diff --git a/src/vnet/tcp/tcp_sack.h b/src/vnet/tcp/tcp_sack.h
new file mode 100644
index 0000000..1c3fa95
--- /dev/null
+++ b/src/vnet/tcp/tcp_sack.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2020 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 SRC_VNET_TCP_TCP_SACK_H_
+#define SRC_VNET_TCP_TCP_SACK_H_
+
+#include <vnet/tcp/tcp_types.h>
+
+always_inline u32
+scoreboard_hole_index (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  ASSERT (!pool_is_free_index (sb->holes, hole - sb->holes));
+  return hole - sb->holes;
+}
+
+always_inline u32
+scoreboard_hole_bytes (sack_scoreboard_hole_t * hole)
+{
+  return hole->end - hole->start;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_get_hole (sack_scoreboard_t * sb, u32 index)
+{
+  if (index != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, index);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_next_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, hole->next);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_prev_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, hole->prev);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_first_hole (sack_scoreboard_t * sb)
+{
+  if (sb->head != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, sb->head);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_last_hole (sack_scoreboard_t * sb)
+{
+  if (sb->tail != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, sb->tail);
+  return 0;
+}
+
+#if TCP_SCOREBOARD_TRACE
+#define tcp_scoreboard_trace_add(_tc, _ack) 				\
+{									\
+    static u64 _group = 0;						\
+    sack_scoreboard_t *_sb = &_tc->sack_sb;				\
+    sack_block_t *_sack, *_sacks;					\
+    scoreboard_trace_elt_t *_elt;					\
+    int i;								\
+    _group++;								\
+    _sacks = _tc->rcv_opts.sacks;					\
+    for (i = 0; i < vec_len (_sacks); i++) 				\
+      {									\
+	_sack = &_sacks[i];						\
+	vec_add2 (_sb->trace, _elt, 1);					\
+	_elt->start = _sack->start;					\
+	_elt->end = _sack->end;						\
+	_elt->ack = _elt->end == _ack ? _ack : 0;			\
+	_elt->snd_una_max = _elt->end == _ack ? _tc->snd_una_max : 0;	\
+	_elt->group = _group;						\
+      }									\
+}
+#else
+#define tcp_scoreboard_trace_add(_tc, _ack)
+#endif
+
+sack_scoreboard_hole_t *scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
+						  sack_scoreboard_hole_t *
+						  start, u8 have_sent_1_smss,
+						  u8 * can_rescue,
+						  u8 * snd_limited);
+void scoreboard_clear (sack_scoreboard_t * sb);
+void scoreboard_clear_reneging (sack_scoreboard_t * sb, u32 start, u32 end);
+void scoreboard_init (sack_scoreboard_t * sb);
+void scoreboard_init_rxt (sack_scoreboard_t * sb, u32 snd_una);
+
+format_function_t format_tcp_scoreboard;
+
+/* Made public for unit testing only */
+void tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end);
+u32 tcp_sack_list_bytes (tcp_connection_t * tc);
+void tcp_rcv_sacks (tcp_connection_t * tc, u32 ack);
+u8 *tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose);
+u8 tcp_scoreboard_is_sane_post_recovery (tcp_connection_t * tc);
+
+#endif /* SRC_VNET_TCP_TCP_SACK_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */