diff --git a/core/federated/RTI/rti_remote.c b/core/federated/RTI/rti_remote.c
index 00d167b16..e8fd3dba9 100644
--- a/core/federated/RTI/rti_remote.c
+++ b/core/federated/RTI/rti_remote.c
@@ -340,7 +340,7 @@ void handle_port_absent_message(federate_info_t* sending_federate, unsigned char
 }
 
 void handle_timed_message(federate_info_t* sending_federate, unsigned char* buffer) {
-  size_t header_size = 1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t) + sizeof(int64_t) + sizeof(uint32_t);
+  size_t header_size = 1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t) + sizeof(int64_t) + sizeof(uint32_t);
   // Read the header, minus the first byte which has already been read.
   read_from_socket_fail_on_error(&sending_federate->socket, header_size - 1, &(buffer[1]), NULL,
                                  "RTI failed to read the timed message header from remote federate.");
@@ -721,8 +721,8 @@ void handle_address_query(uint16_t fed_id) {
   // the port number because it has not yet received an MSG_TYPE_ADDRESS_ADVERTISEMENT message
   // from this federate. In that case, it will respond by sending -1.
 
-  // Response message is also of type MSG_TYPE_ADDRESS_QUERY.
-  buffer[0] = MSG_TYPE_ADDRESS_QUERY;
+  // Response message is MSG_TYPE_ADDRESS_QUERY_REPLY.
+  buffer[0] = MSG_TYPE_ADDRESS_QUERY_REPLY;
 
   // Encode the port number.
   federate_info_t* remote_fed = GET_FED_INFO(remote_fed_id);
diff --git a/core/federated/federate.c b/core/federated/federate.c
index 1805f86ab..f3f2eb85b 100644
--- a/core/federated/federate.c
+++ b/core/federated/federate.c
@@ -453,7 +453,7 @@ static bool handle_message_now(environment_t* env, trigger_t* trigger, tag_t int
 static int handle_message(int* socket, int fed_id) {
   (void)fed_id;
   // Read the header.
-  size_t bytes_to_read = sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t);
+  size_t bytes_to_read = sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t);
   unsigned char buffer[bytes_to_read];
   if (read_from_socket_close_on_error(socket, bytes_to_read, buffer)) {
     // Read failed, which means the socket has been closed between reading the
@@ -511,7 +511,7 @@ static int handle_tagged_message(int* socket, int fed_id) {
 
   // Read the header which contains the timestamp.
   size_t bytes_to_read =
-      sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t) + sizeof(instant_t) + sizeof(microstep_t);
+      sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t) + sizeof(instant_t) + sizeof(microstep_t);
   unsigned char buffer[bytes_to_read];
   if (read_from_socket_close_on_error(socket, bytes_to_read, buffer)) {
     return -1; // Read failed.
@@ -1713,8 +1713,8 @@ void lf_connect_to_federate(uint16_t remote_federate_id) {
                                    "Failed to read the requested port number for federate %d from RTI.",
                                    remote_federate_id);
 
-    if (buffer[0] != MSG_TYPE_ADDRESS_QUERY) {
-      // Unexpected reply.  Could be that RTI has failed and sent a resignation.
+    if (buffer[0] != MSG_TYPE_ADDRESS_QUERY_REPLY) {
+      // Unexpected reply. Could be that RTI has failed and sent a resignation.
       if (buffer[0] == MSG_TYPE_FAILED) {
         lf_print_error_and_exit("RTI has failed.");
       } else {
@@ -2271,7 +2271,7 @@ void lf_reset_status_fields_on_input_port_triggers() {
 
 int lf_send_message(int message_type, unsigned short port, unsigned short federate, const char* next_destination_str,
                     size_t length, unsigned char* message) {
-  unsigned char header_buffer[1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t)];
+  unsigned char header_buffer[1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t)];
   // First byte identifies this as a timed message.
   if (message_type != MSG_TYPE_P2P_MESSAGE) {
     lf_print_error("lf_send_message: Unsupported message type (%d).", message_type);
@@ -2286,12 +2286,12 @@ int lf_send_message(int message_type, unsigned short port, unsigned short federa
   encode_uint16(federate, &(header_buffer[1 + sizeof(uint16_t)]));
 
   // The next four bytes are the message length.
-  encode_int32((int32_t)length, &(header_buffer[1 + sizeof(uint16_t) + sizeof(uint16_t)]));
+  encode_uint32((uint32_t)length, &(header_buffer[1 + sizeof(uint16_t) + sizeof(uint16_t)]));
 
   LF_PRINT_LOG("Sending untagged message to %s.", next_destination_str);
 
   // Header:  message_type + port_id + federate_id + length of message + timestamp + microstep
-  const int header_length = 1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t);
+  const int header_length = 1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t);
 
   // Use a mutex lock to prevent multiple threads from simultaneously sending.
   LF_MUTEX_LOCK(&lf_outbound_socket_mutex);
@@ -2542,7 +2542,7 @@ int lf_send_tagged_message(environment_t* env, interval_t additional_delay, int
   assert(env != GLOBAL_ENVIRONMENT);
 
   size_t header_length =
-      1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(int32_t) + sizeof(instant_t) + sizeof(microstep_t);
+      1 + sizeof(uint16_t) + sizeof(uint16_t) + sizeof(uint32_t) + sizeof(instant_t) + sizeof(microstep_t);
   unsigned char header_buffer[header_length];
 
   if (message_type != MSG_TYPE_TAGGED_MESSAGE && message_type != MSG_TYPE_P2P_TAGGED_MESSAGE) {
@@ -2564,8 +2564,8 @@ int lf_send_tagged_message(environment_t* env, interval_t additional_delay, int
   buffer_head += sizeof(uint16_t);
 
   // The next four bytes are the message length.
-  encode_int32((int32_t)length, &(header_buffer[buffer_head]));
-  buffer_head += sizeof(int32_t);
+  encode_uint32((uint32_t)length, &(header_buffer[buffer_head]));
+  buffer_head += sizeof(uint32_t);
 
   // Apply the additional delay to the current tag and use that as the intended
   // tag of the outgoing message.
diff --git a/core/federated/network/net_util.c b/core/federated/network/net_util.c
index 42d3bcabd..568c692de 100644
--- a/core/federated/network/net_util.c
+++ b/core/federated/network/net_util.c
@@ -412,7 +412,7 @@ void extract_header(unsigned char* buffer, uint16_t* port_id, uint16_t* federate
   // printf("DEBUG: Message for port %d of federate %d.\n", *port_id, *federate_id);
 
   // The next four bytes are the message length.
-  int32_t local_length_signed = extract_int32(&(buffer[sizeof(uint16_t) + sizeof(uint16_t)]));
+  uint32_t local_length_signed = extract_uint32(&(buffer[sizeof(uint16_t) + sizeof(uint16_t)]));
   if (local_length_signed < 0) {
     lf_print_error_and_exit("Received an invalid message length (%d) from federate %d.", local_length_signed,
                             *federate_id);
diff --git a/include/core/federated/network/net_common.h b/include/core/federated/network/net_common.h
index eb27d64d6..2079f113b 100644
--- a/include/core/federated/network/net_common.h
+++ b/include/core/federated/network/net_common.h
@@ -386,7 +386,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * Byte identifying a timestamped message to forward to another federate.
  * The next two bytes will be the ID of the destination reactor port.
  * The next two bytes are the destination federate ID.
- * The four bytes after that will be the length of the message.
+ * The four bytes after that will be the length of the message (as an unsigned 32-bit int).
  * The next eight bytes will be the timestamp of the message.
  * The next four bytes will be the microstep of the message.
  * The remaining bytes are the message.
@@ -528,12 +528,20 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * Byte identifying a address query message, sent by a federate to RTI
  * to ask for another federate's address and port number.
  * The next two bytes are the other federate's ID.
- * The reply from the RTI will a port number (an int32_t), which is -1
+ */
+#define MSG_TYPE_ADDRESS_QUERY 13
+
+/**
+ * Byte identifying a address query message reply, sent by a RTI to a federate
+ * to reply with a remote federate's address and port number.
+ * The reply from the RTI will be a port number (an int32_t), which is -1
  * if the RTI does not know yet (it has not received MSG_TYPE_ADDRESS_ADVERTISEMENT from
  * the other federate), followed by the IP address of the other
  * federate (an IPV4 address, which has length INET_ADDRSTRLEN).
+ * The next four bytes (or sizeof(int32_t)) will be the port number.
+ * The next four bytes (or sizeof(in_addr), which is uint32_t) will be the ip address.
  */
-#define MSG_TYPE_ADDRESS_QUERY 13
+#define MSG_TYPE_ADDRESS_QUERY_REPLY 14
 
 /**
  * Byte identifying a message advertising the port for the TCP connection server
@@ -543,7 +551,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * The sending federate will not wait for a response from the RTI and assumes its
  * request will be processed eventually by the RTI.
  */
-#define MSG_TYPE_ADDRESS_ADVERTISEMENT 14
+#define MSG_TYPE_ADDRESS_ADVERTISEMENT 15
 
 /**
  * Byte identifying a first message that is sent by a federate directly to another federate
@@ -554,7 +562,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * federate does not expect this federate or federation to connect, it will respond
  * instead with MSG_TYPE_REJECT.
  */
-#define MSG_TYPE_P2P_SENDING_FED_ID 15
+#define MSG_TYPE_P2P_SENDING_FED_ID 16
 
 /**
  * Byte identifying a message to send directly to another federate.
@@ -565,7 +573,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * The four bytes after will be the length of the message.
  * The ramaining bytes are the message.
  */
-#define MSG_TYPE_P2P_MESSAGE 16
+#define MSG_TYPE_P2P_MESSAGE 17
 
 /**
  * Byte identifying a timestamped message to send directly to another federate.
@@ -582,7 +590,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * The next four bytes will be the microstep of the sender.
  * The ramaining bytes are the message.
  */
-#define MSG_TYPE_P2P_TAGGED_MESSAGE 17
+#define MSG_TYPE_P2P_TAGGED_MESSAGE 18
 
 ////////////////////////////////////////////////
 /**