diff --git a/src/session/gtest_session_table.cpp b/src/session/gtest_session_table.cpp
index 4539098..ddc174f 100644
--- a/src/session/gtest_session_table.cpp
+++ b/src/session/gtest_session_table.cpp
@@ -85,11 +85,11 @@ TEST(SESSION_TABLE, OP_SESSION)
     session_set_id(sess3, 3);
     session_set_address(sess3, &sess3_addr);
 
-    session_table_add_session(sess_table, sess1);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess1) == 0);
     EXPECT_TRUE(session_table_get_count(sess_table) == 1);
-    session_table_add_session(sess_table, sess2);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess2) == 0);
     EXPECT_TRUE(session_table_get_count(sess_table) == 2);
-    session_table_add_session(sess_table, sess3);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess3) == 0);
     EXPECT_TRUE(session_table_get_count(sess_table) == 3);
 
     // Search session with id
@@ -125,6 +125,73 @@ TEST(SESSION_TABLE, OP_SESSION)
     session_pool_destroy(sess_pool);
 }
 
+TEST(SESSION_TABLE, FIND_OLDEST_NEWEST)
+{
+    struct session *sess1 = NULL;
+    struct session *sess2 = NULL;
+    struct session *sess3 = NULL;
+    struct session_pool *sess_pool = NULL;
+    struct session_table *sess_table = NULL;
+
+    SESSION_ADDRESS_IPV4_TCP(sess1_addr);
+    SESSION_ADDRESS_IPV6_UDP(sess2_addr);
+    SESSION_ADDRESS_IPV4_UDP_IPV6_TCP(sess3_addr);
+
+    // Create
+    sess_pool = session_pool_create(3);
+    EXPECT_TRUE(sess_pool != NULL);
+    sess_table = session_table_create();
+    EXPECT_TRUE(sess_table != NULL);
+    session_table_set_freecb(sess_table, session_free_callback, sess_pool);
+
+    // Add Session
+
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == NULL);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == NULL);
+
+    sess1 = session_pool_alloc(sess_pool);
+    EXPECT_TRUE(sess1 != NULL);
+    session_set_id(sess1, 1);
+    session_set_address(sess1, &sess1_addr);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess1) == 0);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == sess1);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == sess1);
+
+    sess2 = session_pool_alloc(sess_pool);
+    EXPECT_TRUE(sess2 != NULL);
+    session_set_id(sess2, 2);
+    session_set_address(sess2, &sess2_addr);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess2) == 0);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == sess1);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == sess2);
+
+    sess3 = session_pool_alloc(sess_pool);
+    EXPECT_TRUE(sess3 != NULL);
+    session_set_id(sess3, 3);
+    session_set_address(sess3, &sess3_addr);
+    EXPECT_TRUE(session_table_add_session(sess_table, sess3) == 0);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == sess1);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == sess3);
+
+    // Delete Session
+
+    session_table_delete_session_by_id(sess_table, 1);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == sess2);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == sess3);
+
+    session_table_delete_session_by_id(sess_table, 2);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == sess3);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == sess3);
+
+    session_table_delete_session_by_id(sess_table, 3);
+    EXPECT_TRUE(session_table_find_oldest_session(sess_table) == NULL);
+    EXPECT_TRUE(session_table_find_newest_session(sess_table) == NULL);
+
+    // Destroy
+    session_table_destroy(sess_table);
+    session_pool_destroy(sess_pool);
+}
+
 int main(int argc, char **argv)
 {
     ::testing::InitGoogleTest(&argc, argv);
diff --git a/src/session/session.h b/src/session/session.h
index a43acd3..cdb2c0c 100644
--- a/src/session/session.h
+++ b/src/session/session.h
@@ -8,29 +8,31 @@ extern "C"
 
 #include <stdint.h>
 
+#include "session_address.h"
+
 enum session_state
 {
+    SESSION_STATE_NONE = 0,
     SESSION_STATE_OPENING,
     SESSION_STATE_ACTIVE,
-    SESSION_STATE_DISCARD,
     SESSION_STATE_CLOSING,
-    SESSION_STATE_CLOSED,
-    SESSION_STATE_FREE,
+    SESSION_STATE_DISCARD,
 };
 
 enum session_type
 {
+    SESSION_TYPE_NONE = 0,
     SESSION_TYPE_TCP,
-    SESSION_TYPE_TCP_STREAM, // A TCP stream session is derived from the original TCP session
     SESSION_TYPE_UDP,
 };
 
 enum session_event
 {
     SESSION_EVENT_NONE = 0,
-    SESSION_EVENT_OPEN,
-    SESSION_EVENT_DATA,
-    SESSION_EVENT_CLOSE,
+    SESSION_EVENT_OPENING,
+    SESSION_EVENT_ACTIVE,
+    SESSION_EVENT_CLOSING,
+    SESSION_EVENT_DISCARD,
     SESSION_EVENT_TIMEOUT,
 
     // Add new event before SESSION_EVENT_MAX
@@ -46,7 +48,7 @@ struct metadata
 struct session;
 
 /******************************************************************************
- * session
+ * session base info
  ******************************************************************************/
 
 void session_init(struct session *sess);
@@ -84,11 +86,14 @@ struct metadata *session_get0_s2c_1st_md(struct session *sess);
 // session timestamp
 void session_set_create_time(struct session *sess, uint64_t timestamp);
 void session_set_last_time(struct session *sess, uint64_t timestamp);
-void session_set_expire_time(struct session *sess, uint64_t timestamp);
 uint64_t session_get_create_time(struct session *sess);
 uint64_t session_get_last_time(struct session *sess);
 uint64_t session_get_expire_time(struct session *sess);
 
+/******************************************************************************
+ * session event
+ ******************************************************************************/
+
 // session event
 bool session_push_event(struct session *sess, uint32_t event);
 bool session_pop_event(struct session *sess, uint32_t *event);
diff --git a/src/session/session_address.h b/src/session/session_address.h
index 5b45465..b57f4ff 100644
--- a/src/session/session_address.h
+++ b/src/session/session_address.h
@@ -8,6 +8,8 @@ extern "C"
 
 #include <arpa/inet.h>
 
+#include "packet.h"
+
 #define SESSION_ADDR_MAX_LAYER 8
 
 enum layer_type
diff --git a/src/session/session_pool.cpp b/src/session/session_pool.cpp
index b5847a6..1fe3d66 100644
--- a/src/session/session_pool.cpp
+++ b/src/session/session_pool.cpp
@@ -20,9 +20,9 @@ struct session_pool *session_pool_create(uint64_t count)
 
     for (uint64_t i = 0; i < count; i++)
     {
-        pool->sess[i].next = &pool->sess[i + 1];
+        pool->sess[i].next_free_ptr = &pool->sess[i + 1];
     }
-    pool->sess[count - 1].next = NULL;
+    pool->sess[count - 1].next_free_ptr = NULL;
 
     return pool;
 }
@@ -49,8 +49,8 @@ struct session *session_pool_alloc(struct session_pool *pool)
         return NULL;
     }
 
-    pool->sess = sess->next;
-    sess->next = NULL;
+    pool->sess = sess->next_free_ptr;
+    sess->next_free_ptr = NULL;
     pool->count--;
 
     return sess;
@@ -63,7 +63,7 @@ void session_pool_free(struct session_pool *pool, struct session *sess)
         return;
     }
 
-    sess->next = pool->sess;
+    sess->next_free_ptr = pool->sess;
     pool->sess = sess;
     pool->count++;
 }
diff --git a/src/session/session_private.h b/src/session/session_private.h
index 5138e3f..d478d83 100644
--- a/src/session/session_private.h
+++ b/src/session/session_private.h
@@ -79,7 +79,7 @@ struct session
      ******************************/
 
     // session pool recycle handle
-    struct session *next;
+    struct session *next_free_ptr;
 
     /******************************
      * Session Table Zone
@@ -89,9 +89,18 @@ struct session
     uint64_t id;
     struct session_address addr;
 
+    struct session *next_ptr;
+    struct session *prev_ptr;
+
     // session table handle
     UT_hash_handle hh1; /* handle for root_id hash table */
     UT_hash_handle hh2; /* handle for root_addr hash table */
+
+    /******************************
+     * Session Manager Zone
+     ******************************/
+
+    struct session *next_ready_ptr;
 };
 
 #ifdef __cpluscplus
diff --git a/src/session/session_table.cpp b/src/session/session_table.cpp
index c76e23e..4e87a9f 100644
--- a/src/session/session_table.cpp
+++ b/src/session/session_table.cpp
@@ -10,12 +10,71 @@ struct session_table
     session_free_cb free_cb;
     void *arg;
     uint64_t count;
+
+    struct session *oldest_ptr;
+    struct session *newest_ptr;
 };
 
+static void session_table_add_session_to_linklist(struct session_table *table, struct session *sess)
+{
+    if (table == NULL || sess == NULL)
+    {
+        return;
+    }
+
+    if (table->newest_ptr == NULL)
+    {
+        table->oldest_ptr = sess;
+        table->newest_ptr = sess;
+        sess->prev_ptr = NULL;
+        sess->next_ptr = NULL;
+    }
+    else
+    {
+        sess->next_ptr = table->newest_ptr;
+        table->newest_ptr->prev_ptr = sess;
+        sess->prev_ptr = NULL;
+        table->newest_ptr = sess;
+    }
+}
+
+static void session_table_del_session_from_linklist(struct session_table *table, struct session *sess)
+{
+    if (table == NULL || sess == NULL)
+    {
+        return;
+    }
+
+    if (sess->prev_ptr == NULL && sess->next_ptr == NULL)
+    {
+        table->oldest_ptr = NULL;
+        table->newest_ptr = NULL;
+    }
+    else if (sess->prev_ptr == NULL && sess->next_ptr != NULL)
+    {
+        table->newest_ptr = sess->next_ptr;
+        sess->next_ptr->prev_ptr = NULL;
+    }
+    else if (sess->prev_ptr != NULL && sess->next_ptr == NULL)
+    {
+        table->oldest_ptr = sess->prev_ptr;
+        sess->prev_ptr->next_ptr = NULL;
+    }
+    else
+    {
+        sess->prev_ptr->next_ptr = sess->next_ptr;
+        sess->next_ptr->prev_ptr = sess->prev_ptr;
+    }
+    sess->prev_ptr = NULL;
+    sess->next_ptr = NULL;
+}
+
 struct session_table *session_table_create()
 {
     struct session_table *table = (struct session_table *)calloc(1, sizeof(struct session_table));
     table->count = 0;
+    table->oldest_ptr = NULL;
+    table->newest_ptr = NULL;
 
     return table;
 }
@@ -63,11 +122,16 @@ void session_table_set_freecb(struct session_table *table, session_free_cb free_
     }
 }
 
-void session_table_add_session(struct session_table *table, struct session *sess)
+int session_table_add_session(struct session_table *table, struct session *sess)
 {
     if (table == NULL || sess == NULL)
     {
-        return;
+        return -1;
+    }
+
+    if (session_table_find_session_by_id(table, sess->id) || session_table_find_session_by_addr(table, &sess->addr))
+    {
+        return -1;
     }
 
     if (session_address_selfcmp(&sess->addr) > 0)
@@ -78,7 +142,11 @@ void session_table_add_session(struct session_table *table, struct session *sess
     HASH_ADD(hh1, table->root_id, id, sizeof(sess->id), sess);
     HASH_ADD(hh2, table->root_addr, addr, sizeof(sess->addr), sess);
 
+    session_table_add_session_to_linklist(table, sess);
+
     table->count++;
+
+    return 0;
 }
 
 void session_table_delete_session_by_id(struct session_table *table, uint64_t id)
@@ -102,6 +170,8 @@ void session_table_delete_session_by_id(struct session_table *table, uint64_t id
         table->free_cb(sess, table->arg);
     }
 
+    session_table_del_session_from_linklist(table, sess);
+
     table->count--;
 }
 
@@ -126,6 +196,8 @@ void session_table_delete_session_by_addr(struct session_table *table, struct se
         table->free_cb(sess, table->arg);
     }
 
+    session_table_del_session_from_linklist(table, sess);
+
     table->count--;
 }
 
@@ -159,3 +231,23 @@ struct session *session_table_find_session_by_addr(struct session_table *table,
 
     return sess;
 }
+
+struct session *session_table_find_oldest_session(struct session_table *table)
+{
+    if (table == NULL)
+    {
+        return NULL;
+    }
+
+    return table->oldest_ptr;
+}
+
+struct session *session_table_find_newest_session(struct session_table *table)
+{
+    if (table == NULL)
+    {
+        return NULL;
+    }
+
+    return table->newest_ptr;
+}
\ No newline at end of file
diff --git a/src/session/session_table.h b/src/session/session_table.h
index 10c607d..680e0f9 100644
--- a/src/session/session_table.h
+++ b/src/session/session_table.h
@@ -15,16 +15,15 @@ uint64_t session_table_get_count(struct session_table *table);
 
 typedef void (*session_free_cb)(struct session *sess, void *arg);
 void session_table_set_freecb(struct session_table *table, session_free_cb free_cb, void *arg);
-/*
- * Before add session:
- *    user must set session id and session address.
- *    must not add session with same id or same address.
- */
-void session_table_add_session(struct session_table *table, struct session *sess);
+// return  0: success
+// return -1: failed
+int session_table_add_session(struct session_table *table, struct session *sess);
 void session_table_delete_session_by_id(struct session_table *table, uint64_t id);
 void session_table_delete_session_by_addr(struct session_table *table, struct session_address *addr);
 struct session *session_table_find_session_by_id(struct session_table *table, uint64_t id);
 struct session *session_table_find_session_by_addr(struct session_table *table, struct session_address *addr);
+struct session *session_table_find_oldest_session(struct session_table *table);
+struct session *session_table_find_newest_session(struct session_table *table);
 
 #ifdef __cpluscplus
 }