diff --git a/node/main/main.ino b/node/main/main.ino
index fdfeae4..ec039c6 100644
--- a/node/main/main.ino
+++ b/node/main/main.ino
@@ -25,56 +25,76 @@ void setup() {
 
 void loop() {
 
+	delay(500);
+
 	// 1. ignore if no received data
-	if( xbee.receive(recv) == XBWRECV_OK ){
-		uint8_t opcode = recv.getOpcode();
-		Serial.print("+ opcode = ");
-		Serial.println(opcode);
+	if( xbee.receive(recv) != XBWRECV_OK )
+		return;
 
-		// DISCOVER REQUEST
-		if( opcode == 0 ) {
-			Serial.println("+ discover request");
+
+	uint8_t opcode = recv.getOpcode();
+
+	// DISCOVER REQUEST
+	if( opcode == 0 ) {
+		Serial.print("+ discover(");
+		Serial.print(recv.getSender());
+		Serial.print(", ");
+		Serial.print(recv.getWave());
+		Serial.print(", ");
+		Serial.print(recv.getDist());
+		Serial.println(")");
+
+		if( recv.getWave() != wave_id ){
+			wave_id = recv.getWave();
+			dist    = recv.getDist()+1;
+			recv.setDist(dist);
 			Serial.print("  + wave = ");
-			Serial.println(recv.getWave());
+			Serial.println(wave_id);
 			Serial.print("  + dist = ");
-			Serial.println(recv.getDist());
-
-			if( recv.getWave() != wave_id ){
-				wave_id = recv.getWave();
-				dist    = recv.getDist()+1;
-				recv.setDist(dist);
-
-				send.setOpcode(0);
-				send.setWave(wave_id);
-				send.setDist(dist);
-				xbee.broadcast(send);
-				Serial.println("  + propagated");
-
-			}
-
-		// MESSAGE DATA
-		} else {
-
-			Serial.println("+ message data");
-			Serial.print("  + ttl = ");
-			Serial.println(recv.getTTL());
-			Serial.print("  + dist = ");
-			Serial.println(recv.getDist());
-
-			// propagation
-			if( recv.getTTL() > 0 && recv.getDist() <= dist ){
-				send.setOpcode(1);
-				send.setTTL(recv.getTTL()-1);
-				send.setDist(dist);
-				send.setData(recv.getData(), recv.getSize());
-				xbee.broadcast(send);
-				Serial.println("  + propagated");
-			}
+			Serial.println(dist);
 
+			send.setOpcode(0);
+			send.setWave(wave_id);
+			send.setDist(dist);
+			send.setSender(42);
+			xbee.broadcast(send);
+			Serial.print("  + send discover(");
+			Serial.print(send.getSender());
+			Serial.print(", ");
+			Serial.print(send.getWave());
+			Serial.print(", ");
+			Serial.print(send.getDist());
+			Serial.println(")");
 		}
 
+	// MESSAGE DATA
+	} else {
+
+		Serial.print("+ message(");
+		Serial.print(recv.getDist());
+		Serial.print(", ");
+		Serial.print(recv.getTTL());
+		Serial.print(", ");
+		Serial.print(recv.getSize());
+		Serial.println(")");
+
+
+		// propagation
+		if( recv.getTTL() > 0 && recv.getDist() <= dist ){
+			send.setOpcode(1);
+			send.setTTL(recv.getTTL()-1);
+			send.setDist(dist);
+			send.setData(recv.getData(), recv.getSize());
+			xbee.broadcast(send);
+			Serial.print("  + send message(");
+			Serial.print(recv.getDist());
+			Serial.print(", ");
+			Serial.print(recv.getTTL());
+			Serial.print(", ");
+			Serial.print(recv.getSize());
+			Serial.println(")");
+		}
 
-		// manage packet
 	}
 
 }
diff --git a/packet.cpp b/packet.cpp
index 2f125df..0b12746 100644
--- a/packet.cpp
+++ b/packet.cpp
@@ -33,6 +33,9 @@ void Packet::setOpcode(uint8_t value) { opcode = value; dsc.opcode = value; msg.
 uint8_t Packet::getWave()           { return dsc.wave; }
 void Packet::setWave(uint8_t value) { dsc.wave = value; }
 
+uint8_t Packet::getSender()           { return dsc.sender; }
+void Packet::setSender(uint8_t value) { dsc.sender = value; }
+
 uint8_t Packet::getDist()           { return (opcode == 0) ? dsc.dist : msg.dist; }
 void Packet::setDist(uint8_t value) { if(opcode == 0) dsc.dist = value; else msg.dist = value; }
 
@@ -56,6 +59,7 @@ uint8_t Packet::read_discover(uint8_t buf[], size_t size){
 	dsc.opcode = buf[0];
 	dsc.wave   = buf[1];
 	dsc.dist   = buf[2];
+	dsc.sender = buf[3];
 
 	return PKTREAD_OK;
 };
@@ -84,8 +88,9 @@ size_t Packet::write_discover(uint8_t buf[]){
 	buf[0] = dsc.opcode;
 	buf[1] = dsc.wave;
 	buf[2] = dsc.dist;
+	buf[3] = dsc.sender;
 
-	return 3;
+	return 4;
 };
 
 size_t Packet::write_message(uint8_t buf[]){
diff --git a/packet.h b/packet.h
index c3dc120..8a5ec60 100644
--- a/packet.h
+++ b/packet.h
@@ -20,10 +20,10 @@
 			struct message  msg;
 
 			// 3. helpers
-			uint8_t read_discover(uint8_t buf[], size_t size);
-			uint8_t read_message(uint8_t buf[], size_t size);
-			size_t write_discover(uint8_t buf[]);
-			size_t write_message(uint8_t buf[]);
+			uint8_t read_discover(uint8_t  buf[], size_t size);
+			uint8_t read_message(uint8_t   buf[], size_t size);
+			size_t  write_discover(uint8_t buf[]);
+			size_t  write_message(uint8_t  buf[]);
 
 		public:
 			// builds a packet from raw data and returns the status code
@@ -36,6 +36,9 @@
 			uint8_t getOpcode();
 			void setOpcode(uint8_t value);
 
+			uint8_t getSender();
+			void setSender(uint8_t value);
+
 			uint8_t getWave();
 			void setWave(uint8_t value);
 
diff --git a/protocol.h b/protocol.h
index 446e4e3..9d08f1a 100644
--- a/protocol.h
+++ b/protocol.h
@@ -6,11 +6,12 @@
 	#define DISCOVER_TTL     10000
 
 	// discover request (c.f. class node)
-	#define DISCOVER_SIZE    sizeof(uint8_t)*3
+	#define DISCOVER_SIZE    sizeof(uint8_t)*4
 	struct discover {
 		uint8_t opcode; // opcode = 0
 		uint8_t wave;   // id de la wave
 		uint8_t dist;   // current node's distance
+		uint8_t sender; // sender id
 	};
 
 
diff --git a/well/main/main.ino b/well/main/main.ino
index 6ace736..283c603 100644
--- a/well/main/main.ino
+++ b/well/main/main.ino
@@ -35,6 +35,7 @@ void loop() {
 	send.setOpcode(0);
 	send.setWave(++wave_id);
 	send.setDist(0);
+	send.setSender(42);
 
 	if( xbee.broadcast(send) == XBWSEND_OK )
 		Serial.println("sent");