diff --git a/ospfd/ospf_asbr.h b/ospfd/ospf_asbr.h
index ede6c47906..ec02fa15a6 100644
--- a/ospfd/ospf_asbr.h
+++ b/ospfd/ospf_asbr.h
@@ -50,8 +50,57 @@ struct external_info {
 	route_tag_t orig_tag;
 
 	struct route_map_set_values route_map_set;
-#define ROUTEMAP_METRIC(E)      (E)->route_map_set.metric
+#define ROUTEMAP_METRIC(E) (E)->route_map_set.metric
 #define ROUTEMAP_METRIC_TYPE(E) (E)->route_map_set.metric_type
+
+	/* Back pointer to summary address */
+	struct ospf_external_aggr_rt *aggr_route;
+
+	/* To identify the routes to be originated
+	 * after a summary address deletion.
+	 */
+	bool to_be_processed;
+};
+
+#define OSPF_EXTL_AGGR_DEFAULT_DELAY 5
+
+#define OSPF_EXTERNAL_RT_COUNT(aggr)                                           \
+	(((struct ospf_external_aggr_rt *)aggr)->match_extnl_hash->count)
+
+enum ospf_aggr_action_t {
+	OSPF_ROUTE_AGGR_NONE = 0,
+	OSPF_ROUTE_AGGR_ADD,
+	OSPF_ROUTE_AGGR_DEL,
+	OSPF_ROUTE_AGGR_MODIFY
+};
+
+#define OSPF_SUCCESS 1
+#define OSPF_FAILURE 0
+#define OSPF_INVALID -1
+
+#define OSPF_EXTERNAL_AGGRT_NO_ADVERTISE 0x1
+#define OSPF_EXTERNAL_AGGRT_ORIGINATED 0x2
+
+/* Data structures for external route aggregator */
+struct ospf_external_aggr_rt {
+	/* Prefix. */
+	struct prefix_ipv4 p;
+
+	/* Bit 1 : Dont advertise.
+	 * Bit 2 : Originated as Type-5
+	 */
+	uint8_t flags;
+
+	/* Tag for summary route */
+	route_tag_t tag;
+
+	/* Action to be done at the delay
+	 * timer expairy.
+	 */
+	enum ospf_aggr_action_t action;
+
+	/* Hash Table of external routes */
+	struct hash *match_extnl_hash;
 };
 
 #define OSPF_ASBR_CHECK_DELAY 30
diff --git a/ospfd/ospf_dump.h b/ospfd/ospf_dump.h
index a2df4ff22c..ea607fef7c 100644
--- a/ospfd/ospf_dump.h
+++ b/ospfd/ospf_dump.h
@@ -49,6 +49,7 @@
 #define OSPF_DEBUG_LSA_INSTALL  0x04
 #define OSPF_DEBUG_LSA_REFRESH  0x08
 #define OSPF_DEBUG_LSA		0x0F
+#define OSPF_DEBUG_EXTNL_LSA_AGGR 0x10
 
 #define OSPF_DEBUG_ZEBRA_INTERFACE     0x01
 #define OSPF_DEBUG_ZEBRA_REDISTRIBUTE  0x02
diff --git a/ospfd/ospfd.h b/ospfd/ospfd.h
index 5be897400b..bdd09e1e76 100644
--- a/ospfd/ospfd.h
+++ b/ospfd/ospfd.h
@@ -355,6 +355,22 @@ struct ospf {
 	/* last HELPER exit reason */
 	uint32_t last_exit_reason;
 
+	/* delay timer to process external routes
+	 * with summary address.
+	 */
+	struct thread *t_external_aggr;
+
+	/* delay interval in seconds */
+	unsigned int aggr_delay_interval;
+
+	/* Table of configured Aggregate addresses */
+	struct route_table *rt_aggr_tbl;
+
+	/* used as argument for aggr delay
+	 * timer thread.
+	 */
+	int aggr_action;
+
 	/* MPLS LDP-IGP Sync */
 	struct ldp_sync_info_cmd ldp_sync_cmd;