draft-ietf-lisp-map-versioning-02.txt		draft-ietf-lisp-map-versioning-03.txt
	Network Working Group L. Iannone		Network Working Group L. Iannone
	Internet-Draft TU Berlin - Deutsche Telekom		Internet-Draft TU Berlin - Deutsche Telekom
	Intended status: Experimental Laboratories AG		Intended status: Experimental Laboratories AG
	Expires: January 6, 2012 D. Saucez		Expires: March 16, 2012 D. Saucez
	O. Bonaventure		O. Bonaventure
	Universite catholique de Louvain		Universite catholique de Louvain
	July 5, 2011		September 13, 2011
	LISP Map-Versioning		LISP Map-Versioning
	draft-ietf-lisp-map-versioning-02.txt		draft-ietf-lisp-map-versioning-03.txt
	Abstract		Abstract
	This document describes the LISP Map-Versioning mechanism, which		This document describes the LISP (Locator/ID Separation Protocol)
	provides in-packet information about EID-to-RLOC mappings used to		Map-Versioning mechanism, which provides in-packet information about
			Endpoint-ID to Routing Locator (EID-to-RLOC) mappings used to
	encapsulate LISP data packets. The proposed approach is based on		encapsulate LISP data packets. The proposed approach is based on
	associating a version number to EID-to-RLOC mappings and transport		associating a version number to EID-to-RLOC mappings and transport
	such a version number in the LISP specific header of LISP-		such a version number in the LISP specific header of LISP-
	encapsulated packets. LISP Map-Versioning is particularly useful to		encapsulated packets. LISP Map-Versioning is particularly useful to
	inform communicating xTRs about modifications of the mappings used to		inform communicating Ingress Tunnel Routers (ITRs) and Egress Tunnel
			Routers (ETRs) about modifications of the mappings used to
	encapsulate packets. The mechanism is transparent to legacy		encapsulate packets. The mechanism is transparent to legacy
	implementations, since in the LISP-specific header and in the Map		implementations, since in the LISP-specific header and in the Map
	Records, bits used for Map-Versioning can be safely ignored by xTRs		Records, bits used for Map-Versioning can be safely ignored by ITRs
	that do not support the mechanism.		and ETRs that do not support the mechanism.
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on January 6, 2012.		This Internet-Draft will expire on March 16, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2011 IETF Trust and the persons identified as the		Copyright (c) 2011 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 30		skipping to change at page 2, line 31
	4. EID-to-RLOC Map-Version number . . . . . . . . . . . . . . . . 4		4. EID-to-RLOC Map-Version number . . . . . . . . . . . . . . . . 4
	4.1. The Null Map-Version . . . . . . . . . . . . . . . . . . . 5		4.1. The Null Map-Version . . . . . . . . . . . . . . . . . . . 5
	5. Dealing with Map-Version numbers . . . . . . . . . . . . . . . 6		5. Dealing with Map-Version numbers . . . . . . . . . . . . . . . 6
	5.1. Handling Destination Map-Version number . . . . . . . . . 7		5.1. Handling Destination Map-Version number . . . . . . . . . 7
	5.2. Handling Source Map-Version number . . . . . . . . . . . . 8		5.2. Handling Source Map-Version number . . . . . . . . . . . . 8
	6. LISP header and Map-Version numbers . . . . . . . . . . . . . 9		6. LISP header and Map-Version numbers . . . . . . . . . . . . . 9
	7. Map Record and Map-Version . . . . . . . . . . . . . . . . . . 10		7. Map Record and Map-Version . . . . . . . . . . . . . . . . . . 10
	8. Benefits and case studies for Map-Versioning . . . . . . . . . 11		8. Benefits and case studies for Map-Versioning . . . . . . . . . 11
	8.1. Synchronization of different xTRs . . . . . . . . . . . . 11		8.1. Synchronization of different xTRs . . . . . . . . . . . . 11
	8.2. Map-Versioning and unidirectional traffic . . . . . . . . 12		8.2. Map-Versioning and unidirectional traffic . . . . . . . . 12
	8.3. Map-Versioning and interworking . . . . . . . . . . . . . 12		8.3. Map-Versioning and interworking . . . . . . . . . . . . . 13
	8.3.1. Map-Versioning and Proxy-ITRs . . . . . . . . . . . . 13		8.3.1. Map-Versioning and Proxy-ITRs . . . . . . . . . . . . 13
	8.3.2. Map-Versioning and LISP-NAT . . . . . . . . . . . . . 13		8.3.2. Map-Versioning and LISP-NAT . . . . . . . . . . . . . 14
	8.3.3. Map-Versioning and Proxy-ETRs . . . . . . . . . . . . 13		8.3.3. Map-Versioning and Proxy-ETRs . . . . . . . . . . . . 14
	8.4. RLOC shutdown/withdraw . . . . . . . . . . . . . . . . . . 14		8.4. RLOC shutdown/withdraw . . . . . . . . . . . . . . . . . . 15
	8.5. Map-Version for lightweight LISP implementation . . . . . 14		8.5. Map-Version for lightweight LISP implementation . . . . . 15
	9. Incremental deployment and implementation status . . . . . . . 15		9. Incremental deployment and implementation status . . . . . . . 16
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 15		10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
	10.1. Map-Versioning against traffic disruption . . . . . . . . 16		10.1. Map-Versioning against traffic disruption . . . . . . . . 16
	10.2. Map-Versioning against reachability information DoS . . . 16		10.2. Map-Versioning against reachability information DoS . . . 17
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
	12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17		12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
	13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17		13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
	13.1. Normative References . . . . . . . . . . . . . . . . . . . 17		13.1. Normative References . . . . . . . . . . . . . . . . . . . 18
	13.2. Informative References . . . . . . . . . . . . . . . . . . 17		13.2. Informative References . . . . . . . . . . . . . . . . . . 18
	Appendix A. Estimation of time before Map-Version wrap-around . . 18		Appendix A. Estimation of time before Map-Version wrap-around . . 18
	Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 19		Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 19
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
	1. Introduction		1. Introduction
	This document describes the Map-Versioning mechanism used to provide		This document describes the Map-Versioning mechanism used to provide
	information on changes in the EID-to-RLOC mappings used in the LISP		information on changes in the EID-to-RLOC mappings used in the LISP
	([I-D.ietf-lisp]) context to perform packet encapsulation. The		([I-D.ietf-lisp]) context to perform packet encapsulation. The
	mechanism is totally transparent to xTRs not supporting such		mechanism is totally transparent to xTRs not supporting such
	functionality. It is not meant to replace any existing LISP		functionality. It is not meant to replace any existing LISP
	mechanism, but rather to complete them providing new functionalities.		mechanism, but rather to complete them providing new functionalities.
	The basic mechanism is to associate a Map-Version number to each LISP		The basic mechanism is to associate a Map-Version number to each LISP
	skipping to change at page 3, line 48		skipping to change at page 3, line 48
	This operation is two-fold. On the one hand, it enables the ETR		This operation is two-fold. On the one hand, it enables the ETR
	receiving the packet to know if the ITR has the latest version number		receiving the packet to know if the ITR has the latest version number
	that any ETR at the destination EID site has provided to the ITR in a		that any ETR at the destination EID site has provided to the ITR in a
	Map-Reply. If it is not the case the ETR can send to the ITR a Map-		Map-Reply. If it is not the case the ETR can send to the ITR a Map-
	Request containing the updated mapping or soliciting a Map-Request		Request containing the updated mapping or soliciting a Map-Request
	from the ITR (both cases are already defined in [I-D.ietf-lisp]). In		from the ITR (both cases are already defined in [I-D.ietf-lisp]). In
	this way the ITR can update its cache. On the other hand, it enables		this way the ITR can update its cache. On the other hand, it enables
	an ETR receiving such a packet to know if it has in its EID-to-RLOC		an ETR receiving such a packet to know if it has in its EID-to-RLOC
	Cache the latest mapping for the source EID (in case of bidirectional		Cache the latest mapping for the source EID (in case of bidirectional
	traffic). If it is not the case a Map-Request can be send.		traffic). If it is not the case a Map-Request can be sent.
	2. Requirements Notation		2. Requirements Notation
	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 [RFC2119].		document are to be interpreted as described in [RFC2119].
	3. Definitions of Terms		3. Definitions of Terms
	The present document uses terms already defined in main LISP		The present document uses terms already defined in main LISP
	skipping to change at page 6, line 20		skipping to change at page 6, line 20
	The main idea of using Map-Version numbers is that whenever there is		The main idea of using Map-Version numbers is that whenever there is
	a change in the mapping (e.g., adding/removing RLOCs, a change in the		a change in the mapping (e.g., adding/removing RLOCs, a change in the
	weights due to TE policies, or a change in the priorities) or an ISP		weights due to TE policies, or a change in the priorities) or an ISP
	realizes that one or more of its own RLOCs are not reachable anymore		realizes that one or more of its own RLOCs are not reachable anymore
	from a local perspective (e.g., through IGP, or policy changes) the		from a local perspective (e.g., through IGP, or policy changes) the
	ISP updates the mapping also assigning a new Map-Version number.		ISP updates the mapping also assigning a new Map-Version number.
	To each mapping, a version number is associated and changes each time		To each mapping, a version number is associated and changes each time
	the mapping is changed. Note that map-versioning does not introduce		the mapping is changed. Note that map-versioning does not introduce
	any new problem concerning the coordination of different ETRs of a		new problems concerning the coordination of different ETRs of a
	domain. Indeed, ETRs belonging to the same LISP site must return for		domain. Indeed, ETRs belonging to the same LISP site must return for
	a specific EID-prefix the same mapping. In principle this is		a specific EID-prefix the same mapping, including the same Map-
	orthogonal to whether or not map-versioning is used. The ETR's		Version number. In principle this is orthogonal to whether or not
	synchronization problem is out of the scope of this document.		map-versioning is used. The synchronization problem is out of the
			scope of this document.
	In order to announce in a data-driven fashion that the mapping has		In order to announce in a data-driven fashion that the mapping has
	been updated, Map-Version numbers used to create the outer IP header		been updated, Map-Version numbers used to create the outer IP header
	of the LISP-encapsulated packet are embedded in the LISP-specific		of the LISP-encapsulated packet are embedded in the LISP-specific
	header. This means that the header needs to contain two Map-Version		header. This means that the header needs to contain two Map-Version
	numbers:		numbers:
	o The Source Map-Version number of the EID-to-RLOC mapping in the		o The Source Map-Version number of the EID-to-RLOC mapping in the
	EID-to-RLOC Database used to select the source RLOC.		EID-to-RLOC Database used to select the source RLOC.
	skipping to change at page 7, line 24		skipping to change at page 7, line 25
	number can be done, where the following cases can arise:		number can be done, where the following cases can arise:
	1. The packets arrive with the same Destination Map-Version number		1. The packets arrive with the same Destination Map-Version number
	stored in the EID-to-RLOC Database. This is the regular case.		stored in the EID-to-RLOC Database. This is the regular case.
	The ITR sending the packet has in its EID-to-RLOC Cache an up-to-		The ITR sending the packet has in its EID-to-RLOC Cache an up-to-
	date mapping. No further actions are needed.		date mapping. No further actions are needed.
	2. The packet arrives with a Destination Map-Version number greater		2. The packet arrives with a Destination Map-Version number greater
	(i.e., newer) than the one stored in the EID-to-RLOC Database.		(i.e., newer) than the one stored in the EID-to-RLOC Database.
	Since the ETR is authoritative on the mapping, this means that		Since the ETR is authoritative on the mapping, this means that
	someone is not behaving correctly w.r.t. the specifications, thus		someone is not behaving correctly with respect to the
	the packet carries a not valid version number and SHOULD be		specifications, thus the packet carries a not valid version
	silently dropped.		number and SHOULD be silently dropped.
	3. The packets arrive with a Destination Map-Version number smaller		3. The packets arrive with a Destination Map-Version number smaller
	(i.e., older) than the one stored in the EID-to-RLOC Database.		(i.e., older) than the one stored in the EID-to-RLOC Database.
	This means that the ITR sending the packet has an old mapping in		This means that the ITR sending the packet has an old mapping in
	its EID-to-RLOC Cache containing stale information. The ITR		its EID-to-RLOC Cache containing stale information. The ITR
	sending the packet has to be informed that a newer mapping is		sending the packet has to be informed that a newer mapping is
	available. This is done with a Map-Request message sent back to		available. This is done with a Map-Request message sent back to
	the ITR. The Map-Request will either trigger a Map-Request back		the ITR. The Map-Request will either trigger a Map-Request back
	using the SMR bit or it will piggyback the newer mapping. These		using the Solicit-Map-Request (SMR) bit or it will piggyback the
	are not new mechanisms; how to SMR or piggyback mappings in Map-		newer mapping. These are not new mechanisms; how to SMR or
	Request messages is already described in [I-D.ietf-lisp], while		piggyback mappings in Map-Request messages is already described
	their security is discussed in [I-D.ietf-lisp-threats]. These		in [I-D.ietf-lisp], while their security is discussed in
	Map-Request messages should be rate limited (rate limitation		[I-D.ietf-lisp-threats]. These Map-Request messages should be
	policies are also described in [I-D.ietf-lisp]). The feature		rate limited (rate limitation policies are also described in
	introduced by Map-Version numbers is the possibility of blocking		[I-D.ietf-lisp]). The feature introduced by Map-Version numbers
	traffic from ITRs not using the latest mapping. Indeed, after a		is the possibility of blocking traffic not using the latest
	certain number of retries, if the Destination Map-Version number		mapping. Indeed, after a certain number of retries, if the
	in the packets is not updated, the ETR MAY silently drop packets		Destination Map-Version number in the packets is not updated, the
	with a stale Map-Version number. This because either the ITR is		ETR MAY drop packets with a stale Map-Version number while
	refusing to use the mapping for which the ETR is authoritative or		strongly reducing the rate of Map-Request messages. This because
	(worse) it might be some form of attack.		either the ITR is refusing to use the mapping for which the ETR
			is authoritative or (worse) it might be some form of attack.
			Another case might be that the control-plane is experiencing
			transient failures so the Map-Requests cannot reach that ITR. By
			keeping sending Map-Requests at very low rate it is possible to
			recover from this situation.
	The rule in the third case MAY be more restrictive. If the mapping		The rule in the third case MAY be more restrictive. If the mapping
	has been the same for a period of time as long as the TTL (defined in		has been the same for a period of time as long as the TTL (defined in
	[I-D.ietf-lisp]) of the previous version of the mapping, all packets		[I-D.ietf-lisp]) of the previous version of the mapping, all packets
	arriving with an old Map-Version SHOULD be silently dropped right		arriving with an old Map-Version SHOULD be silently dropped right
	away without issuing any Map-Request. The reason that allows such		away without issuing any Map-Request. The reason that allows such
	action is the fact that if the new mapping with the updated version		action is the fact that if the new mapping with the updated version
	number has been unchanged for at least the same time as the TTL of		number has been unchanged for at least the same time as the TTL of
	the older mapping, all the entries in the caches of ITRs must have		the older mapping, all the entries in the caches of ITRs must have
	expired. Hence, all ITRs sending traffic should have refreshed the		expired. Hence, all ITRs sending traffic should have refreshed the
	mapping according to [I-D.ietf-lisp]. If packets with old Map-		mapping according to [I-D.ietf-lisp]. If packets with old Map-
	Version number are still received, then either someone has not		Version number are still received, then either someone has not
	respected the TTL, or it is a form of spoof/attack. In both cases		respected the TTL, or it is a form of spoof/attack. In both cases
	this is not valid behavior w.r.t. the specifications and the packet		this is not valid behavior with respect to the specifications and the
	SHOULD be silently dropped.		packet SHOULD be silently dropped.
	LISP-encapsulated packets with the V-bit set, when the original		LISP-encapsulated packets with the V-bit set, when the original
	mapping in the EID-to-RLOC Database has version number set to the		mapping in the EID-to-RLOC Database has version number set to the
	Null Map-Version value, MAY be silently dropped. As explained in		Null Map-Version value, MAY be silently dropped. As explained in
	Section 4.1, if an EID-to-RLOC mapping has a Null Map-Version, it		Section 4.1, if an EID-to-RLOC mapping has a Null Map-Version, it
	means that ITRs, using the mapping for encapsulation, MUST NOT use		means that ITRs, using the mapping for encapsulation, MUST NOT use
	Map-Version number in the LISP-specific header.		Map-Version number in the LISP-specific header.
	For LISP-encapsulated packets with the V-bit set, when the original		For LISP-encapsulated packets with the V-bit set, when the original
	mapping in the EID-to-RLOC Database has version number set to a value		mapping in the EID-to-RLOC Database has version number set to a value
	skipping to change at page 9, line 7		skipping to change at page 9, line 11
	(i.e., newer) than the one stored in the local EID-to-RLOC Cache.		(i.e., newer) than the one stored in the local EID-to-RLOC Cache.
	This means that ETR has in its cache a mapping that is stale and		This means that ETR has in its cache a mapping that is stale and
	needs to be updated. A Map-Request SHOULD be sent to get the new		needs to be updated. A Map-Request SHOULD be sent to get the new
	mapping for the source EID. This is a normal Map-Request message		mapping for the source EID. This is a normal Map-Request message
	sent through the mapping system and MUST respect the		sent through the mapping system and MUST respect the
	specifications in [I-D.ietf-lisp], including rate limitation		specifications in [I-D.ietf-lisp], including rate limitation
	policies.		policies.
	3. The packet arrives with a Source Map-Version number smaller		3. The packet arrives with a Source Map-Version number smaller
	(i.e., older) than the one stored in the local EID-to-RLOC Cache.		(i.e., older) than the one stored in the local EID-to-RLOC Cache.
	Such a case is not valid w.r.t. the specifications. Indeed, if		Such a case is not valid with respect to the specifications.
	the mapping is already present in the EID-to-RLOC Cache, this		Indeed, if the mapping is already present in the EID-to-RLOC
	means that an explicit Map-Request has been sent and a Map-Reply		Cache, this means that an explicit Map-Request has been sent and
	has been received from an authoritative source. Assuming that		a Map-Reply has been received from an authoritative source.
	the mapping system is not corrupted anyhow, the Map-Version in		Assuming that the mapping system is not corrupted anyhow, the
	the EID-to-RLOC Cache is the correct one and the packet MAY be		Map-Version in the EID-to-RLOC Cache is the correct one and the
	silently dropped.		packet MAY be silently dropped.
	If the ETR does not have an entry in the EID-to-RLOC Cache for the		If the ETR does not have an entry in the EID-to-RLOC Cache for the
	source EID (e.g., in case of unidirectional traffic) then the Source		source EID (e.g., in case of unidirectional traffic) then the Source
	Map-Version number can be safely ignored.		Map-Version number can be safely ignored.
	For LISP-encapsulated packets with the V-bit set, if the Source Map-		For LISP-encapsulated packets with the V-bit set, if the Source Map-
	Version number is the Null Map-Version value, it means that the		Version number is the Null Map-Version value, it means that the
	Source Map-Version number MUST be ignored.		Source Map-Version number MUST be ignored.
	6. LISP header and Map-Version numbers		6. LISP header and Map-Version numbers
	In order for the versioning approach to work, the LISP specific		In order for the versioning approach to work, the LISP specific
	header has to carry both Source Map-Version number and Destination		header has to carry both Source Map-Version number and Destination
	Map-Version number. This is done by setting the V-bit in the LISP		Map-Version number. This is done by setting the V-bit in the LISP
	specific header. When the V-bit is set the low-order 24-bits of the		specific header as defined in [I-D.ietf-lisp] Section 5.3. When the
	first longword (which usually contains the nonce) are used to		V-bit is set the low-order 24-bits of the first longword (which
	transport both source and destination Map-Version numbers. In		usually contains the nonce) are used to transport both source and
	particular the first 12 bits are used for Source Map-Version number		destination Map-Version numbers. In particular the first 12 bits are
	and the second 12 bits for the Destination Map-Version number.		used for Source Map-Version number and the second 12 bits for the
			Destination Map-Version number.
	Hereafter is the example of LISP header carrying version numbers in		Hereafter is the example of LISP header carrying version numbers in
	the case of IPv4-in-IPv4 encapsulation. The same setting can be used		the case of IPv4-in-IPv4 encapsulation. The same setting can be used
	for any other case (IPv4-in-IPv6, IPv6-in-IPv4, and IPv6-in-IPv6).		for any other case (IPv4-in-IPv6, IPv6-in-IPv4, and IPv6-in-IPv6).
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	/ |N|L|E|V|I|flags| Source Map-Version |Destination Map-Version|		/ |N|L|E|V|I|flags| Source Map-Version |Destination Map-Version|
	LISP+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		LISP+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	skipping to change at page 14, line 16		skipping to change at page 14, line 39
	| LISP | | non-LISP |		| LISP | | non-LISP |
	| Domain A | | Domain B |		| Domain A | | Domain B |
	| +-------+ +-----------+ | |		| +-------+ +-----------+ | |
	| | ITR A |------->| Proxy ETR |------->| |		| | ITR A |------->| Proxy ETR |------->| |
	| +-------+ +-----------+ | |		| +-------+ +-----------+ | |
	| | | |		| | | |
	+----------+ +-------------+		+----------+ +-------------+
	Figure 4		Figure 4
	A Proxy-ETR does not have any mapping, since it just decapsulate		A Proxy-ETR does not have any mapping, since it just decapsulates
	packets arriving from LISP site. In this case, the ITR will just put		packets arriving from LISP site. In this case, the ITR will just put
	the Null Map-Version value as Destination Map-Version number, while		the Null Map-Version value as Destination Map-Version number, while
	the receiving Proxy-ETR will ignore the field.		the receiving Proxy-ETR will ignore the field.
	With this setup the Proxy-ETR is able to check whether or not the		With this setup the Proxy-ETR is able to check whether or not the
	mapping has changed. If this is the case the mapping for LISP Domain		mapping has changed. If this is the case the mapping for LISP Domain
	A on the PETR can be updated using one of the mechanisms defined in		A on the PETR can be updated using one of the mechanisms defined in
	[I-D.ietf-lisp] and [I-D.ietf-lisp-interworking].		[I-D.ietf-lisp] and [I-D.ietf-lisp-interworking].
	8.4. RLOC shutdown/withdraw		8.4. RLOC shutdown/withdraw
	Map-Versioning can be even used to perform a graceful shutdown or		Map-Versioning can be even used to perform a graceful shutdown or
	withdraw of a specific RLOC. This is achieved by simply issuing a		withdraw of a specific RLOC. This is achieved by simply issuing a
	new mapping, with an updated Map-Version number, where the specific		new mapping, with an updated Map-Version number, where the specific
	RLOC to be shut down is withdrawn or announced as unreachable (R bit		RLOC to be shut down is withdrawn or announced as unreachable (R bit
	in the Map Record, see [I-D.ietf-lisp]), but without actually turning		in the Map Record, see [I-D.ietf-lisp]), but without actually turning
	it off.		it off.
	Once no more traffic is received by the RLOC, because all sites have		Once no more traffic is received by the RLOC, it can be shut down
	updated the mapping, it can be shut down safely.		gracefully, because at least all sites actively using the mapping
			have updated it.
	It should be pointed out that for frequent up/down changes such a		It should be pointed out that for frequent up/down changes such a
	mechanism should not be used since this can generate excessive load		mechanism should not be used since this can generate excessive load
	on the Mapping System.		on the Mapping System.
	8.5. Map-Version for lightweight LISP implementation		8.5. Map-Version for lightweight LISP implementation
	The use of Map-Versioning can help in developing a lightweight		The use of Map-Versioning can help in developing a lightweight
	implementation of LISP. This comes with the price of not supporting		implementation of LISP. This comes with the price of not supporting
	Loc-Status-Bit, which are useful in some contexts.		Loc-Status-Bit, which are useful in some contexts.
	skipping to change at page 15, line 44		skipping to change at page 16, line 24
	information is already included in the Map Record.		information is already included in the Map Record.
	Map-Versioning is currently implemented in OpenLISP		Map-Versioning is currently implemented in OpenLISP
	[I-D.iannone-openlisp-implementation].		[I-D.iannone-openlisp-implementation].
	Note that the reference document for LISP implementation and		Note that the reference document for LISP implementation and
	interoperability tests remains [I-D.ietf-lisp].		interoperability tests remains [I-D.ietf-lisp].
	10. Security Considerations		10. Security Considerations
	Map-Versioning does not introduce any new security issue concerning		Map-Versioning does not introduce any security issue concerning both
	both the data-plane and the control-plane. On the contrary, as		the data-plane and the control-plane. On the contrary, as described
	described in the following, if Map-Versioning may be used also to		in the following, if Map-Versioning may be used also to update
	update mappings in case of change in the reachability information		mappings in case of change in the reachability information (i.e.,
	(i.e., instead of the Locator Status Bits) it is possible to reduce		instead of the Locator Status Bits) it is possible to reduce the
	the effects of some DoS or spoofing attacks that can happen in an		effects of some DoS or spoofing attacks that can happen in an
	untrusted environment.		untrusted environment.
	A thorough security analysis of LISP is documented in		Robusteness of the Map-Versioning mechanism leverages on a trusted
	[I-D.ietf-lisp-threats].		Mapping Distribution System. A thorough security analysis of LISP is
			documented in [I-D.ietf-lisp-threats].
	10.1. Map-Versioning against traffic disruption		10.1. Map-Versioning against traffic disruption
	An attacker can try to disrupt ongoing communications by creating		An attacker can try to disrupt ongoing communications by creating
	LISP encapsulated packets with wrong Locator Status Bits. If the xTR		LISP encapsulated packets with wrong Locator Status Bits. If the xTR
	blindly trusts the Locator Status Bits it will change the		blindly trusts the Locator Status Bits it will change the
	encapsulation accordingly, which can result in traffic disruption.		encapsulation accordingly, which can result in traffic disruption.
	This does not happen in the case of Map-Versioning. As described in		This does not happen in the case of Map-Versioning. As described in
	Section 5, upon a version number change the xTR first issues a Map-		Section 5, upon a version number change the xTR first issues a Map-
	skipping to change at page 17, line 30		skipping to change at page 18, line 13
	This work has been partially supported by the INFSO-ICT-216372		This work has been partially supported by the INFSO-ICT-216372
	TRILOGY Project (www.trilogy-project.org).		TRILOGY Project (www.trilogy-project.org).
	13. References		13. References
	13.1. Normative References		13.1. Normative References
	[I-D.ietf-lisp]		[I-D.ietf-lisp]
	Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,		Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
	"Locator/ID Separation Protocol (LISP)",		"Locator/ID Separation Protocol (LISP)",
	draft-ietf-lisp-14 (work in progress), June 2011.		draft-ietf-lisp-15 (work in progress), July 2011.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	13.2. Informative References		13.2. Informative References
	[I-D.iannone-openlisp-implementation]		[I-D.iannone-openlisp-implementation]
	Iannone, L., Saucez, D., and O. Bonaventure, "OpenLISP		Iannone, L., Saucez, D., and O. Bonaventure, "OpenLISP
	Implementation Report",		Implementation Report",
	draft-iannone-openlisp-implementation-01 (work in		draft-iannone-openlisp-implementation-01 (work in
	progress), July 2008.		progress), July 2008.
	[I-D.ietf-lisp-alt]		[I-D.ietf-lisp-alt]
	Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "LISP		Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "LISP
	Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-07		Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-08
	(work in progress), June 2011.		(work in progress), September 2011.
	[I-D.ietf-lisp-interworking]		[I-D.ietf-lisp-interworking]
	Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,		Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
	"Interworking LISP with IPv4 and IPv6",		"Interworking LISP with IPv4 and IPv6",
	draft-ietf-lisp-interworking-02 (work in progress),		draft-ietf-lisp-interworking-02 (work in progress),
	June 2011.		June 2011.
	[I-D.ietf-lisp-ms]		[I-D.ietf-lisp-ms]
	Fuller, V. and D. Farinacci, "LISP Map Server",		Fuller, V. and D. Farinacci, "LISP Map Server",
	draft-ietf-lisp-ms-09 (work in progress), June 2011.		draft-ietf-lisp-ms-11 (work in progress), August 2011.
	[I-D.ietf-lisp-threats]		[I-D.ietf-lisp-threats]
	Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats		Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats
	Analysis", draft-ietf-lisp-threats-00 (work in progress),		Analysis", draft-ietf-lisp-threats-00 (work in progress),
	July 2011.		July 2011.
	Appendix A. Estimation of time before Map-Version wrap-around		Appendix A. Estimation of time before Map-Version wrap-around
	The present section proposes an estimation of the wrap-around time		The present section proposes an estimation of the wrap-around time
	for the proposed 12 bits size for the Map-Version number. Using a		for the proposed 12 bits size for the Map-Version number. Using a
	skipping to change at page 19, line 26		skipping to change at page 19, line 41
	| 15 | 22 Days | 9 Hours |		| 15 | 22 Days | 9 Hours |
	| 14 | 11 Days | 4 Hours |		| 14 | 11 Days | 4 Hours |
	| 13 | 5.6 Days | 2.2 Hours |		| 13 | 5.6 Days | 2.2 Hours |
	| 12 | 2.8 Days | 1.1 Hours |		| 12 | 2.8 Days | 1.1 Hours |
	+---------------+---------------------+----------------------+		+---------------+---------------------+----------------------+
	Figure 5: Estimation of time before wrap-around		Figure 5: Estimation of time before wrap-around
	Appendix B. Document Change Log		Appendix B. Document Change Log
			o Version 03 Posted September 2011.
			* Added reference in Section 7 toward the main lisp documents
			specifying the section, as requested by Jari Arkko.
			* Fixed all typos and editorial issues pointed out by Jari Arkko.
			* Added clarification in Section 8.4 as requested by Jari Arkko.
			* Extentend all acronyms in the abstract as requested by Jari
			Arkko.
			* Clarified silent drop polocy in Section 5.2 as requested by
			both Richard Barnes and Jari Arkko.
			* Fixed typos pointed out by Richard Barnes.
	o Version 02 Posted July 2011.		o Version 02 Posted July 2011.
	* Added text in Section 5 about ETR synchronization, as suggested		* Added text in Section 5 about ETR synchronization, as suggested
	by Alia Atlas.		by Alia Atlas.
	* Modified text in Section 8.5 concerning lightweight LISP		* Modified text in Section 8.5 concerning lightweight LISP
	implementation, as suggested by Alia Atlas.		implementation, as suggested by Alia Atlas.
	* Deleted text concerning old versions of [I-D.ietf-lisp-ms] and		* Deleted text concerning old versions of [I-D.ietf-lisp-ms] and
	[I-D.ietf-lisp-alt] in Section 7, as pointed out by Alia Atlas.		[I-D.ietf-lisp-alt] in Section 7, as pointed out by Alia Atlas.
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