+
+  hi = vnet_get_hw_interface (vnm, hw_if_index);
+
+  if (NULL == gm->tunnel_index_by_sw_if_index ||
+      hi->sw_if_index >= vec_len(gm->tunnel_index_by_sw_if_index))
+      return (NULL);
+
+  ti = gm->tunnel_index_by_sw_if_index[hi->sw_if_index];
+
+  if (~0 == ti)
+      /* not one of ours */
+      return (NULL);
+
+  t = pool_elt_at_index(gm->tunnels, ti);
+
+  if (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
+    vnet_hw_interface_set_flags (vnm, hw_if_index, VNET_HW_INTERFACE_FLAG_LINK_UP);
+  else
+    vnet_hw_interface_set_flags (vnm, hw_if_index, 0 /* down */);
+
+  gre_tunnel_restack(t);
+
+  return /* no error */ 0;
+}
+
+static clib_error_t *
+create_gre_tunnel_command_fn (vlib_main_t * vm,
+		 unformat_input_t * input,
+		 vlib_cli_command_t * cmd)
+{
+  unformat_input_t _line_input, * line_input = &_line_input;
+  vnet_gre_add_del_tunnel_args_t _a, * a = &_a;
+  ip4_address_t src, dst;
+  u32 outer_fib_id = 0;
+  u8 teb = 0;
+  int rv;
+  u32 num_m_args = 0;
+  u8 is_add = 1;
+  u32 sw_if_index;
+
+  /* Get a line of input. */
+  if (! unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT) {
+    if (unformat (line_input, "del"))
+      is_add = 0;
+    else if (unformat (line_input, "src %U", unformat_ip4_address, &src))
+      num_m_args++;
+    else if (unformat (line_input, "dst %U", unformat_ip4_address, &dst))
+      num_m_args++;
+    else if (unformat (line_input, "outer-fib-id %d", &outer_fib_id))
+      ;
+    else if (unformat (line_input, "teb"))
+      teb = 1;
+    else
+      return clib_error_return (0, "unknown input `%U'",
+                                format_unformat_error, input);
+  }
+  unformat_free (line_input);
+
+  if (num_m_args < 2)
+      return clib_error_return (0, "mandatory argument(s) missing");
+
+  if (memcmp (&src, &dst, sizeof(src)) == 0)
+      return clib_error_return (0, "src and dst are identical");
+
+  memset (a, 0, sizeof (*a));
+  a->outer_fib_id = outer_fib_id;
+  a->teb = teb;
+  clib_memcpy(&a->src, &src, sizeof(src));
+  clib_memcpy(&a->dst, &dst, sizeof(dst));
+
+  if (is_add)
+    rv = vnet_gre_tunnel_add(a, &sw_if_index);
+  else
+    rv = vnet_gre_tunnel_delete(a, &sw_if_index);
+
+  switch(rv)
+    {
+    case 0:
+      vlib_cli_output(vm, "%U\n", format_vnet_sw_if_index_name, vnet_get_main(), sw_if_index);
+      break;
+    case VNET_API_ERROR_INVALID_VALUE:
+      return clib_error_return (0, "GRE tunnel already exists...");
+    case VNET_API_ERROR_NO_SUCH_FIB:
+      return clib_error_return (0, "outer fib ID %d doesn't exist\n",
+                                outer_fib_id);
+    default:
+      return clib_error_return (0, "vnet_gre_add_del_tunnel returned %d", rv);
+    }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (create_gre_tunnel_command, static) = {
+  .path = "create gre tunnel",
+  .short_help = "create gre tunnel src <addr> dst <addr> "
+                "[outer-fib-id <fib>] [teb] [del]",
+  .function = create_gre_tunnel_command_fn,
+};
+
+static clib_error_t *
+show_gre_tunnel_command_fn (vlib_main_t * vm,
+                            unformat_input_t * input,
+                            vlib_cli_command_t * cmd)
+{
+  gre_main_t * gm = &gre_main;
+  gre_tunnel_t * t;
+  u32 ti = ~0;
+
+  if (pool_elts (gm->tunnels) == 0)
+    vlib_cli_output (vm, "No GRE tunnels configured...");
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%d", &ti))
+        ;
+      else
+        break;
+    }
+
+  if (~0 == ti)
+    {
+      pool_foreach (t, gm->tunnels,
+      ({
+          vlib_cli_output (vm, "%U", format_gre_tunnel, t);
+      }));
+    }
+  else
+  {
+      t = pool_elt_at_index(gm->tunnels, ti);
+
+      vlib_cli_output (vm, "%U", format_gre_tunnel, t);
+  }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (show_gre_tunnel_command, static) = {
+    .path = "show gre tunnel",
+    .function = show_gre_tunnel_command_fn,
+};
+
+/* force inclusion from application's main.c */
+clib_error_t *gre_interface_init (vlib_main_t *vm)
+{
+  fib_node_register_type(FIB_NODE_TYPE_GRE_TUNNEL, &gre_vft);
+
+  return 0;
+}
+VLIB_INIT_FUNCTION(gre_interface_init);
diff --git a/src/vnet/gre/node.c b/src/vnet/gre/node.c
new file mode 100644
index 00000000..86f7a6ee
--- /dev/null
+++ b/src/vnet/gre/node.c
@@ -0,0 +1,531 @@
+/*
+ * node.c: gre packet processing
+ *
+ * Copyright (c) 2012 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/pg/pg.h>
+#include <vnet/gre/gre.h>
+#include <vnet/mpls/mpls.h>
+#include <vppinfra/sparse_vec.h>
+
+#define foreach_gre_input_next			\
+_(PUNT, "error-punt")                           \
+_(DROP, "error-drop")                           \
+_(ETHERNET_INPUT, "ethernet-input")             \
+_(IP4_INPUT, "ip4-input")                       \
+_(IP6_INPUT, "ip6-input")			\
+_(MPLS_INPUT, "mpls-input")
+
+typedef enum {
+#define _(s,n) GRE_INPUT_NEXT_##s,
+  foreach_gre_input_next
+#undef _
+  GRE_INPUT_N_NEXT,
+} gre_input_next_t;
+
+typedef struct {
+  u32 tunnel_id;
+  u32 length;
+  ip4_address_t src;
+  ip4_address_t dst;
+} gre_rx_trace_t;
+
+u8 * format_gre_rx_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  gre_rx_trace_t * t = va_arg (*args, gre_rx_trace_t *);
+    
+  s = format (s, "GRE: tunnel %d len %d src %U dst %U",
+              t->tunnel_id, clib_net_to_host_u16(t->length),
+              format_ip4_address, &t->src.as_u8,
+              format_ip4_address, &t->dst.as_u8);
+  return s;
+}
+
+typedef struct {
+  /* Sparse vector mapping gre protocol in network byte order
+     to next index. */
+  u16 * next_by_protocol;
+} gre_input_runtime_t;
+
+static uword
+gre_input (vlib_main_t * vm,
+	   vlib_node_runtime_t * node,
+	   vlib_frame_t * from_frame)
+{
+  gre_main_t * gm = &gre_main;
+  gre_input_runtime_t * rt = (void *) node->runtime_data;
+  __attribute__((unused)) u32 n_left_from, next_index, * from, * to_next;
+  u64 cached_tunnel_key = (u64) ~0;
+  u32 cached_tunnel_sw_if_index = 0, tunnel_sw_if_index = 0;
+
+  u32 cpu_index = os_get_cpu_number();
+  u32 len;
+  vnet_interface_main_t *im = &gm->vnet_main->interface_main;
+
+  from = vlib_frame_vector_args (from_frame);
+  n_left_from = from_frame->n_vectors;
+
+  next_index = node->cached_next_index;
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index,
+			   to_next, n_left_to_next);
+
+      while (n_left_from >= 4 && n_left_to_next >= 2)
+	{
+	  u32 bi0, bi1;
+	  vlib_buffer_t * b0, * b1;
+	  gre_header_t * h0, * h1;
+          u16 version0, version1;
+          int verr0, verr1;
+	  u32 i0, i1, next0, next1, protocol0, protocol1;
+          ip4_header_t *ip0, *ip1;
+
+	  /* Prefetch next iteration. */
+	  {
+	    vlib_buffer_t * p2, * p3;
+
+	    p2 = vlib_get_buffer (vm, from[2]);
+	    p3 = vlib_get_buffer (vm, from[3]);
+
+	    vlib_prefetch_buffer_header (p2, LOAD);
+	    vlib_prefetch_buffer_header (p3, LOAD);
+
+	    CLIB_PREFETCH (p2->data, sizeof (h0[0]), LOAD);
+	    CLIB_PREFETCH (p3->data, sizeof (h1[0]), LOAD);
+	  }
+
+	  bi0 = from[0];
+	  bi1 = from[1];
+	  to_next[0] = bi0;
+	  to_next[1] = bi1;
+	  from += 2;
+	  to_next += 2;
+	  n_left_to_next -= 2;
+	  n_left_from -= 2;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+	  b1 = vlib_get_buffer (vm, bi1);
+
+          /* ip4_local hands us the ip header, not the gre header */
+          ip0 = vlib_buffer_get_current (b0);
+          ip1 = vlib_buffer_get_current (b1);
+
+          /* Save src + dst ip4 address, e.g. for mpls-o-gre */
+          vnet_buffer(b0)->gre.src = ip0->src_address.as_u32;
+          vnet_buffer(b0)->gre.dst = ip0->dst_address.as_u32;
+          vnet_buffer(b1)->gre.src = ip1->src_address.as_u32;
+          vnet_buffer(b1)->gre.dst = ip1->dst_address.as_u32;
+
+          vlib_buffer_advance (b0, sizeof (*ip0));
+          vlib_buffer_advance (b1, sizeof (*ip1));
+
+	  h0 = vlib_buffer_get_current (b0);
+	  h1 = vlib_buffer_get_current (b1);
+
+	  /* Index sparse array with network byte order. */
+	  protocol0 = h0->protocol;
+	  protocol1 = h1->protocol;
+	  sparse_vec_index2 (rt->next_by_protocol, protocol0, protocol1,
+                             &i0, &i1);
+          next0 = vec_elt(rt->next_by_protocol, i0);
+          next1 = vec_elt(rt->next_by_protocol, i1);
+
+	  b0->error = node->errors[i0 == SPARSE_VEC_INVALID_INDEX ? GRE_ERROR_UNKNOWN_PROTOCOL : GRE_ERROR_NONE];
+	  b1->error = node->errors[i1 == SPARSE_VEC_INVALID_INDEX ? GRE_ERROR_UNKNOWN_PROTOCOL : GRE_ERROR_NONE];
+          
+          version0 = clib_net_to_host_u16 (h0->flags_and_version);
+          verr0 =  version0 & GRE_VERSION_MASK;
+          version1 = clib_net_to_host_u16 (h1->flags_and_version);
+          verr1 =  version1 & GRE_VERSION_MASK;
+
+          b0->error = verr0 ? node->errors[GRE_ERROR_UNSUPPORTED_VERSION]
+              : b0->error;
+          next0 = verr0 ? GRE_INPUT_NEXT_DROP : next0;
+          b1->error = verr1 ? node->errors[GRE_ERROR_UNSUPPORTED_VERSION]
+              : b1->error;
+          next1 = verr1 ? GRE_INPUT_NEXT_DROP : next1;
+
+
+          /* RPF check for ip4/ip6 input */
+          if (PREDICT_TRUE(next0 == GRE_INPUT_NEXT_IP4_INPUT
+			   || next0 == GRE_INPUT_NEXT_IP6_INPUT
+			   || next0 == GRE_INPUT_NEXT_ETHERNET_INPUT
+			   || next0 == GRE_INPUT_NEXT_MPLS_INPUT))
+            {
+              u64 key = ((u64)(vnet_buffer(b0)->gre.dst) << 32) |
+                         (u64)(vnet_buffer(b0)->gre.src);
+
+              if (cached_tunnel_key != key)
+                {
+                  vnet_hw_interface_t * hi;
+                  gre_tunnel_t * t;
+                  uword * p;
+
+                  p = hash_get (gm->tunnel_by_key, key);
+                  if (!p)
+                    {
+                      next0 = GRE_INPUT_NEXT_DROP;
+                      b0->error = node->errors[GRE_ERROR_NO_SUCH_TUNNEL];
+                      goto drop0;
+                    }
+                  t = pool_elt_at_index (gm->tunnels, p[0]);
+                  hi = vnet_get_hw_interface (gm->vnet_main,
+                            t->hw_if_index);
+                  tunnel_sw_if_index = hi->sw_if_index;
+
+                  cached_tunnel_sw_if_index = tunnel_sw_if_index;
+                }
+              else
+                {
+                  tunnel_sw_if_index = cached_tunnel_sw_if_index;
+                }
+            }
+          else
+            {
+		next0 = GRE_INPUT_NEXT_DROP;
+                goto drop0;
+            }
+          len = vlib_buffer_length_in_chain (vm, b0);
+          vlib_increment_combined_counter (im->combined_sw_if_counters
+                                           + VNET_INTERFACE_COUNTER_RX,
+                                           cpu_index,
+                                           tunnel_sw_if_index,
+                                           1 /* packets */,
+                                           len /* bytes */);
+
+          vnet_buffer(b0)->sw_if_index[VLIB_RX] = tunnel_sw_if_index;
+
+drop0:
+          if (PREDICT_TRUE(next1 == GRE_INPUT_NEXT_IP4_INPUT
+			   || next1 == GRE_INPUT_NEXT_IP6_INPUT
+			   || next1 == GRE_INPUT_NEXT_ETHERNET_INPUT
+			   || next1 == GRE_INPUT_NEXT_MPLS_INPUT))
+            {
+              u64 key = ((u64)(vnet_buffer(b1)->gre.dst) << 32) |
+                         (u64)(vnet_buffer(b1)->gre.src);
+
+              if (cached_tunnel_key != key)
+                {
+                  vnet_hw_interface_t * hi;
+                  gre_tunnel_t * t;
+                  uword * p;
+
+                  p = hash_get (gm->tunnel_by_key, key);
+                  if (!p)
+                    {
+                      next1 = GRE_INPUT_NEXT_DROP;
+                      b1->error = node->errors[GRE_ERROR_NO_SUCH_TUNNEL];
+                      goto drop1;
+                    }
+                  t = pool_elt_at_index (gm->tunnels, p[0]);
+                  hi = vnet_get_hw_interface (gm->vnet_main,
+                            t->hw_if_index);
+                  tunnel_sw_if_index = hi->sw_if_index;
+
+                  cached_tunnel_sw_if_index = tunnel_sw_if_index;
+                }
+              else
+                {
+                  tunnel_sw_if_index = cached_tunnel_sw_if_index;
+                }
+            }
+          else
+            {
+		next1 = GRE_INPUT_NEXT_DROP;
+                goto drop1;
+            }
+          len = vlib_buffer_length_in_chain (vm, b1);
+          vlib_increment_combined_counter (im->combined_sw_if_counters
+                                           + VNET_INTERFACE_COUNTER_RX,
+                                           cpu_index,
+                                           tunnel_sw_if_index,
+                                           1 /* packets */,
+                                           len /* bytes */);
+
+          vnet_buffer(b1)->sw_if_index[VLIB_RX] = tunnel_sw_if_index;
+
+drop1:
+          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
+            {
+              gre_rx_trace_t *tr = vlib_add_trace (vm, node,
+                                                   b0, sizeof (*tr));
+              tr->tunnel_id = tunnel_sw_if_index;
+              tr->length = ip0->length;
+              tr->src.as_u32 = ip0->src_address.as_u32;
+              tr->dst.as_u32 = ip0->dst_address.as_u32;
+            }
+
+          if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED))
+            {
+              gre_rx_trace_t *tr = vlib_add_trace (vm, node,
+                                                   b1, sizeof (*tr));
+              tr->tunnel_id = tunnel_sw_if_index;
+              tr->length = ip1->length;
+              tr->src.as_u32 = ip1->src_address.as_u32;
+              tr->dst.as_u32 = ip1->dst_address.as_u32;
+            }
+
+          vlib_buffer_advance (b0, sizeof (*h0));
+          vlib_buffer_advance (b1, sizeof (*h1));
+
+	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, bi1, next0, next1);
+	}
+    
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  u32 bi0;
+	  vlib_buffer_t * b0;
+	  gre_header_t * h0;
+          ip4_header_t * ip0;
+          u16 version0;
+          int verr0;
+	  u32 i0, next0;
+
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+          ip0 = vlib_buffer_get_current (b0);
+
+          vnet_buffer(b0)->gre.src = ip0->src_address.as_u32;
+          vnet_buffer(b0)->gre.dst = ip0->dst_address.as_u32;
+
+          vlib_buffer_advance (b0, sizeof (*ip0));
+
+	  h0 = vlib_buffer_get_current (b0);
+
+	  i0 = sparse_vec_index (rt->next_by_protocol, h0->protocol);
+          next0 = vec_elt(rt->next_by_protocol, i0);
+
+	  b0->error = 
+              node->errors[i0 == SPARSE_VEC_INVALID_INDEX 
+                           ? GRE_ERROR_UNKNOWN_PROTOCOL : GRE_ERROR_NONE];
+	  
+          version0 = clib_net_to_host_u16 (h0->flags_and_version);
+          verr0 =  version0 & GRE_VERSION_MASK;
+          b0->error = verr0 ? node->errors[GRE_ERROR_UNSUPPORTED_VERSION] 
+              : b0->error;
+          next0 = verr0 ? GRE_INPUT_NEXT_DROP : next0;
+
+
+          /* For IP payload we need to find source interface
+             so we can increase counters and help forward node to
+             pick right FIB */
+          /* RPF check for ip4/ip6 input */
+          if (PREDICT_TRUE(next0 == GRE_INPUT_NEXT_IP4_INPUT
+			   || next0 == GRE_INPUT_NEXT_IP6_INPUT
+			   || next0 == GRE_INPUT_NEXT_ETHERNET_INPUT
+			   || next0 == GRE_INPUT_NEXT_MPLS_INPUT))
+            {
+              u64 key = ((u64)(vnet_buffer(b0)->gre.dst) << 32) |
+                         (u64)(vnet_buffer(b0)->gre.src);
+
+              if (cached_tunnel_key != key)
+                {
+                  vnet_hw_interface_t * hi;
+                  gre_tunnel_t * t;
+                  uword * p;
+
+                  p = hash_get (gm->tunnel_by_key, key);
+                  if (!p)
+                    {
+                      next0 = GRE_INPUT_NEXT_DROP;
+                      b0->error = node->errors[GRE_ERROR_NO_SUCH_TUNNEL];
+                      goto drop;
+                    }
+                  t = pool_elt_at_index (gm->tunnels, p[0]);
+                  hi = vnet_get_hw_interface (gm->vnet_main,
+                            t->hw_if_index);
+                  tunnel_sw_if_index = hi->sw_if_index;
+
+                  cached_tunnel_sw_if_index = tunnel_sw_if_index;
+                }
+              else
+                {
+                  tunnel_sw_if_index = cached_tunnel_sw_if_index;
+                }
+            }
+          else
+            {
+		next0 = GRE_INPUT_NEXT_DROP;
+                goto drop;
+            }
+          len = vlib_buffer_length_in_chain (vm, b0);
+          vlib_increment_combined_counter (im->combined_sw_if_counters
+                                           + VNET_INTERFACE_COUNTER_RX,
+                                           cpu_index,
+                                           tunnel_sw_if_index,
+                                           1 /* packets */,
+                                           len /* bytes */);
+
+          vnet_buffer(b0)->sw_if_index[VLIB_RX] = tunnel_sw_if_index;
+
+drop:
+          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) 
+            {
+              gre_rx_trace_t *tr = vlib_add_trace (vm, node, 
+                                                   b0, sizeof (*tr));
+              tr->tunnel_id = tunnel_sw_if_index;
+              tr->length = ip0->length;
+              tr->src.as_u32 = ip0->src_address.as_u32;
+              tr->dst.as_u32 = ip0->dst_address.as_u32;
+            }
+
+          vlib_buffer_advance (b0, sizeof (*h0));
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+  vlib_node_increment_counter (vm, gre_input_node.index,
+                               GRE_ERROR_PKTS_DECAP, from_frame->n_vectors);
+  return from_frame->n_vectors;
+}
+
+static char * gre_error_strings[] = {
+#define gre_error(n,s) s,
+#include "error.def"
+#undef gre_error
+};
+
+VLIB_REGISTER_NODE (gre_input_node) = {
+  .function = gre_input,
+  .name = "gre-input",
+  /* Takes a vector of packets. */
+  .vector_size = sizeof (u32),
+
+  .runtime_data_bytes = sizeof (gre_input_runtime_t),
+
+  .n_errors = GRE_N_ERROR,
+  .error_strings = gre_error_strings,
+
+  .n_next_nodes = GRE_INPUT_N_NEXT,
+  .next_nodes = {
+#define _(s,n) [GRE_INPUT_NEXT_##s] = n,
+    foreach_gre_input_next
+#undef _
+  },
+
+  .format_buffer = format_gre_header_with_length,
+  .format_trace = format_gre_rx_trace,
+  .unformat_buffer = unformat_gre_header,
+};
+
+VLIB_NODE_FUNCTION_MULTIARCH (gre_input_node, gre_input)
+
+void
+gre_register_input_protocol (vlib_main_t * vm,
+			     gre_protocol_t protocol,
+			     u32 node_index)
+{
+  gre_main_t * em = &gre_main;
+  gre_protocol_info_t * pi;
+  gre_input_runtime_t * rt;
+  u16 * n;
+
+  {
+    clib_error_t * error = vlib_call_init_function (vm, gre_input_init);
+    if (error)
+      clib_error_report (error);
+  }
+
+  pi = gre_get_protocol_info (em, protocol);
+  pi->node_index = node_index;
+  pi->next_index = vlib_node_add_next (vm, 
+				       gre_input_node.index,
+				       node_index);
+
+  /* Setup gre protocol -> next index sparse vector mapping. */
+  rt = vlib_node_get_runtime_data (vm, gre_input_node.index);
+  n = sparse_vec_validate (rt->next_by_protocol, 
+                           clib_host_to_net_u16 (protocol));
+  n[0] = pi->next_index;
+}
+
+static void
+gre_setup_node (vlib_main_t * vm, u32 node_index)
+{
+  vlib_node_t * n = vlib_get_node (vm, node_index);
+  pg_node_t * pn = pg_get_node (node_index);
+
+  n->format_buffer = format_gre_header_with_length;
+  n->unformat_buffer = unformat_gre_header;
+  pn->unformat_edit = unformat_pg_gre_header;
+}
+
+static clib_error_t * gre_input_init (vlib_main_t * vm)
+{
+  gre_input_runtime_t * rt;
+  vlib_node_t *ethernet_input, *ip4_input, *ip6_input, *mpls_unicast_input;
+
+  {
+    clib_error_t * error; 
+    error = vlib_call_init_function (vm, gre_init);
+    if (error)
+      clib_error_report (error);
+  }
+
+  gre_setup_node (vm, gre_input_node.index);
+
+  rt = vlib_node_get_runtime_data (vm, gre_input_node.index);
+
+  rt->next_by_protocol = sparse_vec_new
+    (/* elt bytes */ sizeof (rt->next_by_protocol[0]),
+     /* bits in index */ BITS (((gre_header_t *) 0)->protocol));
+
+  /* These could be moved to the supported protocol input node defn's */
+  ethernet_input = vlib_get_node_by_name (vm, (u8 *)"ethernet-input");
+  ASSERT(ethernet_input);
+  ip4_input = vlib_get_node_by_name (vm, (u8 *)"ip4-input");
+  ASSERT(ip4_input);
+  ip6_input = vlib_get_node_by_name (vm, (u8 *)"ip6-input");
+  ASSERT(ip6_input);
+  mpls_unicast_input = vlib_get_node_by_name (vm, (u8 *)"mpls-input");
+  ASSERT(mpls_unicast_input);
+
+  gre_register_input_protocol (vm, GRE_PROTOCOL_teb,
+                               ethernet_input->index);
+
+  gre_register_input_protocol (vm, GRE_PROTOCOL_ip4, 
+                               ip4_input->index);
+
+  gre_register_input_protocol (vm, GRE_PROTOCOL_ip6, 
+                               ip6_input->index);
+
+  gre_register_input_protocol (vm, GRE_PROTOCOL_mpls_unicast,
+                               mpls_unicast_input->index);
+
+  ip4_register_protocol (IP_PROTOCOL_GRE, gre_input_node.index);
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (gre_input_init);
diff --git a/src/vnet/gre/packet.h b/src/vnet/gre/packet.h
new file mode 100644
index 00000000..cc2ccda9
--- /dev/null
+++ b/src/vnet/gre/packet.h
@@ -0,0 +1,55 @@
+#ifndef included_vnet_gre_packet_h
+#define included_vnet_gre_packet_h
+
+/*
+ * GRE packet format
+ *
+ * Copyright (c) 2012 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.
+ */
+
+#define foreach_gre_protocol			\
+_ (0x0800, ip4)                                 \
+_ (0x86DD, ip6)                                 \
+_ (0x6558, teb)                                 \
+_ (0x0806, arp)					\
+_ (0x8847, mpls_unicast)			\
+_ (0x894F, nsh)
+
+typedef enum {
+#define _(n,f) GRE_PROTOCOL_##f = n,
+  foreach_gre_protocol
+#undef _
+} gre_protocol_t;
+
+typedef struct {
+  /* flags and version */
+  u16 flags_and_version;
+  /* unimplemented at the moment */
+#define GRE_FLAGS_CHECKSUM (1 << 15)
+
+  /* deprecated, according to rfc2784 */
+#define GRE_FLAGS_ROUTING (1 << 14)
+#define GRE_FLAGS_KEY (1 << 13)
+#define GRE_FLAGS_SEQUENCE (1 << 12)
+#define GRE_FLAGS_STRICT_SOURCE_ROUTE (1 << 11)
+
+  /* version 1 is PPTP which we don't support */
+#define GRE_SUPPORTED_VERSION 0
+#define GRE_VERSION_MASK 0x7
+
+  /* 0x800 for ip4, etc. */
+  u16 protocol;
+} gre_header_t;
+
+#endif /* included_vnet_gre_packet_h */
diff --git a/src/vnet/gre/pg.c b/src/vnet/gre/pg.c
new file mode 100644
index 00000000..cc065d3b
--- /dev/null
+++ b/src/vnet/gre/pg.c
@@ -0,0 +1,77 @@
+/*
+ * hdlc_pg.c: packet generator gre interface
+ *
+ * Copyright (c) 2012 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/pg/pg.h>
+#include <vnet/gre/gre.h>
+
+typedef struct {
+  pg_edit_t flags_and_version;
+  pg_edit_t protocol;
+} pg_gre_header_t;
+
+static inline void
+pg_gre_header_init (pg_gre_header_t * e)
+{
+  pg_edit_init (&e->flags_and_version, gre_header_t, flags_and_version);
+  pg_edit_init (&e->protocol, gre_header_t, protocol);
+}
+
+uword
+unformat_pg_gre_header (unformat_input_t * input, va_list * args)
+{
+  pg_stream_t * s = va_arg (*args, pg_stream_t *);
+  pg_gre_header_t * h;
+  u32 group_index, error;
+  
+  h = pg_create_edit_group (s, sizeof (h[0]), sizeof (gre_header_t),
+			    &group_index);
+  pg_gre_header_init (h);
+
+  pg_edit_set_fixed (&h->flags_and_version, 0);
+
+  error = 1;
+  if (! unformat (input, "%U",
+		  unformat_pg_edit,
+                  unformat_gre_protocol_net_byte_order, &h->protocol))
+    goto done;
+
+  {
+    gre_main_t * pm = &gre_main;
+    gre_protocol_info_t * pi = 0;
+    pg_node_t * pg_node = 0;
+
+    if (h->protocol.type == PG_EDIT_FIXED)
+      {
+	u16 t = *(u16 *) h->protocol.values[PG_EDIT_LO];
+	pi = gre_get_protocol_info (pm, clib_net_to_host_u16 (t));
+	if (pi && pi->node_index != ~0)
+	  pg_node = pg_get_node (pi->node_index);
+      }
+
+    if (pg_node && pg_node->unformat_edit
+	&& unformat_user (input, pg_node->unformat_edit, s))
+      ;
+  }
+
+  error = 0;
+ done:
+  if (error)
+    pg_free_edit_group (s);
+  return error == 0;
+}
+