diff --git a/raknet/MTUSize.h b/raknet/MTUSize.h
new file mode 100644
index 0000000..0dc2e3e
--- /dev/null
+++ b/raknet/MTUSize.h
@@ -0,0 +1,40 @@
+/// \file
+/// \brief \b [Internal] Defines the default maximum transfer unit.
+///
+/// This file is part of RakNet Copyright 2003 Kevin Jenkins.
+///
+/// Usage of RakNet is subject to the appropriate license agreement.
+/// Creative Commons Licensees are subject to the
+/// license found at
+/// http://creativecommons.org/licenses/by-nc/2.5/
+/// Single application licensees are subject to the license found at
+/// http://www.rakkarsoft.com/SingleApplicationLicense.html
+/// Custom license users are subject to the terms therein.
+/// GPL license users are subject to the GNU General Public
+/// License as published by the Free
+/// Software Foundation; either version 2 of the License, or (at your
+/// option) any later version.
+
+#ifndef DEFAULT_MTU_SIZE
+
+/// The MTU size to use if RakPeer::SetMTUSize() is not called.
+/// \remarks I think many people forget to call RakPeer::SetMTUSize() so I'm setting this to 1500 by default for efficiency.
+/// \li \em 17914 16 Mbit/Sec Token Ring
+/// \li \em 4464 4 Mbits/Sec Token Ring
+/// \li \em 4352 FDDI
+/// \li \em 1500. The largest Ethernet packet size \b recommended. This is the typical setting for non-PPPoE, non-VPN connections. The default value for NETGEAR routers, adapters and switches.
+/// \li \em 1492. The size PPPoE prefers.
+/// \li \em 1472. Maximum size to use for pinging. (Bigger packets are fragmented.)
+/// \li \em 1468. The size DHCP prefers.
+/// \li \em 1460. Usable by AOL if you don't have large email attachments, etc.
+/// \li \em 1430. The size VPN and PPTP prefer.
+/// \li \em 1400. Maximum size for AOL DSL.
+/// \li \em 576. Typical value to connect to dial-up ISPs.
+#ifdef _COMPATIBILITY_1
+#define DEFAULT_MTU_SIZE 1264
+#else
+#define DEFAULT_MTU_SIZE 576
+#endif
+
+#endif
+
diff --git a/raknet/RakPeer.cpp b/raknet/RakPeer.cpp
index 9576aab..f4185d6 100644
--- a/raknet/RakPeer.cpp
+++ b/raknet/RakPeer.cpp
@@ -7,6 +7,7 @@
 
 RakPeer::RakPeer()
 {
+	MTUSize = DEFAULT_MTU_SIZE;
 	maximumIncomingConnections = 0;
 	maximumNumberOfPeers = 0;
 	endThreads = true;
@@ -350,9 +351,16 @@ void RakPeer::vftable_A8()
 	// TODO: RakPeer::vftable_A8() (saco W: 10038860) (server W: 450360 L: 8070050) (bot W: 4042A0 L: 807514E)
 }
 
-void RakPeer::vftable_AC()
+// --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+// Description:
+// Returns the current MTU size
+//
+// Returns:
+// The MTU sized specified in SetMTUSize
+// --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+int RakPeer::GetMTUSize( void ) const
 {
-	// TODO: RakPeer::vftable_AC() (saco W: 100388B0) (server W: 4503B0 L: 806DD50) (bot W: 4042F0 L: 807519E)
+	return MTUSize;
 }
 
 void RakPeer::vftable_B0()
diff --git a/raknet/RakPeer.h b/raknet/RakPeer.h
index f5d2b2e..2595c89 100644
--- a/raknet/RakPeer.h
+++ b/raknet/RakPeer.h
@@ -5,6 +5,7 @@
 
 #include "Export.h"
 #include "RakPeerInterface.h"
+#include "ReliabilityLayer.h"
 #include "RPCNode.h"
 #include "RPCMap.h"
 
@@ -122,7 +123,11 @@ public:
 	void vftable_A0();
 	void vftable_A4();
 	void vftable_A8();
-	void vftable_AC();
+
+	/// Returns the current MTU size
+	/// \return The current MTU size
+	int GetMTUSize( void ) const;
+
 	void vftable_B0();
 	void vftable_B4();
 	void vftable_B8();
@@ -169,8 +174,11 @@ protected:
 	char incomingPassword[256];
 	unsigned char incomingPasswordLength;
 
-	RPCMap rpcMap; // Can't use StrPtrHash because runtime insertions will screw up the indices
+	char _gap334[1230];
 
+	RPCMap rpcMap; // Can't use StrPtrHash because runtime insertions will screw up the indices
+	int MTUSize;
+	bool trackFrequencyTable;
 };
 
 #endif
diff --git a/raknet/RakPeerInterface.h b/raknet/RakPeerInterface.h
index 76062b5..0dfc954 100644
--- a/raknet/RakPeerInterface.h
+++ b/raknet/RakPeerInterface.h
@@ -119,7 +119,11 @@ public:
 	virtual void vftable_A0()=0;
 	virtual void vftable_A4()=0;
 	virtual void vftable_A8()=0;
-	virtual void vftable_AC()=0;
+	
+	/// Returns the current MTU size
+	/// \return The current MTU size
+	virtual int GetMTUSize( void ) const=0;
+
 	virtual void vftable_B0()=0;
 	virtual void vftable_B4()=0;
 	virtual void vftable_B8()=0;
diff --git a/raknet/ReliabilityLayer.h b/raknet/ReliabilityLayer.h
index 3526c0a..26d9198 100644
--- a/raknet/ReliabilityLayer.h
+++ b/raknet/ReliabilityLayer.h
@@ -4,6 +4,7 @@
 #define __RELIABILITY_LAYER_H
 
 #include "SocketLayer.h"
+#include "MTUSize.h"
 
 class ReliabilityLayer
 {