draft-werner-nsis-natfw-nslp-statemachine-01.txt		draft-werner-nsis-natfw-nslp-statemachine-02.txt
	NSIS X. Fu		NSIS C. Werner
	Internet-Draft C. Werner		Internet-Draft X. Fu, Ed.
	Expires: January 18, 2006 Univ. Goettingen		Expires: September 7, 2006 Univ. Goettingen
	H. Tschofenig		H. Tschofenig
	T. Tsenov
	Siemens		Siemens
	C. Aoun		C. Aoun
	Nortel		ENST
	N. Steinleitner		N. Steinleitner
	Univ. Goettingen		Univ. Goettingen
	July 17, 2005		March 6, 2006
	NAT/FW NSLP State Machine		NAT/FW NSLP State Machine
	draft-werner-nsis-natfw-nslp-statemachine-01.txt		draft-werner-nsis-natfw-nslp-statemachine-02.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
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	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 41		skipping to change at page 1, line 40
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	This Internet-Draft will expire on January 18, 2006.		This Internet-Draft will expire on September 7, 2006.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2005).		Copyright (C) The Internet Society (2006).
	Abstract		Abstract
	This document describes the state machines for the NSIS Signaling		This document describes the state machines for the NSIS Signaling
	Layer Protocol for Network Address Translation/Firewall signaling		Layer Protocol for Network Address Translation/Firewall signaling
	(NAT/FW NSLP). A set of state machines for NAT/FW NSLP entities at		(NAT/FW NSLP). A set of state machines for NAT/FW NSLP entities at
	different locations of a signaling path are presented in order to		different locations of a signaling path are presented in order to
	illustrate how NAT/FW NSLP may be implemented.		illustrate how NAT/FW NSLP may be implemented.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Notational conventions used in state diagrams . . . . . . . 3		3. Notational conventions used in state diagrams . . . . . . . . 3
	4. State Machine Symbols . . . . . . . . . . . . . . . . . . . 6		4. State Machine Symbols . . . . . . . . . . . . . . . . . . . . 6
	5. Common Rules . . . . . . . . . . . . . . . . . . . . . . . . 7		5. Common Rules . . . . . . . . . . . . . . . . . . . . . . . . . 7
	5.1 Common Procedures . . . . . . . . . . . . . . . . . . . . 7		5.1. Common Procedures . . . . . . . . . . . . . . . . . . . . 7
	5.2 Common Variables . . . . . . . . . . . . . . . . . . . . . 9		5.2. Common Variables . . . . . . . . . . . . . . . . . . . . . 9
	5.3 Constants . . . . . . . . . . . . . . . . . . . . . . . . 10		5.3. Constants . . . . . . . . . . . . . . . . . . . . . . . . 9
	6. State machine for the NAT/FW NI . . . . . . . . . . . . . . 10		6. State machine for the NAT/FW NI . . . . . . . . . . . . . . . 9
	7. State machines for the NAT/FW NF . . . . . . . . . . . . . . 14		7. State machines for the NAT/FW NF . . . . . . . . . . . . . . . 11
	7.1 State machine for NAT/FW Firewall NF . . . . . . . . . . . 15		8. State machine for the NAT/FW NR . . . . . . . . . . . . . . . 15
	7.2 State machine for NAT/FW NAT NF . . . . . . . . . . . . . 22		9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
	8. State machine for the NAT/FW NR . . . . . . . . . . . . . . 29		10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 18
	9. Security Considerations . . . . . . . . . . . . . . . . . . 33		11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 18
	10. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 34		12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
	11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 34		13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . 34		13.1. Normative References . . . . . . . . . . . . . . . . . . . 19
	12.1 Normative References . . . . . . . . . . . . . . . . . . 34		13.2. Informative References . . . . . . . . . . . . . . . . . . 19
	12.2 Informative References . . . . . . . . . . . . . . . . . 34		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 35		Intellectual Property and Copyright Statements . . . . . . . . . . 21
	Intellectual Property and Copyright Statements . . . . . . . 37
	1. Introduction		1. Introduction
	This document describes the state machines for NAT/FW NSLP [1],		This document describes the state machines for NAT/FW NSLP [1],
	trying to show how NAT/FW NSLP can be implemented to support its		trying to show how NAT/FW NSLP can be implemented to support its
	deployment. The state machines described in this document are		deployment. The state machines described in this document are
	illustrative of how the NAT/FW NSLP protocol defined in [1] may be		illustrative of how the NAT/FW NSLP protocol defined in [1] may be
	implemented for the first NAT/FW NSLP node in the signaling path,		implemented for the first NAT/FW NSLP node in the signaling path,
	intermediate NAT/FW NSLP nodes with Firewall and/or NAT		intermediate NAT/FW NSLP nodes with Firewall and/or NAT
	functionality, and the last NAT/FW NSLP node in the signaling path.		functionality, and the last NAT/FW NSLP node in the signaling path.
	skipping to change at page 3, line 25		skipping to change at page 3, line 25
	machines are informative only. Implementations may achieve the same		machines are informative only. Implementations may achieve the same
	results using different methods.		results using different methods.
	The messages used in the NAT/FW NSLP protocol can be summarized as		The messages used in the NAT/FW NSLP protocol can be summarized as
	follows:		follows:
	Requesting message Responding message		Requesting message Responding message
	------------------------+---------------------------		------------------------+---------------------------
	CREATE |RESPONSE		CREATE |RESPONSE
	REA |RESPONSE		REA |RESPONSE
	QUERY |RESPONSE		TRACE |RESPONSE
	RESPONSE |NONE		RESPONSE |NONE
	NOTIFY |NONE		NOTIFY |NONE
	TRIGGER |CREATE
	------------------------+---------------------------		------------------------+---------------------------
	We describe a set of state machines for different roles of entities		We describe a set of state machines for different roles of entities
	running NAT/FW NSLP to illustrate how NAT/FW NSLP may be implemented.		running NAT/FW NSLP to illustrate how NAT/FW NSLP may be implemented.
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [2].		document are to be interpreted as described in [2].
	skipping to change at page 6, line 39		skipping to change at page 6, line 41
	assignments, e.g., a = b = X the action causes the value of the		assignments, e.g., a = b = X the action causes the value of the
	expression following the right-most assignment operator to be		expression following the right-most assignment operator to be
	assigned to all of the variables that appear to the left of the		assigned to all of the variables that appear to the left of the
	right-most assignment operator.		right-most assignment operator.
	! Logical NOT operator.		! Logical NOT operator.
	&& Logical AND operator.		&& Logical AND operator.
	|| Logical OR operator.		|| Logical OR operator.
	if...then... Conditional action. If the Boolean expression following		if...then... Conditional action. If the Boolean expression following
	the if evaluates to TRUE, then the action following the then is		the if evaluates to TRUE, then the action following the then is
	executed.		executed.
	\{ statement 1, ... statement N \} Compound statement. Braces are		{ statement 1, ... statement N } Compound statement. Braces are used
	used to group statements that are executed together as if they		to group statements that are executed together as if they were a
	were a single statement.		single statement.
	!= Inequality. Evaluates to TRUE if the expression to the left of		!= Inequality. Evaluates to TRUE if the expression to the left of
	the operator is not equal in value to the expression to the right.		the operator is not equal in value to the expression to the right.
	== Equality. Evaluates to TRUE if the expression to the left of the		== Equality. Evaluates to TRUE if the expression to the left of the
	operator is equal in value to the expression to the right.		operator is equal in value to the expression to the right.
	> Greater than. Evaluates to TRUE if the value of the expression to		> Greater than. Evaluates to TRUE if the value of the expression to
	the left of the operator is greater than the value of the		the left of the operator is greater than the value of the
	expression to the right.		expression to the right.
	<= Less than or equal to. Evaluates to TRUE if the value of the		<= Less than or equal to. Evaluates to TRUE if the value of the
	expression to the left of the operator is either less than or		expression to the left of the operator is either less than or
	equal to the value of the expression to the right.		equal to the value of the expression to the right.
	++ Increment the preceding integer operator by 1.		++ Increment the preceding integer operator by 1.
	5. Common Rules		5. Common Rules
	Throughout the document we use terms defined in the [1], such as NI,		Throughout the document we use terms defined in the [1], such as NI,
	NF, NR, NI+, NR+, CREATE, QUERY, or RESPONSE.		NF, NR, CREATE, REA or RESPONSE.
	5.1 Common Procedures		5.1. Common Procedures
	tx_CREATE(): Transmit a CREATE message		tx_CREATE(): Transmit a CREATE message
	tx_CREATE(LIFETIME=0): Transmit CREATE message with lifetime object		tx_CREATE(LIFETIME=0): Transmit CREATE message with lifetime object
	explicitly set to 0 for session deletion		explicitly set to 0 for session deletion
	tx_RESP(code,type): Transmit RESPONSE message with specified code		tx_RESPONSE(code,type): Transmit RESPONSE message with specified code
	(SUCCESS or ERROR) and result type (related to a specific request		(SUCCESS or ERROR) and result type (related to a specific request
	type message: CREATE, REA or QUERY). A code or result type may be		type message: CREATE or REA). A code or result type may be
	omitted, typically when forwarding received RESPONSE messages.		omitted, typically when forwarding received RESPONSE messages.
	tx_QUERY(): Transmit QUERY message.		tx_REA(): Transmit a REA message
	tx_NOTIFY(): Transmit NOTIFY message.		rx_RESPONSE(code, type): Evaluates to TRUE if a RESPONSE message has
	rx_RESP(code, type): Evaluates to TRUE if a RESPONSE message has been		been received with the specified code (SUCCESS or ERROR) and
	received with the specified code (SUCCESS or ERROR) and result		result type (related to a specific request type message: CREATE or
	type (related to a specific request type message: CREATE, REA or		REA). If the code or type is omitted, any received RESPONSE
	QUERY). If the code or type is omitted, any received RESPONSE
	message which is only matching the given code or type will		message which is only matching the given code or type will
	evaluate this procedure to TRUE.		evaluate this procedure to TRUE.
	rx_NOTIFY(): Evaluates to TRUE if a NOTIFY message has been received.
	rx_QUERY(): Evaluates to TRUE if a QUERY message has been received
	rx_CREATE(): Evaluates to TRUE if a CREATE message has been received.		rx_CREATE(): Evaluates to TRUE if a CREATE message has been received.
			rx_REA(): Evaluates to TRUE if a REA message has been received.
	CHECK_AA(): Checks Authorization and Authentication of the received		CHECK_AA(): Checks Authorization and Authentication of the received
	message. Evaluates to TRUE if the check is successful, otherwise		message. Evaluates to TRUE if the check is successful, otherwise
	it evaluates to FALSE. This check is performed on all received		it evaluates to FALSE. This check is performed on all received
	messages hence it will only be shown within the state machine when		messages hence it will only be shown within the state machine when
	the check has failed. This CHECK_AA also MAY include a local		the check has failed. This CHECK_AA also MAY include a local
	policy check for the received message.		policy check for the received message.
	CHECK_NoNR(): Checks if the message can reach its targeted		CreateSession(): Installs all session related states, variables,
	destination, i.e. the NR if it exists at the targeted host.		bindings, policies.
	CHECK_SCOPE(): Checks if the message has reached the network		DeleteSession(): Removes all session related states, variables,
	boundaries defined by the SCOPE object.		bindings, policies.
	Process Event(): Processes a NOTIFY messages and adapts the behaviour		CreatePinhole(): Installs a pinhole for the new session.
	of this node to the new condition.		DeletePinhole(): Removes a previously installed pinhole.
	Process Query(): Processes the received QUERY message and prepares
	the appropriate RESPONSE message.
	Binding.create(): Creates a public/private network translation		CreateReservations(): Creates a matching based on the MRI and open
	binding on a NAT device for the requesting entity.		pinholes for the signaling traffic.
	Binding.clear(): Deletes a previously created a public/private		DeleteReservations(): Deletes previously installed matchings and
			pinholes for the signaling traffic.
			CreateBinding(): Creates a public/private network translation binding
			on a NAT device for the requesting entity.
			DeleteBinding(): Deletes a previously created a public/private
	network translation binding on a NAT device for the requesting		network translation binding on a NAT device for the requesting
	entity.		entity.
	Session.create(): Installs all session related states, variables,		StartTimer(identifier): This procedure starts a timer with a certain
	bindings, policies.		timespan, which is up to the specific implementation. The
	Session.update(): Updates all session related states, variables,
	bindings, policies based on received CREATE or TRIGGER if
	applicable.
	Session.clear(): Removes all session related states, variables,
	bindings, policies.
	PckFilter.create(): Installs a packet filter for the new session.
	PckFilter.update(): Updates the packet filter for changes in the
	session rules.
	PckFilter.clear(): Removes a previously set packet filter.
	Start.STATE_TIMER(identifier): This procedure starts a timer with a
	certain timespan, which is up to the specific implementation. The
	parameter 'identifier' identifies this timer uniquely. Any		parameter 'identifier' identifies this timer uniquely. Any
	subsequent Start_STATE_TIMER(x), Stop_STATE_TIMER(x),		subsequent StartTimer(identifier), StopTimer(identifier),
	TIMEOUT_STATE(x) refer to the same timer labeled x. This timer is		(identifier)_TIMEOUT refer to the same timer labeled x. This
	required to time the lifetime of state, which means that when it		timer is required to time the lifetime of state, which means that
	times out, it indicates the current machine state should be left		when it times out, it indicates the current machine state should
	or its validation has expired. This procedure starts the timer		be left or its validation has expired. This procedure starts the
	'identifier'. If a timer with the same 'identifier' has		timer 'identifier'. If a timer with the same 'identifier' has
	already been started and not yet stopped, the timer is now stopped		already been started and not yet stopped, the timer is now stopped
	and restarted. After the timer has timed out, the procedure		and restarted. After the timer has timed out, the procedure
	TIMEOUT_STATE(identifier) evaluates to TRUE. The timer does not		(identifier)_TIMEOUT evaluates to TRUE. The timer does not
	restart automatically, but must be started again with a		restart automatically, but must be started again with a
	Start_STATE_TIMER(identifier). Notice that there is no difference		StartTimer(identifier). Notice that this function can call as
	to the Start_REFRESH_TIMER(identifier) procedure which has exactly		statetimer or as refreshtimer which represents the
	the same functionality. The different procedure names are only		"Start.REFRESH_TIMER(identifier)" procedure in version 01.
	supplied to underline the purpose of this specific timer.		StopTimer(identifier): This procedure stops the timer labeled
	Stop.STATE_TIMER(identifier): This procedure stops the timer labeled
	'identifier'. If it has already been stopped, this procedure has		'identifier'. If it has already been stopped, this procedure has
	no effect. If the timer has already timed out, this procedure		no effect. If the timer has already timed out, this procedure
	removes the timeout-state from the timer 'identifier', so		removes the timeout-state from the timer 'identifier', so
	subsequent calls to TIMEOUT_STATE(identifier) evaluate to FALSE.		subsequent calls to (identifier)_TIMEOUT evaluate to FALSE. A
	A timeout cannot occur until the timer 'identifier' has been		timeout cannot occur until the timer 'identifier' has been
	(re-)started.		(re-)started.
	TIMEOUT.STATE(identifier): This procedure evaluates to TRUE if the		(identifier)_TIMEOUT: This procedure evaluates to TRUE if the
	timer 'identifier' has timed out and indicates a state lifetime		(identifier)-timer has timed out and indicates a state lifetime
	expiration. Subsequent TIMEOUT_STATE(identifier) calls also		expiration. This procedure cannot evaluate to TRUE if the timer
	evaluate to TRUE until the timer 'identifier' has been		has been stopped. Used timers are STATE_TIMEOUT, REFRESH_TIMEOUT,
	(re-)started. This procedure cannot evaluate to TRUE if the timer		CREATE_TIMEOUT, REA_TIMEOUT or RESPONSE_TIMEOUT.
	has been stopped.
	Start.REFRESH_TIMER(identifier): This procedure starts a timer with a
	certain timespan, which is up to the specific implementation. The
	parameter 'identifier' identifies this timer uniquely. Any
	subsequent Start_REFRESH_TIMER(x), Stop_REFRESH_TIMER(x),
	TIMEOUT_REFRESH(x) refer to the same timer labeled x. This timer
	times a refresh interval, which means that when it times out, it
	indicates a state refresh message is due to be sent. This
	procedure starts the timer 'identifier'. If a timer with the same
	'identifier' has already been started and not yet stopped, the
	timer is now stopped and restarted. After the timer has timed
	out, the procedure TIMEOUT_REFRESH(identifier) evaluates to TRUE.
	The timer does not restart automatically, but must be started
	again with a Start_REFRESH_TIMER(identifier). Notice that there
	is no difference to the Start_STATE_TIMER(identifier) procedure
	which has exactly the same functionality. The different procedure
	names are only supplied to underline the purpose of this specific
	timer.
	Stop.REFRESH_TIMER(identifier): This procedure stops the timer
	labeled 'identifier'. If it has already been stopped, this
	procedure has no effect. If the timer has already timed out, this
	procedure removes the timeout-state from the timer 'identifier',
	so subsequent calls to TIMEOUT_REFRESH(identifier) evaluate to
	FALSE. A timeout cannot occur until the timer 'identifier' has
	been (re-)started.
	TIMEOUT.REFRESH(identifier): This procedure evaluates to TRUE if the
	timer 'identifier' has timed out and indicates a refresh interval
	expiration. Subsequent TIMEOUT_REFRESH(identifier) calls also
	evaluate to TRUE until the timer 'identifier' has been
	(re-)started. This procedure cannot evaluate to TRUE if the timer
	has been stopped.
	tg_QUERY: External trigger to send a QUERY message (typically
	triggered by the application).
	tg_CREATE: External trigger to send a CREATE message (typically		tg_CREATE: External trigger to send a CREATE message (typically
	triggered by the application).		triggered by the application).
	tg_NOTIFY: External trigger to notify the entity of a new event to be
	processed (typically triggered by the application)
	tg_TRIGGER: External trigger to send a TRIGGER message to a NF
	(typically triggered by the application)
	tg_TEARDOWN: External trigger to delete a previously created session		tg_TEARDOWN: External trigger to delete a previously created session
	(typically triggered by the application)		(typically triggered by the application)
	tg_REA: External trigger to send a REA message towards an		tg_REA: External trigger to send a REA message towards an
	opportunistic address (typically triggered by the application)		opportunistic address (typically triggered by the application)
			tg_CREATE_PROXY: Internal trigger to send a CREATE message (used in
			proxy mode, triggered by corresponding NAT/FW NSLP session).
			tg_TEARDOWN_PROXY: Internal trigger to delete a previously created
			session (used in proxy mode, triggered by corresponding NAT/FW
			NSLP session).
			5.2. Common Variables
	5.2 Common Variables
	IS_EDGE: Boolean flag which evaluates to TRUE if the node is on the		IS_EDGE: Boolean flag which evaluates to TRUE if the node is on the
	network edge, otherwise it evaluates to FALSE.		network edge, otherwise it evaluates to FALSE.
	IS_PUBLICSIDE: Boolean flag which evaluates to TRUE if the (CREATE-		IS_PUBLICSIDE: Boolean flag which evaluates to TRUE if the (CREATE-
	or REA-) message has been received on the public side of the		or REA-) message has been received on the public side of the
	network.		network.
	CREATE(LIFETIME?): Gets the value of the LIFETIME object in the		CREATE(LIFETIME): Gets the value of the LIFETIME object in the CREATE
	CREATE message.		message.
	CREATE(TRIGGER?): Evaluates to TRUE if the received CREATE message		counter(CREATE): Denotes the current number of retries of CREATE
	indicates a CREATE trigger.
	CREATE(POLICY?): Gets the policy for the CREATE message.
	CREATE(SOURCE?): Retrieves the sender of the CREATE message.
	CREATE(NoNR?): Evaluates to TRUE if the CREATE message has an active
	NoNR-flag.
	CREATE(Scope?): Evaluates to TRUE if the CREATE message has an active
	Scope-flag.
	Retry_Counter(CREATE): Denotes the current number of retries of
	CREATE message which has been re-transmitted due to previous
	RESPONSE_ERROR message. If the number of Retry_Counter(CREATE)
	equals the value of MAXRETRY(CREATE), the current session creation
	attempt is aborted and the application is being notified.
	Retry_Counter(QUERY): Denotes the current number of retries of QUERY
	message which has been re-transmitted due to previous
	RESPONSE_ERROR message. If the number of Retry_Counter(QUERY)
	equals the value of MAXRETRY(QUERY), the current QUERY attempt is
	aborted and the application is being notified.
	Retry_Counter(REA): Denotes the current number of retries of REA
	message which has been re-transmitted due to previous		message which has been re-transmitted due to previous
	RESPONSE_ERROR message. If the number of Retry_Counter(REA)		RESPONSE_ERROR message. If the number of counter(CREATE) equals
	equals the value of MAXRETRY(REA), the current REA initiation		the value of counterLimit(CREATE), the current session creation
	attempt is aborted and the application is being notified.		attempt is aborted and the application is being notified.
			counter(REA): Denotes the current number of retries of REA message
			which has been re-transmitted due to previous RESPONSE_ERROR
			message. If the number of counter(REA) equals the value of
			counterLimit(REA), the current session creation attempt is aborted
			and the application is being notified.
	5.3 Constants		5.3. Constants
	Max_Retry(CREATE): Contains the maximum number of retransmission		counterLimit(CREATE): Contains the maximum number of retransmission
	attempts of a CREATE message after it is aborted and the		attempts of a CREATE message after it is aborted and the
	application is being notified.		application is being notified.
	Max_Retry(QUERY): Contains the maximum number of retransmission		counterLimit(REA): Contains the maximum number of retransmission
	attempts of a QUERY message after it is aborted and the
	application is being notified.
	Max_Retry(REA): Contains the maximum number of retransmission
	attempts of a REA message after it is aborted and the application		attempts of a REA message after it is aborted and the application
	is being notified.		is being notified.
	6. State machine for the NAT/FW NI		6. State machine for the NAT/FW NI
	This section presents the state machines for the NSIS initator which		This section presents the state machine for the NSIS initator which
	is capable of NSLP NAT/FW signaling		is capable of NAT/FW NSLP signaling.
	-----------		-----------
	State: INITIALIZE		State: INITIALIZE
	-----------		-----------
	Condition Action State Note		Condition Action State
	------------------------+-------------------------+-----------+---		----------------------------+-----------------------------+----------
	UCT |Initialize variables | IDLE |*		UCT |Initialize variables | IDLE
	------------------------+-------------------------+-----------+---		----------------------------+-----------------------------+----------
	NOTE:
	* - Application triggered for forking process
	-----------		-----------
	State: IDLE		State: IDLE
			Entry: DeleteSession();
			Exit : CreateSession();
	-----------		-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	tg_CREATE |tx_CREATE |WAITRESP2- |
	(sid, sig, pubkey)| (sid, sig, pubkey);| SESSION|
	|Start.STATE_TIMER |PENDING |
	| (Response);| |
	| | |
	(tg_CREATE (sid)) |tx_CREATE (sid); |WAITRESP1- |
	|Start.STATE_TIMER | SESSION|
	| (Response);|PENDING |
	------------------------+-------------------------+-----------+---
	-----------
	State: WAITRESP-SESSION PENDING
	-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	TIMEOUT.STATE(Response) |Stop.STATE_TIMER |WAITRESP- |
	| (Response);| SESSION|
	|retry_counter(Create)++; |PENDING |
	|if (retry_counter(Create)| |
	| <=Max_Retry(Create))| |
	|{Start_STATE_TIMER | |
	| (Response)| |
	|tx_CREATE;} | |
	| | |
	(rx_RESPONSE(SUCCESS, |Stop.STATE_TIMER |SESSION |
	Create))| (Response);|ESTABLISHED|
	|Session.create(); | |
	|Start.REFRESH_TIMER | |
	| (Create);| |
	|retry_counter(Create)=0; | |
	| | |
	(Retry_Counter(Create)> |Send info to Appl.; | IDLE |
	Max_Retry(Create)) |||Stop.STATE_TIMER | |
	(tg_TEARDOWN) || | (Response);| |
	(rx_RESPONSE(ERROR, | | |
	Create))| | |
	------------------------+-------------------------+-----------+
	-----------
	State: WAITRESP1-SESSION PENDING
	-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	(TIMEOUT.STATE(Response)|Send info to Appl.; |IDLE |
	|| (rx_RESPONSE(ERROR, | | |
	Create))| | |
	| | |
	(rx_RESPONSE(SUCCESS, |Tx_Create(sid, sig, |WAITPKRESP-|
	Create))| pubkey);| SESSION|
	|Start.STATE_TIMER |PENDING |
	| (Response);| |
	------------------------+-------------------------+-----------+---
	-----------
	State: WAITRESP2-SESSION PENDING
	-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	(tr(RESPONSE(sid)) |tx_CREATE (sid); |WAITRESP- |
	|Start.STATE_TIMER | SESSION|
	| (Response);|PENDING |
	|retry_counter(Create)=0; | |
	------------------------+-------------------------+-----------+---
	-----------
	State: WAITPKRESP-SESSION PENDING
	-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	(tr(RESPONSE(sid)) |tx_CREATE (sid); |WAITRESP- |
	|Start.STATE_TIMER | SESSION|
	| (Response);|PENDING |
	|retry_counter(Create)=0; | |
	------------------------+-------------------------+-----------+---
	-----------
	State: SESSION ESTABLISHED
	-----------
	Condition Action State Note
	------------------------+-------------------------+-----------+---
	(rx_RESPONSE |Stop.STATE_TIMER(QDRQ); |SESSION |
	(SUCCESS, QDRQ))|Send info to appl.; |ESTABLISHED|
	&& (CHECK_AA) | | |
	| | |
	| |
	(rx_RESPONSE |Stop.STATE_TIMER(QDRQ); |SESSION |
	(ERROR, QDRQ)|retry_counter(QDRQ)++; |ESTABLISHED|
	|| TIMEOUT_STATE(QDRQ)) |If (retry_counter(QDRQ)< | |
	| Max_Retry(QDRQ)| |
	|{Start.STATE_TIMER(QDRQ);| |
	| tx_QDRQ;}| |
	|else{send info to appl.;}| |
	| | |
	(tg_QDRQ) |tx_QDRQ; |SESSION |
	|Start.STATE_TIMER(QDRQ); |ESTABLISHED|
	|retry_counter(QDRQ)=0; | |
	| | |
	TIMEOUT.REFRESH(Create) |Start.STATE_TIMER |SESSION |
	| (Response);|ESTABLISHED|
	|tx_CREATE; | |
	| | |
	TIMEOUT.STATE(Response) |Stop.STATE_TIMER |SESSION |
	| (Response);|ESTABLISHED|
	|retry_counter(Create)++; | |
	|If (retry_counter(Create)| |
	| <=Max_Retry(Create))| |
	|{Start.STATE_TIMER | |
	| (Response);| |
	|tx_CREATE;} | |
	| | |
	(rx_RESPONSE(SUCCESS, |Start.REFRESH_TIMER |SESSION |
	Create))| (Create);|ESTABLISHED|
	|Stop.STATE_TIMER | |
	| (Response);| |
	|retry_counter(Create)=0; | |
	| | |
	(rx_NOTIFY)&&(CHECK_AA) |Process Event(); |SESSION |
	| |ESTABLISHED|
	| | |
	(tg_TEARDOWN) |tx_CREATE(LIFETIME=0); |IDLE |
	|Session.clear(); | |
	|Stop.REFRESH_TIMER | |
	| (Create);| |
	|Stop.STATE_TIMER( | |
	| Response);| |
	| | |
	(retry_counter(Create)> |Send info to Appl.; |IDLE |
	Max_Retries(Create) |||Session.clear(); | |
	rx_RESPONSE(ERROR, |Stop.REFRESH_TIMER | |
	Create))| (Create);| |
	------------------------+-------------------------+-----------+
	7. State machines for the NAT/FW NF
	This section describes the state machines for intermediate nodes
	within the signaling path capable of processing NAT/FW NSLP messages.
	These nodes typically implement firewall and/or network address
	translation (NAT) functionality. To keep it simple, the state
	machines are separated in two independent state machines for nodes
	with firewall and nodes with NAT functionality.
	7.1 State machine for NAT/FW Firewall NF
	-------------------
	State: Initialize
	-------------------
	Condition Action State
	------------------------+-------------------------+------------
	UCT |