diff --git a/ws2012/P2P/uebungen/11/src/message/MessageType.java b/ws2012/P2P/uebungen/11/src/message/MessageType.java
index 31816d33..6d535b02 100644
--- a/ws2012/P2P/uebungen/11/src/message/MessageType.java
+++ b/ws2012/P2P/uebungen/11/src/message/MessageType.java
@@ -14,4 +14,5 @@ public class MessageType {
     public final static byte DATA       	= 6;
     public final static byte VALUE_NODES	= 7;
     public final static byte FOUND_VALUE 	= 8;
+    public final static byte ACK			= 9;
 }
diff --git a/ws2012/P2P/uebungen/11/src/node/Node.java b/ws2012/P2P/uebungen/11/src/node/Node.java
index 465cd917..9cfd8b00 100644
--- a/ws2012/P2P/uebungen/11/src/node/Node.java
+++ b/ws2012/P2P/uebungen/11/src/node/Node.java
@@ -150,13 +150,14 @@ public class Node {
 		}
 	}
 
-	void sendFoundValue(NodeIdentifier receiver, Identifier idToFind, Identifier rpcID) {
-		boolean successful = send(receiver, MessageType.FOUND_VALUE, rpcID, values
-				.get(idToFind).getBytes(), true, null);
+	void sendFoundValue(NodeIdentifier receiver, Identifier idToFind,
+			Identifier rpcID) {
+		boolean successful = send(receiver, MessageType.FOUND_VALUE, rpcID,
+				values.get(idToFind).getBytes(), false, null);
 
 		if (successful) {
-			LOGGER.log(Level.INFO, "Sending [FOUND_VALUE {0}] to node {1}",
-					new Object[] { values.get(idToFind), receiver });
+			LOGGER.log(Level.INFO, "Sending [FOUND_VALUE {0} -> {1}] to node {2}",
+					new Object[] { idToFind, values.get(idToFind), receiver });
 		}
 	}
 
@@ -218,6 +219,10 @@ public class Node {
 		}
 	}
 
+	public void sendAck(NodeIdentifier receiver, Identifier rpcID) {
+		send(receiver, MessageType.ACK, rpcID, null, false, null);
+	}
+
 	public void sendData(NodeIdentifier receiver, FileIdentifier fileID,
 			ChunkIdentifier chunckID) {
 
@@ -387,16 +392,19 @@ public class Node {
 	public boolean receivedRPC(NodeIdentifier fromID, Identifier rpcID) {
 		List<Ack> rpcsFromID = rpcs.get(rpcID);
 		boolean removedAck = false;
+				
+		// wohl unschön, hier auf != null zu prüfen, da Fehler wo anders ist.
+		if (rpcsFromID != null) {
+			for (Ack ack : rpcsFromID) {
+				if (ack.check(fromID)) {
+					ack.setReceived();
+					rpcsFromID.remove(ack);
+					removedAck = true;
 
-		for (Ack ack : rpcsFromID) {
-			if (ack.check(fromID)) {
-				ack.setReceived();
-				rpcsFromID.remove(ack);
-				removedAck = true;
+					LOGGER.log(Level.FINEST, "Received RPC ack " + rpcID);
 
-				LOGGER.log(Level.FINEST, "Received RPC ack " + rpcID);
-
-				break;
+					break;
+				}
 			}
 		}
 
@@ -419,34 +427,35 @@ public class Node {
 	private boolean sendLeave(NodeIdentifier n) {
 		return send(n, MessageType.LEAVE, null, false, null);
 	}
-	
-    public void storeFile(File file){
-    	files.add(file);
-    }
+
+	public void storeFile(File file) {
+		files.add(file);
+	}
 
 	private void sendFile(NodeIdentifier nodeID, File file) {
 
-		//calculate chunk size
-    	int CHUNK_SIZE = BUFFER_SIZE - 15;
-    	
-    	int FILE_SIZE = (int)file.length();
-    	
-    	boolean eof = false;
-    	
-    	int NUMBER_OF_CHUNKS = 0;
-    	byte[] temp = null;
-    	
-    	int totalBytesRead = 0;
-    	
-    	Identifier fileID = new Identifier(10, file.getName().getBytes());
-    	
-    	try {
-			InputStream inStream = new BufferedInputStream(new FileInputStream(file));
-			
-			while(totalBytesRead < FILE_SIZE){
-				int bytesReamaining = FILE_SIZE-totalBytesRead;
-				if(bytesReamaining < CHUNK_SIZE){
-					CHUNK_SIZE = bytesReamaining+1;
+		// calculate chunk size
+		int CHUNK_SIZE = BUFFER_SIZE - 15;
+
+		int FILE_SIZE = (int) file.length();
+
+		boolean eof = false;
+
+		int NUMBER_OF_CHUNKS = 0;
+		byte[] temp = null;
+
+		int totalBytesRead = 0;
+
+		Identifier fileID = new Identifier(10, file.getName().getBytes());
+
+		try {
+			InputStream inStream = new BufferedInputStream(new FileInputStream(
+					file));
+
+			while (totalBytesRead < FILE_SIZE) {
+				int bytesReamaining = FILE_SIZE - totalBytesRead;
+				if (bytesReamaining < CHUNK_SIZE) {
+					CHUNK_SIZE = bytesReamaining + 1;
 					eof = true;
 				}
 				temp = new byte[CHUNK_SIZE];
diff --git a/ws2012/P2P/uebungen/11/src/node/UDPHandler.java b/ws2012/P2P/uebungen/11/src/node/UDPHandler.java
index 6ca668bb..6e8c1c4c 100644
--- a/ws2012/P2P/uebungen/11/src/node/UDPHandler.java
+++ b/ws2012/P2P/uebungen/11/src/node/UDPHandler.java
@@ -145,6 +145,9 @@ public class UDPHandler implements Runnable {
 						LOGGER.log(Level.INFO, "Received DATA from {0}",
 								new Object[] { from.toString() });
 						break;
+					case MessageType.ACK:
+						receiveAck(fromID, rpcID);
+						break;
 					default:
 						LOGGER.log(Level.INFO,
 								"Received unknown command from {0}: [{1}]{2}",
@@ -175,7 +178,14 @@ public class UDPHandler implements Runnable {
 		}
 	}
 
+	private void receiveAck(NodeIdentifier fromID, Identifier rpcID) {
+		// This should be the either answer to a prior STORE or FOUND_VALUE ->
+		// mark this RPC ID as received
+		node.receivedRPC(fromID, rpcID);
+	}
+
 	private void receiveFoundValue(NodeIdentifier fromID, Identifier rpcID) {
+		Identifier idToFind = getIDFromBuffer();
 		// TODO Auto-generated method stub
 		// Node kontaktieren, damit Datei gesendet werden kann.
 
@@ -183,8 +193,8 @@ public class UDPHandler implements Runnable {
 		// as received
 		node.receivedRPC(fromID, rpcID);
 
-		LOGGER.log(Level.INFO, "Received [FOUND VALUE] from Node {0}",
-				new Object[] { fromID });
+		LOGGER.log(Level.INFO, "Received [FOUND VALUE on Node {0}] from Node {1}",
+				new Object[] { idToFind, fromID });
 	}
 
 	private void receiveValueNodes(NodeIdentifier fromID, Identifier rpcID) {
@@ -315,6 +325,8 @@ public class UDPHandler implements Runnable {
 				new Object[] { fileID, fromID });
 
 		node.storePair(fileID, fromID);
+
+		node.sendAck(fromID, rpcID);
 	}
 
 	private void receiveFindValue(NodeIdentifier fromID, Identifier rpcID) {