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diff --git a/src/vnet/adj/adj_midchain.h b/src/vnet/adj/adj_midchain.h
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+/*
+ * 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.
+ */
+/**
+ * Midchain Adjacency sub-type. These adjs represent an L3 peer on a
+ * tunnel interface. The tunnel's adjacency is thus not the end of the chain,
+ * and needs to stack on/link to another chain (or portion of the graph) to
+ * reach the tunnel's destination.
+ */
+
+#ifndef __ADJ_MIDCHAIN_H__
+#define __ADJ_MIDCHAIN_H__
+
+#include <vnet/adj/adj.h>
+
+/**
+ * @brief Flags controlling the midchain adjacency
+ */
+typedef enum adj_midchain_flag_t_
+{
+    /**
+     * No flags
+     */
+    ADJ_MIDCHAIN_FLAG_NONE = 0,
+
+    /**
+     * Packets TX through the midchain do not increment the interface
+     * counters. This should be used when the adj is associated with an L2
+     * interface and that L2 interface is in a bridege domain. In that case
+     * the packet will have traversed the interface's TX node, and hence have
+     * been counted, before it traverses ths midchain
+     */
+    ADJ_MIDCHAIN_FLAG_NO_COUNT = (1 << 0),
+} adj_midchain_flag_t;
+
+/**
+ * @brief
+ *  Convert an existing neighbour adjacency into a midchain
+ *
+ * @param adj_index
+ *  The index of the neighbour adjacency.
+ *
+ * @param post_rewrite_node
+ *  The VLIB graph node that provides the post-encap fixup.
+ *  where 'fixup' is e.g., correcting chksum, length, etc.
+ *
+ * @param rewrite
+ *  The rewrite.
+ */
+extern void adj_nbr_midchain_update_rewrite(adj_index_t adj_index,
+					    adj_midchain_fixup_t fixup,
+					    adj_midchain_flag_t flags,
+					    u8 *rewrite);
+
+/**
+ * @brief
+ *  [re]stack a midchain. 'Stacking' is the act of forming parent-child
+ *  relationships in the data-plane graph.
+ *
+ * @param adj_index
+ *  The index of the midchain to stack
+ *
+ * @param dpo
+ *  The parent DPO to stack onto (i.e. become a child of).
+ */
+extern void adj_nbr_midchain_stack(adj_index_t adj_index,
+				   const dpo_id_t *dpo);
+
+/**
+ * @brief
+ *  unstack a midchain. This will break the chain between the midchain and
+ *  the next graph section. This is a implemented as stack-on-drop
+ *
+ * @param adj_index
+ *  The index of the midchain to stack
+ */
+extern void adj_nbr_midchain_unstack(adj_index_t adj_index);
+
+/**
+ * @brief
+ *  Module initialisation
+ */
+extern void adj_midchain_module_init(void);
+
+/**
+ * @brief
+ * Format a midchain adjacency
+ */
+extern u8* format_adj_midchain(u8* s, va_list *ap);
+
+#endif