diff --git a/src/vnet/tunnel/tunnel.c b/src/vnet/tunnel/tunnel.c
new file mode 100644
index 0000000..83b1046
--- /dev/null
+++ b/src/vnet/tunnel/tunnel.c
@@ -0,0 +1,58 @@
+/*
+ * tunnel.h: shared definitions for tunnels.
+ *
+ * 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 <vnet/tunnel/tunnel.h>
+
+u8 *
+format_tunnel_mode (u8 * s, va_list * args)
+{
+  tunnel_mode_t mode = va_arg (*args, int);
+
+  switch (mode)
+    {
+#define _(n, v) case TUNNEL_MODE_##n:       \
+        s = format (s, "%s", v);            \
+        break;
+      foreach_tunnel_mode
+#undef _
+    }
+
+  return (s);
+}
+
+u8 *
+format_tunnel_encap_decap_flags (u8 * s, va_list * args)
+{
+  tunnel_encap_decap_flags_t f = va_arg (*args, int);
+
+  if (f == TUNNEL_ENCAP_DECAP_FLAG_NONE)
+    return (format (s, "none"));
+
+#define _(a,b,c) if (f & TUNNEL_ENCAP_DECAP_FLAG_##a) s = format(s, "%s ", b);
+  forech_tunnel_encap_decap_flag
+#undef _
+    return (s);
+}
+
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */