Network Working GroupInternet Engineering Task Force (IETF) L. IannoneInternet-Draft Telekom Innovation Laboratories Intended status:Request for Comments: 6834 Telecom ParisTech Category: Experimental D. SaucezExpires: September 2, 2012ISSN: 2070-1721 INRIA Sophia Antipolis O. Bonaventure Universite catholique de LouvainMarch 1, 2012 LISPJanuary 2013 Locator/ID Separation Protocol (LISP) Map-Versioningdraft-ietf-lisp-map-versioning-09.txtAbstract This document describes the LISP (Locator/ID Separation Protocol) Map-Versioning mechanism, which provides in-packet information aboutEndpoint-IDEndpoint ID to Routing Locator (EID-to-RLOC) mappings used to encapsulate LISP data packets. The proposed approach is based on associating a version number to EID-to-RLOC mappings and the transport of such a version number in theLISP specificLISP-specific header ofLISP- encapsulatedLISP-encapsulated packets. LISP Map-Versioning is particularly useful 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 implementations not supporting this feature, since in theLISP-specificLISP- specific header and in the Map Records, bits used for Map-Versioning can be safely ignored by ITRs and ETRs that do not support the mechanism. Status ofthisThis Memo ThisInternet-Draftdocument issubmitted in full conformance with the provisions of BCP 78not an Internet Standards Track specification; it is published for examination, experimental implementation, andBCP 79. Internet-Drafts are working documentsevaluation. This document defines an Experimental Protocol for the Internet community. This document is a product of the Internet Engineering Task Force (IETF).Note that other groups may also distribute working documents as Internet-Drafts. The listIt represents the consensus ofcurrent Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents validthe IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are amaximumcandidate for any level of Internet Standard; see Section 2 of RFC 5741. Information about the current status ofsix monthsthis document, any errata, and how to provide feedback on it may beupdated, replaced, or obsoleted by other documentsobtained atany time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 2, 2012.http://www.rfc-editor.org/info/rfc6834. Copyright Notice Copyright (c)20122013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 3....................................................3 2. Requirements Notation. . . . . . . . . . . . . . . . . . . . 4...........................................4 3. Definitions of Terms. . . . . . . . . . . . . . . . . . . . . 4............................................4 4. EID-to-RLOC Map-Versionnumber . . . . . . . . . . . . . . . . 4Number ..................................4 4.1. The Null Map-Version. . . . . . . . . . . . . . . . . . . 5.......................................5 5. Dealing with Map-Versionnumbers . . . . . . . . . . . . . . . 6Numbers ................................6 5.1. Handling Destination Map-Versionnumber . . . . . . . . . 7Number ....................7 5.2. Handling Source Map-Versionnumber . . . . . . . . . . . . 9Number .........................9 6. LISPheaderHeader and Map-Versionnumbers . . . . . . . . . . . . . 10Numbers ............................10 7. Map Record and Map-Version. . . . . . . . . . . . . . . . . . 11.....................................11 8. Benefits andcase studiesCase Studies for Map-Versioning. . . . . . . . . 11...................12 8.1. Map-Versioning andunidirectional traffic . . . . . . . . 12Unidirectional Traffic .................12 8.2. Map-Versioning andinterworking . . . . . . . . . . . . . 12Interworking ...........................12 8.2.1. Map-Versioning and Proxy-ITRs. . . . . . . . . . . . 12......................13 8.2.2. Map-Versioning and LISP-NAT. . . . . . . . . . . . . 13........................13 8.2.3. Map-Versioning and Proxy-ETRs. . . . . . . . . . . . 13......................14 8.3. RLOCshutdown/withdraw . . . . . . . . . . . . . . . . . . 14Shutdown/Withdraw ....................................14 8.4. Map-Version forlightweightLightweight LISPimplementation . . . . . 14Implementation ...........15 9. IncrementaldeploymentDeployment andimplementation status . . . . . . . 15Implementation Status ...............15 10. Security Considerations. . . . . . . . . . . . . . . . . . . 15.......................................16 10.1. Map-Versioning againsttraffic disruption . . . . . . . . 15Traffic Disruption ................16 10.2. Map-Versioning againstreachability informationReachability Information DoS. . . 16......17 11.IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 12.Open Issues and Considerations. . . . . . . . . . . . . . . . 17 12.1.................................17 11.1. Lack of Synchronization among ETRs. . . . . . . . . . . . 17.......................18 12. Acknowledgments ...............................................19 13.Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 14.References. . . . . . . . . . . . . . . . . . . . . . . . . . 19 14.1.....................................................19 13.1. Normative References. . . . . . . . . . . . . . . . . . . 19 14.2......................................19 13.2. Informative References. . . . . . . . . . . . . . . . . . 19...................................20 Appendix A. Estimation oftimeTime before Map-Versionwrap-around . . 19 Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23Wrap-Around .....21 1. Introduction This document describes the Map-Versioning mechanism used to provide information on changes in the EID-to-RLOC(Endsystem(Endpoint ID to RoutingLOCator)Locator) mappings used in the LISP(Locator/Id(Locator/ID Separation Protocol[I-D.ietf-lisp])[RFC6830]) context to perform packet encapsulation. The mechanism is totally transparent to xTRs (Ingress and Egress Tunnel Routers) not supporting such functionality. It is not meant to replace any existing LISPmechanism,mechanisms but rather to extend them by providing new functionalities. If for anyunforseenunforeseen reason a normative conflict betweenthe presentthis document and the LISP main specifications is found, the latter([I-D.ietf-lisp])([RFC6830]) has precedenceon the presentover this document. The basic mechanism is to associate a Map-Version number to each LISP EID-to-RLOC mapping and transport such a version number in the LISP- specific header. When a mapping changes, a new version number is assigned to the updated mapping. A change in an EID-to-RLOC mapping can be a change in the RLOCs set, by adding or removing one or more RLOCs, but it can also be a change in the priority or weight of one or more RLOCs. When Map-Versioning is used, LISP-encapsulated data packets contain the version number of the two mappings used to select the RLOCs in the outer header (i.e., both source and destination). These version numbers are encoded in the 24 low-order bits of the first longword of the LISP header and indicated by a specific bit in the flags (first 8 high-order bits of the first longword of the LISP header). Note that not all packets need to carry version numbers. When an ITR (Ingress Tunnel Router) encapsulates a data packet, with a LISP header containing the Map-Version numbers, it puts in the LISP-specific header two version numbers: 1. The version number assigned to the mapping (contained in theEID- to-RLOCEID-to-RLOC Database) used to select the source RLOC. 2. The version number assigned to the mapping (contained in theEID- to-RLOCEID-to-RLOC Cache) used to select the destination RLOC. This operation is two-fold. On the one hand, it enables the ETR (Egress Tunnel Router) 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 Map-Reply. Ifitthis is not thecasecase, the ETR can send to the ITR a Map-Request containing the updated mapping orsolicitingsolicit a Map-Request from the ITR (both cases are already defined in[I-D.ietf-lisp]).[RFC6830]). In thiswayway, the ITR can update itsEID- to-RLOCEID-to-RLOC Cache. On the other hand, it enables 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 the case of bidirectional traffic). Ifitthis is not thecasecase, a Map-Request can be sent. Issues and concerns about the deployment of LISP for Internet traffic are discussed in[I-D.ietf-lisp].[RFC6830]. Section1211 provides additional issues and concerns raised by this document. In particular, Section12.111.1 provides details about the ETRs' synchronization issue in the context of Map-Versioning. 2. Requirements Notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Definitions of TermsThe presentThis document uses terms already defined in the main LISP specification[I-D.ietf-lisp]. Hereafter are defined only[RFC6830]. Here, we define the terms that are specific to the Map-Versioning mechanism. Throughout the wholedocumentdocument, Big Endian bit ordering is used. Map-Version number: An unsigned12-bits12-bit integer is assigned to an EID-to-RLOC mapping, not including the value 0 (0x000). Null Map-Version: The12-bits12-bit null value of 0 (0x000) is not used as a Map-Version number. It is used to signal that no Map-Version number is assigned to the EID-to-RLOC mapping. Source Map-Version number: This Map-Version number of the EID-to-RLOC mapping is used to select the source address (RLOC) of the outer IP header of LISP-encapsulated packets. Destination Map-Version number: This Map-Version number of theEID-to- RLOCEID-to-RLOC mapping is used to select the destination address (RLOC) of the outer IP header of LISP-encapsulated packets. 4. EID-to-RLOC Map-VersionnumberNumber The EID-to-RLOC Map-Version number consistsinof an unsigned12-bits12-bit integer. The version number is assigned on a per-mapping basis, meaning that different mappings have a different version number, which is also updated independently. An update in the version number (i.e., a newer version) consistsinof incrementing by one the older version number. Appendix A contains a rough estimation of thewrap- aroundwrap-around time for the Map-Version number. The space of version numbers has a circular order where half of the version numbersis greater(i.e.,are greater (i.e., newer) than the current Map-Version number and the other halfisof the version numbers are smaller (i.e., older) than the currentMap- VersionMap-Version number. In a more formal way, assuming that we have two version numbers V1 and V2 and that the numbers are expressedonin N bits, the following steps MUST be performed (in the same order ashereafter)shown below) to strictly define their order: 1. V1 = V2 : Themap-version numberMap-Version numbers are the same. 2. V2 > V1 : if and only if V2 > V1 AND (V2 - V1) <= 2**(N-1) OR V1 > V2 AND (V1 - V2) > 2**(N-1) 3. V1 > V2 : otherwise. Using 12 bits, as defined in this document, and assuming aMap- VersionMap-Version value of 69, Map-Version numbers in the range [70; 69 + 2048] are greater than 69, while Map-Version numbers in the range [69 + 2049; (69 + 4096) mod 4096] are smaller than 69.Map-version numberMap-Version numbers are assigned to mappings by configuration. The initial Map-Version number of a new EID-to-RLOC mapping SHOULD be assigned randomly, but it MUST NOT be set to the Null Map-Version value (0x000), becauseitthe Null Map-Version number has a special meaning (see Section 4.1). Upon reboot, an ETR will use mappings configured in its EID-to-RLOC Database. If those mappings have a Map-Version number, it will be used according to themechnismsmechanisms described in this document. ETRs MUST NOT automatically generate and assign Map-Version numbers to mappings in the EID-to-RLOC Database. 4.1. The Null Map-Version The value 0x000 (zero) is not a valid Map-Version number indicating the version of the EID-to-RLOC mapping. Such a value is used for special purposes and is named the Null Map-Version number. The Null Map-Version MAY appear in theLISP specificLISP-specific header as either a Source Map-Version number (cf. Section 5.2) or a DestinationMap- VersionMap-Version number (cf. Section 5.1). When the Source Map-Version number is set to the NullMap-version valueMap-Version value, it means that no map version information is conveyed for the source site. This means that if a mapping exists for the source EID in the EID-to-RLOC Cache, then the ETR MUST NOT compare the received Null Map-Version with the content of the EID-to-RLOC Cache. When the DestinationMap-versionMap-Version number is set to the NullMap-version valueMap-Version value, it means that no map version information is conveyed for the destination site. This means that the ETR MUST NOT compare the value with the Map-Version number of the mapping for the destination EID present in the EID-to-RLOC Database. The other use of the Null Map-Version number is in the Map Records, which are part of the Map-Request,Map-ReplyMap-Reply, and Map-Register messages (defined in[I-D.ietf-lisp]).[RFC6830]). Map Records that have a Null Map-Version number indicate that there is no Map-Version number associated with the mapping. This means thatLISP encapsulated packets,LISP-encapsulated packets destined to the EID-Prefix referred to by the Map Recordrefers to,MUST either not contain any Map-Version numbers(V bit(V-bit set to0), or0) or, ifit containsthey contain Map-Version numbers(V bit(V-bit set to1)1), then the destination Map-Version number MUST be set to the Null Map-Version number. Any value different from zero means that Map-Versioning is supported and MAY be used. The fact that the 0 value has a special meaning for the Map-Version number implies that, when updating a Map-Version number because of a change in the mapping, if the next value is00, then the Map-Version number MUST be incremented by 2 (i.e., set to 1, which is the next valid value). 5. Dealing with Map-VersionnumbersNumbers 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 weights due toTETraffic Engineering policies, or a change in the priorities) or a LISP site 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 LISP site updates themappingmapping, also assigning a newMap- VersionMap-Version number. To each mapping, a version number is associated and changes each time the mapping is changed. Note thatmap-versioningMap-Versioning does not introduce new problems concerning the coordination of different ETRs of a domain. Indeed, ETRs belonging to the same LISP site must return for a specificEID-prefixEID-Prefix the same mapping, including the sameMap- VersionMap-Version number. Inprincipleprinciple, this is orthogonal to whether or notmap-versioningMap-Versioning is used. The synchronization problem and its implication on the trafficisare out of the scope of this document (see Section12).11). 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 of the LISP-encapsulated packet are embedded in the LISP-specific header. This means that the header needs to contain two Map-Version numbers: o The Source Map-Version number of the EID-to-RLOC mapping in the EID-to-RLOC Database used to select the source RLOC. o The Destination Map-Version number of the EID-to-RLOC mapping in the EID-to-RLOC Cache used to select the destination RLOC. By embedding both the Source Map-Version number and the DestinationMap- Version numberMap-Version number, an ETR receiving a LISP packet with Map-Versionnumbers,numbers can perform the following checks: 1. The ITR that has sent the packet has an up-to-date mapping in its EID-to-RLOC Cache for the destination EID and is performing encapsulation correctly. 2. In the case of bidirectional traffic, the mapping in the local ETR EID-to-RLOC Cache for the source EID isup-to-date.up to date. If one or both of the above conditions do not hold, the ETR can send a Map-Request either to make the ITR aware that a new mapping is available (see Section 5.1) or to update the mapping in the local EID-to-RLOC Cache (see Section 5.2). 5.1. Handling Destination Map-VersionnumberNumber When an ETR receives a packet, the Destination Map-Version number relates to the mapping for the destination EID for which the ETR isaan RLOC. This mapping is part of the ETR EID-to-RLOC Database. Since the ETR is authoritative for the mapping, it has the correct andup- to-dateup-to-date Destination Map-Version number. A check on this version number can be done, where the following cases can arise: 1. Thepackets arrivepacket arrives with the same Destination Map-Version number stored in the EID-to-RLOC Database. This is the regular case. The ITR sending the packet has in its EID-to-RLOC Cache anup-to- dateup-to-date mapping. No further actions are needed. 2. The packet arrives with a Destination Map-Version number greater (i.e., newer) than the one stored in the EID-to-RLOC Database. Since the ETR is authoritative on the mapping, meaning that the Map-Version number of its mapping is the correct one, this implies that someone is not behaving correctly with respect to the specifications. In thiscasecase, the packet carries a version number that is notvalid, otherwisevalid; otherwise, the ETR would have thesame,same number, and the packet SHOULD be silently dropped. 3. The packets arrive with a Destination Map-Version number smaller (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 its EID-to-RLOC Cache containing stale information. The ETR MAY choose to normally process the encapsulated datagram according to[I-D.ietf-lisp],[RFC6830]; however, the ITR sending the packet has to be informed that a newer mapping is available. This is done with a Map-Request message sent back to the ITR. The Map-Request will either trigger a Map-Request back using the Solicit-Map-Request (SMR) bit or it will piggyback the newer mapping. These are not new mechanisms; how to use the SMR bit or how to piggyback mappings in Map-Request messages is already described in[I-D.ietf-lisp],[RFC6830], while their security is discussed in[I-D.ietf-lisp-threats].[LISP-THREATS]. TheseMap- RequestMap-Request messages should berate limited (rate limitationrate-limited (rate-limitation policies are also described in[I-D.ietf-lisp]).[RFC6830]). The feature introduced by Map-Version numbers is the possibility of blocking traffic not using the latest mapping. Indeed, after a certain number of retries, if the Destination Map-Version number in the packets is not updated, the ETR MAY drop packets with a stale Map-Version number while strongly reducing the rate of Map-Request messages. This is because either the ITR is refusing to use the mapping for which the ETR isauthoritativeauthoritative, or (worse) it might be some form of attack. Another case might be that thecontrol-planecontrol plane is experiencing transientfailuresfailures, so the Map-Requests cannot reach that ITR. Bykeepingcontinually sending Map-Requests at a very lowraterate, it is possible to recover from this situation. 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 theTTLTime to Live (TTL) (defined in[I-D.ietf-lisp])[RFC6830]) of the previous version of the mapping, all packets arriving with an old Map-Version SHOULD be silently dropped right away without issuing any Map-Request.The reason that allows suchSuch action isthe fact thatpermitted because if the new mapping with the updated version number has been unchanged for at least the same time as the TTL of the older mapping, all the entries in the EID-to-RLOC Caches of ITRs must have expired. Hence, all ITRs sending traffic should have refreshed the mapping according to[I-D.ietf-lisp].[RFC6830]. If packets with old Map-Versionnumbernumbers are still received, then either someone has not respected theTTL,TTL or it is a form of spoof/attack. In bothcasescases, this is not valid behavior with respect to the specifications and the packet SHOULD be silently dropped. LISP-encapsulated packets with the V-bit set, when the original mapping in the EID-to-RLOC Database has the version number set to the 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 means that ITRs, using the mapping for encapsulation, MUST NOT use a Map-Version number in the LISP-specific header. For LISP-encapsulated packets with the V-bit set, when the original mapping in the EID-to-RLOC Database has the version number set to a value different from the Null Map-Version value, a Destination Map-Version number equal to the Null Map-Version value means that the Destination Map-Version number MUST be ignored. 5.2. Handling Source Map-VersionnumberNumber When an ETR receives a packet, the Source Map-Version number relates to the mapping for the source EID for which the ITR that sent the packet is authoritative. If the ETR has an entry in its EID-to-RLOC Cache for the source EID, then a check can be performed and the following cases can arise: 1. The packet arrives with the same Source Map-Version number as that stored in the EID-to-RLOC Cache. This is the correct regular case. The ITR has in its EID-to-RLOC Cache an up-to-date copy of the mapping. No further actions are needed. 2. The packet arrives with a Source Map-Version number greater (i.e., newer) than the one stored in the local EID-to-RLOC Cache. This means that the ETR has in its EID-to-RLOC Cache a mapping that is stale and needs to be updated. A Map-Request SHOULD be sent to get the new mapping for the source EID. This is a normalMap- RequestMap-Request message sent through the mapping system and MUST respect the specifications in[I-D.ietf-lisp],[RFC6830], includingraterate- limitation policies. 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. Such a case is not valid with respect to the specifications. Indeed, if the mapping is already present in the EID-to-RLOC Cache, this means that an explicit Map-Request has been sent and a Map-Reply has been received from an authoritative source. Assuming that the mapping system is notcorrupted anyhow,corrupted, the Map-Version in the EID-to-RLOC Cache is the correct one, while the one carried by the packet is stale. In thissituationsituation, the packet MAY be silently dropped. If the ETR does not have an entry in the EID-to-RLOC Cache for the source EID (e.g., in the case of unidirectionaltraffic)traffic), then the Source Map-Version number can be safely ignored. For LISP-encapsulated packets with the V-bit set, if the SourceMap- VersionMap-Version number is the Null Map-Version value, it means that the Source Map-Version number MUST be ignored. 6. LISPheaderHeader and Map-VersionnumbersNumbers In order for the versioning approach to work, theLISP specificLISP-specific header has to carry both the Source Map-Version number and Destination Map-Version number. This is done by setting the V-bit in theLISP specificLISP-specific header as defined in[I-D.ietf-lisp][RFC6830] Section 5.3. When the V-bit issetset, the low-order24-bits24 bits of the first longword are used to transport both the source and destination Map-Version numbers. Inparticularparticular, the first 12 bits are used for the Source Map-Version number and the second 12 bits for the Destination Map-Version number.HereafterBelow isthean example of a LISP header carrying version numbers in 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). 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / |N|L|E|V|I|flags| Source Map-Version |Destination Map-Version| LISP+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | InstanceID/Locator Status BitsID/Locator-Status-Bits | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Source Map-Version number (12 bits): Map-Version of the mapping used by the ITR to select the RLOC present in the"Source'Source RoutingLocator"Locator' field.HowSection 5.2 describes how to set this value on transmission and handle it onreception this value is described in Section 5.2.reception. Destination Map-Version number (12 bits): Map-Version of the mapping used by the ITR to select the RLOC present in the"Destination'Destination RoutingLocator"Locator' field.HowSection 5.1 describes how to set this value on transmission and handle it onreception this value is described in Section 5.1. The presentreception. This documentjustonly specifies how to use the low-order24-bits24 bits of the first longword of the LISP-specific header when the V-bit is set to 1. All other cases, including the bit fields of the rest of the LISP-specific header and the whole LISP packetformatformat, are specified in[I-D.ietf-lisp].[RFC6830]. Not all of theLISP encapsulatedLISP-encapsulated packets need to carry version numbers. When Map-Version numbers are carried in these packets, the V-bit MUST be set to 1. Alllegalpermissible combinations of theflags,flags when the V-bit is set to1,1 are described in[I-D.ietf-lisp].[RFC6830]. 7. Map Record and Map-Version To accommodate the proposed mechanism, the Map Records that are transportedonin Map-Request/Map-Reply/Map-Register messages need to carry the Map-Version number as well. For thispurposepurpose, the12-bits12 bits before theEID-AFI'EID-Prefix-AFI' field in the Record thatdescribedescribes a mappingisare used. This is defined in Section 6.1.4 of[I-D.ietf-lisp][RFC6830] and reported here as an example. 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 +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | Record TTL | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ R | Locator Count | EID mask-len | ACT |A| Reserved | e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ c | Rsvd | Map-Version Number |EID-prefix-AFIEID-Prefix-AFI | o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ r |EID-prefixEID-Prefix | d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | /| Priority | Weight | M Priority | M Weight | | L +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | o | Unused Flags |L|p|R| Loc-AFI | | c +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | \| Locator | +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Map-Version Number: Map-Version of the mapping contained in the Record. As explained in Section4.14.1, this field can be zero (0), meaning that no Map-Version is associated to themapping, hencemapping; hence, packets that areLISP-encapsulatedLISP encapsulated using this mapping MUST NOT contain Map-Version numbers in theLISP specific headerLISP-specific header, and the V-bit MUST be set to 0. This packet format works perfectly with xTRs that do not supportMap- Versioning,Map-Versioning, since they can simply ignore those bits. 8. Benefits andcase studiesCase Studies for Map-Versioning In the followingsectionssections, we provide more discussion on various aspects anduseuses oftheMap-Versioning. Security observations areinsteadgrouped in Section 10. 8.1. Map-Versioning andunidirectional trafficUnidirectional Traffic When usingMap-VersioningMap-Versioning, theLISP specificLISP-specific header carries twoMap- VersionMap-Version numbers, for both source and destination mappings. This can raise the question on what will happen in the case of unidirectional flows,likeforinstanceinstance, in the case presented in Figure 1, since the LISP specificationdodoes not mandateforthat the ETRtohave a mapping for the source EID. +-----------------+ +-----------------+ | Domain A | | Domain B | | +---------+ +---------+ | | | ITR A |----------->| ETR B | | | +---------+ +---------+ | | | | | +-----------------+ +-----------------+ Figure1 For what concerns1: Unidirectional Traffic between LISP Domains In the case of the ITR,it isthe ITR is able to put both the source and destination version number in the LISPheaderheader, since the SourceMap- VersionMap-Version number is in the ITR's database, while the DestinationMap- VersionMap-Version number is in the ITR's cache.For what concernsIn the case of the ETR,itthe ETR simply checks only the DestinationMap- VersionMap-Version number in the same way as that described in Section 5, ignoring the Source Map-Version number. 8.2. Map-Versioning andinterworkingInterworking Map-Versioning is compatible with the LISP interworking between LISP and non-LISP sites as defined in[I-D.ietf-lisp-interworking].[RFC6832]. LISP interworking defines three techniques to make LISP sites and non-LISP sites, namely Proxy-ITR, LISP-NAT, and Proxy-ETR.Hereafter it is describedThe following text describes how Map-Versioning relates to these three mechanisms. 8.2.1. Map-Versioning and Proxy-ITRs The purpose of the Proxy-ITR (PITR) is to encapsulate traffic originating in a non-LISP site in order to deliver the packet to one of the ETRs of the LISP site (cf. Figure 2). This case is very similar to the unidirectional traffic case described in Section8.1, hence8.1; hence, similar rules apply. +----------+ +-------------+ | LISP | | non-LISP | | Domain A | | Domain B | | +-------+ +-----------+ | | | | ETR A |<-------|Proxy ITRProxy-ITR |<-------| | | +-------+ +-----------+ | | | | | | +----------+ +-------------+ Figure22: Unidirectional Traffic from Non-LISP Domain to LISP Domain The main difference is that a Proxy-ITR does not have any mapping, since it justencapsulateencapsulates packets arriving from the non-LISPsite,site and thus cannot provide a Source Map-Version. In this case, theproxy-ITRProxy-ITR will just put the Null Map-Version value as the Source Map-Version number, while the receiving ETR will ignore the field. With thissetup thesetup, LISP Domain A is able to check whether or not the PITR is using the latest mapping. If this is not thecasecase, the mapping for LISP Domain A on the PITR can be updated using one of the mechanisms defined in[I-D.ietf-lisp][RFC6830] and[I-D.ietf-lisp-interworking].[RFC6832]. 8.2.2. Map-Versioning and LISP-NAT The LISP-NAT mechanism is based on address translation fromnon- routablenon-routable EIDs to routable EIDs and does not involve any form of encapsulation. Assuchsuch, Map-Versioning does not apply in this case. 8.2.3. Map-Versioning and Proxy-ETRs The purpose of the Proxy-ETR (PETR) is to decapsulate traffic originating in a LISP site in order to deliver the packet to thenon- LISPnon-LISP site (cf. Figure 3). One of the main reasonsofto deploy PETRs is to bypass uRPF (Unicast Reverse Path Forwarding) checks on the provider edge. +----------+ +-------------+ | LISP | | non-LISP | | Domain A | | Domain B | | +-------+ +-----------+ | | | | ITR A |------->|Proxy ETRProxy-ETR |------->| | | +-------+ +-----------+ | | | | | | +----------+ +-------------+ Figure33: Unidirectional Traffic from LISP Domain to Non-LISP Domain A Proxy-ETR does not have any mapping, since it just decapsulates packets arriving from the LISP site. In this case, the ITR will just put the Null Map-Version value as the Destination Map-Version number, while the receiving Proxy-ETR will ignore the field. With thissetupsetup, the Proxy-ETR is able to check whether or not the mapping has changed. If this is thecasecase, the mapping for LISP Domain A on the PETR can be updated using one of the mechanisms defined in[I-D.ietf-lisp][RFC6830] and[I-D.ietf-lisp-interworking].[RFC6832]. 8.3. RLOCshutdown/withdrawShutdown/Withdraw Map-Versioning can also beevenused to perform a graceful shutdown or withdraw of a specific RLOC. This is achieved by simply issuing a new mapping, with an updated Map-Versionnumber,number where the specific RLOC to be shut down is withdrawn or announced as unreachable(R bit(via the R-bit in the MapRecord,Record; see[I-D.ietf-lisp]),[RFC6830]), but without actually turning it off. Once no more traffic is received by the RLOC, it can be shut down gracefully, becauseat leastall sites actively using the mapping have updated it. It should be pointed out that for frequent up/down changes such a mechanism should not beusedused, since this can generate excessive load on theMapping System.mapping system. 8.4. Map-Version forlightweightLightweight LISPimplementationImplementation The use of Map-Versioning can help in developing a lightweight implementation of LISP.ThisHowever, this comes with the price of not supportingLoc-Status-Bit,the Locator-Status-Bit, whichareis useful in some contexts. In the current LISPspecificationsspecifications, the set of RLOCs must always be maintained ordered and consistent with the content of theLoc Status BitsLocator-Status-Bits (seesectionSection 6.5 of[I-D.ietf-lisp]).[RFC6830]). WithMap-VersioningMap-Versioning, suchtypetypes of mechanisms can be avoided. When a new RLOC is added to a mapping, it is not necessary to "append" newlocatorsLocators to the existing ones as explained in Section 6.5 of[I-D.ietf-lisp].[RFC6830]. A new mapping with a new Map-Version number will be issued, and since the oldlocatorsLocators are stillvalidvalid, the transition willbeoccur with no disruptions. The same applies for the caseawhere an RLOC is withdrawn. There is no need to maintain holes in the list oflocators,Locators, as is the case when usingLocator Status Bits,Locator-Status-Bits, for sites that are not using the RLOC that has beenwithdrawnwithdrawn; in this case, the transition willbeoccur with no disruptions. All of these operations, as already stated, do not need to maintain any consistency amongLocator Status Bits,Locator-Status-Bits and in the wayRLOCthat the RLOCs are stored in the EID-to-RLOC Cache. Further,Map-VersionMap-Versioning can be usedtoas a substitute for the "clock sweep" operation described in Section6.5.16.6.1 of[I-D.ietf-lisp].[RFC6830]. Indeed, every LISP site communicating to a specific LISP site that has updated the mapping will be informed of the available new mapping in a data-driven manner. Note that what is proposed inthe presentthis section is just an example and MUST NOT be considered as specifications for a lightweight LISP implementation.In caseIf the IETF decides to undertake suchawork, it will be documented elsewhere. 9. IncrementaldeploymentDeployment andimplementation statusImplementation Status Map-Versioning can be incrementally deployed without any negative impact on existing LISP elements (e.g., xTRs, Map-Servers,Proxy- ITRs, etc).Proxy-ITRs, etc.). Any LISP element that does not support Map-Versioning can safely ignorethem.Map-Version numbers carried in the LISP header. Further, there is no need of any specific mechanism to discoverifwhether or not an xTR supportsor notMap-Versioning. This information is already included in the Map Record. Map-Versioning is currently implemented in OpenLISP[I-D.iannone-openlisp-implementation].[OPENLISP]. Note that the reference document for LISPimplementationimplementations and interoperability tests remains[I-D.ietf-lisp].[RFC6830]. 10. Security Considerations Map-Versioning does not introduce any securityissueissues concerning both thedata-planedata plane and thecontrol-plane.control plane. On the contrary, as describedin the following,below, if Map-Versioning may also be usedalsoto update mappings in the case of change in the reachability information (i.e., instead of theLocator Status Bits)Locator-Status-Bits), it is possible to reduce the effects of some DoS or spoofing attacks that can happen in an untrusted environment. Robustness of the Map-Versioning mechanism leverages on a trusted Mapping Distribution System. A thorough security analysis of LISP is documented in[I-D.ietf-lisp-threats].[LISP-THREATS]. 10.1. Map-Versioning againsttraffic disruptionTraffic Disruption An attacker can try to disrupt ongoing communications by creatingLISP encapsulatedLISP-encapsulated packets with wrongLocator Status Bits.Locator-Status-Bits. If the xTR blindly trusts theLocator Status BitsLocator-Status-Bits, it will change the encapsulation accordingly, which can result in traffic disruption. This does not happen in the case of Map-Versioning. As described in Section 5, upon a version number change the xTR first issues aMap- Request.Map-Request. The assumption is that the mapping distribution system is sufficiently secure that Map-Request and Map-Reply messages and their content can be trusted. Security issues concerning specific mapping distributionsystemsystems are out of the scope of this document. In the case ofMap-VersioningMap-Versioning, the attacker should "guess" a valid version number that triggers aMap-Request,Map-Request as described in Section5, otherwise5; otherwise, the packet is simply dropped. Nevertheless, guessing a version number that generates a Map-Request iseasy, henceeasy; hence, it is important to follow therate limitationsrate-limitation policies described in[I-D.ietf-lisp][RFC6830] in order to avoid DoS attacks. Note that a similar level of security can be obtained withLoc Status Bits,Locator-Status-Bits by simply making it mandatory to verify any change through aMap- Request.Map-Request. However, in this caseLocator Status Bits looseLocator-Status-Bits lose their meaning,because,because it does not matter anymore which specific bitshas changed,have changed; the xTR will query the mapping system and trust the content of the received Map-Reply.FurthermoreFurthermore, there is no way to perform filtering as intheMap-Versioning in order to drop packets that do not carry a valid Map-Version number. In the case ofLocator Status Bits,Locator-Status-Bits, any random change can trigger a Map-Request (unless rate limitation isenabledenabled, whichraiseraises another type of attack as discussed in Section 10.2). 10.2. Map-Versioning againstreachability informationReachability Information DoS Attackers can try to trigger a large amount ofMap-RequestMap-Requests by simply forging packets with randomMap-VersionMap-Versions or randomLocator Status Bits.Locator-Status-Bits. In bothcasescases, the Map-Requests arerate limitedrate-limited as described in[I-D.ietf-lisp].[RFC6830]. However,differently from Locator Status Bitin contrast to the Locator-Status-Bit, where there is no filtering possible, in the case of Map-Versioning it is possible to filternot validinvalid version numbers before triggering a Map-Request, thus helpingin reducingto reduce the effects of DoS attacks. In otherwordswords, the use of Map-Versioning enables a fine control on when to update a mapping or when to notify someone that a mapping has been updated. It isclear,clear that Map-Versioning does not protect against DoS and DDoS attacks, where an xTRloosesloses processing power when doing checks on the LISP header of packets sent by attackers. This is independentfromof Map-Versioning and is the same forLoc Status Bits.Locator-Status-Bits. 11.IANA Considerations This document has no actions for IANA. 12.Open Issues and Considerations There are a number of implications of the use of Map-Versioning that are not yet completely explored. Among these are: o Performance of the convergence time when an EID-to-RLOC mapping changes, i.e., how much time is needed to update mappings in the EID-to-RLOC Cache of the ITRs currently sending traffic to ETRs for the EID whose mapping has been changed. o Supporttofor ETR synchronization. The implications that a temporary lack of synchronization may have on the trafficisare yet to be fully explored. Details on how tokeepmaintain synchronization are presented in Section 6.6 of[I-D.ietf-lisp].[RFC6830]. Section12.1 hereafter11.1 discusses the issue in furtherdetailsdetail with respect to the Map-Versioning mechanism. The authors expect that experimentation will help assess the performance andthelimitations of the Map-Versioning mechanism. Issues and concerns about the deployment of LISP for Internet traffic are discussed in[I-D.ietf-lisp]. 12.1.[RFC6830]. 11.1. Lack of Synchronization among ETRs Even without Map-Versioning, LISP([I-D.ietf-lisp])([RFC6830]) requires ETRs to announce the same mapping for the same EID-Prefix to a requester. The implications that a temporary lack of synchronization may have on the trafficisare yet to be fully explored. Map-Versioning does not require additional synchronizationmechanismmechanisms as compared to the normal functioning of LISP without Map-Versioning.ClearlyClearly, all the ETRs have to reply with the same Map-Versionnumber, otherwisenumber; otherwise, there can be an inconsistency that creates additional control traffic, instabilities, and traffic disruptions. It is the same without Map-Versioning, with ETRs that have to reply with the samemapping, otherwisemapping; otherwise, the same problems can arise. There are two ways Map-Versioning is helpful with respect to the synchronization problem. On the one hand, assigning version numbers to mappings helps in debugging, since quick checks on the consistency of the mappings on different ETRs can be done by looking at theMap- VersionMap-Version number. On the other hand, Map-Versioning can be used to control the traffic toward ETRs that announce the latest mapping. As an example, let's consider the topology of Figure 4 where ITR A.1 ofdomainDomain A is sending unidirectional traffic tothe domainDomain B, while A.2 ofdomainDomain A exchanges bidirectional traffic withdomainDomain B. In particular, ITR A.2 sends traffic to ETRBB, and ETR A.2 receives traffic from ITR B. +-----------------+ +-----------------+ | Domain A | | Domain B | | +---------+ | | | | ITR A.1 |--- | | | +---------+ \ +---------+ | | | ------->| ETR B | | | | ------->| | | | +---------+ / | | | | | ITR A.2 |--- -----| ITR B | | | | | / +---------+ | | | ETR A.2 |<----- | | | +---------+ | | | | | | +-----------------+ +-----------------+ Figure4 Obviously4: Example Topology Obviously, in the case ofMap-VersioningMap-Versioning, both ITR A.1 and ITR A.2 ofdomainDomain A must use the samevalue otherwisevalue; otherwise, the ETR ofdomainDomain B will start to send Map-Requests. The same problem can, however, arise withoutMap-Versioning. ForMap-Versioning, for instance, if the two ITRs ofdomainDomain A send differentLocator Status Bits.Locator-Status-Bits. In thiscasecase, either the traffic isdisrupted,disrupted iftheETR B trusts theLocator Status Bits,Locator-Status-Bits, or if ETR B does not trust theLocator Status BitsLocator-Status-Bits it will start sending Map-Requests to confirmtheeach change inthereachability. So far, LISP does not provide any specific synchronizationmechanism,mechanism but assumes that synchronization is provided by configuring the different xTRs consistently (see Section 6.6 in[I-D.ietf-lisp]).[RFC6830]). The same applies for Map-Versioning. If in the future any synchronization mechanism is provided, Map-Versioning will take advantage of itautomaticallyautomatically, since it is included in the Record format, as described in Section 7.13. Acknowledgements12. Acknowledgments The authors would like to thank Alia Atlas, Jesper Skriver, Pierre Francois, Noel Chiappa, and Dino Farinacci for their comments and review. This work has been partially supported by the INFSO-ICT-216372 TRILOGY Project(www.trilogy-project.org). 14.(http://www.trilogy-project.org). 13. References14.1.13.1. Normative References[I-D.ietf-lisp] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "Locator/ID Separation Protocol (LISP)", draft-ietf-lisp-22 (work in progress), February 2012. [I-D.ietf-lisp-interworking] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, "Interworking LISP with IPv4 and IPv6", draft-ietf-lisp-interworking-05 (work in progress), February 2012.[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.14.2. Informative References [I-D.iannone-openlisp-implementation] Iannone, L., Saucez,[RFC6830] Farinacci, D.,and O. Bonaventure, "OpenLISP Implementation Report", draft-iannone-openlisp-implementation-01 (work in progress), July 2008. [I-D.ietf-lisp-alt]Fuller, V.,Farinacci, D.,Meyer, D., and D. Lewis,"LISP Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-10 (work in progress), December 2011. [I-D.ietf-lisp-ms] Fuller,"The Locator/ID Separation Protocol (LISP)", RFC 6830, January 2013. [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, "Interworking between Locator/ID Separation Protocol (LISP) andD. Farinacci, "LISP Map Server Interface", draft-ietf-lisp-ms-15 (work in progress),Non-LISP Sites", RFC 6832, January2012. [I-D.ietf-lisp-threats]2013. 13.2. Informative References [LISP-THREATS] Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats Analysis",draft-ietf-lisp-threats-00 (workWork inprogress), JulyProgress, October 2012. [OPENLISP] Iannone, L., Saucez, D., and O. Bonaventure, "Implementing the Locator/ID Separation Protocol: Design and experience", Computer Networks Vol. 55, Number 4, Pages 948-958, March 2011. Appendix A. Estimation oftimeTime before Map-Versionwrap-around The presentWrap-Around This section proposes an estimation of the wrap-around time for the12 bits12-bit size of the Map-Version number. Using a granularity of seconds and assuming asworst-caseworst case that a new version is issued each second, it takes slightly more than 1 hour before the version wraps around. Note that the granularity of seconds is in line with therate limitationrate-limitation policy for Map-Request messages, as proposed in the LISP main specifications([I-D.ietf-lisp]). Alternatively([RFC6830]). Alternatively, a granularity of minutes can also be used, as for the TTL of the Map-Reply([I-D.ietf-lisp]).([RFC6830]). In thiscasecase, theworstworst-case scenario is when a new version is issued every minute, leading to a much longer time before wrap-around. In particular, when using 12 bits, the wrap-around time is almost 3 days. For general information,hereafter there is a table withFigure 5 below provides a rough estimation of the time before wrap-around in the worst-case scenario, considering different sizes(bits length)(length in bits) of the Map-Version number and different timegranularity.granularities. Since even in the case of a high mapping change rate (1 per second) thewrap aroundwrap-around time using 12 bits is far largerthenthan any reasonableRound-Trip-TimeRound-Trip Time (RTT), there is no risk of race conditions. +---------------+--------------------------------------------+ |Version Number | Time beforewrap aroundWrap-Around | | Size (bits) +---------------------+----------------------+ | |Granularity: Minutes | Granularity: Seconds | | | (mapping changes | (mapping changes | | | every 1 minute) | every 1 second) | +-------------------------------------+----------------------+ | 32 | 8171Yearsyears | 136Yearsyears | | 30 | 2042Yearsyears | 34Yearsyears | | 24 | 31Yearsyears | 194Daysdays | | 16 | 45Daysdays | 18Hourshours | | 15 | 22Daysdays | 9Hourshours | | 14 | 11Daysdays | 4Hourshours | | 13 | 5.6Daysdays | 2.2Hourshours | | 12 | 2.8Daysdays | 1.1Hourshours | +---------------+---------------------+----------------------+ Figure 5: Estimation oftimeTime beforewrap-around Appendix B. Document Change Log o Version 09 Posted March 2012. * Text in Section 5.1 made more explicit in the case of smaller (i.e., older) Destination Map-Version Number, as pointed out by Ralph E. Droms. o Version 08 Posted Ferbruary 2012. * Clarifications added to Appendix A as requested by S. Bryant. o Version 07 Posted January 2012. * Moved Subsection 8.1 in Section 12 as requested by R. Bonica. * Added explicit reference to the discussion about ETR synchronization at the end of the Introduction, as requested by R. Bonica. * Added cross-reference to Section 6.6 in [I-D.ietf-lisp] as requested by R. Bonica. * Moved [I-D.ietf-lisp-interworking] as normative reference as requested by R. Droms. * Added long version of all acronyms in the Introduction as requested by S. Bryant. o Version 06 Posted October 2011. * Added disclaimer in the Introduction about general issues concerning LISP as requested by A. Farrel. * Fixed sentence about legacy systems in the abstract as requested by A. Farrel. * Added Section 12 as requested by A. Farrel. o Version 05 Posted October 2011. * Added sentence in Section 3 on the use of Big Endian, as for comment of P. Resnick. * Extended the end of Section 4 in order to clarify that Map- Version numbers are assigned to mappings by configuration and not automatically generated by ETRs, as for comments of R. Sparks * Changed formal definition of Map-Version order (greater vs. smaller) in Section 4 as for comments from R. Housley and R. Sparks. * Added disclaimer in Section 1 stating that in case of unforseen conflict with the main spec the base document has precedence on the present one, as for comment from Sthephen Farrell. o Version 04 Posted September 2011. * Added clarifications in Section 1, Section 4, Section 5.2, and Section 5.1 to address Stephen Farrell's comments. * Used the term LISP Site instead of ISP in Section 5 as suggested by Stephen Farrell. * Deleted "(usually contains the nonce)" from Section 6 because confusing, as suggested by Stephen Farrell. * Fixed several typos pointed out by Stephen Farrell. 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 8.3 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. * Added text in Section 5 about ETR synchronization, as suggested by Alia Atlas. * Modified text in Section 8.4 concerning lightweight LISP implementation, as suggested by Alia Atlas. * 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. * Fixed section 4.1 to be less restrictive, as suggested by Jesper Skriver. o Version 01 Posted March 2011. * Changed the wording from "Map-Version number 0" to "Null Map- Version. * Clarification of the use of the Null Map-Version value as Source Map-Version Number and Destination Map-Version Number. * Extended the section describing Map-Versioning and LISP Interworking co-existence. * Reduce packet format description to avoid double definitions with the main specs. o Version 00 Posted September 2010. * Added Section "Definitions of Terms". * Editorial polishing of all sections. * Added clarifications in section "Dealing with Map-Version numbers" for the case of the special Map-Version number 0. * Rename of draft-iannone-mapping-versioning-02.txt.Wrap-Around Authors' Addresses Luigi IannoneTelekom Innovation Laboratories Ernst-Reuter Platz 7 Berlin Germany Email: luigi@net.t-labs.tu-berlin.deTelecom ParisTech EMail: luigi.iannone@telecom-paristech.fr Damien Saucez INRIA Sophia Antipolis 2004 route des Lucioles - BP 93 Sophia Antipolis FranceEmail:EMail: damien.saucez@inria.fr Olivier Bonaventure Universite catholique de Louvain Place St. Barbe 2 Louvain-la-Neuve BelgiumEmail:EMail: olivier.bonaventure@uclouvain.be