L2 Emulation

L2 Emulation is a feautre that is applied to L2 ports to 'extract'
IP packets from the L2 path and inject them into the L3 path (i.e.
into the appropriate ip[4|6]_input node).
L3 routes in the table_id for that interface should then be configured
as DVR routes, therefore the forwarded packet has the L2 header
preserved and togehter the L3 routed system behaves like an L2 bridge.

Change-Id: I8effd7e2f4c67ee277b73c7bc79aa3e5a3e34d03
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/configure.ac b/src/configure.ac
index b4c0c70..0e75403 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -222,6 +222,7 @@
 PLUGIN_ENABLED(sixrd)
 PLUGIN_ENABLED(nat)
 PLUGIN_ENABLED(stn)
+PLUGIN_ENABLED(l2e)
 
 ###############################################################################
 # Dependency checks
diff --git a/src/plugins/Makefile.am b/src/plugins/Makefile.am
index 746b4e0..03aef22 100644
--- a/src/plugins/Makefile.am
+++ b/src/plugins/Makefile.am
@@ -87,6 +87,10 @@
 include stn.am
 endif
 
+if ENABLE_L2E_PLUGIN
+include l2e.am
+endif
+
 include ../suffix-rules.mk
 
 # Remove *.la files
diff --git a/src/plugins/l2e.am b/src/plugins/l2e.am
new file mode 100644
index 0000000..da2c456
--- /dev/null
+++ b/src/plugins/l2e.am
@@ -0,0 +1,28 @@
+# Copyright (c) 2016 Cisco Systems, Inc.
+# 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.
+
+vppplugins_LTLIBRARIES += l2e_plugin.la
+
+l2e_plugin_la_SOURCES = 	\
+	l2e/l2e.c		\
+	l2e/l2e_api.c
+
+API_FILES += l2e/l2e.api
+
+noinst_HEADERS += 		\
+	l2e/l2e.h		\
+	l2e/l2e_all_api_h.h	\
+	l2e/l2e_msg_enum.h	\
+	l2e/l2e.api.h
+
+# vi:syntax=automake
diff --git a/src/plugins/l2e/l2e.api b/src/plugins/l2e/l2e.api
new file mode 100644
index 0000000..172ed48
--- /dev/null
+++ b/src/plugins/l2e/l2e.api
@@ -0,0 +1,38 @@
+/* Hey Emacs use -*- mode: C -*- */
+/*
+ * 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.
+ */
+
+vl_api_version 1.0.0
+
+/** \brief L2 emulation at L3
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param sw_if_index - interface the operation is applied to
+    @param enable - Turn the service on or off
+*/
+autoreply define l2_emulation
+{
+  u32 client_index;
+  u32 context;
+  u32 sw_if_index;
+  u32 ip_table_id;
+  u8  enable;
+};
+
+/*
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/l2e/l2e.c b/src/plugins/l2e/l2e.c
new file mode 100644
index 0000000..633d1f9
--- /dev/null
+++ b/src/plugins/l2e/l2e.c
@@ -0,0 +1,485 @@
+/*
+ * l2_emulation.h : Extract L3 packets from the L2 input and feed
+ *                   them into the L3 path.
+ *
+ * Copyright (c) 2013 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 <plugins/l2e/l2e.h>
+#include <vnet/l2/l2_input.h>
+
+/**
+ * Grouping of global data for the L2 emulation feature
+ */
+typedef struct l2_emulation_main_t_
+{
+  /**
+   * Next nodes for L2 output features
+   */
+  u32 l2_input_feat_next[32];
+} l2_emulation_main_t;
+
+static l2_emulation_main_t l2_emulation_main;
+
+/**
+ * Per-interface L2 configuration
+ */
+typedef struct l2_emulation_t_
+{
+  /**
+   * Enabled or Disabled.
+   *  this is required since one L3 protocl can be enabled, but others not
+   */
+  u8 enabled;
+} l2_emulation_t;
+
+/**
+ * A zero'd out struct we can use in the vec_validate
+ */
+static const l2_emulation_t ezero = { };
+
+/**
+ * Per-interface vector of emulation configs
+ */
+l2_emulation_t *l2_emulations;
+
+void
+l2_emulation_enable (u32 sw_if_index)
+{
+  vec_validate_init_empty (l2_emulations, sw_if_index, ezero);
+
+  l2_emulation_t *l23e = &l2_emulations[sw_if_index];
+
+  l23e->enabled = 1;
+
+  /*
+   * L3 enable the interface - using IP unnumbered from the control
+   * plane may not be possible since there may be no BVI interface
+   * to which to unnumber
+   */
+  ip4_sw_interface_enable_disable (sw_if_index, 1);
+  ip6_sw_interface_enable_disable (sw_if_index, 1);
+
+  l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_L2_EMULATION, 1);
+}
+
+
+void
+l2_emulation_disable (u32 sw_if_index)
+{
+  if (vec_len (l2_emulations) >= sw_if_index)
+    {
+      l2_emulation_t *l23e = &l2_emulations[sw_if_index];
+      memset (l23e, 0, sizeof (*l23e));
+
+      l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_L2_EMULATION, 0);
+      ip4_sw_interface_enable_disable (sw_if_index, 0);
+      ip6_sw_interface_enable_disable (sw_if_index, 0);
+    }
+}
+
+static clib_error_t *
+l2_emulation_interface_add_del (vnet_main_t * vnm,
+				u32 sw_if_index, u32 is_add)
+{
+  if (is_add)
+    {
+      vec_validate_init_empty (l2_emulations, sw_if_index, ezero);
+    }
+
+  return (NULL);
+}
+
+VNET_SW_INTERFACE_ADD_DEL_FUNCTION (l2_emulation_interface_add_del);
+
+static clib_error_t *
+l2_emulation_cli (vlib_main_t * vm,
+		  unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 sw_if_index = ~0;
+  u8 enable = 1;
+
+  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"))
+	enable = 1;
+      else if (unformat (input, "disable"))
+	enable = 0;
+      else
+	break;
+    }
+
+  if (~0 == sw_if_index)
+    return clib_error_return (0, "interface must be specified");
+
+  if (enable)
+    l2_emulation_enable (sw_if_index);
+  else
+    l2_emulation_disable (sw_if_index);
+
+  return (NULL);
+}
+
+/*?
+ * Configure l2 emualtion.
+ *  When the interface is in L2 mode, configure the extraction of L3
+ *  packets out of the L2 path and into the L3 path.
+ *
+ * @cliexpar
+ * @cliexstart{set interface l2 input l2-emulation <interface-name> [disable]
+ * @cliexend
+ ?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (l2_emulation_cli_node, static) = {
+  .path = "set interface l2 l2-emulation",
+  .short_help =
+  "set interface l2 l2-emulation <interface-name> [disable|enable]\n",
+  .function = l2_emulation_cli,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+l2_emulation_show (vlib_main_t * vm,
+		   unformat_input_t * input, vlib_cli_command_t * cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  l2_emulation_t *l23e;
+  u32 sw_if_index;
+
+  vec_foreach_index (sw_if_index, l2_emulations)
+  {
+    l23e = &l2_emulations[sw_if_index];
+    if (l23e->enabled)
+      {
+	vlib_cli_output (vm, "%U\n",
+			 format_vnet_sw_if_index_name, vnm, sw_if_index);
+      }
+  }
+  return (NULL);
+}
+
+/*?
+ * Show l2 emulation.
+ *  When the interface is in L2 mode, configure the extraction of L3
+ *  packets out of the L2 path and into the L3 path.
+ *
+ * @cliexpar
+ * @cliexstart{show interface l2 l2-emulation
+ * @cliexend
+ ?*/
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (l2_emulation_show_node, static) = {
+  .path = "show interface l2 l2-emulation",
+  .short_help = "show interface l2 l2-emulation\n",
+  .function = l2_emulation_show,
+};
+/* *INDENT-ON* */
+
+#define foreach_l2_emulation                    \
+  _(IP4, "Extract IPv4")                        \
+  _(IP6, "Extract IPv6")
+
+typedef enum
+{
+#define _(sym,str) L2_EMULATION_ERROR_##sym,
+  foreach_l2_emulation
+#undef _
+    L2_EMULATION_N_ERROR,
+} l2_emulation_error_t;
+
+static char *l2_emulation_error_strings[] = {
+#define _(sym,string) string,
+  foreach_l2_emulation
+#undef _
+};
+
+typedef enum
+{
+#define _(sym,str) L2_EMULATION_NEXT_##sym,
+  foreach_l2_emulation
+#undef _
+    L2_EMULATION_N_NEXT,
+} l2_emulation_next_t;
+
+/**
+ * per-packet trace data
+ */
+typedef struct l2_emulation_trace_t_
+{
+  /* per-pkt trace data */
+  u8 extracted;
+} l2_emulation_trace_t;
+
+static uword
+l2_emulation_node_fn (vlib_main_t * vm,
+		      vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  l2_emulation_main_t *em = &l2_emulation_main;
+  u32 n_left_from, *from, *to_next;
+  l2_emulation_next_t next_index;
+  u32 ip4_hits = 0;
+  u32 ip6_hits = 0;
+
+  next_index = 0;
+  n_left_from = frame->n_vectors;
+  from = vlib_frame_vector_args (frame);
+
+  while (n_left_from > 0)
+    {
+      u32 n_left_to_next;
+
+      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
+      while (n_left_from >= 4 && n_left_to_next >= 2)
+	{
+	  vlib_buffer_t *b0, *b1;
+	  u32 sw_if_index0, sw_if_index1;
+	  u16 ether_type0, ether_type1;
+	  u32 next0 = ~0, next1 = ~0;
+	  u8 l2_len0, l2_len1;
+	  u32 bi0, bi1;
+	  u8 *h0, *h1;
+
+	  bi0 = to_next[0] = from[0];
+	  bi1 = to_next[1] = from[1];
+
+	  from += 2;
+	  n_left_from -= 2;
+	  to_next += 2;
+	  n_left_to_next -= 2;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+	  b1 = vlib_get_buffer (vm, bi1);
+	  l2_len0 = vnet_buffer (b0)->l2.l2_len;
+	  l2_len1 = vnet_buffer (b1)->l2.l2_len;
+
+	  h0 = vlib_buffer_get_current (b0);
+	  h1 = vlib_buffer_get_current (b1);
+
+	  ether_type0 = clib_net_to_host_u16 (*(u16 *) (h0 + l2_len0 - 2));
+	  ether_type1 = clib_net_to_host_u16 (*(u16 *) (h1 + l2_len1 - 2));
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+	  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
+
+	  /*
+	   * only extract unicast
+	   */
+	  if (PREDICT_TRUE (!(h0[0] & 0x1)))
+	    {
+	      switch (ether_type0)
+		{
+		case ETHERNET_TYPE_IP4:
+		  ASSERT (l2_emulations[sw_if_index0].enabled);
+		  ++ip4_hits;
+		  next0 = L2_EMULATION_NEXT_IP4;
+		  vlib_buffer_advance (b0, l2_len0);
+		  break;
+		case ETHERNET_TYPE_IP6:
+		  ASSERT (l2_emulations[sw_if_index0].enabled);
+		  ++ip6_hits;
+		  next0 = L2_EMULATION_NEXT_IP6;
+		  vlib_buffer_advance (b0, l2_len0);
+		default:
+		  break;
+		}
+	    }
+	  if (PREDICT_TRUE (!(h1[0] & 0x1)))
+	    {
+	      switch (ether_type1)
+		{
+		case ETHERNET_TYPE_IP4:
+		  ASSERT (l2_emulations[sw_if_index1].enabled);
+		  ++ip4_hits;
+		  next1 = L2_EMULATION_NEXT_IP4;
+		  vlib_buffer_advance (b1, l2_len1);
+		  break;
+		case ETHERNET_TYPE_IP6:
+		  ASSERT (l2_emulations[sw_if_index1].enabled);
+		  ++ip6_hits;
+		  next1 = L2_EMULATION_NEXT_IP6;
+		  vlib_buffer_advance (b1, l2_len1);
+		default:
+		  break;
+		}
+	    }
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      l2_emulation_trace_t *t =
+		vlib_add_trace (vm, node, b0, sizeof (*t));
+	      t->extracted = (next0 != ~0);
+	    }
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			     && (b1->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      l2_emulation_trace_t *t =
+		vlib_add_trace (vm, node, b1, sizeof (*t));
+	      t->extracted = (next1 != ~0);
+	    }
+
+	  /* Determine the next node and remove ourself from bitmap */
+	  if (PREDICT_TRUE (next0 == ~0))
+	    next0 = vnet_l2_feature_next (b0, em->l2_input_feat_next,
+					  L2INPUT_FEAT_L2_EMULATION);
+
+	  /* Determine the next node and remove ourself from bitmap */
+	  if (PREDICT_TRUE (next1 == ~0))
+	    next1 = vnet_l2_feature_next (b1, em->l2_input_feat_next,
+					  L2INPUT_FEAT_L2_EMULATION);
+
+	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, bi1, next0, next1);
+	}
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t *b0;
+	  u32 sw_if_index0;
+	  u16 ether_type0;
+	  u32 next0 = ~0;
+	  u8 l2_len0;
+	  u32 bi0;
+	  u8 *h0;
+
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+	  l2_len0 = vnet_buffer (b0)->l2.l2_len;
+
+	  h0 = vlib_buffer_get_current (b0);
+	  ether_type0 = clib_net_to_host_u16 (*(u16 *) (h0 + l2_len0 - 2));
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+
+	  /*
+	   * only extract unicast
+	   */
+	  if (PREDICT_TRUE (!(h0[0] & 0x1)))
+	    {
+	      switch (ether_type0)
+		{
+		case ETHERNET_TYPE_IP4:
+		  ASSERT (l2_emulations[sw_if_index0].enabled);
+		  ++ip4_hits;
+		  next0 = L2_EMULATION_NEXT_IP4;
+		  vlib_buffer_advance (b0, l2_len0);
+		  break;
+		case ETHERNET_TYPE_IP6:
+		  ASSERT (l2_emulations[sw_if_index0].enabled);
+		  ++ip6_hits;
+		  next0 = L2_EMULATION_NEXT_IP6;
+		  vlib_buffer_advance (b0, l2_len0);
+		default:
+		  break;
+		}
+	    }
+
+	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
+			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      l2_emulation_trace_t *t =
+		vlib_add_trace (vm, node, b0, sizeof (*t));
+	      t->extracted = (next0 != ~0);
+	    }
+
+	  /* Determine the next node and remove ourself from bitmap */
+	  if (PREDICT_TRUE (next0 == ~0))
+	    next0 = vnet_l2_feature_next (b0, em->l2_input_feat_next,
+					  L2INPUT_FEAT_L2_EMULATION);
+
+	  /* verify speculative enqueue, maybe switch current next frame */
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					   to_next, n_left_to_next,
+					   bi0, next0);
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, node->node_index,
+			       L2_EMULATION_ERROR_IP4, ip4_hits);
+  vlib_node_increment_counter (vm, node->node_index,
+			       L2_EMULATION_ERROR_IP6, ip6_hits);
+
+  return frame->n_vectors;
+}
+
+/* packet trace format function */
+static u8 *
+format_l2_emulation_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  l2_emulation_trace_t *t = va_arg (*args, l2_emulation_trace_t *);
+
+  s = format (s, "l2-emulation: %s", (t->extracted ? "yes" : "no"));
+
+  return s;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (l2_emulation_node) = {
+  .function = l2_emulation_node_fn,
+  .name = "l2-emulation",
+  .vector_size = sizeof (u32),
+  .format_trace = format_l2_emulation_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+
+  .n_errors = ARRAY_LEN(l2_emulation_error_strings),
+  .error_strings = l2_emulation_error_strings,
+
+  .n_next_nodes = L2_EMULATION_N_NEXT,
+
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [L2_EMULATION_NEXT_IP4] = "ip4-input",
+    [L2_EMULATION_NEXT_IP6] = "ip6-input",
+  },
+};
+/* *INDENT-ON* */
+
+VLIB_NODE_FUNCTION_MULTIARCH (l2_emulation_node, l2_emulation_node_fn);
+
+
+static clib_error_t *
+l2_emulation_init (vlib_main_t * vm)
+{
+  l2_emulation_main_t *em = &l2_emulation_main;
+
+  /* Initialize the feature next-node indexes */
+  feat_bitmap_init_next_nodes (vm,
+			       l2_emulation_node.index,
+			       L2INPUT_N_FEAT,
+			       l2input_get_feat_names (),
+			       em->l2_input_feat_next);
+
+  return 0;
+}
+
+VLIB_INIT_FUNCTION (l2_emulation_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/l2e/l2e.h b/src/plugins/l2e/l2e.h
new file mode 100644
index 0000000..9549501
--- /dev/null
+++ b/src/plugins/l2e/l2e.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2013 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef included_vnet_l2_emulation_h
+#define included_vnet_l2_emulation_h
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+
+/**
+ * L2 Emulation is a feautre that is applied to L2 ports to 'extract'
+ * IP packets from the L2 path and inject them into the L3 path (i.e.
+ * into the appropriate ip[4|6]_input node).
+ * L3 routes in the table_id for that interface should then be configured
+ * as DVR routes, therefore the forwarded packet has the L2 header
+ * preserved and togehter the L3 routed system behaves like an L2 bridge.
+ */
+extern void l2_emulation_enable (u32 sw_if_index);
+extern void l2_emulation_disable (u32 sw_if_index);
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/l2e/l2e_all_api_h.h b/src/plugins/l2e/l2e_all_api_h.h
new file mode 100644
index 0000000..44fad6b
--- /dev/null
+++ b/src/plugins/l2e/l2e_all_api_h.h
@@ -0,0 +1,17 @@
+/*
+ * 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 the generated file, see BUILT_SOURCES in Makefile.am */
+#include <l2e/l2e.api.h>
+
diff --git a/src/plugins/l2e/l2e_api.c b/src/plugins/l2e/l2e_api.c
new file mode 100644
index 0000000..470427e
--- /dev/null
+++ b/src/plugins/l2e/l2e_api.c
@@ -0,0 +1,162 @@
+/*
+ *------------------------------------------------------------------
+ * l2e_api.c - layer 2 emulation api
+ *
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#include <vnet/vnet.h>
+#include <vnet/plugin/plugin.h>
+
+#include <vnet/interface.h>
+#include <vnet/api_errno.h>
+#include <vpp/app/version.h>
+
+#include <l2e/l2e.h>
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+
+/* define message IDs */
+#include <l2e/l2e_msg_enum.h>
+
+#define vl_typedefs		/* define message structures */
+#include <l2e/l2e_all_api_h.h>
+#undef vl_typedefs
+
+#define vl_endianfun		/* define message structures */
+#include <l2e/l2e_all_api_h.h>
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+#define vl_printfun
+#include <l2e/l2e_all_api_h.h>
+#undef vl_printfun
+
+/* Get the API version number */
+#define vl_api_version(n,v) static u32 api_version=(v);
+#include <acl/acl_all_api_h.h>
+#undef vl_api_version
+
+#include <vlibapi/api_helper_macros.h>
+
+#define foreach_l2e_api_msg                                 \
+_(L2_EMULATION, l2_emulation)
+
+/**
+ * L2 Emulation Main
+ */
+typedef struct l2_emulation_main_t_
+{
+  u16 msg_id_base;
+} l2_emulation_main_t;
+
+static l2_emulation_main_t l2_emulation_main;
+
+#define L2E_MSG_BASE l2_emulation_main.msg_id_base
+
+static void
+vl_api_l2_emulation_t_handler (vl_api_l2_emulation_t * mp)
+{
+  vl_api_l2_emulation_reply_t *rmp;
+  int rv = 0;
+
+  VALIDATE_SW_IF_INDEX (mp);
+
+  u32 sw_if_index = ntohl (mp->sw_if_index);
+
+  if (mp->enable)
+    l2_emulation_enable (sw_if_index);
+  else
+    l2_emulation_disable (sw_if_index);
+
+  BAD_SW_IF_INDEX_LABEL;
+
+  REPLY_MACRO (VL_API_L2_EMULATION_REPLY + L2E_MSG_BASE);
+}
+
+/*
+ * l2_api_hookup
+ * Add vpe's API message handlers to the table.
+ * vlib has alread mapped shared memory and
+ * added the client registration handlers.
+ * See .../vlib-api/vlibmemory/memclnt_vlib.c:memclnt_process()
+ */
+#define vl_msg_name_crc_list
+#include <l2e/l2e_all_api_h.h>
+#undef vl_msg_name_crc_list
+
+static void
+setup_message_id_table (api_main_t * am)
+{
+#define _(id,n,crc)                                     \
+  vl_msg_api_add_msg_name_crc (am, #n "_" #crc, id + L2E_MSG_BASE);
+  foreach_vl_msg_name_crc_l2e;
+#undef _
+}
+
+static void
+l2e_api_hookup (vlib_main_t * vm)
+{
+#define _(N,n)                                                  \
+    vl_msg_api_set_handlers(VL_API_##N + L2E_MSG_BASE,          \
+                            #n,                                 \
+                            vl_api_##n##_t_handler,             \
+                            vl_noop_handler,                    \
+                            vl_api_##n##_t_endian,              \
+                            vl_api_##n##_t_print,               \
+                            sizeof(vl_api_##n##_t), 1);
+  foreach_l2e_api_msg;
+#undef _
+}
+
+static clib_error_t *
+l2e_init (vlib_main_t * vm)
+{
+  api_main_t *am = &api_main;
+  l2_emulation_main_t *l2em = &l2_emulation_main;
+  u8 *name = format (0, "l2e_%08x%c", api_version, 0);
+
+  /* Ask for a correctly-sized block of API message decode slots */
+  l2em->msg_id_base = vl_msg_api_get_msg_ids ((char *) name,
+					      VL_MSG_FIRST_AVAILABLE);
+
+  l2e_api_hookup (vm);
+
+  /* Add our API messages to the global name_crc hash table */
+  setup_message_id_table (am);
+
+  vec_free (name);
+  return (NULL);
+}
+
+VLIB_API_INIT_FUNCTION (l2e_init);
+
+/* *INDENT-OFF* */
+VLIB_PLUGIN_REGISTER () = {
+    .version = VPP_BUILD_VER,
+    .description = "L2 Emulation",
+};
+/* *INDENT-ON* */
+
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/l2e/l2e_msg_enum.h b/src/plugins/l2e/l2e_msg_enum.h
new file mode 100644
index 0000000..85c8328
--- /dev/null
+++ b/src/plugins/l2e/l2e_msg_enum.h
@@ -0,0 +1,28 @@
+/*
+ * 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.
+ */
+#ifndef included_l2e_msg_enum_h
+#define included_l2e_msg_enum_h
+
+#include <vppinfra/byte_order.h>
+
+#define vl_msg_id(n,h) n,
+typedef enum {
+#include <l2e/l2e_all_api_h.h>
+    /* We'll want to know how many messages IDs we need... */
+    VL_MSG_FIRST_AVAILABLE,
+} vl_msg_id_t;
+#undef vl_msg_id
+
+#endif
diff --git a/src/vnet/dpo/l2_bridge_dpo.c b/src/vnet/dpo/l2_bridge_dpo.c
index 7317fcd..fd92a61 100644
--- a/src/vnet/dpo/l2_bridge_dpo.c
+++ b/src/vnet/dpo/l2_bridge_dpo.c
@@ -312,7 +312,7 @@
             vnet_buffer(b0)->sw_if_index[VLIB_TX] = l2b0->l2b_sw_if_index;
 
             /*
-             * take that, and rewind it back...
+             * take that, rewind it back...
              */
             len0 = ((u8*)vlib_buffer_get_current(b0) -
                     (u8*)ethernet_buffer_get_header(b0));
diff --git a/src/vnet/l2/l2_input.h b/src/vnet/l2/l2_input.h
index e8a6c77..dc9d954 100644
--- a/src/vnet/l2/l2_input.h
+++ b/src/vnet/l2/l2_input.h
@@ -112,6 +112,7 @@
  _(FWD,           "l2-fwd")                     \
  _(RW,            "l2-rw")                      \
  _(LEARN,         "l2-learn")                   \
+ _(L2_EMULATION,  "l2-emulation")               \
  _(VTR,           "l2-input-vtr")               \
  _(VPATH,         "vpath-input-l2")             \
  _(ACL,           "l2-input-acl")               \
diff --git a/src/vpp-api/vom/Makefile.am b/src/vpp-api/vom/Makefile.am
index 8eab140..b1fbfee 100644
--- a/src/vpp-api/vom/Makefile.am
+++ b/src/vpp-api/vom/Makefile.am
@@ -72,6 +72,8 @@
 	ip_unnumbered.cpp		\
 	l2_binding_cmds.cpp		\
 	l2_binding.cpp			\
+	l2_emulation_cmds.cpp		\
+	l2_emulation.cpp		\
 	l3_binding_cmds.cpp		\
 	l3_binding.cpp			\
 	lldp_binding_cmds.cpp		\
@@ -130,6 +132,7 @@
 	interface_span.hpp		\
 	ip_unnumbered.hpp		\
 	l2_binding.hpp			\
+	l2_emulation.hpp		\
 	l3_binding.hpp			\
 	lldp_binding.hpp		\
 	lldp_global.hpp			\
diff --git a/src/vpp-api/vom/bridge_domain.cpp b/src/vpp-api/vom/bridge_domain.cpp
index ef737d9..17144a6 100644
--- a/src/vpp-api/vom/bridge_domain.cpp
+++ b/src/vpp-api/vom/bridge_domain.cpp
@@ -67,7 +67,7 @@
 bool
 bridge_domain::operator==(const bridge_domain& b) const
 {
-  return (id() == b.id());
+  return ((m_learning_mode == b.m_learning_mode) && id() == b.id());
 }
 
 void
diff --git a/src/vpp-api/vom/l2_emulation.cpp b/src/vpp-api/vom/l2_emulation.cpp
new file mode 100644
index 0000000..2a27576
--- /dev/null
+++ b/src/vpp-api/vom/l2_emulation.cpp
@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2017 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 "vom/l2_emulation.hpp"
+#include "vom/l2_emulation_cmds.hpp"
+
+namespace VOM {
+/**
+ * A DB of all the L2 Configs
+ */
+singular_db<l2_emulation::key_t, l2_emulation> l2_emulation::m_db;
+
+l2_emulation::event_handler l2_emulation::m_evh;
+
+/**
+ * Construct a new object matching the desried state
+ */
+l2_emulation::l2_emulation(const interface& itf)
+  : m_itf(itf.singular())
+  , m_emulation(0)
+{
+}
+
+l2_emulation::l2_emulation(const l2_emulation& o)
+  : m_itf(o.m_itf)
+  , m_emulation(0)
+{
+}
+
+const l2_emulation::key_t&
+l2_emulation::key() const
+{
+  return (m_itf->key());
+}
+
+bool
+l2_emulation::operator==(const l2_emulation& l) const
+{
+  return ((*m_itf == *l.m_itf));
+}
+
+std::shared_ptr<l2_emulation>
+l2_emulation::find(const key_t& key)
+{
+  return (m_db.find(key));
+}
+
+void
+l2_emulation::sweep()
+{
+  if (m_emulation && handle_t::INVALID != m_itf->handle()) {
+    HW::enqueue(
+      new l2_emulation_cmds::enable_cmd(m_emulation, m_itf->handle()));
+  }
+
+  // no need to undo the VTR operation.
+  HW::write();
+}
+
+void
+l2_emulation::replay()
+{
+  if (m_emulation && handle_t::INVALID != m_itf->handle()) {
+    HW::enqueue(
+      new l2_emulation_cmds::disable_cmd(m_emulation, m_itf->handle()));
+  }
+}
+
+l2_emulation::~l2_emulation()
+{
+  sweep();
+
+  // not in the DB anymore.
+  m_db.release(m_itf->key(), this);
+}
+
+std::string
+l2_emulation::to_string() const
+{
+  std::ostringstream s;
+  s << "L2-emulation:[" << m_itf->to_string() << "]";
+
+  return (s.str());
+}
+
+void
+l2_emulation::update(const l2_emulation& desired)
+{
+  /*
+   * the desired state is always that the interface should be created
+   */
+  if (rc_t::OK != m_emulation.rc()) {
+    HW::enqueue(
+      new l2_emulation_cmds::enable_cmd(m_emulation, m_itf->handle()));
+  }
+}
+
+std::shared_ptr<l2_emulation>
+l2_emulation::find_or_add(const l2_emulation& temp)
+{
+  return (m_db.find_or_add(temp.m_itf->key(), temp));
+}
+
+std::shared_ptr<l2_emulation>
+l2_emulation::singular() const
+{
+  return find_or_add(*this);
+}
+
+void
+l2_emulation::dump(std::ostream& os)
+{
+  m_db.dump(os);
+}
+
+l2_emulation::event_handler::event_handler()
+{
+  OM::register_listener(this);
+  inspect::register_handler({ "l2e" }, "L2 Emulation", this);
+}
+
+void
+l2_emulation::event_handler::handle_replay()
+{
+  m_db.replay();
+}
+
+void
+l2_emulation::event_handler::handle_populate(const client_db::key_t& key)
+{
+  /**
+   * This is done while populating the bridge-domain
+   */
+}
+
+dependency_t
+l2_emulation::event_handler::order() const
+{
+  return (dependency_t::BINDING);
+}
+
+void
+l2_emulation::event_handler::show(std::ostream& os)
+{
+  m_db.dump(os);
+}
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "mozilla")
+ * End:
+ */
diff --git a/src/vpp-api/vom/l2_emulation.hpp b/src/vpp-api/vom/l2_emulation.hpp
new file mode 100644
index 0000000..faf4df8
--- /dev/null
+++ b/src/vpp-api/vom/l2_emulation.hpp
@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2017 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 __VOM_L2_EMULATION_H__
+#define __VOM_L2_EMULATION_H__
+
+#include "vom/bridge_domain.hpp"
+#include "vom/hw.hpp"
+#include "vom/inspect.hpp"
+#include "vom/interface.hpp"
+#include "vom/object_base.hpp"
+#include "vom/om.hpp"
+#include "vom/singular_db.hpp"
+
+namespace VOM {
+/**
+ * A Clas representing the binding of an L2 interface to a bridge-domain
+ * and the properties of that binding.
+ */
+class l2_emulation : public object_base
+{
+public:
+  /**
+   * Key type for an L2 emulation in the singular DB
+   */
+  typedef interface::key_t key_t;
+
+  /**
+   * Construct a new object matching the desried state
+   */
+  l2_emulation(const interface& itf);
+
+  /**
+   * Copy Constructor
+   */
+  l2_emulation(const l2_emulation& o);
+
+  /**
+   * Destructor
+   */
+  ~l2_emulation();
+
+  /**
+   * Return the binding's key
+   */
+  const key_t& key() const;
+
+  /**
+   * Comparison operator - for UT
+   */
+  bool operator==(const l2_emulation& l) const;
+
+  /**
+   * Return the 'singular instance' of the L2 config that matches this
+   * object
+   */
+  std::shared_ptr<l2_emulation> singular() const;
+
+  /**
+   * convert to string format for debug purposes
+   */
+  std::string to_string() const;
+
+  /**
+   * Dump all l2_emulations into the stream provided
+   */
+  static void dump(std::ostream& os);
+
+  /**
+   * Static function to find the bridge_domain in the model
+   */
+  static std::shared_ptr<l2_emulation> find(const key_t& key);
+
+private:
+  /**
+   * Class definition for listeners to OM events
+   */
+  class event_handler : public OM::listener, public inspect::command_handler
+  {
+  public:
+    event_handler();
+    virtual ~event_handler() = default;
+
+    /**
+     * Handle a populate event
+     */
+    void handle_populate(const client_db::key_t& key);
+
+    /**
+     * Handle a replay event
+     */
+    void handle_replay();
+
+    /**
+     * Show the object in the Singular DB
+     */
+    void show(std::ostream& os);
+
+    /**
+     * Get the sortable Id of the listener
+     */
+    dependency_t order() const;
+  };
+
+  /**
+   * event_handler to register with OM
+   */
+  static event_handler m_evh;
+
+  /**
+   * Enquue commonds to the VPP command Q for the update
+   */
+  void update(const l2_emulation& obj);
+
+  /**
+   * Find or Add the singular instance in the DB
+   */
+  static std::shared_ptr<l2_emulation> find_or_add(const l2_emulation& temp);
+
+  /*
+   * It's the OM class that calls singular()
+   */
+  friend class OM;
+
+  /**
+   * It's the singular_db class that calls replay()
+   */
+  friend class singular_db<key_t, l2_emulation>;
+
+  /**
+   * Sweep/reap the object if still stale
+   */
+  void sweep(void);
+
+  /**
+   * replay the object to create it in hardware
+   */
+  void replay(void);
+
+  /**
+   * A reference counting pointer the interface that this L2 layer
+   * represents. By holding the reference here, we can guarantee that
+   * this object will outlive the interface
+   */
+  const std::shared_ptr<interface> m_itf;
+
+  /**
+   * HW configuration for the emulation. The bool representing the
+   * enable/disable.
+   */
+  HW::item<bool> m_emulation;
+
+  /**
+   * A map of all L2 emulation configurations
+   */
+  static singular_db<key_t, l2_emulation> m_db;
+};
+};
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "mozilla")
+ * End:
+ */
+
+#endif
diff --git a/src/vpp-api/vom/l2_emulation_cmds.cpp b/src/vpp-api/vom/l2_emulation_cmds.cpp
new file mode 100644
index 0000000..07107d6
--- /dev/null
+++ b/src/vpp-api/vom/l2_emulation_cmds.cpp
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017 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 "vom/l2_emulation_cmds.hpp"
+
+DEFINE_VAPI_MSG_IDS_L2E_API_JSON;
+
+namespace VOM {
+namespace l2_emulation_cmds {
+enable_cmd::enable_cmd(HW::item<bool>& item, const handle_t& itf)
+  : rpc_cmd(item)
+  , m_itf(itf)
+{
+}
+
+bool
+enable_cmd::operator==(const enable_cmd& other) const
+{
+  return (m_itf == other.m_itf);
+}
+
+rc_t
+enable_cmd::issue(connection& con)
+{
+  msg_t req(con.ctx(), std::ref(*this));
+
+  auto& payload = req.get_request().get_payload();
+  payload.sw_if_index = m_itf.value();
+  payload.enable = 1;
+
+  VAPI_CALL(req.execute());
+
+  m_hw_item.set(wait());
+
+  return (rc_t::OK);
+}
+
+std::string
+enable_cmd::to_string() const
+{
+  std::ostringstream s;
+  s << "L2-emulation: " << m_hw_item.to_string()
+    << " itf:" << m_itf.to_string();
+
+  return (s.str());
+}
+
+disable_cmd::disable_cmd(HW::item<bool>& item, const handle_t& itf)
+  : rpc_cmd(item)
+  , m_itf(itf)
+{
+}
+
+bool
+disable_cmd::operator==(const disable_cmd& other) const
+{
+  return (m_itf == other.m_itf);
+}
+
+rc_t
+disable_cmd::issue(connection& con)
+{
+  msg_t req(con.ctx(), std::ref(*this));
+
+  auto& payload = req.get_request().get_payload();
+  payload.sw_if_index = m_itf.value();
+  payload.enable = 0;
+
+  VAPI_CALL(req.execute());
+
+  wait();
+
+  return (rc_t::OK);
+}
+
+std::string
+disable_cmd::to_string() const
+{
+  std::ostringstream s;
+  s << "L2-emulation: " << m_hw_item.to_string()
+    << " itf:" << m_itf.to_string();
+
+  return (s.str());
+}
+
+}; // namespace l2_emulation_cmds
+}; // namespace VOM
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "mozilla")
+ * End:
+ */
diff --git a/src/vpp-api/vom/l2_emulation_cmds.hpp b/src/vpp-api/vom/l2_emulation_cmds.hpp
new file mode 100644
index 0000000..aeff3a8
--- /dev/null
+++ b/src/vpp-api/vom/l2_emulation_cmds.hpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2017 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 __VOM_L2_EMULATION_CMDS_H__
+#define __VOM_L2_EMULATION_CMDS_H__
+
+#include "vom/l2_emulation.hpp"
+#include "vom/rpc_cmd.hpp"
+
+#include <vapi/l2e.api.vapi.hpp>
+
+namespace VOM {
+namespace l2_emulation_cmds {
+
+/**
+ * A functor class that enable L2 emulation to an interface
+ */
+class enable_cmd : public rpc_cmd<HW::item<bool>, rc_t, vapi::L2_emulation>
+{
+public:
+  /**
+   * Constructor
+   */
+  enable_cmd(HW::item<bool>& item, const handle_t& itf);
+
+  /**
+   * Issue the command to VPP/HW
+   */
+  rc_t issue(connection& con);
+  /**
+   * convert to string format for debug purposes
+   */
+  std::string to_string() const;
+
+  /**
+   * Comparison operator - only used for UT
+   */
+  bool operator==(const enable_cmd& i) const;
+
+private:
+  /**
+   * The interface to bind
+   */
+  const handle_t m_itf;
+};
+
+/**
+ * A cmd class that Unbinds L2 configuration from an interface
+ */
+class disable_cmd : public rpc_cmd<HW::item<bool>, rc_t, vapi::L2_emulation>
+{
+public:
+  /**
+   * Constructor
+   */
+  disable_cmd(HW::item<bool>& item, const handle_t& itf);
+
+  /**
+   * Issue the command to VPP/HW
+   */
+  rc_t issue(connection& con);
+  /**
+   * convert to string format for debug purposes
+   */
+  std::string to_string() const;
+
+  /**
+   * Comparison operator - only used for UT
+   */
+  bool operator==(const disable_cmd& i) const;
+
+private:
+  /**
+   * The interface to bind
+   */
+  const handle_t m_itf;
+};
+
+}; // namespace l2_emulation_cmds
+}; // namespace VOM
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "mozilla")
+ * End:
+ */
+
+#endif