ip: Protocol Independent IP Neighbors

Type: feature

 - ip-neighbour: generic neighbour handling; APIs, DBs, event handling,
aging
 - arp: ARP protocol implementation
 - ip6-nd; IPv6 neighbor discovery implementation; separate ND,
MLD, RA
 - ip6-link; manage link-local addresses
 - l2-arp-term; events separated from IP neighbours, since they are not
the same.

vnet retains just enough education to perform ND/ARP packet
construction.
arp and ip6-nd to be moved to plugins soon.

Change-Id: I88dedd0006b299344f4c7024a0aa5baa6b9a8bbe
Signed-off-by: Neale Ranns <nranns@cisco.com>

7 files changed, 1975 insertions, 0 deletions

diff --git a/src/vnet/arp/arp.api b/src/vnet/arp/arp.api
new file mode 100644
index 00000000000..27bfa3b65c6
--- /dev/null
+++ b/src/vnet/arp/arp.api
@@ -0,0 +1,100 @@
+/* Hey Emacs use -*- mode: C -*- */
+/*
+ * Copyright (c) 2019 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.
+ */
+
+/** \file
+    This file defines the vpp control-plane API messages
+    used to control the ABF plugin
+*/
+
+option version = "1.0.0";
+
+import "vnet/ip/ip_types.api";
+import "vnet/ethernet/ethernet_types.api";
+import "vnet/interface_types.api";
+
+/** \brief Proxy ARP configuration type
+    @param table_id - VRF / Fib table ID
+    @param low - Low address of the Proxy ARP range
+    @param hi - High address of the Proxy ARP range
+*/
+typedef proxy_arp
+{
+  u32 table_id;
+  vl_api_ip4_address_t low;
+  vl_api_ip4_address_t hi;
+};
+
+/** \brief Proxy ARP add / del request
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param is_add - 1 if adding the Proxy ARP range, 0 if deleting
+    @param proxy - Proxy configuration
+*/
+autoreply define proxy_arp_add_del
+{
+  u32 client_index;
+  u32 context;
+  bool is_add;
+  vl_api_proxy_arp_t proxy;
+};
+
+/** \brief Proxy ARP dump request
+ */
+define proxy_arp_dump
+{
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief Proxy ARP dump details reply
+ * @param proxy - Same data as used to configure
+ */
+define proxy_arp_details
+{
+  u32 context;
+  vl_api_proxy_arp_t proxy;
+};
+
+/** \brief Proxy ARP add / del interface request
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param sw_if_index - Which interface to enable / disable Proxy Arp on
+    @param enable - 1 to enable Proxy ARP on interface, 0 to disable
+*/
+autoreply define proxy_arp_intfc_enable_disable
+{
+  u32 client_index;
+  u32 context;
+  vl_api_interface_index_t sw_if_index;
+  bool enable;
+};
+
+/** \brief Proxy ARP interface dump request
+ */
+define proxy_arp_intfc_dump
+{
+  u32 client_index;
+  u32 context;
+};
+
+/** \brief Proxy ARP interface dump details reply
+ * @param sw_if_index The interface on which ARP proxy is enabled.
+ */
+define proxy_arp_intfc_details
+{
+  u32 context;
+  u32 sw_if_index;
+};
diff --git a/src/vnet/arp/arp.c b/src/vnet/arp/arp.c
new file mode 100644
index 00000000000..14a1ae97d1e
--- /dev/null
+++ b/src/vnet/arp/arp.c
@@ -0,0 +1,934 @@
+/*
+ * 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/arp/arp.h>
+#include <vnet/arp/arp_packet.h>
+
+#include <vnet/fib/ip4_fib.h>
+#include <vnet/fib/fib_entry_src.h>
+#include <vnet/adj/adj_nbr.h>
+#include <vnet/adj/adj_mcast.h>
+
+#include <vnet/ip-neighbor/ip_neighbor.h>
+#include <vnet/ip-neighbor/ip_neighbor_dp.h>
+
+#include <vlibmemory/api.h>
+
+/**
+ * @file
+ * @brief IPv4 ARP.
+ *
+ * This file contains code to manage the IPv4 ARP tables (IP Address
+ * to MAC Address lookup).
+ */
+
+/**
+ * @brief Per-interface ARP configuration and state
+ */
+typedef struct ethernet_arp_interface_t_
+{
+  /**
+   * Is ARP enabled on this interface
+   */
+  u32 enabled;
+} ethernet_arp_interface_t;
+
+typedef struct
+{
+  /* Hash tables mapping name to opcode. */
+  uword *opcode_by_name;
+
+  /** Per interface state */
+  ethernet_arp_interface_t *ethernet_arp_by_sw_if_index;
+
+  /* ARP feature arc index */
+  u8 feature_arc_index;
+} ethernet_arp_main_t;
+
+static ethernet_arp_main_t ethernet_arp_main;
+
+static const u8 vrrp_prefix[] = { 0x00, 0x00, 0x5E, 0x00, 0x01 };
+
+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;
+}
+
+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 int
+arp_is_enabled (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (vec_len (am->ethernet_arp_by_sw_if_index) <= sw_if_index)
+    return 0;
+
+  return (am->ethernet_arp_by_sw_if_index[sw_if_index].enabled);
+}
+
+static void
+arp_enable (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (arp_is_enabled (am, sw_if_index))
+    return;
+
+  vec_validate (am->ethernet_arp_by_sw_if_index, sw_if_index);
+
+  am->ethernet_arp_by_sw_if_index[sw_if_index].enabled = 1;
+
+  vnet_feature_enable_disable ("arp", "arp-reply", sw_if_index, 1, NULL, 0);
+  vnet_feature_enable_disable ("arp", "arp-disabled", sw_if_index, 0, NULL,
+			       0);
+}
+
+static void
+arp_disable (ethernet_arp_main_t * am, u32 sw_if_index)
+{
+  if (!arp_is_enabled (am, sw_if_index))
+    return;
+
+  vnet_feature_enable_disable ("arp", "arp-disabled", sw_if_index, 1, NULL,
+			       0);
+  vnet_feature_enable_disable ("arp", "arp-reply", sw_if_index, 0, NULL, 0);
+
+  am->ethernet_arp_by_sw_if_index[sw_if_index].enabled = 0;
+}
+
+static int
+arp_unnumbered (vlib_buffer_t * p0,
+		u32 input_sw_if_index, u32 conn_sw_if_index)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  vnet_interface_main_t *vim = &vnm->interface_main;
+  vnet_sw_interface_t *si;
+
+  /* verify that the input interface is unnumbered to the connected.
+   * the connected interface is the interface on which the subnet is
+   * configured */
+  si = &vim->sw_interfaces[input_sw_if_index];
+
+  if (!(si->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED &&
+	(si->unnumbered_sw_if_index == conn_sw_if_index)))
+    {
+      /* the input interface is not unnumbered to the interface on which
+       * the sub-net is configured that covers the ARP request.
+       * So this is not the case for unnumbered.. */
+      return 0;
+    }
+
+  return !0;
+}
+
+always_inline u32
+arp_learn (u32 sw_if_index,
+	   const ethernet_arp_ip4_over_ethernet_address_t * addr)
+{
+  ip_neighbor_learn_t l = {
+    .ip.ip4 = addr->ip4,
+    .type = IP46_TYPE_IP4,
+    .mac = addr->mac,
+    .sw_if_index = sw_if_index,
+  };
+
+  ip_neighbor_learn_dp (&l);
+
+  return (ETHERNET_ARP_ERROR_l3_src_address_learned);
+}
+
+typedef enum arp_input_next_t_
+{
+  ARP_INPUT_NEXT_DROP,
+  ARP_INPUT_NEXT_DISABLED,
+  ARP_INPUT_N_NEXT,
+} arp_input_next_t;
+
+static uword
+arp_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, next_index, *from, *to_next, n_left_to_next;
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  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)
+    {
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  const ethernet_arp_header_t *arp0;
+	  arp_input_next_t next0;
+	  vlib_buffer_t *p0;
+	  u32 pi0, error0;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  arp0 = vlib_buffer_get_current (p0);
+
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  next0 = ARP_INPUT_NEXT_DROP;
+
+	  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);
+	  error0 =
+	    (0 == arp0->ip4_over_ethernet[0].ip4.as_u32 ?
+	     ETHERNET_ARP_ERROR_l3_dst_address_unset : error0);
+
+	  if (ETHERNET_ARP_ERROR_replies_sent == error0)
+	    {
+	      next0 = ARP_INPUT_NEXT_DISABLED;
+	      vnet_feature_arc_start (am->feature_arc_index,
+				      vnet_buffer (p0)->sw_if_index[VLIB_RX],
+				      &next0, p0);
+	    }
+	  else
+	    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);
+    }
+
+  return frame->n_vectors;
+}
+
+typedef enum arp_disabled_next_t_
+{
+  ARP_DISABLED_NEXT_DROP,
+  ARP_DISABLED_N_NEXT,
+} arp_disabled_next_t;
+
+#define foreach_arp_disabled_error					\
+  _ (DISABLED, "ARP Disabled on this interface")                    \
+
+typedef enum
+{
+#define _(sym,string) ARP_DISABLED_ERROR_##sym,
+  foreach_arp_disabled_error
+#undef _
+    ARP_DISABLED_N_ERROR,
+} arp_disabled_error_t;
+
+static char *arp_disabled_error_strings[] = {
+#define _(sym,string) string,
+  foreach_arp_disabled_error
+#undef _
+};
+
+static uword
+arp_disabled (vlib_main_t * vm,
+	      vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, next_index, *from, *to_next, n_left_to_next;
+
+  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)
+    {
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  arp_disabled_next_t next0 = ARP_DISABLED_NEXT_DROP;
+	  vlib_buffer_t *p0;
+	  u32 pi0, error0;
+
+	  next0 = ARP_DISABLED_NEXT_DROP;
+	  error0 = ARP_DISABLED_ERROR_DISABLED;
+
+	  pi0 = to_next[0] = from[0];
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  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);
+    }
+
+  return frame->n_vectors;
+}
+
+enum arp_dst_fib_type
+{
+  ARP_DST_FIB_NONE,
+  ARP_DST_FIB_ADJ,
+  ARP_DST_FIB_CONN
+};
+
+/*
+ * we're looking for FIB sources that indicate the destination
+ * is attached. There may be interposed DPO prior to the one
+ * we are looking for
+ */
+static enum arp_dst_fib_type
+arp_dst_fib_check (const fib_node_index_t fei, fib_entry_flag_t * flags)
+{
+  const fib_entry_t *entry = fib_entry_get (fei);
+  const fib_entry_src_t *entry_src;
+  fib_source_t src;
+  /* *INDENT-OFF* */
+  FOR_EACH_SRC_ADDED(entry, entry_src, src,
+  ({
+    *flags = fib_entry_get_flags_for_source (fei, src);
+    if (fib_entry_is_sourced (fei, FIB_SOURCE_ADJ))
+        return ARP_DST_FIB_ADJ;
+      else if (FIB_ENTRY_FLAG_CONNECTED & *flags)
+        return ARP_DST_FIB_CONN;
+  }))
+  /* *INDENT-ON* */
+
+  return ARP_DST_FIB_NONE;
+}
+
+static uword
+arp_reply (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 n_left_from, next_index, *from, *to_next;
+  u32 n_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;
+	  ethernet_arp_header_t *arp0;
+	  ethernet_header_t *eth_rx;
+	  const ip4_address_t *if_addr0;
+	  u32 pi0, error0, next0, sw_if_index0, conn_sw_if_index0, fib_index0;
+	  u8 dst_is_local0, is_vrrp_reply0;
+	  fib_node_index_t dst_fei, src_fei;
+	  const 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;
+
+	  p0 = vlib_get_buffer (vm, pi0);
+	  arp0 = vlib_buffer_get_current (p0);
+	  /* Fill in ethernet header. */
+	  eth_rx = ethernet_buffer_get_header (p0);
+
+	  next0 = ARP_REPLY_NEXT_DROP;
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+
+	  /* 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 drop;
+
+	    }
+
+	  {
+	    /*
+	     * we're looking for FIB entries that indicate the source
+	     * is attached. There may be more specific non-attached
+	     * routes that match the source, but these do not influence
+	     * whether we respond to an ARP request, i.e. they do not
+	     * influence whether we are the correct way for the sender
+	     * to reach us, they only affect how we reach the sender.
+	     */
+	    fib_entry_t *src_fib_entry;
+	    const fib_prefix_t *pfx;
+	    fib_entry_src_t *src;
+	    fib_source_t source;
+	    int attached;
+	    int mask;
+
+	    mask = 32;
+	    attached = 0;
+
+	    do
+	      {
+		src_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+						&arp0->
+						ip4_over_ethernet[0].ip4,
+						mask);
+		src_fib_entry = fib_entry_get (src_fei);
+
+		/*
+		 * It's possible that the source that provides the
+		 * flags we need, or the flags we must not have,
+		 * is not the best source, so check then all.
+		 */
+                /* *INDENT-OFF* */
+                FOR_EACH_SRC_ADDED(src_fib_entry, src, source,
+                ({
+                  src_flags = fib_entry_get_flags_for_source (src_fei, source);
+
+                  /* Reject requests/replies with our local interface
+                     address. */
+                  if (FIB_ENTRY_FLAG_LOCAL & src_flags)
+                    {
+                      error0 = ETHERNET_ARP_ERROR_l3_src_address_is_local;
+                      /*
+                       * When VPP has an interface whose address is also
+                       * applied to a TAP interface on the host, then VPP's
+                       * TAP interface will be unnumbered  to the 'real'
+                       * interface and do proxy ARP from the host.
+                       * The curious aspect of this setup is that ARP requests
+                       * from the host will come from the VPP's own address.
+                       * So don't drop immediately here, instead go see if this
+                       * is a proxy ARP case.
+                       */
+                      goto next_feature;
+                    }
+                  /* A Source must also be local to subnet of matching
+                   * interface address. */
+                  if ((FIB_ENTRY_FLAG_ATTACHED & src_flags) ||
+                      (FIB_ENTRY_FLAG_CONNECTED & src_flags))
+                    {
+                      attached = 1;
+                      break;
+                    }
+                  /*
+                   * else
+                   *  The packet was sent from an address that is not
+                   *  connected nor attached i.e. it is not from an
+                   *  address that is covered by a link's sub-net,
+                   *  nor is it a already learned host resp.
+                   */
+                }));
+                /* *INDENT-ON* */
+
+		/*
+		 * shorter mask lookup for the next iteration.
+		 */
+		pfx = fib_entry_get_prefix (src_fei);
+		mask = pfx->fp_len - 1;
+
+		/*
+		 * continue until we hit the default route or we find
+		 * the attached we are looking for. The most likely
+		 * outcome is we find the attached with the first source
+		 * on the first lookup.
+		 */
+	      }
+	    while (!attached &&
+		   !fib_entry_is_sourced (src_fei, FIB_SOURCE_DEFAULT_ROUTE));
+
+	    if (!attached)
+	      {
+		/*
+		 * the matching route is a not attached, i.e. it was
+		 * added as a result of routing, rather than interface/ARP
+		 * configuration. If the matching route is not a host route
+		 * (i.e. a /32)
+		 */
+		error0 = ETHERNET_ARP_ERROR_l3_src_address_not_local;
+		goto drop;
+	      }
+	  }
+
+	  dst_fei = ip4_fib_table_lookup (ip4_fib_get (fib_index0),
+					  &arp0->ip4_over_ethernet[1].ip4,
+					  32);
+	  switch (arp_dst_fib_check (dst_fei, &dst_flags))
+	    {
+	    case ARP_DST_FIB_ADJ:
+	      /*
+	       * We matched an adj-fib on ths source subnet (a /32 previously
+	       * added as a result of ARP). If this request is a gratuitous
+	       * ARP, then learn from it.
+	       * The check for matching an adj-fib, is to prevent hosts
+	       * from spamming us with gratuitous ARPS that might otherwise
+	       * blow our ARP cache
+	       */
+	      if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+		  arp0->ip4_over_ethernet[1].ip4.as_u32)
+		error0 =
+		  arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[0]);
+	      goto drop;
+	    case ARP_DST_FIB_CONN:
+	      /* destination is connected, continue to process */
+	      break;
+	    case ARP_DST_FIB_NONE:
+	      /* destination is not connected, stop here */
+	      error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+	      goto next_feature;
+	    }
+
+	  dst_is_local0 = (FIB_ENTRY_FLAG_LOCAL & dst_flags);
+	  pfx0 = fib_entry_get_prefix (dst_fei);
+	  if_addr0 = &pfx0->fp_addr.ip4;
+
+	  is_vrrp_reply0 =
+	    ((arp0->opcode ==
+	      clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
+	     &&
+	     (!memcmp
+	      (arp0->ip4_over_ethernet[0].mac.bytes, vrrp_prefix,
+	       sizeof (vrrp_prefix))));
+
+	  /* Trash ARP packets whose ARP-level source addresses do not
+	     match their L2-frame-level source addresses, unless it's
+	     a reply from a VRRP virtual router */
+	  if (!ethernet_mac_address_equal
+	      (eth_rx->src_address,
+	       arp0->ip4_over_ethernet[0].mac.bytes) && !is_vrrp_reply0)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_l2_address_mismatch;
+	      goto drop;
+	    }
+
+	  /* Learn or update sender's mapping only for replies to addresses
+	   * that are local to the subnet */
+	  if (arp0->opcode ==
+	      clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply))
+	    {
+	      if (dst_is_local0)
+		error0 =
+		  arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[0]);
+	      else
+		/* a reply for a non-local destination could be a GARP.
+		 * GARPs for hosts we know were handled above, so this one
+		 * we drop */
+		error0 = ETHERNET_ARP_ERROR_l3_dst_address_not_local;
+
+	      goto next_feature;
+	    }
+	  else if (arp0->opcode ==
+		   clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_request) &&
+		   (dst_is_local0 == 0))
+	    {
+	      goto next_feature;
+	    }
+
+	  /* Honor unnumbered interface, if any */
+	  conn_sw_if_index0 = fib_entry_get_resolving_interface (dst_fei);
+	  if (sw_if_index0 != conn_sw_if_index0 ||
+	      sw_if_index0 != fib_entry_get_resolving_interface (src_fei))
+	    {
+	      /*
+	       * The interface the ARP is sent to or was received on is not the
+	       * interface on which the covering prefix is configured.
+	       * Maybe this is a case for unnumbered.
+	       */
+	      if (!arp_unnumbered (p0, sw_if_index0, conn_sw_if_index0))
+		{
+		  error0 = ETHERNET_ARP_ERROR_unnumbered_mismatch;
+		  goto drop;
+		}
+	    }
+	  if (arp0->ip4_over_ethernet[0].ip4.as_u32 ==
+	      arp0->ip4_over_ethernet[1].ip4.as_u32)
+	    {
+	      error0 = ETHERNET_ARP_ERROR_gratuitous_arp;
+	      goto drop;
+	    }
+
+	  next0 = arp_mk_reply (vnm, p0, sw_if_index0,
+				if_addr0, arp0, eth_rx);
+
+	  /* We are going to reply to this request, so, in the absence of
+	     errors, learn the sender */
+	  if (!error0)
+	    error0 = arp_learn (sw_if_index0, &arp0->ip4_over_ethernet[1]);
+
+	  n_replies_sent += 1;
+	  goto enqueue;
+
+	next_feature:
+	  vnet_feature_next (&next0, p0);
+	  goto enqueue;
+
+	drop:
+	  p0->error = node->errors[error0];
+
+	enqueue:
+	  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;
+}
+
+
+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_DISABLED] = "arp-disabled",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+VLIB_REGISTER_NODE (arp_disabled_node, static) =
+{
+  .function = arp_disabled,
+  .name = "arp-disabled",
+  .vector_size = sizeof (u32),
+  .n_errors = ARP_DISABLED_N_ERROR,
+  .error_strings = arp_disabled_error_strings,
+  .n_next_nodes = ARP_DISABLED_N_NEXT,
+  .next_nodes = {
+    [ARP_INPUT_NEXT_DROP] = "error-drop",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+VLIB_REGISTER_NODE (arp_reply_node, static) =
+{
+  .function = arp_reply,
+  .name = "arp-reply",
+  .vector_size = sizeof (u32),
+  .n_errors = ETHERNET_ARP_N_ERROR,
+  .error_strings = ethernet_arp_error_strings,
+  .n_next_nodes = ARP_REPLY_N_NEXT,
+  .next_nodes = {
+    [ARP_REPLY_NEXT_DROP] = "error-drop",
+    [ARP_REPLY_NEXT_REPLY_TX] = "interface-output",
+  },
+  .format_buffer = format_ethernet_arp_header,
+  .format_trace = format_ethernet_arp_input_trace,
+};
+
+/* Built-in ARP rx feature path definition */
+VNET_FEATURE_ARC_INIT (arp_feat, static) =
+{
+  .arc_name = "arp",
+  .start_nodes = VNET_FEATURES ("arp-input"),
+  .last_in_arc = "error-drop",
+  .arc_index_ptr = &ethernet_arp_main.feature_arc_index,
+};
+
+VNET_FEATURE_INIT (arp_reply_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-reply",
+  .runs_before = VNET_FEATURES ("arp-disabled"),
+};
+
+VNET_FEATURE_INIT (arp_proxy_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-proxy",
+  .runs_after = VNET_FEATURES ("arp-reply"),
+  .runs_before = VNET_FEATURES ("arp-disabled"),
+};
+
+VNET_FEATURE_INIT (arp_disabled_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "arp-disabled",
+  .runs_before = VNET_FEATURES ("error-drop"),
+};
+
+VNET_FEATURE_INIT (arp_drop_feat_node, static) =
+{
+  .arc_name = "arp",
+  .node_name = "error-drop",
+  .runs_before = 0,	/* last feature */
+};
+
+/* *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 mac;
+    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].mac);
+  _(ip4_over_ethernet[0].ip4);
+  _(ip4_over_ethernet[1].mac);
+  _(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_mac_address_t, &p->ip4_over_ethernet[0].mac,
+		 unformat_pg_edit,
+		 unformat_ip4_address, &p->ip4_over_ethernet[0].ip4,
+		 unformat_pg_edit,
+		 unformat_mac_address_t, &p->ip4_over_ethernet[1].mac,
+		 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;
+}
+
+/*
+ * callback when an interface address is added or deleted
+ */
+static void
+arp_enable_disable_interface (ip4_main_t * im,
+			      uword opaque, u32 sw_if_index, u32 is_enable)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  if (is_enable)
+    arp_enable (am, sw_if_index);
+  else
+    arp_disable (am, sw_if_index);
+}
+
+/*
+ * Remove any arp entries associated with the specified interface
+ */
+static clib_error_t *
+vnet_arp_add_del_sw_interface (vnet_main_t * vnm, u32 sw_if_index, u32 is_add)
+{
+  ethernet_arp_main_t *am = &ethernet_arp_main;
+
+  if (!is_add && sw_if_index != ~0)
+    {
+      arp_disable (am, sw_if_index);
+    }
+  else if (is_add)
+    {
+      vnet_feature_enable_disable ("arp", "arp-disabled",
+				   sw_if_index, 1, NULL, 0);
+    }
+
+  return (NULL);
+}
+
+VNET_SW_INTERFACE_ADD_DEL_FUNCTION (vnet_arp_add_del_sw_interface);
+
+const static ip_neighbor_vft_t arp_vft = {
+  .inv_proxy4_add = arp_proxy_add,
+  .inv_proxy4_del = arp_proxy_del,
+  .inv_proxy4_enable = arp_proxy_disable,
+  .inv_proxy4_disable = arp_proxy_disable,
+};
+
+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;
+  pg_node_t *pn;
+
+  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 _
+
+  /* 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_enable_disable_interface_callback_t cb = {
+      .function = arp_enable_disable_interface,
+    };
+    vec_add1 (im->enable_disable_interface_callbacks, cb);
+  }
+
+  ip_neighbor_register (IP46_TYPE_IP4, &arp_vft);
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_INIT_FUNCTION (ethernet_arp_init) =
+{
+  .runs_after = VLIB_INITS("ethernet_init",
+                           "ip_neighbor_init"),
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/arp/arp.h b/src/vnet/arp/arp.h
new file mode 100644
index 00000000000..7446564b0cf
--- /dev/null
+++ b/src/vnet/arp/arp.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2015 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 __ARP_H__
+#define __ARP_H__
+
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/arp_packet.h>
+
+#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_dst_address_unset, "IP4 destination address is unset")          \
+  _ (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") \
+  _ (gratuitous_arp, "ARP probe or announcement dropped") \
+  _ (interface_no_table, "Interface is not mapped to an IP table") \
+  _ (interface_not_ip_enabled, "Interface is not IP enabled") \
+  _ (unnumbered_mismatch, "RX interface is unnumbered to different subnet") \
+
+typedef enum
+{
+#define _(sym,string) ETHERNET_ARP_ERROR_##sym,
+  foreach_ethernet_arp_error
+#undef _
+    ETHERNET_ARP_N_ERROR,
+} ethernet_arp_reply_error_t;
+
+extern int arp_proxy_add (u32 fib_index,
+			  const ip4_address_t * lo_addr,
+			  const ip4_address_t * hi_addr);
+extern int arp_proxy_del (u32 fib_index,
+			  const ip4_address_t * lo_addr,
+			  const ip4_address_t * hi_addr);
+
+extern int arp_proxy_enable (u32 sw_if_index);
+extern int arp_proxy_disable (u32 sw_if_index);
+
+/**
+ * call back function when walking the DB of proxy ARPs
+ * @return 0 to stop the walk !0 to continue
+ */
+typedef walk_rc_t (proxy_arp_walk_t) (const ip4_address_t * lo_addr,
+				      const ip4_address_t * hi_addr,
+				      u32 fib_index, void *dat);
+
+extern void proxy_arp_walk (proxy_arp_walk_t cb, void *data);
+
+/**
+ * call back function when walking the DB of proxy ARP interface
+ * @return 0 to stop the walk !0 to continue
+ */
+typedef walk_rc_t (proxy_arp_intf_walk_t) (u32 sw_if_index, void *data);
+
+extern void proxy_arp_intfc_walk (proxy_arp_intf_walk_t cb, void *data);
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/arp/arp_api.c b/src/vnet/arp/arp_api.c
new file mode 100644
index 00000000000..170bace2b0a
--- /dev/null
+++ b/src/vnet/arp/arp_api.c
@@ -0,0 +1,190 @@
+/*
+ * 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 <stddef.h>
+
+#include <vnet/arp/arp.h>
+
+#include <vnet/fib/fib_table.h>
+#include <vnet/ip/ip_types_api.h>
+
+#include <vpp/app/version.h>
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+
+/* define message IDs */
+#include <vnet/format_fns.h>
+#include <vnet/arp/arp.api_enum.h>
+#include <vnet/arp/arp.api_types.h>
+
+/**
+ * Base message ID fot the plugin
+ */
+static u32 arp_base_msg_id;
+#define REPLY_MSG_ID_BASE arp_base_msg_id
+
+#include <vlibapi/api_helper_macros.h>
+
+static void
+vl_api_proxy_arp_add_del_t_handler (vl_api_proxy_arp_add_del_t * mp)
+{
+  vl_api_proxy_arp_add_del_reply_t *rmp;
+  ip4_address_t lo, hi;
+  u32 fib_index;
+  int rv;
+
+  fib_index = fib_table_find (FIB_PROTOCOL_IP4, ntohl (mp->proxy.table_id));
+
+  if (~0 == fib_index)
+    {
+      rv = VNET_API_ERROR_NO_SUCH_FIB;
+      goto out;
+    }
+
+  ip4_address_decode (mp->proxy.low, &lo);
+  ip4_address_decode (mp->proxy.hi, &hi);
+
+  if (mp->is_add)
+    rv = arp_proxy_add (fib_index, &lo, &hi);
+  else
+    rv = arp_proxy_del (fib_index, &lo, &hi);
+
+out:
+  REPLY_MACRO (VL_API_PROXY_ARP_ADD_DEL_REPLY);
+}
+
+typedef struct proxy_arp_walk_ctx_t_
+{
+  vl_api_registration_t *reg;
+  u32 context;
+} proxy_arp_walk_ctx_t;
+
+static walk_rc_t
+send_proxy_arp_details (const ip4_address_t * lo_addr,
+			const ip4_address_t * hi_addr,
+			u32 fib_index, void *data)
+{
+  vl_api_proxy_arp_details_t *mp;
+  proxy_arp_walk_ctx_t *ctx;
+
+  ctx = data;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  clib_memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (VL_API_PROXY_ARP_DETAILS + REPLY_MSG_ID_BASE);
+  mp->context = ctx->context;
+  mp->proxy.table_id = htonl (fib_index);
+
+  ip4_address_encode (lo_addr, mp->proxy.low);
+  ip4_address_encode (hi_addr, mp->proxy.hi);
+
+  vl_api_send_msg (ctx->reg, (u8 *) mp);
+
+  return (WALK_CONTINUE);
+}
+
+static void
+vl_api_proxy_arp_dump_t_handler (vl_api_proxy_arp_dump_t * mp)
+{
+  vl_api_registration_t *reg;
+
+  reg = vl_api_client_index_to_registration (mp->client_index);
+  if (!reg)
+    return;
+
+  proxy_arp_walk_ctx_t wctx = {
+    .reg = reg,
+    .context = mp->context,
+  };
+
+  proxy_arp_walk (send_proxy_arp_details, &wctx);
+}
+
+static walk_rc_t
+send_proxy_arp_intfc_details (u32 sw_if_index, void *data)
+{
+  vl_api_proxy_arp_intfc_details_t *mp;
+  proxy_arp_walk_ctx_t *ctx;
+
+  ctx = data;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  clib_memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (VL_API_PROXY_ARP_INTFC_DETAILS + REPLY_MSG_ID_BASE);
+  mp->context = ctx->context;
+  mp->sw_if_index = htonl (sw_if_index);
+
+  vl_api_send_msg (ctx->reg, (u8 *) mp);
+
+  return (WALK_CONTINUE);
+}
+
+static void
+vl_api_proxy_arp_intfc_dump_t_handler (vl_api_proxy_arp_intfc_dump_t * mp)
+{
+  vl_api_registration_t *reg;
+
+  reg = vl_api_client_index_to_registration (mp->client_index);
+  if (!reg)
+    return;
+
+  proxy_arp_walk_ctx_t wctx = {
+    .reg = reg,
+    .context = mp->context,
+  };
+
+  proxy_arp_intfc_walk (send_proxy_arp_intfc_details, &wctx);
+}
+
+static void
+  vl_api_proxy_arp_intfc_enable_disable_t_handler
+  (vl_api_proxy_arp_intfc_enable_disable_t * mp)
+{
+  vl_api_proxy_arp_intfc_enable_disable_reply_t *rmp;
+  int rv;
+
+  VALIDATE_SW_IF_INDEX (mp);
+
+  if (mp->enable)
+    rv = arp_proxy_enable (ntohl (mp->sw_if_index));
+  else
+    rv = arp_proxy_disable (ntohl (mp->sw_if_index));
+
+  BAD_SW_IF_INDEX_LABEL;
+
+  REPLY_MACRO (VL_API_PROXY_ARP_INTFC_ENABLE_DISABLE_REPLY);
+}
+
+#include <vnet/arp/arp.api.c>
+
+static clib_error_t *
+arp_api_init (vlib_main_t * vm)
+{
+  /* Ask for a correctly-sized block of API message decode slots */
+  arp_base_msg_id = setup_message_id_table ();
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (arp_api_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/arp/arp_packet.h b/src/vnet/arp/arp_packet.h
new file mode 100644
index 00000000000..a860c258f75
--- /dev/null
+++ b/src/vnet/arp/arp_packet.h
@@ -0,0 +1,91 @@
+/*
+ * 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.
+ */
+
+#ifndef __ARP_PACKET_H__
+#define __ARP_PACKET_H__
+
+#include <vnet/arp/arp.h>
+
+/* Either we drop the packet or we send a reply to the sender. */
+typedef enum
+{
+  ARP_REPLY_NEXT_DROP,
+  ARP_REPLY_NEXT_REPLY_TX,
+  ARP_REPLY_N_NEXT,
+} arp_reply_next_t;
+
+static_always_inline u32
+arp_mk_reply (vnet_main_t * vnm,
+	      vlib_buffer_t * p0,
+	      u32 sw_if_index0,
+	      const ip4_address_t * if_addr0,
+	      ethernet_arp_header_t * arp0, ethernet_header_t * eth_rx)
+{
+  vnet_hw_interface_t *hw_if0;
+  u8 *rewrite0, rewrite0_len;
+  ethernet_header_t *eth_tx;
+  u32 next0;
+
+  /* Send a reply.
+     An adjacency to the sender is not always present,
+     so we use the interface to build us a rewrite string
+     which will contain all the necessary tags. */
+  rewrite0 = ethernet_build_rewrite (vnm, sw_if_index0,
+				     VNET_LINK_ARP, eth_rx->src_address);
+  rewrite0_len = vec_len (rewrite0);
+
+  /* Figure out how much to rewind current data from adjacency. */
+  vlib_buffer_advance (p0, -rewrite0_len);
+  eth_tx = vlib_buffer_get_current (p0);
+
+  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_REPLY_NEXT_REPLY_TX;
+
+  arp0->opcode = clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_reply);
+
+  arp0->ip4_over_ethernet[1] = arp0->ip4_over_ethernet[0];
+
+  mac_address_from_bytes (&arp0->ip4_over_ethernet[0].mac,
+			  hw_if0->hw_address);
+  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);
+
+  /* the rx nd tx ethernet headers wil overlap in the case
+   * when we received a tagged VLAN=0 packet, but we are sending
+   * back untagged */
+  clib_memcpy_fast (eth_tx, rewrite0, vec_len (rewrite0));
+  vec_free (rewrite0);
+
+  return (next0);
+}
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/arp/arp_proxy.c b/src/vnet/arp/arp_proxy.c
new file mode 100644
index 00000000000..346a21775f8
--- /dev/null
+++ b/src/vnet/arp/arp_proxy.c
@@ -0,0 +1,407 @@
+/*
+ * 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/arp/arp.h>
+#include <vnet/arp/arp_packet.h>
+
+#include <vnet/fib/ip4_fib.h>
+
+typedef struct
+{
+  ip4_address_t lo_addr;
+  ip4_address_t hi_addr;
+  u32 fib_index;
+} ethernet_proxy_arp_t;
+
+typedef struct arp_proxy_main_t_
+{
+  /** Per interface state */
+  bool *enabled_by_sw_if_index;
+
+  /* Proxy arp vector */
+  ethernet_proxy_arp_t *proxy_arps;
+} arp_proxy_main_t;
+
+arp_proxy_main_t arp_proxy_main;
+
+void
+proxy_arp_walk (proxy_arp_walk_t cb, void *data)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+  ethernet_proxy_arp_t *pa;
+
+  vec_foreach (pa, am->proxy_arps)
+  {
+    if (!cb (&pa->lo_addr, &pa->hi_addr, pa->fib_index, data))
+      break;
+  }
+}
+
+int
+arp_proxy_disable (u32 sw_if_index)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+
+  vec_validate (am->enabled_by_sw_if_index, sw_if_index);
+
+  if (am->enabled_by_sw_if_index[sw_if_index])
+    {
+      vnet_feature_enable_disable ("arp", "arp-proxy",
+				   sw_if_index, 0, NULL, 0);
+    }
+  am->enabled_by_sw_if_index[sw_if_index] = false;
+
+  return (0);
+}
+
+int
+arp_proxy_enable (u32 sw_if_index)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+
+  vec_validate (am->enabled_by_sw_if_index, sw_if_index);
+
+  if (!am->enabled_by_sw_if_index[sw_if_index])
+    {
+      vnet_feature_enable_disable ("arp", "arp-proxy",
+				   sw_if_index, 1, NULL, 0);
+    }
+  am->enabled_by_sw_if_index[sw_if_index] = true;
+
+  return (0);
+}
+
+static int
+vnet_proxy_arp_add_del (const ip4_address_t * lo_addr,
+			const ip4_address_t * hi_addr,
+			u32 fib_index, int is_del)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+  ethernet_proxy_arp_t *pa;
+  u32 found_at_index = ~0;
+
+  vec_foreach (pa, am->proxy_arps)
+  {
+    if (pa->lo_addr.as_u32 == lo_addr->as_u32 &&
+	pa->hi_addr.as_u32 == 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.as_u32 = lo_addr->as_u32;
+  pa->hi_addr.as_u32 = hi_addr->as_u32;
+  pa->fib_index = fib_index;
+  return 0;
+}
+
+int
+arp_proxy_add (u32 fib_index,
+	       const ip4_address_t * lo, const ip4_address_t * hi)
+{
+  return (vnet_proxy_arp_add_del (lo, hi, fib_index, 0));
+}
+
+int
+arp_proxy_del (u32 fib_index,
+	       const ip4_address_t * lo, const ip4_address_t * hi)
+{
+  return (vnet_proxy_arp_add_del (lo, hi, fib_index, 1));
+}
+
+void
+proxy_arp_intfc_walk (proxy_arp_intf_walk_t cb, void *data)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+  bool *enabled;
+
+  vec_foreach (enabled, am->enabled_by_sw_if_index)
+  {
+    if (*enabled)
+      cb (enabled - am->enabled_by_sw_if_index, data);
+  }
+}
+
+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;
+  int enable = 0;
+
+  sw_if_index = ~0;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_vnet_sw_interface,
+		    vnm, &sw_if_index))
+	;
+      else if (unformat (input, "enable") || unformat (input, "on"))
+	enable = 1;
+      else if (unformat (input, "disable") || unformat (input, "off"))
+	enable = 0;
+      else
+	break;
+    }
+
+  if (~0 == sw_if_index)
+    return clib_error_return (0, "unknown input '%U'",
+			      format_unformat_error, input);
+
+  if (enable)
+    arp_proxy_enable (sw_if_index);
+  else
+    arp_proxy_disable (sw_if_index);
+
+  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* */
+
+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 uword
+arp_proxy (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 n_left_from, next_index, *from, *to_next;
+  u32 n_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;
+	  ethernet_arp_header_t *arp0;
+	  ethernet_header_t *eth_rx;
+	  ip4_address_t proxy_src;
+	  u32 pi0, error0, next0, sw_if_index0, fib_index0;
+	  u8 is_request0;
+	  ethernet_proxy_arp_t *pa;
+
+	  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);
+	  arp0 = vlib_buffer_get_current (p0);
+	  /* Fill in ethernet header. */
+	  eth_rx = ethernet_buffer_get_header (p0);
+
+	  is_request0 = arp0->opcode
+	    == clib_host_to_net_u16 (ETHERNET_ARP_OPCODE_request);
+
+	  error0 = ETHERNET_ARP_ERROR_replies_sent;
+	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
+	  next0 = ARP_REPLY_NEXT_DROP;
+
+	  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;
+	    }
+
+	  if (0 == error0 && is_request0)
+	    {
+	      u32 this_addr = clib_net_to_host_u32
+		(arp0->ip4_over_ethernet[1].ip4.as_u32);
+
+	      vec_foreach (pa, am->proxy_arps)
+	      {
+		u32 lo_addr = clib_net_to_host_u32 (pa->lo_addr.as_u32);
+		u32 hi_addr = clib_net_to_host_u32 (pa->hi_addr.as_u32);
+
+		/* an ARP request hit in the proxy-arp table? */
+		if ((this_addr >= lo_addr && this_addr <= hi_addr) &&
+		    (fib_index0 == pa->fib_index))
+		  {
+		    proxy_src.as_u32 =
+		      arp0->ip4_over_ethernet[1].ip4.data_u32;
+
+		    /*
+		     * change the interface address to the proxied
+		     */
+		    n_arp_replies_sent++;
+
+		    next0 =
+		      arp_mk_reply (vnm, p0, sw_if_index0, &proxy_src, arp0,
+				    eth_rx);
+		  }
+	      }
+	    }
+	  else
+	    {
+	      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_arp_replies_sent);
+
+  return frame->n_vectors;
+}
+
+static char *ethernet_arp_error_strings[] = {
+#define _(sym,string) string,
+  foreach_ethernet_arp_error
+#undef _
+};
+
+VLIB_REGISTER_NODE (arp_proxy_node, static) =
+{
+  .function = arp_proxy,.name = "arp-proxy",.vector_size =
+    sizeof (u32),.n_errors = ETHERNET_ARP_N_ERROR,.error_strings =
+    ethernet_arp_error_strings,.n_next_nodes = ARP_REPLY_N_NEXT,.next_nodes =
+  {
+  [ARP_REPLY_NEXT_DROP] = "error-drop",
+      [ARP_REPLY_NEXT_REPLY_TX] = "interface-output",}
+,.format_buffer = format_ethernet_arp_header,.format_trace =
+    format_ethernet_arp_input_trace,};
+
+static clib_error_t *
+show_ip4_arp (vlib_main_t * vm,
+	      unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  arp_proxy_main_t *am = &arp_proxy_main;
+  ethernet_proxy_arp_t *pa;
+
+  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 (NULL);
+}
+
+/*?
+ * Display all the IPv4 ARP proxy 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 arp proxy",
+  .function = show_ip4_arp,
+  .short_help = "show ip arp",
+};
+/* *INDENT-ON* */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/arp/arp_test.c b/src/vnet/arp/arp_test.c
new file mode 100644
index 00000000000..861d0739406
--- /dev/null
+++ b/src/vnet/arp/arp_test.c
@@ -0,0 +1,168 @@
+/*
+ *------------------------------------------------------------------
+ * arp_test.c
+ *
+ * Copyright (c) 2019 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 <vat/vat.h>
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+#include <vppinfra/error.h>
+
+#include <vnet/ip/ip_format_fns.h>
+
+#include <vpp/api/types.h>
+
+typedef struct
+{
+  /* API message ID base */
+  u16 msg_id_base;
+  u32 ping_id;
+  vat_main_t *vat_main;
+} arp_test_main_t;
+
+arp_test_main_t arp_test_main;
+
+#define __plugin_msg_base arp_test_main.msg_id_base
+#include <vlibapi/vat_helper_macros.h>
+uword unformat_sw_if_index (unformat_input_t * input, va_list * args);
+
+/* Declare message IDs */
+#include <arp/arp.api_enum.h>
+#include <arp/arp.api_types.h>
+#include <vpp/api/vpe.api_types.h>
+
+static int
+api_proxy_arp_dump (vat_main_t * vam)
+{
+  return -1;
+}
+
+static int
+api_proxy_arp_intfc_dump (vat_main_t * vam)
+{
+  return -1;
+}
+
+static void
+vl_api_proxy_arp_details_t_handler (vl_api_proxy_arp_details_t * mp)
+{
+}
+
+static void
+vl_api_proxy_arp_intfc_details_t_handler (vl_api_proxy_arp_intfc_details_t *
+					  mp)
+{
+}
+
+static int
+api_proxy_arp_add_del (vat_main_t * vam)
+{
+  unformat_input_t *i = vam->input;
+  vl_api_proxy_arp_add_del_t *mp;
+  u32 vrf_id = 0;
+  u8 is_add = 1;
+  vl_api_ip4_address_t lo, hi;
+  u8 range_set = 0;
+  int ret;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "vrf %d", &vrf_id))
+	;
+      else if (unformat (i, "%U - %U", unformat_vl_api_ip4_address, &lo,
+			 unformat_vl_api_ip4_address, &hi))
+	range_set = 1;
+      else if (unformat (i, "del"))
+	is_add = 0;
+      else
+	{
+	  clib_warning ("parse error '%U'", format_unformat_error, i);
+	  return -99;
+	}
+    }
+
+  if (range_set == 0)
+    {
+      errmsg ("address range not set");
+      return -99;
+    }
+
+  M (PROXY_ARP_ADD_DEL, mp);
+
+  mp->proxy.table_id = ntohl (vrf_id);
+  mp->is_add = is_add;
+  clib_memcpy (mp->proxy.low, &lo, sizeof (lo));
+  clib_memcpy (mp->proxy.hi, &hi, sizeof (hi));
+
+  S (mp);
+  W (ret);
+  return ret;
+}
+
+static int
+api_proxy_arp_intfc_enable_disable (vat_main_t * vam)
+{
+  unformat_input_t *i = vam->input;
+  vl_api_proxy_arp_intfc_enable_disable_t *mp;
+  u32 sw_if_index;
+  u8 enable = 1;
+  u8 sw_if_index_set = 0;
+  int ret;
+
+  while (unformat_check_input (i) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (i, "%U", unformat_sw_if_index, vam, &sw_if_index))
+	sw_if_index_set = 1;
+      else if (unformat (i, "sw_if_index %d", &sw_if_index))
+	sw_if_index_set = 1;
+      else if (unformat (i, "enable"))
+	enable = 1;
+      else if (unformat (i, "disable"))
+	enable = 0;
+      else
+	{
+	  clib_warning ("parse error '%U'", format_unformat_error, i);
+	  return -99;
+	}
+    }
+
+  if (sw_if_index_set == 0)
+    {
+      errmsg ("missing interface name or sw_if_index");
+      return -99;
+    }
+
+  M (PROXY_ARP_INTFC_ENABLE_DISABLE, mp);
+
+  mp->sw_if_index = ntohl (sw_if_index);
+  mp->enable = enable;
+
+  S (mp);
+  W (ret);
+  return ret;
+}
+
+#include <arp/arp.api_test.c>
+
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */