diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index 722d7fe..3113bd4 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -275,44 +275,82 @@
 depends_on:MBEDTLS_SSL_PROTO_TLS1_2:MBEDTLS_RSA_C:MBEDTLS_ECP_DP_SECP384R1_ENABLED:MBEDTLS_SSL_PROTO_DTLS
 handshake:"":MBEDTLS_SSL_MINOR_VERSION_3:MBEDTLS_PK_RSA:"":1:1
 
-Test sending app data MFL=512 without fragmentation
+Sending app data via TLS, MFL=512 without fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_512:400:512:1:1
 
-Test sending app data MFL=512 with fragmentation
+Sending app data via TLS, MFL=512 with fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_512:513:1536:2:3
 
-Test sending app data MFL=1024 without fragmentation
+Sending app data via TLS, MFL=1024 without fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_1024:1000:1024:1:1
 
-Test sending app data MFL=1024 with fragmentation
+Sending app data via TLS, MFL=1024 with fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_1024:1025:5120:2:5
 
-Test sending app data MFL=2048 without fragmentation
+Sending app data via TLS, MFL=2048 without fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_2048:2000:2048:1:1
 
-Test sending app data MFL=2048 with fragmentation
+Sending app data via TLS, MFL=2048 with fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_2048:2049:8192:2:4
 
-Test sending app data MFL=4096 without fragmentation
+Sending app data via TLS, MFL=4096 without fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_4096:4000:4096:1:1
 
-Test sending app data MFL=4096 with fragmentation
+Sending app data via TLS, MFL=4096 with fragmentation
 depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_4096:4097:12288:2:3
 
-Test sending app data without MFL and without fragmentation
+Sending app data via TLS without MFL and without fragmentation
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_NONE:16001:16384:1:1
 
-Test sending app data without MFL and with fragmentation
+Sending app data via TLS without MFL and with fragmentation
 send_application_data:MBEDTLS_SSL_MAX_FRAG_LEN_NONE:16385:100000:2:7
 
+Sending app data via DTLS, MFL=512 without fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_512:400:512:1:1
+
+Sending app data via DTLS, MFL=512 with fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_512:513:1536:0:0
+
+Sending app data via DTLS, MFL=1024 without fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_1024:1000:1024:1:1
+
+Sending app data via DTLS, MFL=1024 with fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_1024:1025:5120:0:0
+
+Sending app data via DTLS, MFL=2048 without fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_2048:2000:2048:1:1
+
+Sending app data via DTLS, MFL=2048 with fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_2048:2049:8192:0:0
+
+Sending app data via DTLS, MFL=4096 without fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_4096:4000:4096:1:1
+
+Sending app data via DTLS, MFL=4096 with fragmentation
+depends_on:MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_4096:4097:12288:0:0
+
+Sending app data via DTLS, without MFL and without fragmentation
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_NONE:16001:16384:1:1
+
+Sending app data via DTLS, without MFL and with fragmentation
+send_application_data_dtls:MBEDTLS_SSL_MAX_FRAG_LEN_NONE:16385:100000:0:0
+
 SSL DTLS replay: initial state, seqnum 0
 ssl_dtls_replay:"":"000000000000":0
 
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index f25ad65..88e405b 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -928,31 +928,87 @@
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
 /*
- * Write application data. Then increase write and fragments counter
+ * Write application data. Increase write counter and fragments counter if
+ * necessary.
  */
 int mbedtls_ssl_write_fragment( mbedtls_ssl_context *ssl, unsigned char *buf,
-                                int ln, int *writen, int *fragments )
+                                int buf_len, int *written,
+                                int *fragments, const int expected_fragments )
 {
-    int ret = mbedtls_ssl_write( ssl, buf + *writen, ln - *writen );
-    if( ret >= 0 )
+    int ret = mbedtls_ssl_write( ssl, buf + *written, buf_len - *written );
+    if( ret > 0 )
     {
         (*fragments)++;
-        *writen += ret;
+        *written += ret;
     }
-    return ret;
+
+    if( expected_fragments == 0 )
+    {
+        /* Used for DTLS and the message size larger than MFL. In that case
+         * the message can not be fragmented and the library should return
+         * MBEDTLS_ERR_SSL_BAD_INPUT_DATA error. This error must be returned
+         * to prevent a dead loop inside mbedtls_exchange_data(). */
+        return ret;
+    }
+    else if( expected_fragments == 1 )
+    {
+        /* Used for TLS/DTLS and the message size lower than MFL */
+        TEST_ASSERT( ret == buf_len ||
+                     ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                     ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+    }
+    else
+    {
+        /* Used for TLS and the message size larger than MFL */
+        TEST_ASSERT( expected_fragments > 1 );
+        TEST_ASSERT( ( ret >= 0 && ret <= buf_len ) ||
+                       ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                       ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+    }
+
+    return 0;
+
+exit:
+    /* Some of the tests failed */
+    return -1;
 }
 
 /*
- * Read application data and increase read counter
+ * Read application data and increase read counter if necessary.
  */
-int mbedtls_ssl_read_fragment( mbedtls_ssl_context *ssl, unsigned char *buf, int ln, int *read )
+int mbedtls_ssl_read_fragment( mbedtls_ssl_context *ssl, unsigned char *buf,
+                               int buf_len, int *read,
+                               const int expected_fragments )
 {
-    int ret = mbedtls_ssl_read( ssl, buf + *read, ln - *read );
-    if( ret >= 0 )
+    int ret = mbedtls_ssl_read( ssl, buf + *read, buf_len - *read );
+    if( ret > 0 )
     {
         *read += ret;
     }
-    return ret;
+
+    if( expected_fragments == 0 )
+    {
+        TEST_ASSERT( ret == 0 );
+    }
+    else if( expected_fragments == 1 )
+    {
+        TEST_ASSERT( ret == buf_len ||
+                     ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                     ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+    }
+    else
+    {
+        TEST_ASSERT( expected_fragments > 1 );
+        TEST_ASSERT( ( ret >= 0 && ret <= buf_len ) ||
+                       ret == MBEDTLS_ERR_SSL_WANT_READ ||
+                       ret == MBEDTLS_ERR_SSL_WANT_WRITE );
+    }
+
+    return 0;
+
+exit:
+    /* Some of the tests failed */
+    return -1;
 }
 
 /*
@@ -1347,6 +1403,146 @@
     return( 0 );
 }
 
+/*
+ * Perform data exchanging between \p ssl_1 and \p ssl_2 and check if the
+ * message was sent in the correct number of fragments.
+ *
+ * /p ssl_1 and /p ssl_2    Endpoints represented by mbedtls_ssl_context. Both
+ *                          of them must be initialized and connected beforehand.
+ * /p msg_len_1 and /p msg_len_2 specify the size of the message to send.
+ * /p expected_fragments_1 and /p expected_fragments_2 determine in how many
+ *                          fragments the message should be sent.
+ *      expected_fragments is 0: can be used for DTLS testing while the message
+ *                          size is larger than MFL. In that case the message
+ *                          cannot be fragmented and sent to the second endpoint.
+ *                          This value can be used for negative tests.
+ *      expected_fragments is 1: can be used for TLS/DTLS testing while the
+ *                          message size is below MFL
+ *      expected_fragments > 1: can be used for TLS testing while the message
+ *                          size is larger than MFL
+ *
+ * \retval  0 on success, otherwise error code.
+ */
+int mbedtls_exchange_data( mbedtls_ssl_context *ssl_1,
+                           int msg_len_1, const int expected_fragments_1,
+                           mbedtls_ssl_context *ssl_2,
+                           int msg_len_2, const int expected_fragments_2 )
+{
+    unsigned char *msg_buf_1 = malloc( msg_len_1 );
+    unsigned char *msg_buf_2 = malloc( msg_len_2 );
+    unsigned char *in_buf_1  = malloc( msg_len_2 );
+    unsigned char *in_buf_2  = malloc( msg_len_1 );
+    int msg_type, ret = -1;
+
+    /* Perform this test with two message types. At first use a message
+     * consisting of only 0x00 for the client and only 0xFF for the server.
+     * At the second time use message with generated data */
+    for( msg_type = 0; msg_type < 2; msg_type++ )
+    {
+        int written_1 = 0;
+        int written_2 = 0;
+        int read_1 = 0;
+        int read_2 = 0;
+        int fragments_1 = 0;
+        int fragments_2 = 0;
+
+        if( msg_type == 0 )
+        {
+            memset( msg_buf_1, 0x00, msg_len_1 );
+            memset( msg_buf_2, 0xff, msg_len_2 );
+        }
+        else
+        {
+            int i, j = 0;
+            for( i = 0; i < msg_len_1; i++ )
+            {
+                msg_buf_1[i] = j++ & 0xFF;
+            }
+            for( i = 0; i < msg_len_2; i++ )
+            {
+                msg_buf_2[i] = ( j -= 5 ) & 0xFF;
+            }
+        }
+
+        while( read_1 < msg_len_2 || read_2 < msg_len_1 )
+        {
+            /* ssl_1 sending */
+            if( msg_len_1 > written_1 )
+            {
+                ret = mbedtls_ssl_write_fragment( ssl_1, msg_buf_1,
+                                                  msg_len_1, &written_1,
+                                                  &fragments_1,
+                                                  expected_fragments_1 );
+                if( expected_fragments_1 == 0 )
+                {
+                    /* This error is expected when the message is too large and
+                     * cannot be fragmented */
+                    TEST_ASSERT( ret == MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+                    msg_len_1 = 0;
+                }
+                else
+                {
+                    TEST_ASSERT( ret == 0 );
+                }
+            }
+
+            /* ssl_2 sending */
+            if( msg_len_2 > written_2 )
+            {
+                ret = mbedtls_ssl_write_fragment( ssl_2, msg_buf_2,
+                                                  msg_len_2, &written_2,
+                                                  &fragments_2,
+                                                  expected_fragments_2 );
+                if( expected_fragments_2 == 0 )
+                {
+                    /* This error is expected when the message is too large and
+                     * cannot be fragmented */
+                    TEST_ASSERT( ret == MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+                    msg_len_2 = 0;
+                }
+                else
+                {
+                    TEST_ASSERT( ret == 0 );
+                }
+            }
+
+            /* ssl_1 reading */
+            if( read_1 < msg_len_2 )
+            {
+                ret = mbedtls_ssl_read_fragment( ssl_1, in_buf_1,
+                                                 msg_len_2, &read_1,
+                                                 expected_fragments_1 );
+                TEST_ASSERT( ret == 0 );
+            }
+
+            /* ssl_2 reading */
+            if( read_2 < msg_len_1 )
+            {
+                ret = mbedtls_ssl_read_fragment( ssl_2, in_buf_2,
+                                                 msg_len_1, &read_2,
+                                                 expected_fragments_2 );
+                TEST_ASSERT( ret == 0 );
+            }
+        }
+
+        ret = -1;
+        TEST_ASSERT( 0 == memcmp( msg_buf_1, in_buf_2, msg_len_1 ) );
+        TEST_ASSERT( 0 == memcmp( msg_buf_2, in_buf_1, msg_len_2 ) );
+        TEST_ASSERT( fragments_1 == expected_fragments_1 );
+        TEST_ASSERT( fragments_2 == expected_fragments_2 );
+    }
+
+    ret = 0;
+
+exit:
+    free( msg_buf_1 );
+    free( in_buf_1 );
+    free( msg_buf_2 );
+    free( in_buf_2 );
+
+    return ret;
+}
+
 /* END_HEADER */
 
 /* BEGIN_DEPENDENCIES
@@ -3262,15 +3458,11 @@
 
 /* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_ECP_DP_SECP384R1_ENABLED:!MBEDTLS_USE_PSA_CRYPTO:MBEDTLS_PKCS1_V15 */
 void send_application_data( int mfl, int cli_msg_len, int srv_msg_len,
-                            const int expected_cli_frames,
-                            const int expected_srv_frames )
+                            const int expected_cli_fragments,
+                            const int expected_srv_fragments )
 {
     enum { BUFFSIZE = 2048 };
     mbedtls_endpoint server, client;
-    unsigned char *cli_msg_buf = malloc( cli_msg_len );
-    unsigned char *cli_in_buf  = malloc( srv_msg_len );
-    unsigned char *srv_msg_buf = malloc( srv_msg_len );
-    unsigned char *srv_in_buf  = malloc( cli_msg_len );
     int ret = -1;
 
     ret = mbedtls_endpoint_init( &server, MBEDTLS_SSL_IS_SERVER, MBEDTLS_PK_RSA,
@@ -3302,83 +3494,79 @@
     TEST_ASSERT( client.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
     TEST_ASSERT( server.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
 
-    /* Perform this test with two message types. At first use a message
-     * consisting of only 0x00 for the client and only 0xFF for the server.
-     * At the second time use message with generated data */
-    for( int msg_type = 0; msg_type < 2; msg_type++ )
-    {
-        int cli_writen = 0;
-        int srv_writen = 0;
-        int cli_read = 0;
-        int srv_read = 0;
-        int cli_fragments = 0;
-        int srv_fragments = 0;
-
-        if( msg_type == 0 )
-        {
-            memset( cli_msg_buf, 0x00, cli_msg_len );
-            memset( srv_msg_buf, 0xff, srv_msg_len );
-        }
-        else
-        {
-            int j = 0;
-            for( int i = 0; i < cli_msg_len; i++ )
-                cli_msg_buf[i] = j++ & 0xFF;
-            for( int i = 0; i < srv_msg_len; i++ )
-                srv_msg_buf[i] = ( j -= 5 ) & 0xFF;
-        }
-
-        while( cli_read < srv_msg_len || srv_read < cli_msg_len )
-        {
-            /* Client sending */
-            if( cli_msg_len > cli_writen )
-            {
-                ret = mbedtls_ssl_write_fragment( &(client.ssl), cli_msg_buf,
-                                    cli_msg_len, &cli_writen, &cli_fragments );
-                TEST_ASSERT( ( ret >= 0 && ret <= cli_msg_len ) ||
-                               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
-            }
-
-            /* Server sending */
-            if( srv_msg_len > srv_writen )
-            {
-                ret = mbedtls_ssl_write_fragment( &(server.ssl), srv_msg_buf,
-                                    srv_msg_len, &srv_writen, &srv_fragments );
-                TEST_ASSERT( ( ret >= 0 && ret <= srv_msg_len ) ||
-                               ret == MBEDTLS_ERR_SSL_WANT_WRITE );
-            }
-
-            /* Client reading */
-            if( cli_read < srv_msg_len )
-            {
-                ret = mbedtls_ssl_read_fragment( &(client.ssl), cli_in_buf,
-                                                    srv_msg_len, &cli_read );
-                TEST_ASSERT( ( ret >= 0 && ret <= srv_msg_len ) ||
-                               ret == MBEDTLS_ERR_SSL_WANT_READ );
-            }
-
-            /* Server reading */
-            if( srv_read < cli_msg_len )
-            {
-                ret = mbedtls_ssl_read_fragment( &(server.ssl), srv_in_buf,
-                                                    cli_msg_len, &srv_read );
-                TEST_ASSERT( ( ret >= 0 && ret <= cli_msg_len ) ||
-                               ret == MBEDTLS_ERR_SSL_WANT_READ );
-            }
-        }
-
-        TEST_ASSERT( 0 == memcmp( cli_msg_buf, srv_in_buf, cli_msg_len ) );
-        TEST_ASSERT( 0 == memcmp( srv_msg_buf, cli_in_buf, srv_msg_len ) );
-        TEST_ASSERT( cli_fragments == expected_cli_frames );
-        TEST_ASSERT( srv_fragments == expected_srv_frames );
-    }
+    /* Start data exchanging test */
+    ret = mbedtls_exchange_data( &(client.ssl), cli_msg_len, expected_cli_fragments,
+                                 &(server.ssl), srv_msg_len, expected_srv_fragments );
+    TEST_ASSERT( ret == 0 );
 
 exit:
     mbedtls_endpoint_free( &client, NULL );
     mbedtls_endpoint_free( &server, NULL );
-    free( cli_msg_buf );
-    free( cli_in_buf );
-    free( srv_msg_buf );
-    free( srv_in_buf );
+}
+/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_X509_CRT_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_ECP_DP_SECP384R1_ENABLED:!MBEDTLS_USE_PSA_CRYPTO:MBEDTLS_PKCS1_V15 */
+void send_application_data_dtls( int mfl, int cli_msg_len, int srv_msg_len,
+                                 const int expected_cli_fragments,
+                                 const int expected_srv_fragments )
+{
+    enum { BUFFSIZE = 17000 };
+#if defined(MBEDTLS_TIMING_C)
+    mbedtls_timing_delay_context timer_client, timer_server;
+#endif
+    mbedtls_endpoint server, client;
+    mbedtls_test_message_queue server_queue, client_queue;
+    mbedtls_test_message_socket_context server_context, client_context;
+    int ret = -1;
+
+    /* Initializing endpoints and communication */
+    ret = mbedtls_endpoint_init( &server, MBEDTLS_SSL_IS_SERVER, MBEDTLS_PK_RSA,
+                                 &server_context, &server_queue, &client_queue );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_endpoint_init( &client, MBEDTLS_SSL_IS_CLIENT, MBEDTLS_PK_RSA,
+                                 &client_context, &client_queue, &server_queue );
+    TEST_ASSERT( ret == 0 );
+
+#if defined(MBEDTLS_TIMING_C)
+    mbedtls_ssl_set_timer_cb( &client.ssl, &timer_client,
+                              mbedtls_timing_set_delay,
+                              mbedtls_timing_get_delay );
+
+    mbedtls_ssl_set_timer_cb( &server.ssl, &timer_server,
+                              mbedtls_timing_set_delay,
+                              mbedtls_timing_get_delay );
+#endif /* MBEDTLS_TIMING_C */
+
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    ret = mbedtls_ssl_conf_max_frag_len( &(server.conf), (unsigned char) mfl );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_ssl_conf_max_frag_len( &(client.conf), (unsigned char) mfl );
+    TEST_ASSERT( ret == 0 );
+#else
+    TEST_ASSERT( MBEDTLS_SSL_MAX_FRAG_LEN_NONE == mfl );
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
+    ret = mbedtls_mock_socket_connect( &(server.socket), &(client.socket),
+                                       BUFFSIZE );
+    TEST_ASSERT( ret == 0 );
+
+    ret = mbedtls_move_handshake_to_state( &(client.ssl),
+                                           &(server.ssl),
+                                           MBEDTLS_SSL_HANDSHAKE_OVER );
+    TEST_ASSERT( ret == 0 );
+    TEST_ASSERT( client.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
+    TEST_ASSERT( server.ssl.state == MBEDTLS_SSL_HANDSHAKE_OVER );
+
+    /* Start data exchanging test */
+    ret = mbedtls_exchange_data( &(client.ssl), cli_msg_len, expected_cli_fragments,
+                                 &(server.ssl), srv_msg_len, expected_srv_fragments );
+    TEST_ASSERT( ret == 0 );
+
+
+exit:
+    mbedtls_endpoint_free( &client, &client_context );
+    mbedtls_endpoint_free( &server, &server_context );
 }
 /* END_CASE */