diff --git a/client/streamconfigdialog.cpp b/client/streamconfigdialog.cpp
index 30649b3..5201099 100644
--- a/client/streamconfigdialog.cpp
+++ b/client/streamconfigdialog.cpp
@@ -43,60 +43,60 @@ StreamConfigDialog::StreamConfigDialog(Port &port, uint streamIndex,
 
 	// Time to play match the signals and slots!
 
-	// If L1/FT = None, force subsequent protocol level(s) also to None
-	connect(rbL1None, SIGNAL(toggled(bool)), this, SLOT(forceProtocolNone(bool)));
-	connect(rbFtNone, SIGNAL(toggled(bool)), this, SLOT(forceProtocolNone(bool)));
+	// If L1/L2(FT)/L3 = None, force subsequent protocol level(s) also to None
+	connect(rbL1None, SIGNAL(toggled(bool)), SLOT(forceProtocolNone(bool)));
+	connect(rbFtNone, SIGNAL(toggled(bool)), SLOT(forceProtocolNone(bool)));
+	connect(rbL3None, SIGNAL(toggled(bool)), SLOT(forceProtocolNone(bool)));
 
-	// Enable/Disable L3 Protocol Choices for FT Ethernet2
-	connect(rbFtEthernet2, SIGNAL(toggled(bool)), rbL3Ipv4, SLOT(setEnabled(bool)));
-	connect(rbFtEthernet2, SIGNAL(toggled(bool)), rbL3Arp, SLOT(setEnabled(bool)));
-
-	// Force L3 = None if FT = 802.3 Raw
-	connect(rbFt802Dot3Raw, SIGNAL(clicked(bool)), rbL3None, SLOT(click()));
-	connect(rbFt802Dot3Raw, SIGNAL(toggled(bool)), rbL3Ipv4, SLOT(setDisabled(bool)));
-	connect(rbFt802Dot3Raw, SIGNAL(toggled(bool)), rbL3Arp, SLOT(setDisabled(bool)));
-
-	// Force L3 = None if FT = 802.3 LLC (to ensure a valid L3 is selected)
-	connect(rbFt802Dot3Llc, SIGNAL(clicked(bool)), rbL3None, SLOT(click()));
-
-	// Enable/Disable L3 Protocol Choices for FT 802Dot3Llc
-	connect(rbFt802Dot3Llc, SIGNAL(toggled(bool)), rbL3Ipv4, SLOT(setEnabled(bool)));
-	connect(rbFt802Dot3Llc, SIGNAL(toggled(bool)), rbL3Arp, SLOT(setDisabled(bool)));
-
-	// Enable/Disable L3 Protocol Choices for FT 802.3 LLC SNAP
-	connect(rbFtLlcSnap, SIGNAL(toggled(bool)), rbL3Ipv4, SLOT(setEnabled(bool)));
-	connect(rbFtLlcSnap, SIGNAL(toggled(bool)), rbL3Arp, SLOT(setEnabled(bool)));
-
-	// Force L3 = Other if FT = Other
+	// If L1/L2(FT)/L3/L4 = Other, force subsequent protocol to Other and 
+	// disable the subsequent protocol group as well
+	connect(rbL1Other, SIGNAL(toggled(bool)), rbFtOther, SLOT(setChecked(bool)));
+	connect(rbL1Other, SIGNAL(toggled(bool)), gbFrameType, SLOT(setDisabled(bool)));
 	connect(rbFtOther, SIGNAL(toggled(bool)), rbL3Other, SLOT(setChecked(bool)));
 	connect(rbFtOther, SIGNAL(toggled(bool)), gbL3Proto, SLOT(setDisabled(bool)));
-
-	// If L3 = None, force subsequent protocol level also to None
-	connect(rbL3None, SIGNAL(toggled(bool)), this, SLOT(forceProtocolNone(bool)));
-
-	// Enable/Disable L4 Protocol Choices for L3 Protocol IPv4
-	connect(rbL3Ipv4, SIGNAL(toggled(bool)), rbL4Icmp, SLOT(setEnabled(bool)));
-	connect(rbL3Ipv4, SIGNAL(toggled(bool)), rbL4Igmp, SLOT(setEnabled(bool)));
-	connect(rbL3Ipv4, SIGNAL(toggled(bool)), rbL4Tcp, SLOT(setEnabled(bool)));
-	connect(rbL3Ipv4, SIGNAL(toggled(bool)), rbL4Udp, SLOT(setEnabled(bool)));
-
-	// Enable/Disable L4 Protocol Choices for L3 Protocol ARP
-	connect(rbL3Arp, SIGNAL(toggled(bool)), rbL4Icmp, SLOT(setDisabled(bool)));
-	connect(rbL3Arp, SIGNAL(toggled(bool)), rbL4Igmp, SLOT(setDisabled(bool)));
-	connect(rbL3Arp, SIGNAL(toggled(bool)), rbL4Tcp, SLOT(setDisabled(bool)));
-	connect(rbL3Arp, SIGNAL(toggled(bool)), rbL4Udp, SLOT(setDisabled(bool)));
-
-	// Force L4 Protocol = None if L3 Protocol is set to ARP
-	connect(rbL3Arp, SIGNAL(clicked(bool)), rbL4None, SLOT(click()));
-
-	// Force L4 = Other if L3 = Other
 	connect(rbL3Other, SIGNAL(toggled(bool)), rbL4Other, SLOT(setChecked(bool)));
 	connect(rbL3Other, SIGNAL(toggled(bool)), gbL4Proto, SLOT(setDisabled(bool)));
-
-	// Force Payload = Other if L4 = Other
 	connect(rbL4Other, SIGNAL(toggled(bool)), rbPayloadOther, SLOT(setChecked(bool)));
 	connect(rbL4Other, SIGNAL(toggled(bool)), gbPayloadProto, SLOT(setDisabled(bool)));
 
+	// Setup valid subsequent protocols for L2 and L3 protocols
+	for (int i = ProtoL2; i <= ProtoL3; i++)
+	{
+		foreach(QAbstractButton *btn1, bgProto[i]->buttons())
+		{
+			int id1 = bgProto[i]->id(btn1);
+
+			if (id1 != ButtonIdNone && id1 != ButtonIdOther)
+			{
+				int validProtocolCount = 0;
+
+				foreach(QAbstractButton *btn2, bgProto[i+1]->buttons())
+				{
+					int id2 = bgProto[i+1]->id(btn2);
+
+					if (id2 != ButtonIdNone && id2 != ButtonIdOther)
+					{
+						if (OstProtocolManager.isValidNeighbour(id1, id2))
+						{
+							connect(btn1, SIGNAL(toggled(bool)), 
+									btn2, SLOT(setEnabled(bool)));
+							validProtocolCount++;
+						}
+						else
+							connect(btn1, SIGNAL(toggled(bool)), 
+									btn2, SLOT(setDisabled(bool)));
+					}
+				}
+
+				// If btn1 has no subsequent valid protocols, 
+				// force subsequent Protocol to 'None'
+				if (validProtocolCount == 0)
+					connect(btn1, SIGNAL(clicked(bool)),
+						bgProto[i+1]->button(ButtonIdNone), SLOT(click()));
+			}
+		}
+	}
+
 	mpAvailableProtocolsModel = new QStringListModel(
 		OstProtocolManager.protocolDatabase(), this);
 	lvAllProtocols->setModel(mpAvailableProtocolsModel);
@@ -729,8 +729,16 @@ void StreamConfigDialog::updateSelectProtocolsSimpleWidget()
 		id = _iter->next()->protocolNumber();
 		btn = bgProto[i]->button(id);
 
-		if (btn && btn->isEnabled())
-			btn->click();
+		if (btn)
+		{
+			if (btn->isEnabled())
+				btn->click();
+			else
+			{
+				btn->setChecked(true);
+				__updateProtocol(i, id);
+			}
+		}
 		else
 		{
 			switch (i)
diff --git a/common/abstractprotocol.cpp b/common/abstractprotocol.cpp
index 10678fb..3dd58ae 100644
--- a/common/abstractprotocol.cpp
+++ b/common/abstractprotocol.cpp
@@ -44,7 +44,7 @@ AbstractProtocol* AbstractProtocol::createInstance(StreamBase *stream,
 
 quint32 AbstractProtocol::protocolNumber() const
 {
-	qDebug("Something wrong!!!");
+	qFatal("Something wrong!!!");
 	return 0xFFFFFFFF;
 }
 
@@ -193,6 +193,11 @@ bool AbstractProtocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+AbstractProtocol::ProtocolIdType AbstractProtocol::protocolIdType() const
+{
+	return ProtocolIdNone;
+}
+
 quint32 AbstractProtocol::protocolId(ProtocolIdType type) const
 {
 	return 0;
@@ -360,6 +365,49 @@ QByteArray AbstractProtocol::protocolFrameValue(int streamIndex, bool forCksum)
 	return proto;
 }
 
+bool AbstractProtocol::isProtocolFrameValueVariable() const
+{
+	return false;
+}
+
+bool AbstractProtocol::isProtocolFrameSizeVariable() const
+{
+	return false;
+}
+
+bool AbstractProtocol::isProtocolFramePayloadValueVariable() const
+{
+	AbstractProtocol *p = next;
+
+	while (p)
+	{
+		if (p->isProtocolFrameValueVariable())
+			return true;
+		p = p->next;
+	}
+	if (parent && parent->isProtocolFramePayloadValueVariable())
+		return true;
+
+	return false;
+}
+
+bool AbstractProtocol::isProtocolFramePayloadSizeVariable() const
+{
+	AbstractProtocol *p = next;
+
+	while (p)
+	{
+		if (p->isProtocolFrameSizeVariable())
+			return true;
+		p = p->next;
+	}
+	if (parent && parent->isProtocolFramePayloadSizeVariable())
+		return true;
+
+	return false;
+}
+
+
 /*!
   \note If a subclass uses protocolFrameCksum() from within fieldData() to
   derive a cksum field, it MUST handle and return the 'FieldBitSize'
diff --git a/common/abstractprotocol.h b/common/abstractprotocol.h
index 3e1dc12..ccf1b12 100644
--- a/common/abstractprotocol.h
+++ b/common/abstractprotocol.h
@@ -56,6 +56,7 @@ public:
 	};
 
 	enum ProtocolIdType {
+		ProtocolIdNone,
 		ProtocolIdLlc,
 		ProtocolIdEth,
 		ProtocolIdIp,
@@ -82,6 +83,7 @@ public:
 	virtual QString name() const;
 	virtual QString shortName() const;
 
+	virtual ProtocolIdType protocolIdType() const;
 	virtual quint32 protocolId(ProtocolIdType type) const;
 	quint32 payloadProtocolId(ProtocolIdType type) const;
 
@@ -101,6 +103,11 @@ public:
 	int protocolFrameOffset(int streamIndex = 0) const;
 	int protocolFramePayloadSize(int streamIndex = 0) const;
 
+	virtual bool isProtocolFrameValueVariable() const;
+	virtual bool isProtocolFrameSizeVariable() const;
+	bool isProtocolFramePayloadValueVariable() const;
+	bool isProtocolFramePayloadSizeVariable() const;
+
 	virtual quint32 protocolFrameCksum(int streamIndex = 0,
 		CksumType cksumType = CksumIp) const;
 	quint32 protocolFrameHeaderCksum(int streamIndex = 0,
diff --git a/common/comboprotocol.h b/common/comboprotocol.h
index 34cba86..dbfd682 100644
--- a/common/comboprotocol.h
+++ b/common/comboprotocol.h
@@ -84,6 +84,11 @@ public:
 		return protoA->shortName() + "/" + protoB->shortName();
 	}
 
+	virtual ProtocolIdType protocolIdType() const
+	{
+		return protoB->protocolIdType();
+	}
+
 	virtual quint32 protocolId(ProtocolIdType type) const
 	{
 		return protoA->protocolId(type);
@@ -133,7 +138,21 @@ public:
 	virtual int protocolFrameSize() const;
 	int protocolFrameOffset() const;
 	int protocolFramePayloadSize() const;
+#endif
 
+	virtual bool isProtocolFrameValueVariable() const
+	{
+		return (protoA->isProtocolFrameValueVariable()
+			|| protoB->isProtocolFrameValueVariable());
+	}
+
+	virtual bool isProtocolFrameSizeVariable() const
+	{
+		return (protoA->isProtocolFrameSizeVariable()
+			|| protoB->isProtocolFrameSizeVariable());
+	}
+
+#if 0
 	virtual quint32 protocolFrameCksum(int streamIndex = 0,
 		CksumType cksumType = CksumIp) const;
 	quint32 protocolFrameHeaderCksum(int streamIndex = 0,
diff --git a/common/dot3.cpp b/common/dot3.cpp
index 0a88d50..ac2a878 100644
--- a/common/dot3.cpp
+++ b/common/dot3.cpp
@@ -119,6 +119,10 @@ bool Dot3Protocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+bool Dot3Protocol::isProtocolFrameValueVariable() const
+{
+	return isProtocolFramePayloadSizeVariable();
+}
 
 QWidget* Dot3Protocol::configWidget()
 {
diff --git a/common/dot3.h b/common/dot3.h
index def1031..9e0e8c1 100644
--- a/common/dot3.h
+++ b/common/dot3.h
@@ -46,6 +46,8 @@ public:
 	virtual bool setFieldData(int index, const QVariant &value, 
 			FieldAttrib attrib = FieldValue);
 
+	virtual bool isProtocolFrameValueVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/common/eth2.cpp b/common/eth2.cpp
index 7a6f7b5..0028b51 100644
--- a/common/eth2.cpp
+++ b/common/eth2.cpp
@@ -54,6 +54,11 @@ QString Eth2Protocol::shortName() const
 	return QString("Eth II");
 }
 
+AbstractProtocol::ProtocolIdType Eth2Protocol::protocolIdType() const
+{
+	return ProtocolIdEth;
+}
+
 int	Eth2Protocol::fieldCount() const
 {
 	return eth2_fieldCount;
diff --git a/common/eth2.h b/common/eth2.h
index 0555d65..fcf6b7d 100644
--- a/common/eth2.h
+++ b/common/eth2.h
@@ -39,6 +39,8 @@ public:
 	virtual QString name() const;
 	virtual QString shortName() const;
 
+	virtual ProtocolIdType protocolIdType() const;
+
 	virtual int	fieldCount() const;
 
 	virtual QVariant fieldData(int index, FieldAttrib attrib,
diff --git a/common/ip4.cpp b/common/ip4.cpp
index c929872..4c28bfb 100644
--- a/common/ip4.cpp
+++ b/common/ip4.cpp
@@ -94,6 +94,11 @@ QString Ip4Protocol::shortName() const
 	return QString("IPv4");
 }
 
+AbstractProtocol::ProtocolIdType Ip4Protocol::protocolIdType() const
+{
+	return ProtocolIdIp;
+}
+
 quint32 Ip4Protocol::protocolId(ProtocolIdType type) const
 {
 	switch(type)
@@ -572,6 +577,15 @@ bool Ip4Protocol::setFieldData(int index, const QVariant &value,
 	return isOk;
 }
 
+bool Ip4Protocol::isProtocolFrameValueVariable() const
+{
+	if ((data.src_ip_mode() != OstProto::Ip4::e_im_fixed) 
+			|| (data.dst_ip_mode() != OstProto::Ip4::e_im_fixed))
+		return true;
+	else
+		return false;
+}
+
 quint32 Ip4Protocol::protocolFrameCksum(int streamIndex,
 	CksumType cksumType) const
 {
diff --git a/common/ip4.h b/common/ip4.h
index e378755..34f4c37 100644
--- a/common/ip4.h
+++ b/common/ip4.h
@@ -71,6 +71,7 @@ public:
 
 	virtual QString name() const;
 	virtual QString shortName() const;
+	virtual ProtocolIdType protocolIdType() const;
 	virtual quint32 protocolId(ProtocolIdType type) const;
 	virtual int	fieldCount() const;
 
@@ -82,6 +83,8 @@ public:
 	virtual quint32 protocolFrameCksum(int streamIndex = 0,
 		CksumType cksumType = CksumIp) const;
 
+	virtual bool isProtocolFrameValueVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/common/llc.cpp b/common/llc.cpp
index e949e08..25cc307 100644
--- a/common/llc.cpp
+++ b/common/llc.cpp
@@ -54,6 +54,11 @@ QString LlcProtocol::shortName() const
 	return QString("LLC");
 }
 
+AbstractProtocol::ProtocolIdType LlcProtocol::protocolIdType() const
+{
+	return ProtocolIdLlc;
+}
+
 int	LlcProtocol::fieldCount() const
 {
 	return llc_fieldCount;
diff --git a/common/llc.h b/common/llc.h
index 3555e92..741f493 100644
--- a/common/llc.h
+++ b/common/llc.h
@@ -44,6 +44,8 @@ public:
 	virtual QString name() const;
 	virtual QString shortName() const;
 
+	virtual ProtocolIdType protocolIdType() const;
+
 	virtual int	fieldCount() const;
 
 	virtual QVariant fieldData(int index, FieldAttrib attrib,
diff --git a/common/mac.cpp b/common/mac.cpp
index 8e468a3..1d7ed87 100644
--- a/common/mac.cpp
+++ b/common/mac.cpp
@@ -239,6 +239,15 @@ bool MacProtocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+bool MacProtocol::isProtocolFrameValueVariable() const
+{
+	if ((data.dst_mac_mode() != OstProto::Mac::e_mm_fixed) ||
+		(data.src_mac_mode() != OstProto::Mac::e_mm_fixed))
+		return true;
+	else
+		return false;
+}
+
 
 QWidget* MacProtocol::configWidget()
 {
diff --git a/common/mac.h b/common/mac.h
index a493bd6..b6165b7 100644
--- a/common/mac.h
+++ b/common/mac.h
@@ -61,6 +61,8 @@ public:
 	virtual bool setFieldData(int index, const QVariant &value, 
 			FieldAttrib attrib = FieldValue);
 
+	virtual bool isProtocolFrameValueVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/common/payload.cpp b/common/payload.cpp
index 1125b73..4bbca2e 100644
--- a/common/payload.cpp
+++ b/common/payload.cpp
@@ -187,6 +187,23 @@ bool PayloadProtocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+bool PayloadProtocol::isProtocolFrameValueVariable() const
+{
+	if (isProtocolFrameSizeVariable() 
+			|| data.pattern_mode() == OstProto::Payload::e_dp_random)
+		return true;
+	else
+		return false;
+}
+
+bool PayloadProtocol::isProtocolFrameSizeVariable() const
+{
+	if (mpStream->lenMode() == StreamBase::e_fl_fixed)
+		return false;
+	else
+		return true;
+}
+
 
 QWidget* PayloadProtocol::configWidget()
 {
diff --git a/common/payload.h b/common/payload.h
index c2d5f4d..9437a8c 100644
--- a/common/payload.h
+++ b/common/payload.h
@@ -54,6 +54,9 @@ public:
 	virtual bool setFieldData(int index, const QVariant &value, 
 			FieldAttrib attrib = FieldValue);
 
+	virtual bool isProtocolFrameValueVariable() const;
+	virtual bool isProtocolFrameSizeVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/common/protocolmanager.cpp b/common/protocolmanager.cpp
index 56c1912..8a9547d 100644
--- a/common/protocolmanager.cpp
+++ b/common/protocolmanager.cpp
@@ -24,42 +24,69 @@ ProtocolManager::ProtocolManager()
 	 themselves (once this is done remove the #includes for all the protocols)
 	 */
 	registerProtocol(OstProto::Protocol::kMacFieldNumber,
-			QString("mac"),  (void*) MacProtocol::createInstance);
+			(void*) MacProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kPayloadFieldNumber,
-		   	QString("payload"), (void*) PayloadProtocol::createInstance);
+		   	(void*) PayloadProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kEth2FieldNumber,
-		   	QString("eth2"), (void*) Eth2Protocol::createInstance);
+		   	(void*) Eth2Protocol::createInstance);
 	registerProtocol(OstProto::Protocol::kDot3FieldNumber,
-		   	QString("dot3"), (void*) Dot3Protocol::createInstance);
+		   	(void*) Dot3Protocol::createInstance);
 	registerProtocol(OstProto::Protocol::kLlcFieldNumber,
-		   	QString("llc"),  (void*) LlcProtocol::createInstance);
+		   	(void*) LlcProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kSnapFieldNumber,
-		   	QString("snap"), (void*) SnapProtocol::createInstance);
+		   	(void*) SnapProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kDot2LlcFieldNumber,
-			QString("dot2Llc"), (void*) Dot2LlcProtocol::createInstance);
+			(void*) Dot2LlcProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kDot2SnapFieldNumber,
-			QString("dot2Snap"), (void*) Dot2SnapProtocol::createInstance);
+			(void*) Dot2SnapProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kSvlanFieldNumber,
-		   	QString("svlan"), (void*) VlanProtocol::createInstance);
+		   	(void*) SVlanProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kVlanFieldNumber,
-		   	QString("vlan"), (void*) VlanProtocol::createInstance);
+		   	(void*) VlanProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kVlanStackFieldNumber,
-			QString("vlanstack"), (void*) VlanStackProtocol::createInstance);
+			(void*) VlanStackProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kIp4FieldNumber,
-		   	QString("ip4"),  (void*) Ip4Protocol::createInstance);
+		   	(void*) Ip4Protocol::createInstance);
 	registerProtocol(OstProto::Protocol::kTcpFieldNumber,
-		   	QString("tcp"),  (void*) TcpProtocol::createInstance);
+		   	(void*) TcpProtocol::createInstance);
 	registerProtocol(OstProto::Protocol::kUdpFieldNumber,
-		   	QString("udp"),  (void*) UdpProtocol::createInstance);
+		   	(void*) UdpProtocol::createInstance);
+
+	populateNeighbourProtocols();
 }
 
-void ProtocolManager::registerProtocol(int protoNumber, QString protoName,
+void ProtocolManager::registerProtocol(int protoNumber,
 	void *protoInstanceCreator)
 {
+	AbstractProtocol *p;
+
 	//! \todo (MED) validate incoming params for duplicates with existing
-	nameToNumberMap.insert(protoName, protoNumber);
-	numberToNameMap.insert(protoNumber, protoName);
+
 	factory.insert(protoNumber, protoInstanceCreator);
+
+	p = createProtocol(protoNumber, NULL);
+	protocolList.append(p);
+
+	numberToNameMap.insert(protoNumber, p->shortName());
+	nameToNumberMap.insert(p->shortName(), protoNumber);
+}
+
+void ProtocolManager::populateNeighbourProtocols()
+{
+	neighbourProtocols.clear();
+
+	foreach(AbstractProtocol *p, protocolList)
+	{
+		if (p->protocolIdType() != AbstractProtocol::ProtocolIdNone)
+		{
+			foreach(AbstractProtocol *q, protocolList)
+			{
+				if (q->protocolId(p->protocolIdType()))
+					neighbourProtocols.insert(
+						p->protocolNumber(), q->protocolNumber());
+			}
+		}
+	}
 }
 
 AbstractProtocol* ProtocolManager::createProtocol(int protoNumber,
@@ -84,6 +111,14 @@ AbstractProtocol* ProtocolManager::createProtocol(QString protoName,
 	return createProtocol(nameToNumberMap.value(protoName), stream, parent);
 }
 
+bool ProtocolManager::isValidNeighbour(int protoPrefix, int protoSuffix)
+{
+	if (neighbourProtocols.contains(protoPrefix, protoSuffix))
+		return true;
+	else
+		return false;
+}
+
 QStringList ProtocolManager::protocolDatabase()
 {
 	return numberToNameMap.values();
diff --git a/common/protocolmanager.h b/common/protocolmanager.h
index 985253b..c619099 100644
--- a/common/protocolmanager.h
+++ b/common/protocolmanager.h
@@ -11,19 +11,24 @@ class ProtocolManager
 {
 	QMap<int, QString>	numberToNameMap;
 	QMap<QString, int>	nameToNumberMap;
+	QMultiMap<int, int> neighbourProtocols;
 	QMap<int, void*>	factory;
+	QList<AbstractProtocol*>	protocolList;
+
+	void populateNeighbourProtocols();
 
 public:
 	ProtocolManager();
 
-	void registerProtocol(int protoNumber, QString protoName,
-		void *protoCreator);
+	void registerProtocol(int protoNumber, void *protoInstanceCreator);
 
 	AbstractProtocol* createProtocol(int protoNumber, StreamBase *stream,
 		AbstractProtocol *parent = 0);
 	AbstractProtocol* createProtocol(QString protoName, StreamBase *stream,
 		AbstractProtocol *parent = 0);
 
+	bool isValidNeighbour(int protoPrefix, int protoSuffix);
+
 	QStringList protocolDatabase();
 };
 
diff --git a/common/snap.cpp b/common/snap.cpp
index 3dfd7e4..0f7d477 100644
--- a/common/snap.cpp
+++ b/common/snap.cpp
@@ -54,6 +54,11 @@ QString SnapProtocol::shortName() const
 	return QString("SNAP");
 }
 
+AbstractProtocol::ProtocolIdType SnapProtocol::protocolIdType() const
+{
+	return ProtocolIdEth;
+}
+
 quint32 SnapProtocol::protocolId(ProtocolIdType type) const
 {
 	switch(type)
diff --git a/common/snap.h b/common/snap.h
index a2531f6..c4018ad 100644
--- a/common/snap.h
+++ b/common/snap.h
@@ -39,6 +39,8 @@ public:
 
 	virtual QString name() const;
 	virtual QString shortName() const;
+
+	virtual ProtocolIdType protocolIdType() const;
 	virtual quint32 protocolId(ProtocolIdType type) const;
 
 	virtual int	fieldCount() const;
diff --git a/common/streambase.cpp b/common/streambase.cpp
index 1ed8d7f..5bd2dcb 100644
--- a/common/streambase.cpp
+++ b/common/streambase.cpp
@@ -20,11 +20,13 @@ StreamBase::StreamBase() :
 
 	iter = createProtocolListIterator();
 	// By default newly created streams have the mac and payload protocols
-	proto = OstProtocolManager.createProtocol("mac", this);
+	proto = OstProtocolManager.createProtocol(
+			OstProto::Protocol::kMacFieldNumber, this);
 	iter->insert(proto);
 	qDebug("stream: mac = %p", proto);
 
-	proto = OstProtocolManager.createProtocol("payload", this);
+	proto = OstProtocolManager.createProtocol(
+			OstProto::Protocol::kPayloadFieldNumber, this);
 	iter->insert(proto);
 	qDebug("stream: payload = %p", proto);
 
@@ -104,7 +106,7 @@ void StreamBase::setFrameProtocol(ProtocolList protocolList)
 }
 #endif
 
-ProtocolListIterator*  StreamBase::createProtocolListIterator()
+ProtocolListIterator*  StreamBase::createProtocolListIterator() const
 {
 	return new ProtocolListIterator(*currentFrameProtocols);
 }
@@ -158,7 +160,7 @@ bool StreamBase::setName(QString name)
 	return true;
 }
 
-StreamBase::FrameLengthMode	StreamBase::lenMode()
+StreamBase::FrameLengthMode	StreamBase::lenMode() const
 {
 	return (StreamBase::FrameLengthMode) mCore->len_mode();
 }
@@ -169,7 +171,7 @@ bool StreamBase::setLenMode(FrameLengthMode	lenMode)
 	return true;
 }
 
-quint16	StreamBase::frameLen(int streamIndex)
+quint16	StreamBase::frameLen(int streamIndex) const
 {
 	int		pktLen;
 
@@ -211,7 +213,7 @@ bool StreamBase::setFrameLen(quint16 frameLen)
 	return true;
 }
 
-quint16	StreamBase::frameLenMin()
+quint16	StreamBase::frameLenMin() const
 {
 	return mCore->frame_len_min();
 }
@@ -222,7 +224,7 @@ bool StreamBase::setFrameLenMin(quint16 frameLenMin)
 	return true;
 }
 
-quint16	StreamBase::frameLenMax()
+quint16	StreamBase::frameLenMax() const
 {
 	return mCore->frame_len_max();
 }
@@ -233,17 +235,18 @@ bool StreamBase::setFrameLenMax(quint16 frameLenMax)
 	return true;
 }
 
-StreamBase::SendUnit StreamBase::sendUnit()
+StreamBase::SendUnit StreamBase::sendUnit() const
 {
 	return (StreamBase::SendUnit) mControl->unit();
 }
+
 bool StreamBase::setSendUnit(SendUnit sendUnit)
 {
 	mControl->set_unit((OstProto::StreamControl::SendUnit) sendUnit); 
 	return true;
 }
 
-StreamBase::SendMode StreamBase::sendMode()
+StreamBase::SendMode StreamBase::sendMode() const
 {
 	return (StreamBase::SendMode) mControl->mode();
 }
@@ -255,7 +258,7 @@ bool StreamBase::setSendMode(SendMode sendMode)
 	return true;
 }
 
-StreamBase::NextWhat StreamBase::nextWhat()
+StreamBase::NextWhat StreamBase::nextWhat() const
 {
 	return (StreamBase::NextWhat) mControl->next();
 }
@@ -266,7 +269,7 @@ bool StreamBase::setNextWhat(NextWhat nextWhat)
 	return true;
 }
 
-quint32 StreamBase::numPackets()
+quint32 StreamBase::numPackets() const
 {
 	return (quint32) mControl->num_packets();
 }
@@ -277,7 +280,7 @@ bool StreamBase::setNumPackets(quint32 numPackets)
 	return true;
 }
 
-quint32 StreamBase::numBursts()
+quint32 StreamBase::numBursts() const
 {
 	return (quint32) mControl->num_bursts();
 }
@@ -288,7 +291,7 @@ bool StreamBase::setNumBursts(quint32 numBursts)
 	return true;
 }
 
-quint32 StreamBase::burstSize()
+quint32 StreamBase::burstSize() const
 {
 	return (quint32) mControl->packets_per_burst();
 }
@@ -299,7 +302,7 @@ bool StreamBase::setBurstSize(quint32 packetsPerBurst)
 	return true;
 }
 
-quint32 StreamBase::packetRate()
+quint32 StreamBase::packetRate() const
 {
 	return (quint32) mControl->packets_per_sec();
 }
@@ -310,7 +313,7 @@ bool StreamBase::setPacketRate(quint32 packetsPerSec)
 	return true;
 }
 
-quint32 StreamBase::burstRate()
+quint32 StreamBase::burstRate() const
 {
 	return (quint32) mControl->bursts_per_sec();
 }
@@ -320,3 +323,57 @@ bool StreamBase::setBurstRate(quint32 burstsPerSec)
 	mControl->set_bursts_per_sec(burstsPerSec); 
 	return true;
 }
+
+bool StreamBase::isFrameVariable() const
+{
+	ProtocolListIterator	*iter;
+
+	iter = createProtocolListIterator();
+	while (iter->hasNext())
+	{
+		AbstractProtocol	*proto;
+
+		proto = iter->next();
+		if (proto->isProtocolFrameValueVariable())
+			goto _exit;
+	}
+	delete iter;
+	return false;
+
+_exit:
+	delete iter;
+	return true;
+}
+
+int StreamBase::frameValue(uchar *buf, int bufMaxSize, int n) const
+{
+	int		pktLen, len = 0;
+
+	pktLen = frameLen(n);
+
+	// pktLen is adjusted for CRC/FCS which will be added by the NIC
+	pktLen -=  4;
+
+	if ((pktLen < 0) || (pktLen > bufMaxSize))
+		return 0;
+
+	ProtocolListIterator	*iter;
+
+	iter = createProtocolListIterator();
+	while (iter->hasNext())
+	{
+		AbstractProtocol	*proto;
+		QByteArray			ba;
+
+		proto = iter->next();
+		ba = proto->protocolFrameValue(n);
+
+		if (len + ba.size() < bufMaxSize)
+			memcpy(buf+len, ba.constData(), ba.size());
+		len += ba.size();
+	}
+	delete iter;
+
+	return pktLen;
+}
+
diff --git a/common/streambase.h b/common/streambase.h
index 878b2d7..45f0cbb 100644
--- a/common/streambase.h
+++ b/common/streambase.h
@@ -26,7 +26,7 @@ public:
 	void protoDataCopyFrom(const OstProto::Stream &stream);
 	void protoDataCopyInto(OstProto::Stream &stream) const;
 
-	ProtocolListIterator* createProtocolListIterator();
+	ProtocolListIterator* createProtocolListIterator() const;
 
 	//! \todo (LOW) should we have a copy constructor??
 
@@ -76,41 +76,44 @@ public:
 	bool setName(QString name) ;
 
 	// Frame Length (includes FCS);
-	FrameLengthMode	lenMode();
+	FrameLengthMode	lenMode() const;
 	bool setLenMode(FrameLengthMode	lenMode);
 
-	quint16	frameLen(int streamIndex = 0);
+	quint16	frameLen(int streamIndex = 0) const;
 	bool setFrameLen(quint16 frameLen);
 
-	quint16	frameLenMin();
+	quint16	frameLenMin() const;
 	bool setFrameLenMin(quint16 frameLenMin);
 
-	quint16	frameLenMax();
+	quint16	frameLenMax() const;
 	bool setFrameLenMax(quint16 frameLenMax);
 
-	SendUnit sendUnit();
+	SendUnit sendUnit() const;
 	bool setSendUnit(SendUnit sendUnit);
 
-	SendMode sendMode();
+	SendMode sendMode() const;
 	bool setSendMode(SendMode sendMode);
 
-	NextWhat nextWhat();
+	NextWhat nextWhat() const;
 	bool setNextWhat(NextWhat nextWhat);
 
-	quint32 numPackets();
+	quint32 numPackets() const;
 	bool setNumPackets(quint32 numPackets);
 
-	quint32 numBursts();
+	quint32 numBursts() const;
 	bool setNumBursts(quint32 numBursts);
 
-	quint32 burstSize();
+	quint32 burstSize() const;
 	bool setBurstSize(quint32 packetsPerBurst);
 
-	quint32 packetRate();
+	quint32 packetRate() const;
 	bool setPacketRate(quint32 packetsPerSec);
 
-	quint32 burstRate();
+	quint32 burstRate() const;
 	bool setBurstRate(quint32 burstsPerSec);
+
+	bool isFrameVariable() const;
+	int frameValue(uchar *buf, int bufMaxSize, int n) const;
 };
 
 #endif
diff --git a/common/tcp.cpp b/common/tcp.cpp
index be16120..6bbc271 100644
--- a/common/tcp.cpp
+++ b/common/tcp.cpp
@@ -380,6 +380,13 @@ bool TcpProtocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+bool TcpProtocol::isProtocolFrameValueVariable() const
+{
+	if (data.is_override_cksum())
+		return false;
+	else
+		return isProtocolFramePayloadValueVariable();
+}
 
 QWidget* TcpProtocol::configWidget()
 {
diff --git a/common/tcp.h b/common/tcp.h
index cfd43a6..72cfbf8 100644
--- a/common/tcp.h
+++ b/common/tcp.h
@@ -67,6 +67,8 @@ public:
 	virtual bool setFieldData(int index, const QVariant &value, 
 			FieldAttrib attrib = FieldValue);
 
+	virtual bool isProtocolFrameValueVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/common/udp.cpp b/common/udp.cpp
index 0d5b772..9cb74ec 100644
--- a/common/udp.cpp
+++ b/common/udp.cpp
@@ -258,6 +258,13 @@ bool UdpProtocol::setFieldData(int index, const QVariant &value,
 	return false;
 }
 
+bool UdpProtocol::isProtocolFrameValueVariable() const
+{
+	if (data.is_override_totlen() && data.is_override_cksum())
+		return false;
+	else
+		return isProtocolFramePayloadValueVariable();
+}
 
 QWidget* UdpProtocol::configWidget()
 {
diff --git a/common/udp.h b/common/udp.h
index 278809a..663456b 100644
--- a/common/udp.h
+++ b/common/udp.h
@@ -54,6 +54,8 @@ public:
 	virtual bool setFieldData(int index, const QVariant &value, 
 			FieldAttrib attrib = FieldValue);
 
+	virtual bool isProtocolFrameValueVariable() const;
+
 	virtual QWidget* configWidget();
 	virtual void loadConfigWidget();
 	virtual void storeConfigWidget();
diff --git a/server/myservice.cpp b/server/myservice.cpp
index 54b0895..93afc8b 100644
--- a/server/myservice.cpp
+++ b/server/myservice.cpp
@@ -25,39 +25,6 @@ StreamInfo::~StreamInfo()
 {
 }
 
-int StreamInfo::makePacket(uchar *buf, int bufMaxSize, int n)
-{
-	int		pktLen, len = 0;
-
-	pktLen = frameLen(n);
-
-	// pktLen is adjusted for CRC/FCS which will be added by the NIC
-	pktLen -=  4;
-
-	if ((pktLen < 0) || (pktLen > bufMaxSize))
-		return 0;
-
-	ProtocolListIterator	*iter;
-
-	iter = createProtocolListIterator();
-	while (iter->hasNext())
-	{
-		AbstractProtocol	*proto;
-		QByteArray			ba;
-
-		proto = iter->next();
-		ba = proto->protocolFrameValue(n);
-
-		if (len + ba.size() < bufMaxSize)
-			memcpy(buf+len, ba.constData(), ba.size());
-		len += ba.size();
-	}
-	delete iter;
-
-	return pktLen;
-}
-
-
 //
 // ------------------ PortInfo --------------------
 //
@@ -195,6 +162,8 @@ void PortInfo::updateLinkState()
 
 void PortInfo::update()
 {
+	int		len;
+	bool	isVariable;
 	uchar				pktBuf[2000];
 	pcap_pkthdr			pktHdr;
 	ost_pcap_send_queue	sendQ;
@@ -249,17 +218,25 @@ void PortInfo::update()
 					numBursts, numPackets);
 			qDebug("ibg = %ld, ipg = %ld\n", ibg, ipg);
 
+			if (streamList[i]->isFrameVariable())
+			{
+				isVariable = true;
+			}
+			else
+			{
+				isVariable = false;
+				len = streamList[i]->frameValue(pktBuf, sizeof(pktBuf), 0);
+			}
+
 			for (int j = 0; j < numBursts; j++)
 			{
 				for (int k = 0; k < numPackets; k++)
 				{
-					int len;
-
-					/*! \todo (HIGH) if pkt contents do not change across
-					pkts then don't call makePacket(), rather reuse the 
-					previous */
-					len = streamList[i]->makePacket(pktBuf, sizeof(pktBuf), 
+					if (isVariable)
+					{
+						len = streamList[i]->frameValue(pktBuf, sizeof(pktBuf), 
 							j * numPackets + k);
+					}
 					if (len > 0)
 					{
 						pktHdr.caplen = pktHdr.len = len;
@@ -784,7 +761,6 @@ void PortInfo::PortCapture::run()
 	{
 		if (!capFile.open())
 			qFatal("Unable to open temp cap file");
-		return;
 	}
 
 	qDebug("cap file = %s", capFile.fileName().toAscii().constData());
diff --git a/server/myservice.h b/server/myservice.h
index ebd1db1..bafe9b9 100644
--- a/server/myservice.h
+++ b/server/myservice.h
@@ -46,9 +46,6 @@ class StreamInfo : public StreamBase
 public:
 	StreamInfo();
 	~StreamInfo();
-
-private:
-	int makePacket(uchar *buf, int bufMaxSize, int n);
 };