Reorganize source tree to use single autotools instance

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

1 files changed, 2355 insertions, 0 deletions

diff --git a/src/vnet/ethernet/arp.c b/src/vnet/ethernet/arp.c
new file mode 100644
index 00000000000..b388e778ac8
--- /dev/null
+++ b/src/vnet/ethernet/arp.c
@@ -0,0 +1,2355 @@
+/*
+ * ethernet/arp.c: IP v4 ARP node
+ *
+ * Copyright (c) 2010 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/ip/ip.h>
+#include <vnet/ip/ip6.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ethernet/arp_packet.h>
+#include <vnet/l2/l2_input.h>
+#include <vppinfra/mhash.h>
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/adj/adj_nbr.h>
+#include <vnet/mpls/mpls.h>
+
+/**
+ * @file
+ * @brief IPv4 ARP.
+ *
+ * This file contains code to manage the IPv4 ARP tables (IP Address
+ * to MAC Address lookup).
+ */
+
+
+void vl_api_rpc_call_main_thread (void *fp, u8 * data, u32 data_length);
+
+/**
+ * @brief Per-interface ARP configuration and state
+ */
+typedef struct ethernet_arp_interface_t_
+{
+  /**
+   * Hash table of ARP entries.
+   * Since this hash table is per-interface, the key is only the IPv4 address.
+   */
+  uword *arp_entries;
+} ethernet_arp_interface_t;
+
+typedef struct
+{
+  u32 lo_addr;
+  u32 hi_addr;
+  u32 fib_index;
+} ethernet_proxy_arp_t;
+
+typedef struct
+{
+  u32 next_index;
+  uword node_index;
+  uword type_opaque;
+  uword data;
+  /* Used for arp event notification only */
+  void *data_callback;
+  u32 pid;
+} pending_resolution_t;
+
+typedef struct
+{
+  /* Hash tables mapping name to opcode. */
+  uword *opcode_by_name;
+
+  /* lite beer "glean" adjacency handling */
+  uword *pending_resolutions_by_address;
+  pending_resolution_t *pending_resolutions;
+
+  /* Mac address change notification */
+  uword *mac_changes_by_address;
+  pending_resolution_t *mac_changes;
+
+  ethernet_arp_ip4_entry_t *ip4_entry_pool;
+
+  /* ARP attack mitigation */
+  u32 arp_delete_rotor;
+  u32 limit_arp_cache_size;
+
+  /** Per interface state */
+  ethernet_arp_interface_t *ethernet_arp_by_sw_if_index;
+
+  /* Proxy arp vector */
+  ethernet_proxy_arp_t *proxy_arps;
+} ethernet_arp_main_t;
+
+static ethernet_arp_main_t ethernet_arp_main;
+
+typedef struct
+{
+  u32 sw_if_index;
+  ethernet_arp_ip4_over_ethernet_address_t a;
+  int is_static;
+  int flags;
+#define ETHERNET_ARP_ARGS_REMOVE (1<<0)
+#define ETHERNET_ARP_ARGS_FLUSH  (1<<1)
+#define ETHERNET_ARP_ARGS_POPULATE  (1<<2)
+} vnet_arp_set_ip4_over_ethernet_rpc_args_t;
+
+static void
+set_ip4_over_ethernet_rpc_callback (vnet_arp_set_ip4_over_ethernet_rpc_args_t
+				    * a);
+
+static u8 *
+format_ethernet_arp_hardware_type (u8 * s, va_list * va)
+{
+  ethernet_arp_hardware_type_t h = va_arg (*va, ethernet_arp_hardware_type_t);
+  char *t = 0;
+  switch (h)
+    {
+#define _(n,f) case n: t = #f; break;
+      foreach_ethernet_arp_hardware_type;
+#undef _
+
+    default:
+      return format (s, "unknown 0x%x", h);
+    }
+
+  return format (s, "%s", t);
+}
+
+static u8 *
+format_ethernet_arp_opcode (u8 * s, va_list * va)
+{
+  ethernet_arp_opcode_t o = va_arg (*va, ethernet_arp_opcode_t);
+  char *t = 0;
+  switch (o)
+    {
+#define _(f) case ETHERNET_ARP_OPCODE_##f: t = #f; break;
+      foreach_ethernet_arp_opcode;
+#undef _
+
+    default:
+      return format (s, "unknown 0x%x", o);
+    }
+
+  return format (s, "%s", t);
+}
+
+static uword
+unformat_ethernet_arp_opcode_host_byte_order (unformat_input_t * input,
+					      va_list * args)
+{
+  int *result = va_arg (*args, int *);
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  int x, i;
+
+  /* Numeric opcode. */
+  if (unformat (input, "0x%x", &x) || unformat (input, "%d", &x))
+    {
+      if (x >= (1 << 16))
+	return 0;
+      *result = x;
+      return 1;
+    }
+
+  /* Named type. */
+  if (unformat_user (input, unformat_vlib_number_by_name,
+		     am->opcode_by_name, &i))
+    {
+      *result = i;
+      return 1;
+    }
+
+  return 0;
+}
+
+static uword
+unformat_ethernet_arp_opcode_net_byte_order (unformat_input_t * input,
+					     va_list * args)
+{
+  int *result = va_arg (*args, int *);
+  if (!unformat_user
+      (input, unformat_ethernet_arp_opcode_host_byte_order, result))
+    return 0;
+
+  *result = clib_host_to_net_u16 ((u16) * result);
+  return 1;
+}
+
+static u8 *
+format_ethernet_arp_header (u8 * s, va_list * va)
+{
+  ethernet_arp_header_t *a = va_arg (*va, ethernet_arp_header_t *);
+  u32 max_header_bytes = va_arg (*va, u32);
+  uword indent;
+  u16 l2_type, l3_type;
+
+  if (max_header_bytes != 0 && sizeof (a[0]) > max_header_bytes)
+    return format (s, "ARP header truncated");
+
+  l2_type = clib_net_to_host_u16 (a->l2_type);
+  l3_type = clib_net_to_host_u16 (a->l3_type);
+
+  indent = format_get_indent (s);
+
+  s = format (s, "%U, type %U/%U, address size %d/%d",
+	      format_ethernet_arp_opcode, clib_net_to_host_u16 (a->opcode),
+	      format_ethernet_arp_hardware_type, l2_type,
+	      format_ethernet_type, l3_type,
+	      a->n_l2_address_bytes, a->n_l3_address_bytes);
+
+  if (l2_type == ETHERNET_ARP_HARDWARE_TYPE_ethernet
+      && l3_type == ETHERNET_TYPE_IP4)
+    {
+      s = format (s, "\n%U%U/%U -> %U/%U",
+		  format_white_space, indent,
+		  format_ethernet_address, a->ip4_over_ethernet[0].ethernet,
+		  format_ip4_address, &a->ip4_over_ethernet[0].ip4,
+		  format_ethernet_address, a->ip4_over_ethernet[1].ethernet,
+		  format_ip4_address, &a->ip4_over_ethernet[1].ip4);
+    }
+  else
+    {
+      uword n2 = a->n_l2_address_bytes;
+      uword n3 = a->n_l3_address_bytes;
+      s = format (s, "\n%U%U/%U -> %U/%U",
+		  format_white_space, indent,
+		  format_hex_bytes, a->data + 0 * n2 + 0 * n3, n2,
+		  format_hex_bytes, a->data + 1 * n2 + 0 * n3, n3,
+		  format_hex_bytes, a->data + 1 * n2 + 1 * n3, n2,
+		  format_hex_bytes, a->data + 2 * n2 + 1 * n3, n3);
+    }
+
+  return s;
+}
+
+u8 *
+format_ethernet_arp_ip4_entry (u8 * s, va_list * va)
+{
+  vnet_main_t *vnm = va_arg (*va, vnet_main_t *);
+  ethernet_arp_ip4_entry_t *e = va_arg (*va, ethernet_arp_ip4_entry_t *);
+  vnet_sw_interface_t *si;
+  u8 *flags = 0;
+
+  if (!e)
+    return format (s, "%=12s%=16s%=6s%=20s%=24s", "Time", "IP4",
+		   "Flags", "Ethernet", "Interface");
+
+  si = vnet_get_sw_interface (vnm, e->sw_if_index);
+
+  if (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC)
+    flags = format (flags, "S");
+
+  if (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC)
+    flags = format (flags, "D");
+
+  s = format (s, "%=12U%=16U%=6s%=20U%=24U",
+	      format_vlib_cpu_time, vnm->vlib_main, e->cpu_time_last_updated,
+	      format_ip4_address, &e->ip4_address,
+	      flags ? (char *) flags : "",
+	      format_ethernet_address, e->ethernet_address,
+	      format_vnet_sw_interface_name, vnm, si);
+
+  vec_free (flags);
+  return s;
+}
+
+typedef struct
+{
+  u8 packet_data[64];
+} ethernet_arp_input_trace_t;
+
+static u8 *
+format_ethernet_arp_input_trace (u8 * s, va_list * va)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
+  ethernet_arp_input_trace_t *t = va_arg (*va, ethernet_arp_input_trace_t *);
+
+  s = format (s, "%U",
+	      format_ethernet_arp_header,
+	      t->packet_data, sizeof (t->packet_data));
+
+  return s;
+}
+
+static u8 *
+format_arp_term_input_trace (u8 * s, va_list * va)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
+  ethernet_arp_input_trace_t *t = va_arg (*va, ethernet_arp_input_trace_t *);
+
+  /* arp-term trace data saved is either arp or ip6/icmp6 packet:
+     - for arp, the 1st 16-bit field is hw type of value of 0x0001.
+     - for ip6, the first nibble has value of 6. */
+  s = format (s, "%U", t->packet_data[0] == 0 ?
+	      format_ethernet_arp_header : format_ip6_header,
+	      t->packet_data, sizeof (t->packet_data));
+
+  return s;
+}
+
+static void
+arp_nbr_probe (ip_adjacency_t * adj)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  ip4_main_t *im = &ip4_main;
+  ip_interface_address_t *ia;
+  ethernet_arp_header_t *h;
+  vnet_hw_interface_t *hi;
+  vnet_sw_interface_t *si;
+  ip4_address_t *src;
+  vlib_buffer_t *b;
+  vlib_main_t *vm;
+  u32 bi = 0;
+
+  vm = vlib_get_main ();
+
+  si = vnet_get_sw_interface (vnm, adj->rewrite_header.sw_if_index);
+
+  if (!(si->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP))
+    {
+      return;
+    }
+
+  src =
+    ip4_interface_address_matching_destination (im,
+						&adj->sub_type.nbr.next_hop.
+						ip4,
+						adj->rewrite_header.
+						sw_if_index, &ia);
+  if (!src)
+    {
+      return;
+    }
+
+  h =
+    vlib_packet_template_get_packet (vm, &im->ip4_arp_request_packet_template,
+				     &bi);
+
+  hi = vnet_get_sup_hw_interface (vnm, adj->rewrite_header.sw_if_index);
+
+  clib_memcpy (h->ip4_over_ethernet[0].ethernet,
+	       hi->hw_address, sizeof (h->ip4_over_ethernet[0].ethernet));
+
+  h->ip4_over_ethernet[0].ip4 = src[0];
+  h->ip4_over_ethernet[1].ip4 = adj->sub_type.nbr.next_hop.ip4;
+
+  b = vlib_get_buffer (vm, bi);
+  vnet_buffer (b)->sw_if_index[VLIB_RX] =
+    vnet_buffer (b)->sw_if_index[VLIB_TX] = adj->rewrite_header.sw_if_index;
+
+  /* Add encapsulation string for software interface (e.g. ethernet header). */
+  vnet_rewrite_one_header (adj[0], h, sizeof (ethernet_header_t));
+  vlib_buffer_advance (b, -adj->rewrite_header.data_bytes);
+
+  {
+    vlib_frame_t *f = vlib_get_frame_to_node (vm, hi->output_node_index);
+    u32 *to_next = vlib_frame_vector_args (f);
+    to_next[0] = bi;
+    f->n_vectors = 1;
+    vlib_put_frame_to_node (vm, hi->output_node_index, f);
+  }
+}
+
+static void
+arp_mk_complete (adj_index_t ai, ethernet_arp_ip4_entry_t * e)
+{
+  adj_nbr_update_rewrite
+    (ai, ADJ_NBR_REWRITE_FLAG_COMPLETE,
+     ethernet_build_rewrite (vnet_get_main (),
+			     e->sw_if_index,
+			     adj_get_link_type (ai), e->ethernet_address));
+}
+
+static void
+arp_mk_incomplete (adj_index_t ai)
+{
+  ip_adjacency_t *adj = adj_get (ai);
+
+  adj_nbr_update_rewrite
+    (ai,
+     ADJ_NBR_REWRITE_FLAG_INCOMPLETE,
+     ethernet_build_rewrite (vnet_get_main (),
+			     adj->rewrite_header.sw_if_index,
+			     VNET_LINK_ARP,
+			     VNET_REWRITE_FOR_SW_INTERFACE_ADDRESS_BROADCAST));
+}
+
+static ethernet_arp_ip4_entry_t *
+arp_entry_find (ethernet_arp_interface_t * eai, const ip4_address_t * addr)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e = NULL;
+  uword *p;
+
+  if (NULL != eai->arp_entries)
+    {
+      p = hash_get (eai->arp_entries, addr->as_u32);
+      if (!p)
+	return (NULL);
+
+      e = pool_elt_at_index (am->ip4_entry_pool, p[0]);
+    }
+
+  return (e);
+}
+
+static adj_walk_rc_t
+arp_mk_complete_walk (adj_index_t ai, void *ctx)
+{
+  ethernet_arp_ip4_entry_t *e = ctx;
+
+  arp_mk_complete (ai, e);
+
+  return (ADJ_WALK_RC_CONTINUE);
+}
+
+static adj_walk_rc_t
+arp_mk_incomplete_walk (adj_index_t ai, void *ctx)
+{
+  arp_mk_incomplete (ai);
+
+  return (ADJ_WALK_RC_CONTINUE);
+}
+
+void
+arp_update_adjacency (vnet_main_t * vnm, u32 sw_if_index, u32 ai)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_interface_t *arp_int;
+  ethernet_arp_ip4_entry_t *e;
+  ip_adjacency_t *adj;
+
+  adj = adj_get (ai);
+
+  vec_validate (am->ethernet_arp_by_sw_if_index, sw_if_index);
+  arp_int = &am->ethernet_arp_by_sw_if_index[sw_if_index];
+  e = arp_entry_find (arp_int, &adj->sub_type.nbr.next_hop.ip4);
+
+  if (NULL != e)
+    {
+      adj_nbr_walk_nh4 (sw_if_index,
+			&e->ip4_address, arp_mk_complete_walk, e);
+    }
+  else
+    {
+      /*
+       * no matching ARP entry.
+       * construct the rewire required to for an ARP packet, and stick
+       * that in the adj's pipe to smoke.
+       */
+      adj_nbr_update_rewrite (ai,
+			      ADJ_NBR_REWRITE_FLAG_INCOMPLETE,
+			      ethernet_build_rewrite (vnm,
+						      sw_if_index,
+						      VNET_LINK_ARP,
+						      VNET_REWRITE_FOR_SW_INTERFACE_ADDRESS_BROADCAST));
+
+      /*
+       * since the FIB has added this adj for a route, it makes sense it may
+       * want to forward traffic sometime soon. Let's send a speculative ARP.
+       * just one. If we were to do periodically that wouldn't be bad either,
+       * but that's more code than i'm prepared to write at this time for
+       * relatively little reward.
+       */
+      arp_nbr_probe (adj);
+    }
+}
+
+int
+vnet_arp_set_ip4_over_ethernet_internal (vnet_main_t * vnm,
+					 vnet_arp_set_ip4_over_ethernet_rpc_args_t
+					 * args)
+{
+  ethernet_arp_ip4_entry_t *e = 0;
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_over_ethernet_address_t *a = &args->a;
+  vlib_main_t *vm = vlib_get_main ();
+  int make_new_arp_cache_entry = 1;
+  uword *p;
+  pending_resolution_t *pr, *mc;
+  ethernet_arp_interface_t *arp_int;
+  int is_static = args->is_static;
+  u32 sw_if_index = args->sw_if_index;
+
+  vec_validate (am->ethernet_arp_by_sw_if_index, sw_if_index);
+
+  arp_int = &am->ethernet_arp_by_sw_if_index[sw_if_index];
+
+  if (NULL != arp_int->arp_entries)
+    {
+      p = hash_get (arp_int->arp_entries, a->ip4.as_u32);
+      if (p)
+	{
+	  e = pool_elt_at_index (am->ip4_entry_pool, p[0]);
+
+	  /* Refuse to over-write static arp. */
+	  if (!is_static && (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC))
+	    return -2;
+	  make_new_arp_cache_entry = 0;
+	}
+    }
+
+  if (make_new_arp_cache_entry)
+    {
+      fib_prefix_t pfx = {
+	.fp_len = 32,
+	.fp_proto = FIB_PROTOCOL_IP4,
+	.fp_addr = {
+		    .ip4 = a->ip4,
+		    }
+	,
+      };
+      u32 fib_index;
+
+      pool_get (am->ip4_entry_pool, e);
+
+      if (NULL == arp_int->arp_entries)
+	{
+	  arp_int->arp_entries = hash_create (0, sizeof (u32));
+	}
+
+      hash_set (arp_int->arp_entries, a->ip4.as_u32, e - am->ip4_entry_pool);
+
+      e->sw_if_index = sw_if_index;
+      e->ip4_address = a->ip4;
+      clib_memcpy (e->ethernet_address,
+		   a->ethernet, sizeof (e->ethernet_address));
+
+      fib_index = ip4_fib_table_get_index_for_sw_if_index (e->sw_if_index);
+      e->fib_entry_index =
+	fib_table_entry_update_one_path (fib_index,
+					 &pfx,
+					 FIB_SOURCE_ADJ,
+					 FIB_ENTRY_FLAG_ATTACHED,
+					 FIB_PROTOCOL_IP4,
+					 &pfx.fp_addr,
+					 e->sw_if_index,
+					 ~0,
+					 1, NULL, FIB_ROUTE_PATH_FLAG_NONE);
+    }
+  else
+    {
+      /*
+       * prevent a DoS attack from the data-plane that
+       * spams us with no-op updates to the MAC address
+       */
+      if (0 == memcmp (e->ethernet_address,
+		       a->ethernet, sizeof (e->ethernet_address)))
+	return -1;
+
+      /* Update time stamp and ethernet address. */
+      clib_memcpy (e->ethernet_address, a->ethernet,
+		   sizeof (e->ethernet_address));
+    }
+
+  e->cpu_time_last_updated = clib_cpu_time_now ();
+  if (is_static)
+    e->flags |= ETHERNET_ARP_IP4_ENTRY_FLAG_STATIC;
+  else
+    e->flags |= ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC;
+
+  adj_nbr_walk_nh4 (sw_if_index, &e->ip4_address, arp_mk_complete_walk, e);
+
+  /* Customer(s) waiting for this address to be resolved? */
+  p = hash_get (am->pending_resolutions_by_address, a->ip4.as_u32);
+  if (p)
+    {
+      u32 next_index;
+      next_index = p[0];
+
+      while (next_index != (u32) ~ 0)
+	{
+	  pr = pool_elt_at_index (am->pending_resolutions, next_index);
+	  vlib_process_signal_event (vm, pr->node_index,
+				     pr->type_opaque, pr->data);
+	  next_index = pr->next_index;
+	  pool_put (am->pending_resolutions, pr);
+	}
+
+      hash_unset (am->pending_resolutions_by_address, a->ip4.as_u32);
+    }
+
+  /* Customer(s) requesting ARP event for this address? */
+  p = hash_get (am->mac_changes_by_address, a->ip4.as_u32);
+  if (p)
+    {
+      u32 next_index;
+      next_index = p[0];
+
+      while (next_index != (u32) ~ 0)
+	{
+	  int (*fp) (u32, u8 *, u32, u32);
+	  int rv = 1;
+	  mc = pool_elt_at_index (am->mac_changes, next_index);
+	  fp = mc->data_callback;
+
+	  /* Call the user's data callback, return 1 to suppress dup events */
+	  if (fp)
+	    rv = (*fp) (mc->data, a->ethernet, sw_if_index, 0);
+
+	  /*
+	   * Signal the resolver process, as long as the user
+	   * says they want to be notified
+	   */
+	  if (rv == 0)
+	    vlib_process_signal_event (vm, mc->node_index,
+				       mc->type_opaque, mc->data);
+	  next_index = mc->next_index;
+	}
+    }
+
+  return 0;
+}
+
+void
+vnet_register_ip4_arp_resolution_event (vnet_main_t * vnm,
+					void *address_arg,
+					uword node_index,
+					uword type_opaque, uword data)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ip4_address_t *address = address_arg;
+  uword *p;
+  pending_resolution_t *pr;
+
+  pool_get (am->pending_resolutions, pr);
+
+  pr->next_index = ~0;
+  pr->node_index = node_index;
+  pr->type_opaque = type_opaque;
+  pr->data = data;
+  pr->data_callback = 0;
+
+  p = hash_get (am->pending_resolutions_by_address, address->as_u32);
+  if (p)
+    {
+      /* Insert new resolution at the head of the list */
+      pr->next_index = p[0];
+      hash_unset (am->pending_resolutions_by_address, address->as_u32);
+    }
+
+  hash_set (am->pending_resolutions_by_address, address->as_u32,
+	    pr - am->pending_resolutions);
+}
+
+int
+vnet_add_del_ip4_arp_change_event (vnet_main_t * vnm,
+				   void *data_callback,
+				   u32 pid,
+				   void *address_arg,
+				   uword node_index,
+				   uword type_opaque, uword data, int is_add)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ip4_address_t *address = address_arg;
+  uword *p;
+  pending_resolution_t *mc;
+  void (*fp) (u32, u8 *) = data_callback;
+
+  if (is_add)
+    {
+      pool_get (am->mac_changes, mc);
+
+      mc->next_index = ~0;
+      mc->node_index = node_index;
+      mc->type_opaque = type_opaque;
+      mc->data = data;
+      mc->data_callback = data_callback;
+      mc->pid = pid;
+
+      p = hash_get (am->mac_changes_by_address, address->as_u32);
+      if (p)
+	{
+	  /* Insert new resolution at the head of the list */
+	  mc->next_index = p[0];
+	  hash_unset (am->mac_changes_by_address, address->as_u32);
+	}
+
+      hash_set (am->mac_changes_by_address, address->as_u32,
+		mc - am->mac_changes);
+      return 0;
+    }
+  else
+    {
+      u32 index;
+      pending_resolution_t *mc_last = 0;
+
+      p = hash_get (am->mac_changes_by_address, address->as_u32);
+      if (p == 0)
+	return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+      index = p[0];
+
+      while (index != (u32) ~ 0)
+	{
+	  mc = pool_elt_at_index (am->mac_changes, index);
+	  if (mc->node_index == node_index &&
+	      mc->type_opaque == type_opaque && mc->pid == pid)
+	    {
+	      /* Clients may need to clean up pool entries, too */
+	      if (fp)
+		(*fp) (mc->data, 0 /* no new mac addrs */ );
+	      if (index == p[0])
+		{
+		  hash_unset (am->mac_changes_by_address, address->as_u32);
+		  if (mc->next_index != ~0)
+		    hash_set (am->mac_changes_by_address, address->as_u32,
+			      mc->next_index);
+		  pool_put (am->mac_changes, mc);
+		  return 0;
+		}
+	      else
+		{
+		  ASSERT (mc_last);
+		  mc_last->next_index = mc->next_index;
+		  pool_put (am->mac_changes, mc);
+		  return 0;
+		}
+	    }
+	  mc_last = mc;
+	  index = mc->next_index;
+	}
+
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
+}
+
+/* Either we drop the packet or we send a reply to the sender. */
+typedef enum
+{
+  ARP_INPUT_NEXT_DROP,
+  ARP_INPUT_NEXT_REPLY_TX,
+  ARP_INPUT_N_NEXT,
+} arp_input_next_t;
+
+#define foreach_ethernet_arp_error					\
+  _ (replies_sent, "ARP replies sent")					\
+  _ (l2_type_not_ethernet, "L2 type not ethernet")			\
+  _ (l3_type_not_ip4, "L3 type not IP4")				\
+  _ (l3_src_address_not_local, "IP4 source address not local to subnet") \
+  _ (l3_dst_address_not_local, "IP4 destination address not local to subnet") \
+  _ (l3_src_address_is_local, "IP4 source address matches local interface") \
+  _ (l3_src_address_learned, "ARP request IP4 source address learned")  \
+  _ (replies_received, "ARP replies received")				\
+  _ (opcode_not_request, "ARP opcode not request")                      \
+  _ (proxy_arp_replies_sent, "Proxy ARP replies sent")			\
+  _ (l2_address_mismatch, "ARP hw addr does not match L2 frame src addr") \
+  _ (missing_interface_address, "ARP missing interface address") \
+  _ (gratuitous_arp, "ARP probe or announcement dropped") \
+  _ (interface_no_table, "Interface is not mapped to an IP table") \
+
+typedef enum
+{
+#define _(sym,string) ETHERNET_ARP_ERROR_##sym,
+  foreach_ethernet_arp_error
+#undef _
+    ETHERNET_ARP_N_ERROR,
+} ethernet_arp_input_error_t;
+
+
+static void
+unset_random_arp_entry (void)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+  vnet_main_t *vnm = vnet_get_main ();
+  ethernet_arp_ip4_over_ethernet_address_t delme;
+  u32 index;
+
+  index = pool_next_index (am->ip4_entry_pool, am->arp_delete_rotor);
+  am->arp_delete_rotor = index;
+
+  /* Try again from elt 0, could happen if an intfc goes down */
+  if (index == ~0)
+    {
+      index = pool_next_index (am->ip4_entry_pool, am->arp_delete_rotor);
+      am->arp_delete_rotor = index;
+    }
+
+  /* Nothing left in the pool */
+  if (index == ~0)
+    return;
+
+  e = pool_elt_at_index (am->ip4_entry_pool, index);
+
+  clib_memcpy (&delme.ethernet, e->ethernet_address, 6);
+  delme.ip4.as_u32 = e->ip4_address.as_u32;
+
+  vnet_arp_unset_ip4_over_ethernet (vnm, e->sw_if_index, &delme);
+}
+
+static int
+arp_unnumbered (vlib_buffer_t * p0,
+		u32 pi0, ethernet_header_t * eth0, u32 sw_if_index)
+{
+  vlib_main_t *vm = vlib_get_main ();
+  vnet_main_t *vnm = vnet_get_main ();
+  vnet_interface_main_t *vim = &vnm->interface_main;
+  vnet_sw_interface_t *si;
+  vnet_hw_interface_t *hi;
+  u32 unnum_src_sw_if_index;
+  u32 *broadcast_swifs = 0;
+  u32 *buffers = 0;
+  u32 n_alloc = 0;
+  vlib_buffer_t *b0;
+  int i;
+  u8 dst_mac_address[6];
+  i16 header_size;
+  ethernet_arp_header_t *arp0;
+
+  /* Save the dst mac address */
+  clib_memcpy (dst_mac_address, eth0->dst_address, sizeof (dst_mac_address));
+
+  /* Figure out which sw_if_index supplied the address */
+  unnum_src_sw_if_index = sw_if_index;
+
+  /* Track down all users of the unnumbered source */
+  /* *INDENT-OFF* */
+  pool_foreach (si, vim->sw_interfaces,
+  ({
+    if (si->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED &&
+	(si->unnumbered_sw_if_index == unnum_src_sw_if_index))
+      {
+	vec_add1 (broadcast_swifs, si->sw_if_index);
+      }
+  }));
+  /* *INDENT-ON* */
+
+  /* If there are no interfaces un-unmbered to this interface,
+     we are done  here. */
+  if (0 == vec_len (broadcast_swifs))
+    return 0;
+
+  /* Allocate buffering if we need it */
+  if (vec_len (broadcast_swifs) > 1)
+    {
+      vec_validate (buffers, vec_len (broadcast_swifs) - 2);
+      n_alloc = vlib_buffer_alloc (vm, buffers, vec_len (buffers));
+      _vec_len (buffers) = n_alloc;
+      for (i = 0; i < n_alloc; i++)
+	{
+	  b0 = vlib_get_buffer (vm, buffers[i]);
+
+	  /* xerox (partially built) ARP pkt */
+	  clib_memcpy (b0->data, p0->data,
+		       p0->current_length + p0->current_data);
+	  b0->current_data = p0->current_data;
+	  b0->current_length = p0->current_length;
+	  vnet_buffer (b0)->sw_if_index[VLIB_RX] =
+	    vnet_buffer (p0)->sw_if_index[VLIB_RX];
+	}
+    }
+
+  vec_insert (buffers, 1, 0);
+  buffers[0] = pi0;
+
+  for (i = 0; i < vec_len (buffers); i++)
+    {
+      b0 = vlib_get_buffer (vm, buffers[i]);
+      arp0 = vlib_buffer_get_current (b0);
+
+      hi = vnet_get_sup_hw_interface (vnm, broadcast_swifs[i]);
+      si = vnet_get_sw_interface (vnm, broadcast_swifs[i]);
+
+      /* For decoration, most likely */
+      vnet_buffer (b0)->sw_if_index[VLIB_TX] = hi->sw_if_index;
+
+      /* Fix ARP pkt src address */
+      clib_memcpy (arp0->ip4_over_ethernet[0].ethernet, hi->hw_address, 6);
+
+      /* Build L2 encaps for this swif */
+      header_size = sizeof (ethernet_header_t);
+      if (si->sub.eth.flags.one_tag)
+	header_size += 4;
+      else if (si->sub.eth.flags.two_tags)
+	header_size += 8;
+
+      vlib_buffer_advance (b0, -header_size);
+      eth0 = vlib_buffer_get_current (b0);
+
+      if (si->sub.eth.flags.one_tag)
+	{
+	  ethernet_vlan_header_t *outer = (void *) (eth0 + 1);
+
+	  eth0->type = si->sub.eth.flags.dot1ad ?
+	    clib_host_to_net_u16 (ETHERNET_TYPE_DOT1AD) :
+	    clib_host_to_net_u16 (ETHERNET_TYPE_VLAN);
+	  outer->priority_cfi_and_id =
+	    clib_host_to_net_u16 (si->sub.eth.outer_vlan_id);
+	  outer->type = clib_host_to_net_u16 (ETHERNET_TYPE_ARP);
+
+	}
+      else if (si->sub.eth.flags.two_tags)
+	{
+	  ethernet_vlan_header_t *outer = (void *) (eth0 + 1);
+	  ethernet_vlan_header_t *inner = (void *) (outer + 1);
+
+	  eth0->type = si->sub.eth.flags.dot1ad ?
+	    clib_host_to_net_u16 (ETHERNET_TYPE_DOT1AD) :
+	    clib_host_to_net_u16 (ETHERNET_TYPE_VLAN);
+	  outer->priority_cfi_and_id =
+	    clib_host_to_net_u16 (si->sub.eth.outer_vlan_id);
+	  outer->type = clib_host_to_net_u16 (ETHERNET_TYPE_VLAN);
+	  inner->priority_cfi_and_id =
+	    clib_host_to_net_u16 (si->sub.eth.inner_vlan_id);
+	  inner->type = clib_host_to_net_u16 (ETHERNET_TYPE_ARP);
+
+	}
+      else
+	{
+	  eth0->type = clib_host_to_net_u16 (ETHERNET_TYPE_ARP);
+	}
+
+      /* Restore the original dst address, set src address */
+      clib_memcpy (eth0->dst_address, dst_mac_address,
+		   sizeof (eth0->dst_address));
+      clib_memcpy (eth0->src_address, hi->hw_address,
+		   sizeof (eth0->src_address));
+
+      /* Transmit replicas */
+      if (i > 0)
+	{
+	  vlib_frame_t *f =
+	    vlib_get_frame_to_node (vm, hi->output_node_index);
+	  u32 *to_next = vlib_frame_vector_args (f);
+	  to_next[0] = buffers[i];
+	  f->n_vectors = 1;
+	  vlib_put_frame_to_node (vm, hi->output_node_index, f);
+	}
+    }
+
+  /* The regular path outputs the original pkt.. */
+  vnet_buffer (p0)->sw_if_index[VLIB_TX] = broadcast_swifs[0];
+
+  vec_free (broadcast_swifs);
+  vec_free (buffers);
+
+  return !0;
+}
+
+static uword
+arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  ip4_main_t *im4 = &ip4_main;
+  u32 n_left_from, next_index, *from, *to_next;
+  u32 n_replies_sent = 0, n_proxy_arp_replies_sent = 0;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  next_index = node->cached_next_index;
+
+  if (node->flags & VLIB_NODE_FLAG_TRACE)
+    vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
+				   /* stride */ 1,
+				   sizeof (ethernet_arp_input_trace_t));
+
+  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 > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t *p0;
+	  vnet_hw_interface_t *hw_if0;
+	  ethernet_arp_header_t *arp0;
+	  ethernet_header_t *eth0;
+	  ip_adjacency_t *adj0;
+	  ip4_address_t *if_addr0, proxy_src;
+	  u32 pi0, error0, next0, sw_if_index0, conn_sw_if_index0, fib_index0;
+	  u8 is_request0, dst_is_local0, is_unnum0;
+	  ethernet_proxy_arp_t *pa;
+	  fib_node_index_t dst_fei, src_fei;
+	  fib_prefix_t pfx0;
+	  fib_entry_flag_t src_flags, dst_flags;
+
+	  pi0 = from[0];
+	  to_next[0] = pi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+	  pa = 0;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  arp0 = vlib_buffer_get_current (p0);
+
+	  is_request0 = arp0->opcode
+	    == clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_request);
+
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+
+	  error0 =
+	    (arp0->l2_type !=
+	     clib_net_to_host_u16 (ETHERNET_ARP_HARDWARE_TYPE_ethernet) ?
+	     ETHERNET_ARP_ERROR_l2_type_not_ethernet : error0);
+	  error0 =
+	    (arp0->l3_type !=
+	     clib_net_to_host_u16 (ETHERNET_TYPE_IP4) ?
+	     ETHERNET_ARP_ERROR_l3_type_not_ip4 : error0);
+
+	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+
+	  if (error0)
+	    goto drop2;
+
+	  /* Check that IP address is local and matches incoming interface. */
+	  fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
+	  if (~0 == fib_index0)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_interface_no_table;
+	      goto drop2;
+
+	    }
+	  dst_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+					  &arp0->ip4_over_ethernet[1].ip4,
+					  32);
+	  dst_flags = fib_entry_get_flags_for_source (dst_fei,
+						      FIB_SOURCE_INTERFACE);
+
+	  conn_sw_if_index0 =
+	    fib_entry_get_resolving_interface_for_source (dst_fei,
+							  FIB_SOURCE_INTERFACE);
+
+	  if (!(FIB_ENTRY_FLAG_CONNECTED & dst_flags))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+	      goto drop1;
+	    }
+
+	  /* Honor unnumbered interface, if any */
+	  is_unnum0 = sw_if_index0 != conn_sw_if_index0;
+
+	  /* Source must also be local to subnet of matching interface address. */
+	  src_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+					  &arp0->ip4_over_ethernet[0].ip4,
+					  32);
+	  src_flags = fib_entry_get_flags (src_fei);
+
+	  if (!((FIB_ENTRY_FLAG_ATTACHED & src_flags) ||
+		(FIB_ENTRY_FLAG_CONNECTED & src_flags)) ||
+	      sw_if_index0 != fib_entry_get_resolving_interface (src_fei))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l3_src_address_not_local;
+	      goto drop2;
+	    }
+
+	  /* Reject requests/replies with our local interface address. */
+	  if (FIB_ENTRY_FLAG_LOCAL & src_flags)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l3_src_address_is_local;
+	      goto drop2;
+	    }
+
+	  dst_is_local0 = (FIB_ENTRY_FLAG_LOCAL & dst_flags);
+	  fib_entry_get_prefix (dst_fei, &pfx0);
+	  if_addr0 = &pfx0.fp_addr.ip4;
+
+	  /* Fill in ethernet header. */
+	  eth0 = ethernet_buffer_get_header (p0);
+
+	  /* Trash ARP packets whose ARP-level source addresses do not
+	     match their L2-frame-level source addresses */
+	  if (memcmp (eth0->src_address, arp0->ip4_over_ethernet[0].ethernet,
+		      sizeof (eth0->src_address)))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l2_address_mismatch;
+	      goto drop2;
+	    }
+
+	  /* Learn or update sender's mapping only for requests or unicasts
+	     that don't match local interface address. */
+	  if (ethernet_address_cast (eth0->dst_address) ==
+	      ETHERNET_ADDRESS_UNICAST || is_request0)
+	    {
+	      if (am->limit_arp_cache_size &&
+		  pool_elts (am->ip4_entry_pool) >= am->limit_arp_cache_size)
+		unset_random_arp_entry ();
+
+	      vnet_arp_set_ip4_over_ethernet (vnm, sw_if_index0,
+					      &arp0->ip4_over_ethernet[0],
+					      0 /* is_static */ );
+	      error0 = ETHERNET_ARP_ERROR_l3_src_address_learned;
+	    }
+
+	  /* Only send a reply for requests sent which match a local interface. */
+	  if (!(is_request0 && dst_is_local0))
+	    {
+	      error0 =
+		(arp0->opcode ==
+		 clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply) ?
+		 ETHERNET_ARP_ERROR_replies_received : error0);
+	      goto drop1;
+	    }
+
+	  /* Send a reply. */
+	send_reply:
+	  vnet_buffer (p0)->sw_if_index[VLIB_TX] = sw_if_index0;
+	  hw_if0 = vnet_get_sup_hw_interface (vnm, sw_if_index0);
+
+	  /* Send reply back through input interface */
+	  vnet_buffer (p0)->sw_if_index[VLIB_TX] = sw_if_index0;
+	  next0 = ARP_INPUT_NEXT_REPLY_TX;
+
+	  arp0->opcode = clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply);
+
+	  arp0->ip4_over_ethernet[1] = arp0->ip4_over_ethernet[0];
+
+	  clib_memcpy (arp0->ip4_over_ethernet[0].ethernet,
+		       hw_if0->hw_address, 6);
+	  clib_mem_unaligned (&arp0->ip4_over_ethernet[0].ip4.data_u32, u32) =
+	    if_addr0->data_u32;
+
+	  /* Hardware must be ethernet-like. */
+	  ASSERT (vec_len (hw_if0->hw_address) == 6);
+
+	  clib_memcpy (eth0->dst_address, eth0->src_address, 6);
+	  clib_memcpy (eth0->src_address, hw_if0->hw_address, 6);
+
+	  /* Figure out how much to rewind current data from adjacency. */
+	  /* get the adj from the destination's covering connected */
+	  if (NULL == pa)
+	    {
+	      adj0 =
+		adj_get (fib_entry_get_adj_for_source
+			 (ip4_fib_table_lookup
+			  (ip4_fib_get (fib_index0),
+			   &arp0->ip4_over_ethernet[1].ip4, 31),
+			  FIB_SOURCE_INTERFACE));
+	      if (adj0->lookup_next_index != IP_LOOKUP_NEXT_GLEAN)
+		{
+		  error0 = ETHERNET_ARP_ERROR_missing_interface_address;
+		  goto drop2;
+		}
+	      if (is_unnum0)
+		{
+		  if (!arp_unnumbered (p0, pi0, eth0, conn_sw_if_index0))
+		    goto drop2;
+		}
+	      else
+		vlib_buffer_advance (p0, -adj0->rewrite_header.data_bytes);
+	    }
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+
+	  n_replies_sent += 1;
+	  continue;
+
+	drop1:
+	  if (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ||
+	      (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+	       arp0->ip4_over_ethernet[1].ip4.as_u32))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_gratuitous_arp;
+	      goto drop2;
+	    }
+	  /* See if proxy arp is configured for the address */
+	  if (is_request0)
+	    {
+	      vnet_sw_interface_t *si;
+	      u32 this_addr = clib_net_to_host_u32
+		(arp0->ip4_over_ethernet[1].ip4.as_u32);
+	      u32 fib_index0;
+
+	      si = vnet_get_sw_interface (vnm, sw_if_index0);
+
+	      if (!(si->flags & VNET_SW_INTERFACE_FLAG_PROXY_ARP))
+		goto drop2;
+
+	      fib_index0 = vec_elt (im4->fib_index_by_sw_if_index,
+				    sw_if_index0);
+
+	      vec_foreach (pa, am->proxy_arps)
+	      {
+		u32 lo_addr = clib_net_to_host_u32 (pa->lo_addr);
+		u32 hi_addr = clib_net_to_host_u32 (pa->hi_addr);
+
+		/* an ARP request hit in the proxy-arp table? */
+		if ((this_addr >= lo_addr && this_addr <= hi_addr) &&
+		    (fib_index0 == pa->fib_index))
+		  {
+		    eth0 = ethernet_buffer_get_header (p0);
+		    proxy_src.as_u32 =
+		      arp0->ip4_over_ethernet[1].ip4.data_u32;
+
+		    /*
+		     * Rewind buffer, direct code above not to
+		     * think too hard about it.
+		     */
+		    if_addr0 = &proxy_src;
+		    is_unnum0 = 0;
+		    i32 ethernet_start =
+		      vnet_buffer (p0)->ethernet.start_of_ethernet_header;
+		    i32 rewind = p0->current_data - ethernet_start;
+		    vlib_buffer_advance (p0, -rewind);
+		    n_proxy_arp_replies_sent++;
+		    goto send_reply;
+		  }
+	      }
+	    }
+
+	drop2:
+
+	  next0 = ARP_INPUT_NEXT_DROP;
+	  p0->error = node->errors[error0];
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, pi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_error_count (vm, node->node_index,
+		    ETHERNET_ARP_ERROR_replies_sent,
+		    n_replies_sent - n_proxy_arp_replies_sent);
+
+  vlib_error_count (vm, node->node_index,
+		    ETHERNET_ARP_ERROR_proxy_arp_replies_sent,
+		    n_proxy_arp_replies_sent);
+  return frame->n_vectors;
+}
+
+static char *ethernet_arp_error_strings[] = {
+#define _(sym,string) string,
+  foreach_ethernet_arp_error
+#undef _
+};
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (arp_input_node, static) =
+{
+  .function = arp_input,
+  .name = "arp-input",
+  .vector_size = sizeof (u32),
+  .n_errors = ETHERNET_ARP_N_ERROR,
+  .error_strings = ethernet_arp_error_strings,
+  .n_next_nodes = ARP_INPUT_N_NEXT,
+  .next_nodes = {
+    [ARP_INPUT_NEXT_DROP] = "error-drop",
+    [ARP_INPUT_NEXT_REPLY_TX] = "interface-output",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+/* *INDENT-ON* */
+
+static int
+ip4_arp_entry_sort (void *a1, void *a2)
+{
+  ethernet_arp_ip4_entry_t *e1 = a1;
+  ethernet_arp_ip4_entry_t *e2 = a2;
+
+  int cmp;
+  vnet_main_t *vnm = vnet_get_main ();
+
+  cmp = vnet_sw_interface_compare (vnm, e1->sw_if_index, e2->sw_if_index);
+  if (!cmp)
+    cmp = ip4_address_compare (&e1->ip4_address, &e2->ip4_address);
+  return cmp;
+}
+
+ethernet_arp_ip4_entry_t *
+ip4_neighbor_entries (u32 sw_if_index)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *n, *ns = 0;
+
+  /* *INDENT-OFF* */
+  pool_foreach (n, am->ip4_entry_pool, ({
+    if (sw_if_index != ~0 && n->sw_if_index != sw_if_index)
+      continue;
+    vec_add1 (ns, n[0]);
+  }));
+  /* *INDENT-ON* */
+
+  if (ns)
+    vec_sort_with_function (ns, ip4_arp_entry_sort);
+  return ns;
+}
+
+static clib_error_t *
+show_ip4_arp (vlib_main_t * vm,
+	      unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e, *es;
+  ethernet_proxy_arp_t *pa;
+  clib_error_t *error = 0;
+  u32 sw_if_index;
+
+  /* Filter entries by interface if given. */
+  sw_if_index = ~0;
+  (void) unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index);
+
+  es = ip4_neighbor_entries (sw_if_index);
+  if (es)
+    {
+      vlib_cli_output (vm, "%U", format_ethernet_arp_ip4_entry, vnm, 0);
+      vec_foreach (e, es)
+      {
+	vlib_cli_output (vm, "%U", format_ethernet_arp_ip4_entry, vnm, e);
+      }
+      vec_free (es);
+    }
+
+  if (vec_len (am->proxy_arps))
+    {
+      vlib_cli_output (vm, "Proxy arps enabled for:");
+      vec_foreach (pa, am->proxy_arps)
+      {
+	vlib_cli_output (vm, "Fib_index %d   %U - %U ",
+			 pa->fib_index,
+			 format_ip4_address, &pa->lo_addr,
+			 format_ip4_address, &pa->hi_addr);
+      }
+    }
+
+  return error;
+}
+
+/*?
+ * Display all the IPv4 ARP entries.
+ *
+ * @cliexpar
+ * Example of how to display the IPv4 ARP table:
+ * @cliexstart{show ip arp}
+ *    Time      FIB        IP4       Flags      Ethernet              Interface
+ *    346.3028   0       6.1.1.3            de:ad:be:ef:ba:be   GigabitEthernet2/0/0
+ *   3077.4271   0       6.1.1.4       S    de:ad:be:ef:ff:ff   GigabitEthernet2/0/0
+ *   2998.6409   1       6.2.2.3            de:ad:be:ef:00:01   GigabitEthernet2/0/0
+ * Proxy arps enabled for:
+ * Fib_index 0   6.0.0.1 - 6.0.0.11
+ * @cliexend
+ ?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (show_ip4_arp_command, static) = {
+  .path = "show ip arp",
+  .function = show_ip4_arp,
+  .short_help = "show ip arp",
+};
+/* *INDENT-ON* */
+
+typedef struct
+{
+  pg_edit_t l2_type, l3_type;
+  pg_edit_t n_l2_address_bytes, n_l3_address_bytes;
+  pg_edit_t opcode;
+  struct
+  {
+    pg_edit_t ethernet;
+    pg_edit_t ip4;
+  } ip4_over_ethernet[2];
+} pg_ethernet_arp_header_t;
+
+static inline void
+pg_ethernet_arp_header_init (pg_ethernet_arp_header_t * p)
+{
+  /* Initialize fields that are not bit fields in the IP header. */
+#define _(f) pg_edit_init (&p->f, ethernet_arp_header_t, f);
+  _(l2_type);
+  _(l3_type);
+  _(n_l2_address_bytes);
+  _(n_l3_address_bytes);
+  _(opcode);
+  _(ip4_over_ethernet[0].ethernet);
+  _(ip4_over_ethernet[0].ip4);
+  _(ip4_over_ethernet[1].ethernet);
+  _(ip4_over_ethernet[1].ip4);
+#undef _
+}
+
+uword
+unformat_pg_arp_header (unformat_input_t * input, va_list * args)
+{
+  pg_stream_t *s = va_arg (*args, pg_stream_t *);
+  pg_ethernet_arp_header_t *p;
+  u32 group_index;
+
+  p = pg_create_edit_group (s, sizeof (p[0]), sizeof (ethernet_arp_header_t),
+			    &group_index);
+  pg_ethernet_arp_header_init (p);
+
+  /* Defaults. */
+  pg_edit_set_fixed (&p->l2_type, ETHERNET_ARP_HARDWARE_TYPE_ethernet);
+  pg_edit_set_fixed (&p->l3_type, ETHERNET_TYPE_IP4);
+  pg_edit_set_fixed (&p->n_l2_address_bytes, 6);
+  pg_edit_set_fixed (&p->n_l3_address_bytes, 4);
+
+  if (!unformat (input, "%U: %U/%U -> %U/%U",
+		 unformat_pg_edit,
+		 unformat_ethernet_arp_opcode_net_byte_order, &p->opcode,
+		 unformat_pg_edit,
+		 unformat_ethernet_address, &p->ip4_over_ethernet[0].ethernet,
+		 unformat_pg_edit,
+		 unformat_ip4_address, &p->ip4_over_ethernet[0].ip4,
+		 unformat_pg_edit,
+		 unformat_ethernet_address, &p->ip4_over_ethernet[1].ethernet,
+		 unformat_pg_edit,
+		 unformat_ip4_address, &p->ip4_over_ethernet[1].ip4))
+    {
+      /* Free up any edits we may have added. */
+      pg_free_edit_group (s);
+      return 0;
+    }
+  return 1;
+}
+
+clib_error_t *
+ip4_set_arp_limit (u32 arp_limit)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  am->limit_arp_cache_size = arp_limit;
+  return 0;
+}
+
+/**
+ * @brief Control Plane hook to remove an ARP entry
+ */
+int
+vnet_arp_unset_ip4_over_ethernet (vnet_main_t * vnm,
+				  u32 sw_if_index, void *a_arg)
+{
+  ethernet_arp_ip4_over_ethernet_address_t *a = a_arg;
+  vnet_arp_set_ip4_over_ethernet_rpc_args_t args;
+
+  args.sw_if_index = sw_if_index;
+  args.flags = ETHERNET_ARP_ARGS_REMOVE;
+  clib_memcpy (&args.a, a, sizeof (*a));
+
+  vl_api_rpc_call_main_thread (set_ip4_over_ethernet_rpc_callback,
+			       (u8 *) & args, sizeof (args));
+  return 0;
+}
+
+/**
+ * @brief Internally generated event to flush the ARP cache on an
+ * interface state change event.
+ * A flush will remove dynamic ARP entries, and for statics remove the MAC
+ * address from the corresponding adjacencies.
+ */
+static int
+vnet_arp_flush_ip4_over_ethernet (vnet_main_t * vnm,
+				  u32 sw_if_index, void *a_arg)
+{
+  ethernet_arp_ip4_over_ethernet_address_t *a = a_arg;
+  vnet_arp_set_ip4_over_ethernet_rpc_args_t args;
+
+  args.sw_if_index = sw_if_index;
+  args.flags = ETHERNET_ARP_ARGS_FLUSH;
+  clib_memcpy (&args.a, a, sizeof (*a));
+
+  vl_api_rpc_call_main_thread (set_ip4_over_ethernet_rpc_callback,
+			       (u8 *) & args, sizeof (args));
+  return 0;
+}
+
+/**
+ * @brief Internally generated event to populate the ARP cache on an
+ * interface state change event.
+ * For static entries this will re-source the adjacencies.
+ *
+ * @param sw_if_index The interface on which the ARP entires are acted
+ */
+static int
+vnet_arp_populate_ip4_over_ethernet (vnet_main_t * vnm,
+				     u32 sw_if_index, void *a_arg)
+{
+  ethernet_arp_ip4_over_ethernet_address_t *a = a_arg;
+  vnet_arp_set_ip4_over_ethernet_rpc_args_t args;
+
+  args.sw_if_index = sw_if_index;
+  args.flags = ETHERNET_ARP_ARGS_POPULATE;
+  clib_memcpy (&args.a, a, sizeof (*a));
+
+  vl_api_rpc_call_main_thread (set_ip4_over_ethernet_rpc_callback,
+			       (u8 *) & args, sizeof (args));
+  return 0;
+}
+
+/*
+ * arp_add_del_interface_address
+ *
+ * callback when an interface address is added or deleted
+ */
+static void
+arp_add_del_interface_address (ip4_main_t * im,
+			       uword opaque,
+			       u32 sw_if_index,
+			       ip4_address_t * address,
+			       u32 address_length,
+			       u32 if_address_index, u32 is_del)
+{
+  /*
+   * Flush the ARP cache of all entries covered by the address
+   * that is being removed.
+   */
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+
+  if (vec_len (am->ethernet_arp_by_sw_if_index) <= sw_if_index)
+    return;
+
+  if (is_del)
+    {
+      ethernet_arp_interface_t *eai;
+      u32 i, *to_delete = 0;
+      hash_pair_t *pair;
+
+      eai = &am->ethernet_arp_by_sw_if_index[sw_if_index];
+
+      /* *INDENT-OFF* */
+      hash_foreach_pair (pair, eai->arp_entries,
+      ({
+	e = pool_elt_at_index(am->ip4_entry_pool,
+			      pair->value[0]);
+	if (ip4_destination_matches_route (im, &e->ip4_address,
+					   address, address_length))
+	  {
+	    vec_add1 (to_delete, e - am->ip4_entry_pool);
+	  }
+      }));
+      /* *INDENT-ON* */
+
+      for (i = 0; i < vec_len (to_delete); i++)
+	{
+	  ethernet_arp_ip4_over_ethernet_address_t delme;
+	  e = pool_elt_at_index (am->ip4_entry_pool, to_delete[i]);
+
+	  clib_memcpy (&delme.ethernet, e->ethernet_address, 6);
+	  delme.ip4.as_u32 = e->ip4_address.as_u32;
+
+	  vnet_arp_flush_ip4_over_ethernet (vnet_get_main (),
+					    e->sw_if_index, &delme);
+	}
+
+      vec_free (to_delete);
+    }
+}
+
+static clib_error_t *
+ethernet_arp_init (vlib_main_t * vm)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ip4_main_t *im = &ip4_main;
+  clib_error_t *error;
+  pg_node_t *pn;
+
+  if ((error = vlib_call_init_function (vm, ethernet_init)))
+    return error;
+
+  ethernet_register_input_type (vm, ETHERNET_TYPE_ARP, arp_input_node.index);
+
+  pn = pg_get_node (arp_input_node.index);
+  pn->unformat_edit = unformat_pg_arp_header;
+
+  am->opcode_by_name = hash_create_string (0, sizeof (uword));
+#define _(o) hash_set_mem (am->opcode_by_name, #o, ETHERNET_ARP_OPCODE_##o);
+  foreach_ethernet_arp_opcode;
+#undef _
+
+  /* $$$ configurable */
+  am->limit_arp_cache_size = 50000;
+
+  am->pending_resolutions_by_address = hash_create (0, sizeof (uword));
+  am->mac_changes_by_address = hash_create (0, sizeof (uword));
+
+  /* don't trace ARP error packets */
+  {
+    vlib_node_runtime_t *rt =
+      vlib_node_get_runtime (vm, arp_input_node.index);
+
+#define _(a,b)                                  \
+    vnet_pcap_drop_trace_filter_add_del         \
+        (rt->errors[ETHERNET_ARP_ERROR_##a],    \
+         1 /* is_add */);
+    foreach_ethernet_arp_error
+#undef _
+  }
+
+  ip4_add_del_interface_address_callback_t cb;
+  cb.function = arp_add_del_interface_address;
+  cb.function_opaque = 0;
+  vec_add1 (im->add_del_interface_address_callbacks, cb);
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (ethernet_arp_init);
+
+static void
+arp_entry_free (ethernet_arp_interface_t * eai, ethernet_arp_ip4_entry_t * e)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  fib_table_entry_delete_index (e->fib_entry_index, FIB_SOURCE_ADJ);
+  hash_unset (eai->arp_entries, e->ip4_address.as_u32);
+  pool_put (am->ip4_entry_pool, e);
+}
+
+static inline int
+vnet_arp_unset_ip4_over_ethernet_internal (vnet_main_t * vnm,
+					   vnet_arp_set_ip4_over_ethernet_rpc_args_t
+					   * args)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+  ethernet_arp_interface_t *eai;
+
+  eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
+
+  e = arp_entry_find (eai, &args->a.ip4);
+
+  if (NULL != e)
+    {
+      arp_entry_free (eai, e);
+
+      adj_nbr_walk_nh4 (e->sw_if_index,
+			&e->ip4_address, arp_mk_incomplete_walk, NULL);
+    }
+
+  return 0;
+}
+
+static int
+vnet_arp_flush_ip4_over_ethernet_internal (vnet_main_t * vnm,
+					   vnet_arp_set_ip4_over_ethernet_rpc_args_t
+					   * args)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+  ethernet_arp_interface_t *eai;
+
+  eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
+
+  e = arp_entry_find (eai, &args->a.ip4);
+
+  if (NULL != e)
+    {
+      adj_nbr_walk_nh4 (e->sw_if_index,
+			&e->ip4_address, arp_mk_incomplete_walk, e);
+
+      /*
+       * The difference between flush and unset, is that an unset
+       * means delete for static and dynamic entries. A flush
+       * means delete only for dynamic. Flushing is what the DP
+       * does in response to interface events. unset is only done
+       * by the control plane.
+       */
+      if (e->flags & ETHERNET_ARP_IP4_ENTRY_FLAG_DYNAMIC)
+	{
+	  arp_entry_free (eai, e);
+	}
+    }
+  return (0);
+}
+
+static int
+vnet_arp_populate_ip4_over_ethernet_internal (vnet_main_t * vnm,
+					      vnet_arp_set_ip4_over_ethernet_rpc_args_t
+					      * args)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+  ethernet_arp_interface_t *eai;
+
+  eai = &am->ethernet_arp_by_sw_if_index[args->sw_if_index];
+
+  e = arp_entry_find (eai, &args->a.ip4);
+
+  if (NULL != e)
+    {
+      adj_nbr_walk_nh4 (e->sw_if_index,
+			&e->ip4_address, arp_mk_complete_walk, e);
+    }
+  return (0);
+}
+
+static void
+set_ip4_over_ethernet_rpc_callback (vnet_arp_set_ip4_over_ethernet_rpc_args_t
+				    * a)
+{
+  vnet_main_t *vm = vnet_get_main ();
+  ASSERT (os_get_cpu_number () == 0);
+
+  if (a->flags & ETHERNET_ARP_ARGS_REMOVE)
+    vnet_arp_unset_ip4_over_ethernet_internal (vm, a);
+  else if (a->flags & ETHERNET_ARP_ARGS_FLUSH)
+    vnet_arp_flush_ip4_over_ethernet_internal (vm, a);
+  else if (a->flags & ETHERNET_ARP_ARGS_POPULATE)
+    vnet_arp_populate_ip4_over_ethernet_internal (vm, a);
+  else
+    vnet_arp_set_ip4_over_ethernet_internal (vm, a);
+}
+
+/**
+ * @brief Invoked when the interface's admin state changes
+ */
+static clib_error_t *
+ethernet_arp_sw_interface_up_down (vnet_main_t * vnm,
+				   u32 sw_if_index, u32 flags)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+  u32 i, *to_delete = 0;
+
+  /* *INDENT-OFF* */
+  pool_foreach (e, am->ip4_entry_pool,
+  ({
+    if (e->sw_if_index == sw_if_index)
+      vec_add1 (to_delete,
+		e - am->ip4_entry_pool);
+  }));
+  /* *INDENT-ON* */
+
+  for (i = 0; i < vec_len (to_delete); i++)
+    {
+      ethernet_arp_ip4_over_ethernet_address_t delme;
+      e = pool_elt_at_index (am->ip4_entry_pool, to_delete[i]);
+
+      clib_memcpy (&delme.ethernet, e->ethernet_address, 6);
+      delme.ip4.as_u32 = e->ip4_address.as_u32;
+
+      if (flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
+	{
+	  vnet_arp_populate_ip4_over_ethernet (vnm, e->sw_if_index, &delme);
+	}
+      else
+	{
+	  vnet_arp_flush_ip4_over_ethernet (vnm, e->sw_if_index, &delme);
+	}
+
+    }
+  vec_free (to_delete);
+
+  return 0;
+}
+
+VNET_SW_INTERFACE_ADMIN_UP_DOWN_FUNCTION (ethernet_arp_sw_interface_up_down);
+
+static void
+increment_ip4_and_mac_address (ethernet_arp_ip4_over_ethernet_address_t * a)
+{
+  u8 old;
+  int i;
+
+  for (i = 3; i >= 0; i--)
+    {
+      old = a->ip4.as_u8[i];
+      a->ip4.as_u8[i] += 1;
+      if (old < a->ip4.as_u8[i])
+	break;
+    }
+
+  for (i = 5; i >= 0; i--)
+    {
+      old = a->ethernet[i];
+      a->ethernet[i] += 1;
+      if (old < a->ethernet[i])
+	break;
+    }
+}
+
+int
+vnet_arp_set_ip4_over_ethernet (vnet_main_t * vnm,
+				u32 sw_if_index, void *a_arg, int is_static)
+{
+  ethernet_arp_ip4_over_ethernet_address_t *a = a_arg;
+  vnet_arp_set_ip4_over_ethernet_rpc_args_t args;
+
+  args.sw_if_index = sw_if_index;
+  args.is_static = is_static;
+  args.flags = 0;
+  clib_memcpy (&args.a, a, sizeof (*a));
+
+  vl_api_rpc_call_main_thread (set_ip4_over_ethernet_rpc_callback,
+			       (u8 *) & args, sizeof (args));
+  return 0;
+}
+
+int
+vnet_proxy_arp_add_del (ip4_address_t * lo_addr,
+			ip4_address_t * hi_addr, u32 fib_index, int is_del)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_proxy_arp_t *pa;
+  u32 found_at_index = ~0;
+
+  vec_foreach (pa, am->proxy_arps)
+  {
+    if (pa->lo_addr == lo_addr->as_u32
+	&& pa->hi_addr == hi_addr->as_u32 && pa->fib_index == fib_index)
+      {
+	found_at_index = pa - am->proxy_arps;
+	break;
+      }
+  }
+
+  if (found_at_index != ~0)
+    {
+      /* Delete, otherwise it's already in the table */
+      if (is_del)
+	vec_delete (am->proxy_arps, 1, found_at_index);
+      return 0;
+    }
+  /* delete, no such entry */
+  if (is_del)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+
+  /* add, not in table */
+  vec_add2 (am->proxy_arps, pa, 1);
+  pa->lo_addr = lo_addr->as_u32;
+  pa->hi_addr = hi_addr->as_u32;
+  pa->fib_index = fib_index;
+  return 0;
+}
+
+/*
+ * Remove any proxy arp entries asdociated with the
+ * specificed fib.
+ */
+int
+vnet_proxy_arp_fib_reset (u32 fib_id)
+{
+  ip4_main_t *im = &ip4_main;
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_proxy_arp_t *pa;
+  u32 *entries_to_delete = 0;
+  u32 fib_index;
+  uword *p;
+  int i;
+
+  p = hash_get (im->fib_index_by_table_id, fib_id);
+  if (!p)
+    return VNET_API_ERROR_NO_SUCH_ENTRY;
+  fib_index = p[0];
+
+  vec_foreach (pa, am->proxy_arps)
+  {
+    if (pa->fib_index == fib_index)
+      {
+	vec_add1 (entries_to_delete, pa - am->proxy_arps);
+      }
+  }
+
+  for (i = 0; i < vec_len (entries_to_delete); i++)
+    {
+      vec_delete (am->proxy_arps, 1, entries_to_delete[i]);
+    }
+
+  vec_free (entries_to_delete);
+
+  return 0;
+}
+
+static clib_error_t *
+ip_arp_add_del_command_fn (vlib_main_t * vm,
+			   unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 sw_if_index;
+  ethernet_arp_ip4_over_ethernet_address_t lo_addr, hi_addr, addr;
+  int addr_valid = 0;
+  int is_del = 0;
+  int count = 1;
+  u32 fib_index = 0;
+  u32 fib_id;
+  int is_static = 0;
+  int is_proxy = 0;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      /* set ip arp TenGigE1/1/0/1 1.2.3.4 aa:bb:... or aabb.ccdd... */
+      if (unformat (input, "%U %U %U",
+		    unformat_vnet_sw_interface, vnm, &sw_if_index,
+		    unformat_ip4_address, &addr.ip4,
+		    unformat_ethernet_address, &addr.ethernet))
+	addr_valid = 1;
+
+      else if (unformat (input, "delete") || unformat (input, "del"))
+	is_del = 1;
+
+      else if (unformat (input, "static"))
+	is_static = 1;
+
+      else if (unformat (input, "count %d", &count))
+	;
+
+      else if (unformat (input, "fib-id %d", &fib_id))
+	{
+	  ip4_main_t *im = &ip4_main;
+	  uword *p = hash_get (im->fib_index_by_table_id, fib_id);
+	  if (!p)
+	    return clib_error_return (0, "fib ID %d doesn't exist\n", fib_id);
+	  fib_index = p[0];
+	}
+
+      else if (unformat (input, "proxy %U - %U",
+			 unformat_ip4_address, &lo_addr.ip4,
+			 unformat_ip4_address, &hi_addr.ip4))
+	is_proxy = 1;
+      else
+	break;
+    }
+
+  if (is_proxy)
+    {
+      (void) vnet_proxy_arp_add_del (&lo_addr.ip4, &hi_addr.ip4,
+				     fib_index, is_del);
+      return 0;
+    }
+
+  if (addr_valid)
+    {
+      int i;
+
+      for (i = 0; i < count; i++)
+	{
+	  if (is_del == 0)
+	    {
+	      uword event_type, *event_data = 0;
+
+	      /* Park the debug CLI until the arp entry is installed */
+	      vnet_register_ip4_arp_resolution_event
+		(vnm, &addr.ip4, vlib_current_process (vm),
+		 1 /* type */ , 0 /* data */ );
+
+	      vnet_arp_set_ip4_over_ethernet
+		(vnm, sw_if_index, &addr, is_static);
+
+	      vlib_process_wait_for_event (vm);
+	      event_type = vlib_process_get_events (vm, &event_data);
+	      vec_reset_length (event_data);
+	      if (event_type != 1)
+		clib_warning ("event type %d unexpected", event_type);
+	    }
+	  else
+	    vnet_arp_unset_ip4_over_ethernet (vnm, sw_if_index, &addr);
+
+	  increment_ip4_and_mac_address (&addr);
+	}
+    }
+  else
+    {
+      return clib_error_return (0, "unknown input `%U'",
+				format_unformat_error, input);
+    }
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+/*?
+ * Add or delete IPv4 ARP cache entries.
+ *
+ * @note 'set ip arp' options (e.g. delete, static, 'fib-id <id>',
+ * 'count <number>', 'interface ip4_addr mac_addr') can be added in
+ * any order and combination.
+ *
+ * @cliexpar
+ * @parblock
+ * Add or delete IPv4 ARP cache entries as follows. MAC Address can be in
+ * either aa:bb:cc:dd:ee:ff format or aabb.ccdd.eeff format.
+ * @cliexcmd{set ip arp GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ * @cliexcmd{set ip arp delete GigabitEthernet2/0/0 6.0.0.3 de:ad:be:ef:ba:be}
+ *
+ * To add or delete an IPv4 ARP cache entry to or from a specific fib
+ * table:
+ * @cliexcmd{set ip arp fib-id 1 GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ * @cliexcmd{set ip arp fib-id 1 delete GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ *
+ * Add or delete IPv4 static ARP cache entries as follows:
+ * @cliexcmd{set ip arp static GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ * @cliexcmd{set ip arp static delete GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ *
+ * For testing / debugging purposes, the 'set ip arp' command can add or
+ * delete multiple entries. Supply the 'count N' parameter:
+ * @cliexcmd{set ip arp count 10 GigabitEthernet2/0/0 6.0.0.3 dead.beef.babe}
+ * @endparblock
+ ?*/
+VLIB_CLI_COMMAND (ip_arp_add_del_command, static) = {
+  .path = "set ip arp",
+  .short_help =
+  "set ip arp [del] <intfc> <ip-address> <mac-address> [static] [count <count>] [fib-id <fib-id>] [proxy <lo-addr> - <hi-addr>]",
+  .function = ip_arp_add_del_command_fn,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+set_int_proxy_arp_command_fn (vlib_main_t * vm,
+			      unformat_input_t *
+			      input, vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 sw_if_index;
+  vnet_sw_interface_t *si;
+  int enable = 0;
+  int intfc_set = 0;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_vnet_sw_interface,
+		    vnm, &sw_if_index))
+	intfc_set = 1;
+      else if (unformat (input, "enable") || unformat (input, "on"))
+	enable = 1;
+      else if (unformat (input, "disable") || unformat (input, "off"))
+	enable = 0;
+      else
+	break;
+    }
+
+  if (intfc_set == 0)
+    return clib_error_return (0, "unknown input '%U'",
+			      format_unformat_error, input);
+
+  si = vnet_get_sw_interface (vnm, sw_if_index);
+  ASSERT (si);
+  if (enable)
+    si->flags |= VNET_SW_INTERFACE_FLAG_PROXY_ARP;
+  else
+    si->flags &= ~VNET_SW_INTERFACE_FLAG_PROXY_ARP;
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+/*?
+ * Enable proxy-arp on an interface. The vpp stack will answer ARP
+ * requests for the indicated address range. Multiple proxy-arp
+ * ranges may be provisioned.
+ *
+ * @note Proxy ARP as a technology is infamous for blackholing traffic.
+ * Also, the underlying implementation has not been performance-tuned.
+ * Avoid creating an unnecessarily large set of ranges.
+ *
+ * @cliexpar
+ * To enable proxy arp on a range of addresses, use:
+ * @cliexcmd{set ip arp proxy 6.0.0.1 - 6.0.0.11}
+ * Append 'del' to delete a range of proxy ARP addresses:
+ * @cliexcmd{set ip arp proxy 6.0.0.1 - 6.0.0.11 del}
+ * You must then specifically enable proxy arp on individual interfaces:
+ * @cliexcmd{set interface proxy-arp GigabitEthernet0/8/0 enable}
+ * To disable proxy arp on an individual interface:
+ * @cliexcmd{set interface proxy-arp GigabitEthernet0/8/0 disable}
+ ?*/
+VLIB_CLI_COMMAND (set_int_proxy_enable_command, static) = {
+  .path = "set interface proxy-arp",
+  .short_help =
+  "set interface proxy-arp <intfc> [enable|disable]",
+  .function = set_int_proxy_arp_command_fn,
+};
+/* *INDENT-ON* */
+
+
+/*
+ * ARP/ND Termination in a L2 Bridge Domain based on IP4/IP6 to MAC
+ * hash tables mac_by_ip4 and mac_by_ip6 for each BD.
+ */
+typedef enum
+{
+  ARP_TERM_NEXT_L2_OUTPUT,
+  ARP_TERM_NEXT_DROP,
+  ARP_TERM_N_NEXT,
+} arp_term_next_t;
+
+u32 arp_term_next_node_index[32];
+
+static uword
+arp_term_l2bd (vlib_main_t * vm,
+	       vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  l2input_main_t *l2im = &l2input_main;
+  u32 n_left_from, next_index, *from, *to_next;
+  u32 n_replies_sent = 0;
+  u16 last_bd_index = ~0;
+  l2_bridge_domain_t *last_bd_config = 0;
+  l2_input_config_t *cfg0;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_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 > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t *p0;
+	  ethernet_header_t *eth0;
+	  ethernet_arp_header_t *arp0;
+	  ip6_header_t *iph0;
+	  u8 *l3h0;
+	  u32 pi0, error0, next0, sw_if_index0;
+	  u16 ethertype0;
+	  u16 bd_index0;
+	  u32 ip0;
+	  u8 *macp0;
+
+	  pi0 = from[0];
+	  to_next[0] = pi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  eth0 = vlib_buffer_get_current (p0);
+	  l3h0 = (u8 *) eth0 + vnet_buffer (p0)->l2.l2_len;
+	  ethertype0 = clib_net_to_host_u16 (*(u16 *) (l3h0 - 2));
+	  arp0 = (ethernet_arp_header_t *) l3h0;
+
+	  if (PREDICT_FALSE ((ethertype0 != ETHERNET_TYPE_ARP) ||
+			     (arp0->opcode !=
+			      clib_host_to_net_u16
+			      (ETHERNET_ARP_OPCODE_request))))
+	    goto check_ip6_nd;
+
+	  /* Must be ARP request packet here */
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
+			     (p0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      u8 *t0 = vlib_add_trace (vm, node, p0,
+				       sizeof (ethernet_arp_input_trace_t));
+	      clib_memcpy (t0, l3h0, sizeof (ethernet_arp_input_trace_t));
+	    }
+
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  error0 =
+	    (arp0->l2_type !=
+	     clib_net_to_host_u16 (ETHERNET_ARP_HARDWARE_TYPE_ethernet)
+	     ? ETHERNET_ARP_ERROR_l2_type_not_ethernet : error0);
+	  error0 =
+	    (arp0->l3_type !=
+	     clib_net_to_host_u16 (ETHERNET_TYPE_IP4) ?
+	     ETHERNET_ARP_ERROR_l3_type_not_ip4 : error0);
+
+	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+
+	  if (error0)
+	    goto drop;
+
+	  /* Trash ARP packets whose ARP-level source addresses do not
+	     match their L2-frame-level source addresses  */
+	  if (PREDICT_FALSE
+	      (memcmp
+	       (eth0->src_address, arp0->ip4_over_ethernet[0].ethernet,
+		sizeof (eth0->src_address))))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l2_address_mismatch;
+	      goto drop;
+	    }
+
+	  /* Check if anyone want ARP request events for L2 BDs */
+	  {
+	    pending_resolution_t *mc;
+	    ethernet_arp_main_t *am = &ethernet_arp_main;
+	    uword *p = hash_get (am->mac_changes_by_address, 0);
+	    if (p && (vnet_buffer (p0)->l2.shg == 0))
+	      {			// Only SHG 0 interface which is more likely local
+		u32 next_index = p[0];
+		while (next_index != (u32) ~ 0)
+		  {
+		    int (*fp) (u32, u8 *, u32, u32);
+		    int rv = 1;
+		    mc = pool_elt_at_index (am->mac_changes, next_index);
+		    fp = mc->data_callback;
+		    /* Call the callback, return 1 to suppress dup events */
+		    if (fp)
+		      rv = (*fp) (mc->data,
+				  arp0->ip4_over_ethernet[0].ethernet,
+				  sw_if_index0,
+				  arp0->ip4_over_ethernet[0].ip4.as_u32);
+		    /* Signal the resolver process */
+		    if (rv == 0)
+		      vlib_process_signal_event (vm, mc->node_index,
+						 mc->type_opaque, mc->data);
+		    next_index = mc->next_index;
+		  }
+	      }
+	  }
+
+	  /* lookup BD mac_by_ip4 hash table for MAC entry */
+	  ip0 = arp0->ip4_over_ethernet[1].ip4.as_u32;
+	  bd_index0 = vnet_buffer (p0)->l2.bd_index;
+	  if (PREDICT_FALSE ((bd_index0 != last_bd_index)
+			     || (last_bd_index == (u16) ~ 0)))
+	    {
+	      last_bd_index = bd_index0;
+	      last_bd_config = vec_elt_at_index (l2im->bd_configs, bd_index0);
+	    }
+	  macp0 = (u8 *) hash_get (last_bd_config->mac_by_ip4, ip0);
+
+	  if (PREDICT_FALSE (!macp0))
+	    goto next_l2_feature;	/* MAC not found */
+
+	  /* MAC found, send ARP reply -
+	     Convert ARP request packet to ARP reply */
+	  arp0->opcode = clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply);
+	  arp0->ip4_over_ethernet[1] = arp0->ip4_over_ethernet[0];
+	  arp0->ip4_over_ethernet[0].ip4.as_u32 = ip0;
+	  clib_memcpy (arp0->ip4_over_ethernet[0].ethernet, macp0, 6);
+	  clib_memcpy (eth0->dst_address, eth0->src_address, 6);
+	  clib_memcpy (eth0->src_address, macp0, 6);
+	  n_replies_sent += 1;
+
+	output_response:
+	  /* For BVI, need to use l2-fwd node to send ARP reply as
+	     l2-output node cannot output packet to BVI properly */
+	  cfg0 = vec_elt_at_index (l2im->configs, sw_if_index0);
+	  if (PREDICT_FALSE (cfg0->bvi))
+	    {
+	      vnet_buffer (p0)->l2.feature_bitmap |= L2INPUT_FEAT_FWD;
+	      vnet_buffer (p0)->sw_if_index[VLIB_RX] = 0;
+	      goto next_l2_feature;
+	    }
+
+	  /* Send ARP/ND reply back out input interface through l2-output */
+	  vnet_buffer (p0)->sw_if_index[VLIB_TX] = sw_if_index0;
+	  next0 = ARP_TERM_NEXT_L2_OUTPUT;
+	  /* Note that output to VXLAN tunnel will fail due to SHG which
+	     is probably desireable since ARP termination is not intended
+	     for ARP requests from other hosts. If output to VXLAN tunnel is
+	     required, however, can just clear the SHG in packet as follows:
+	     vnet_buffer(p0)->l2.shg = 0;         */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next, pi0,
+					   next0);
+	  continue;
+
+	check_ip6_nd:
+	  /* IP6 ND event notification or solicitation handling to generate
+	     local response instead of flooding */
+	  iph0 = (ip6_header_t *) l3h0;
+	  if (PREDICT_FALSE (ethertype0 == ETHERNET_TYPE_IP6 &&
+			     iph0->protocol == IP_PROTOCOL_ICMP6 &&
+			     !ip6_address_is_unspecified
+			     (&iph0->src_address)))
+	    {
+	      sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+	      if (vnet_ip6_nd_term
+		  (vm, node, p0, eth0, iph0, sw_if_index0,
+		   vnet_buffer (p0)->l2.bd_index, vnet_buffer (p0)->l2.shg))
+		goto output_response;
+	    }
+
+	next_l2_feature:
+	  {
+	    u32 feature_bitmap0 =
+	      vnet_buffer (p0)->l2.feature_bitmap & ~L2INPUT_FEAT_ARP_TERM;
+	    vnet_buffer (p0)->l2.feature_bitmap = feature_bitmap0;
+	    next0 =
+	      feat_bitmap_get_next_node_index (arp_term_next_node_index,
+					       feature_bitmap0);
+	    vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					     to_next, n_left_to_next,
+					     pi0, next0);
+	    continue;
+	  }
+
+	drop:
+	  if (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ||
+	      (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+	       arp0->ip4_over_ethernet[1].ip4.as_u32))
+	    {
+	      error0 = ETHERNET_ARP_ERROR_gratuitous_arp;
+	    }
+	  next0 = ARP_TERM_NEXT_DROP;
+	  p0->error = node->errors[error0];
+
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next, pi0,
+					   next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_error_count (vm, node->node_index,
+		    ETHERNET_ARP_ERROR_replies_sent, n_replies_sent);
+  return frame->n_vectors;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (arp_term_l2bd_node, static) = {
+  .function = arp_term_l2bd,
+  .name = "arp-term-l2bd",
+  .vector_size = sizeof (u32),
+  .n_errors = ETHERNET_ARP_N_ERROR,
+  .error_strings = ethernet_arp_error_strings,
+  .n_next_nodes = ARP_TERM_N_NEXT,
+  .next_nodes = {
+    [ARP_TERM_NEXT_L2_OUTPUT] = "l2-output",
+    [ARP_TERM_NEXT_DROP] = "error-drop",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_arp_term_input_trace,
+};
+/* *INDENT-ON* */
+
+clib_error_t *
+arp_term_init (vlib_main_t * vm)
+{
+  // Initialize the feature next-node indexes
+  feat_bitmap_init_next_nodes (vm,
+			       arp_term_l2bd_node.index,
+			       L2INPUT_N_FEAT,
+			       l2input_get_feat_names (),
+			       arp_term_next_node_index);
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (arp_term_init);
+
+void
+change_arp_mac (u32 sw_if_index, ethernet_arp_ip4_entry_t * e)
+{
+  if (e->sw_if_index == sw_if_index)
+    {
+      adj_nbr_walk_nh4 (e->sw_if_index,
+			&e->ip4_address, arp_mk_complete_walk, e);
+    }
+}
+
+void
+ethernet_arp_change_mac (u32 sw_if_index)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+  ethernet_arp_ip4_entry_t *e;
+
+  /* *INDENT-OFF* */
+  pool_foreach (e, am->ip4_entry_pool,
+  ({
+    change_arp_mac (sw_if_index, e);
+  }));
+  /* *INDENT-ON* */
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */