draft-ietf-lisp-map-versioning-00.txt   draft-ietf-lisp-map-versioning-01.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: April 1, 2011 D. Saucez Expires: September 12, 2011 D. Saucez
O. Bonaventure O. Bonaventure
Universite catholique de Louvain Universite catholique de Louvain
September 28, 2010 March 11, 2011
LISP Map-Versioning LISP Map-Versioning
draft-ietf-lisp-map-versioning-00.txt draft-ietf-lisp-map-versioning-01.txt
Abstract Abstract
This document describes the LISP Map-Versioning mechanism, which This document describes the LISP Map-Versioning mechanism, which
provides in-packet information about EID-to-RLOC mappings used to provides in-packet information about 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 xTRs about modifications of the mappings used to
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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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 1, 2011. This Internet-Draft will expire on September 12, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 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.
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described in the BSD License. described in the BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5
3. Definitions of Terms . . . . . . . . . . . . . . . . . . . . . 4 3. Definitions of Terms . . . . . . . . . . . . . . . . . . . . . 5
4. EID-to-RLOC Map-Version number . . . . . . . . . . . . . . . . 4 4. EID-to-RLOC Map-Version number . . . . . . . . . . . . . . . . 5
4.1. The special Map-Version 0 . . . . . . . . . . . . . . . . 5 4.1. The Null Map-Version . . . . . . . . . . . . . . . . . . . 6
5. Dealing with Map-Version numbers . . . . . . . . . . . . . . . 5 5. Dealing with Map-Version numbers . . . . . . . . . . . . . . . 7
5.1. Handling Destination Map-Version number . . . . . . . . . 6 5.1. Handling Destination Map-Version number . . . . . . . . . 7
5.2. Handling Source Map-Version number . . . . . . . . . . . . 7 5.2. Handling Source Map-Version number . . . . . . . . . . . . 9
6. LISP header and Map-Version numbers . . . . . . . . . . . . . 8 6. LISP header and Map-Version numbers . . . . . . . . . . . . . 10
7. Map Record and Map-Version . . . . . . . . . . . . . . . . . . 10 7. Map Record and Map-Version . . . . . . . . . . . . . . . . . . 11
8. Benefits and case studies for Map-Versioning . . . . . . . . . 11 8. Benefits and case studies for Map-Versioning . . . . . . . . . 12
8.1. Synchronization of different xTRs . . . . . . . . . . . . 11 8.1. Synchronization of different xTRs . . . . . . . . . . . . 12
8.2. Map-Versioning and unidirectional traffic . . . . . . . . 12 8.2. Map-Versioning and unidirectional traffic . . . . . . . . 13
8.3. Map-Versioning and interworking . . . . . . . . . . . . . 13 8.3. Map-Versioning and interworking . . . . . . . . . . . . . 13
8.4. Graceful RLOC shutdown/withdraw . . . . . . . . . . . . . 13 8.3.1. Map-Versioning and Proxy-ITRs . . . . . . . . . . . . 14
8.5. Map-Version for lightweight LISP implementation . . . . . 13 8.3.2. Map-Versioning and LISP-NAT . . . . . . . . . . . . . 14
9. Incremental deployment and implementation status . . . . . . . 14 8.3.3. Map-Versioning and Proxy-ETRs . . . . . . . . . . . . 14
10. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8.4. RLOC shutdown/withdraw . . . . . . . . . . . . . . . . . . 15
10.1. Map-Versioning against traffic disruption . . . . . . . . 14 8.5. Map-Version for lightweight LISP implementation . . . . . 15
10.2. Map-Versioning against reachability information DoS . . . 15 9. Incremental deployment and implementation status . . . . . . . 16
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 10. Security Considerations . . . . . . . . . . . . . . . . . . . 16
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 10.1. Map-Versioning against traffic disruption . . . . . . . . 17
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 10.2. Map-Versioning against reachability information DoS . . . 17
13.1. Normative References . . . . . . . . . . . . . . . . . . . 16 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
13.2. Informative References . . . . . . . . . . . . . . . . . . 16 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
Appendix A. Estimation of time before Map-Version wrap-around . . 17 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 17 13.1. Normative References . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 13.2. Informative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Estimation of time before Map-Version wrap-around . . 19
Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 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 a 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 Map-Version numbers to each LISP 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- EID-to-RLOC mapping and transport such a version number in the LISP-
specific header. When a mapping changes, a new version number is specific header. When a mapping changes, a new version number is
assigned to the updated mapping. A change in an EID-to-RLOC mapping 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 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 RLOCs, but it can also be a change in the priority or weight of one
or more RLOCs. or more RLOCs.
When Map-Versioning is used, LISP-encapsulated data packets contain When Map-Versioning is used, LISP-encapsulated data packets contain
the version number of the two mappings used to select the RLOCs in the version number of the two mappings used to select the RLOCs in
the outer header (i.e., both source and destination). These version the outer header (i.e., both source and destination). These version
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When an ITR encapsulates a data packet, with a LISP header containing When an ITR encapsulates a data packet, with a LISP header containing
the Map-Version numbers, it puts in the LISP-specific header two the Map-Version numbers, it puts in the LISP-specific header two
version numbers: version numbers:
1. The version number assigned to the mapping (contained in the EID- 1. The version number assigned to the mapping (contained in the EID-
to-RLOC Database) used to select the source RLOC. to-RLOC Database) used to select the source RLOC.
2. The version number assigned to the mapping (contained in the EID- 2. The version number assigned to the mapping (contained in the EID-
to-RLOC Cache) used to select the destination RLOC. to-RLOC Cache) used to select the destination RLOC.
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 that sent it is using the receiving the packet to know if the ITR has the latest version number
latest mapping for the destination EID. If it is not the case the that any ETR at the destination EID site has provided to the ITR in a
ETR can send to the ITR a Map-Request containing the updated mapping Map-Reply. If it is not the case the ETR can send to the ITR a Map-
or invoking a Map-Request from the ITR (both cases are already Request containing the updated mapping or soliciting a Map-Request
defined in [I-D.ietf-lisp]). In this way the ITR can update its from the ITR (both cases are already defined in [I-D.ietf-lisp]). In
cache. On the other hand, it enables an xTR receiving such a packet this way the ITR can update its cache. On the other hand, it enables
to know if it has in its cache the latest mapping for the source EID an ETR receiving such a packet to know if it has in its EID-to-RLOC
(in case of bidirectional traffic). If it is not the case a Map- Cache the latest mapping for the source EID (in case of bidirectional
Request can be send. traffic). If it is not the case a Map-Request can be send.
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
specification [I-D.ietf-lisp]. Hereafter are defined only the terms
that are specific to the Map-Versioning mechanism.
Map-Version number: An unsigned 12-bits assigned to an EID-to-RLOC Map-Version number: An unsigned 12-bits assigned to an EID-to-RLOC
mapping, not including the value 0 (0x000). mapping, not including the value 0 (0x000).
Map-Version 0: The 12-bits value 0 (0x000) is not used as Map- Null Map-Version: The 12-bits null value of 0 (0x000) is not used as
Version number. It is used to signal that no Map-Version number Map-Version number. It is used to signal that no Map-Version
is assigned to the EID-to-RLOC mapping. number is assigned to the EID-to-RLOC mapping.
Source Map-Version number: Map-Version number of the EID-to-RLOC Source Map-Version number: Map-Version number of the EID-to-RLOC
mapping used to select the source address (RLOC) of the outer IP mapping used to select the source address (RLOC) of the outer IP
header. header of LISP-encapsulated packets.
Destination Map-Version number: Map-Version number of the EID-to- Destination Map-Version number: Map-Version number of the EID-to-
RLOC mapping used to select the destination address (RLOC) of the RLOC mapping used to select the destination address (RLOC) of the
outer IP header. outer IP header of LISP-encapsulated packets.
4. EID-to-RLOC Map-Version number 4. EID-to-RLOC Map-Version number
The EID-to-RLOC Map-Version number consists in an unsigned 12-bits The EID-to-RLOC Map-Version number consists in an unsigned 12-bits
integer. The version number is assigned in a per-mapping fashion, integer. The version number is assigned in a per-mapping fashion,
meaning that different mappings will have assigned a different meaning that different mappings will have assigned a different
version number, which is also updated independently. An update in version number, which is also updated independently. An update in
the version number (i.e., a newer version) consist in incrementing by the version number (i.e., a newer version) consist in incrementing by
one the older version number. Appendix A contains a rough estimation one the older version number. Appendix A contains a rough estimation
of the wrap-around time for the Map-Version number. of the wrap-around time for the Map-Version number.
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V1 < V2 : True if and only if V1 < V2 < (V1 + 2**(N-1)). V1 < V2 : True if and only if V1 < V2 < (V1 + 2**(N-1)).
V1 > V2 : True if and only if V1 > V2 > (V1 - 2**(N-1)). V1 > V2 : True if and only if V1 > V2 > (V1 - 2**(N-1)).
Using 12 bits, as defined in this document, and assuming a Map- Using 12 bits, as defined in this document, and assuming a Map-
Version value of 69, Map-Version numbers in the range [70; 69 + 2047] Version value of 69, Map-Version numbers in the range [70; 69 + 2047]
are greater than 69, while Map-Version numbers in the range [69 + are greater than 69, while Map-Version numbers in the range [69 +
2048; (69 + 4095) mod 4096] are smaller than 69. 2048; (69 + 4095) mod 4096] are smaller than 69.
The initial Map-Version number of a new EID-to-RLOC mapping can be The initial Map-Version number of a new EID-to-RLOC mapping SHOULD be
randomly generated. However, it MUST NOT be zero (0x000) because it randomly generated. However, it MUST NOT be set to the Null Map-
has a special meaning (see Section 4.1). Version value (0x000), because it has a special meaning (see
Section 4.1).
4.1. The special Map-Version 0 4.1. The Null Map-Version
The value 0x000 (zero) is not a valid Map-Version number indicating The value 0x000 (zero) is not a valid Map-Version number indicating
the version of the EID-to-RLOC mapping. The only valid use of Map- the version of the EID-to-RLOC mapping. Such a value is used for
Version number equal to 0 is in the Map Records, which are part of special purposes and is named the Null Map-Version number.
the Map-Request and Map-Reply messages (defined in [I-D.ietf-lisp]).
Map Records that have Map-Version number equal 0 indicate that there The Null Map-Version MAY appear in the LISP specific header as either
is no Map-Version number associated with the mapping. This means Source Map-Version number (cf. Section 5.2) or Destination Map-
that LISP encapsulated packets, destined to the EID-Prefix the Map Version number (cf. Section 5.1). When the Source Map-Version number
Record refers to, MUST never contain Map-Version number (i.e., V bit is set to the Null Map-version value it means that no map version
MUST always be 0). In other words, Map-Version number equal to 0 information is conveyed for the source site. This means that if a
signals to the ITR using the mapping that the Map-Versioning is not mapping exists for the source EID in the EID-to-RLOC Cache, then the
supported, or even if supported it MUST NOT be used for that specific ETR MUST NOT compare the received Null Map-Version with the content
EID-Prefix. Any value different from zero means that Map-Versioning of the EID-to-RLOC cache. When the Destination Map-version number is
is supported and MAY be used. set to the Null Map-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-Reply and Map-Register
messages (defined in [I-D.ietf-lisp]). Map Records that have a Null
Map-Version number indicate that there is no Map-Version number
associated with the mapping. This means that LISP encapsulated
packets, destined to the EID-Prefix the Map Record refers to, MUST
NOT contain Map-Version numbers (i.e., V bit MUST always be 0). In
other words, the Null Map-Version number signals to the ITR using the
mapping that the Map-Versioning is not supported, or even if
supported it MUST NOT be used for that specific EID-Prefix. 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 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 number implies that, when updating a Map-Version number because of a
change in the mapping, if the next value is 0 then Map-Version number change in the mapping, if the next value is 0 then Map-Version number
MUST be incremented by 2 (i.e., set to 1, which is the next valid MUST be incremented by 2 (i.e., set to 1, which is the next valid
value). value).
5. Dealing with Map-Version numbers 5. Dealing with Map-Version numbers
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
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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.
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 A first one from the EID-to-RLOC mapping in the EID-to-RLOC o The Source Map-Version number of the EID-to-RLOC mapping in the
Database used to select the source RLOC, and called Source Map- EID-to-RLOC Database used to select the source RLOC.
Version number.
o A second one from the EID-to-RLOC mapping in the EID-to-RLOC Cache o The Destination Map-Version number of the EID-to-RLOC mapping in
used to select the destination RLOC, and called Destination Map- the EID-to-RLOC Cache used to select the destination RLOC.
Version number.
By embedding both Source Map-Version number and Destination Map- By embedding both Source Map-Version number and Destination Map-
Version number an xTR receiving a LISP packet with Map-Version Version number an ETR receiving a LISP packet with Map-Version
number, can perform the following checks: numbers, can perform the following checks:
1. The ITR that has sent the packet has an up-to-date mapping in its 1. The ITR that has sent the packet has an up-to-date mapping in its
cache for the destination EID and is performing encapsulation cache for the destination EID and is performing encapsulation
correctly. correctly.
2. In case of bidirectional traffic, the mapping in the local xTR 2. In case of bidirectional traffic, the mapping in the local ETR
cache for the source EID is up-to-date. EID-to-RLOC cache for the source EID is up-to-date.
If one or both of the above conditions do not hold, the xTR can send 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 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 available (see Section 5.1) or to update the mapping in the local
cache (see Section 5.2). cache (see Section 5.2).
5.1. Handling Destination Map-Version number 5.1. Handling Destination Map-Version number
When an ETR receives a packet, the Destination Map-Version number When an ETR receives a packet, the Destination Map-Version number
relates to the mapping for the destination EID for which the ETR is a relates to the mapping for the destination EID for which the ETR is a
RLOC. This mapping is part of the ETR LISP Database. Since the ETR RLOC. This mapping is part of the ETR EID-to-RLOC Database. Since
is authoritative for the mapping, it has the correct and up-to-date the ETR is authoritative for the mapping, it has the correct and up-
Destination Map-Version number. A check on this version number is to-date Destination Map-Version number. A check on this version
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.
Further actions are needed. Since the ETR is authoritative on Since the ETR is authoritative on the mapping, this means that
the mapping, this means that someone is not behaving correctly someone is not behaving correctly w.r.t. the specifications, thus
w.r.t. the specifications, thus the packet carries a not valid the packet carries a not valid version number and SHOULD be
version number and SHOULD be silently dropped. 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. Further its EID-to-RLOC Cache containing stale information. The ITR
actions are needed. The ITR sending the packet must be informed sending the packet has to be informed that a newer mapping is
that a newer mapping is available. This is done with a Map- available. This is done with a Map-Request message sent back to
Request message sent back to the ITR. The Map-Request will the ITR. The Map-Request will either trigger a Map-Request back
either trigger a Map-Request back using the SMR bit or it will using the SMR bit or it will piggyback the newer mapping. These
piggyback the newer mapping. These are not new mechanisms; how are not new mechanisms; how to SMR or piggyback mappings in Map-
to SMR or piggyback mappings in Map-Request messages is already Request messages is already described in [I-D.ietf-lisp], while
described in [I-D.ietf-lisp], while their security is discussed their security is discussed in [I-D.saucez-lisp-security]. These
in [I-D.saucez-lisp-security]. These Map-Request messages should Map-Request messages should be rate limited (rate limitation
be rate limited (rate limitation policies are also described in policies are also described in [I-D.ietf-lisp]). The feature
[I-D.ietf-lisp]). The gain introduced by Map-Version Numbers is introduced by Map-Version numbers is the possibility of blocking
that after a certain number of retries, if the Destination Map- traffic from ITRs not using the latest mapping. Indeed, after a
Version number in the packets is not updated, packet MAY be certain number of retries, if the Destination Map-Version number
silently dropped because either the ITR is refusing to use the in the packets is not updated, the ETR MAY silently drop packets
mapping for which the ETR is authoritative or it might be some with a stale Map-Version number. This because either the ITR is
form of attack. refusing to use the mapping for which the ETR is authoritative or
(worse) it might be some form of attack.
Note that the rule in case 3 can be even more restrictive. If the The rule in the third case MAY be more restrictive. If the mapping
mapping has been the same for a period of time as long as the TTL has been the same for a period of time as long as the TTL (defined in
(defined in LISP [I-D.ietf-lisp]) of the previous version of the [I-D.ietf-lisp]) of the previous version of the mapping, all packets
mapping, all packets arriving with an old Map-Version SHOULD be arriving with an old Map-Version SHOULD be silently dropped right
silently dropped right away without issuing any Map-Request. Indeed, away without issuing any Map-Request. The reason that allows such
if the new mapping with the updated version number has been stable action is the fact that if the new mapping with the updated version
for at least the same time as the TTL of the older mapping, all the number has been unchanged for at least the same time as the TTL of
entries in the caches of ITRs must have expired. If packets with old the older mapping, all the entries in the caches of ITRs must have
Map-Version number are still received, the reason is that either expired. Hence, all ITRs sending traffic should have refreshed the
someone has not respected the TTL, or it is a form of spoof/attack. mapping according to [I-D.ietf-lisp]. If packets with old Map-
In both cases this is not valid behavior w.r.t. the specifications Version number are still received, then either someone has not
and the packet MAY be silently dropped. 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
SHOULD be silently dropped.
For LISP-encapsulated packets with the V-bit set, the Destination LISP-encapsulated packets with the V-bit set, when the original
Map-Version can never contain the special value 0. Indeed, as mapping in the EID-to-RLOC Database has version number set to the
explained in Section 4.1, if an EID-to-RLOC mapping has Map-Version Null Map-Version value, MAY be silently dropped. As explained in
0, it means that ITRs, using the mapping for encapsulation, MUST NOT Section 4.1, if an EID-to-RLOC mapping has a Null Map-Version, it
put Map-Version number in the LISP-specific header. An ETR receiving means that ITRs, using the mapping for encapsulation, MUST NOT use
a packet with the V-bit set but Destination Map-Version 0 SHOULD Map-Version number in the LISP-specific header.
silently drop the packet.
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
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-Version number 5.2. Handling Source Map-Version number
When an xTR receives a packet, the Source Map-Version number relates 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 to the mapping for the source EID for which the ITR that sent the
packet is authoritative. If the xTR does not have an entry in the packet is authoritative. If the ETR has an entry in its EID-to-RLOC
LISP Cache for the source EID, then the Source Map-Version number can Cache for the source EID, then a check can be performed and the
be safely ignored. If the xTR has an entry in its LISP Cache for the following cases can arise:
source EID, then a check is performed and the following cases can
arise:
1. The packet arrives with the same Source Map-Version number stored 1. The packet arrives with the same Source Map-Version number stored
in the LISP Cache. This is the correct regular case. The xTR in the EID-to-RLOC Cache. This is the correct regular case. The
has in its cache an up-to-date copy of the mapping. No further ITR has in its cache an up-to-date copy of the mapping. No
actions are needed. further actions are needed.
2. The packet arrives with a Source Map-Version number greater 2. The packet arrives with a Source Map-Version number greater
(i.e., newer) than the one stored in the local LISP Cache. This (i.e., newer) than the one stored in the local EID-to-RLOC Cache.
means that xTR has in its cache a mapping that is stale and needs This means that ETR has in its cache a mapping that is stale and
to be updated. The packet is considered valid but further needs to be updated. A Map-Request SHOULD be sent to get the new
actions are needed. In particular a Map-Request must be sent to mapping for the source EID. This is a normal Map-Request message
get the new mapping for the source EID. This is a normal Map- sent through the mapping system and MUST respect the
Request message sent through the mapping system and MUST respect specifications in [I-D.ietf-lisp], including rate limitation
the 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 LISP Cache. Such (i.e., older) than the one stored in the local EID-to-RLOC Cache.
a case is not valid w.r.t. the specifications. Indeed, if the Such a case is not valid w.r.t. the specifications. Indeed, if
mapping is already present in the LISP Cache, this means that an the mapping is already present in the EID-to-RLOC Cache, this
explicit Map-Request has been sent and a Map-Reply has been means that an explicit Map-Request has been sent and a Map-Reply
received from an authoritative source. Assuming that the mapping has been received from an authoritative source. Assuming that
system is not corrupted anyhow, the Map-Version in the LISP Cache the mapping system is not corrupted anyhow, the Map-Version in
is the correct one; hence the packet is not valid and SHOULD be the EID-to-RLOC Cache is the correct one and the packet MAY be
silently dropped. silently dropped.
Otherwise, if the xTR does not have an entry in its cache (e.g. If the ETR does not have an entry in the EID-to-RLOC Cache for the
unidirectional traffic) the Source Map-Version can be safely ignored. source EID (e.g., in case of unidirectional traffic) then the Source
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 special value 0, it means that the Source Map- Version number is the Null Map-Version value, it means that the
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. When the V-bit is set the low-order 24-bits of the
first longword (which usually contains the nonce) are used to first longword (which usually contains the nonce) are used to
transport both source and destination Map-Version numbers. In transport both source and destination Map-Version numbers. In
particular the first 12 bits are used for Source Map-Version number particular the first 12 bits are used for Source Map-Version number
and the second 12 bits for the Destination 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).
The present document just specifies how to use the low-order 24-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 packet format are
specified in [I-D.ietf-lisp]. In the following example we include
all the headers of a LISP encapsulated packet just for the sake of
clarity.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/|Version| IHL |Type of Service| Total Length |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Identification |Flags| Fragment Offset |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OH | Time to Live | Protocol = 17 | Header Checksum |
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | Source Routing Locator |
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\| Destination Routing Locator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Source Port = xxxx | Dest Port = 4341 |
UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ |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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | Instance ID/Locator Status Bits | \ | Instance ID/Locator Status Bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/|Version| IHL |Type of Service| Total Length |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Identification |Flags| Fragment Offset |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IH | Time to Live | Protocol | Header Checksum |
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | Source EID |
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\| Destination EID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
V (1 bit): this is the Map-Version bit as defined in
[I-D.ietf-lisp]. When this bit is set to 1 the low-order 24-bits
of the first longword of the LISP header contain Map-Version
numbers.
Source Map-Version number (12 bits): Map-Version of the mapping used Source Map-Version number (12 bits): Map-Version of the mapping used
by the ITR to select the RLOC present in the "Source Routing by the ITR to select the RLOC present in the "Source Routing
Locator" field. Note that the mapping used for such a selection Locator" field. How to set on transmission and handle on
is determined by the Source EID through a search in the LISP reception this value is described in Section 5.2.
Database of the ITR.
Destination Map-Version number (12 bits): Map-Version of the mapping Destination Map-Version number (12 bits): Map-Version of the mapping
used by the ITR to select the RLOC present in the "Destination used by the ITR to select the RLOC present in the "Destination
Routing Locator" field. Note that the mapping used for such a Routing Locator" field. How to set on transmission and handle on
selection is determined by the Destination EID, used as lookup key reception this value is described in Section 5.1.
in the LISP Cache of the ITR.
Not all of the LISP encapsulated packets need to carry version The present document just specifies how to use the low-order 24-bits
numbers. When Map-Version numbers are carried the V-bit MUST be set of the first longword of the LISP-specific header when the V-bit is
to 1. All legal combination of the flags, when the V-bit is set to set to 1. All other cases, including the bit fields of the rest of
1, are described in [I-D.ietf-lisp]. As a recall and in summary, the LISP-specific header and the whole LISP packet format are
Map-Version cannot be used with the Echo-Nonce feature (E = 1) and specified in [I-D.ietf-lisp]. Not all of the LISP encapsulated
the Nonce feature (N = 1), since they use the same bitfield. packets need to carry version numbers. When Map-Version numbers are
carried the V-bit MUST be set to 1. All legal combinations of the
flags, when the V-bit is set to 1, are described in [I-D.ietf-lisp].
7. Map Record and Map-Version 7. Map Record and Map-Version
To accommodate the proposed mechanism, the Map Records that are To accommodate the proposed mechanism, the Map Records that are
transported on Map-Request/Map-Reply messages need to carry the Map- transported on Map-Request/Map-Reply/Map-Register messages need to
Version number as well. For this purpose the 12-bits before the EID- carry the Map-Version number as well. For this purpose the 12-bits
AFI field in the Record that describe a mapping is used. This is before the EID-AFI field in the Record that describe a mapping is
defined in [I-D.ietf-lisp] and reported here as example. used. This is defined in [I-D.ietf-lisp] and reported here as
example.
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
+-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Record TTL | | | Record TTL |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
R | Locator Count | EID mask-len | ACT |A| Reserved | R | Locator Count | EID mask-len | ACT |A| Reserved |
e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
c | Rsvd | Map-Version Number | EID-AFI | c | Rsvd | Map-Version Number | EID-AFI |
o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 11, line 31 skipping to change at page 12, line 22
Map-Versioning does not require additional synchronization mechanism Map-Versioning does not require additional synchronization mechanism
compared to the normal functioning of LISP without Map-Versioning. compared to the normal functioning of LISP without Map-Versioning.
Clearly all the ETRs have to reply with the same Map-Version number, Clearly all the ETRs have to reply with the same Map-Version number,
otherwise there can be an inconsistency that creates additional otherwise there can be an inconsistency that creates additional
control traffic, instabilities, traffic disruptions. It is the same control traffic, instabilities, traffic disruptions. It is the same
without Map-Versioning, with ETRs that have to reply with the same without Map-Versioning, with ETRs that have to reply with the same
mapping, otherwise the same problems can arise. mapping, otherwise the same problems can arise.
As an example, let's consider the topology of Figure 1 where ITR A.1 As an example, let's consider the topology of Figure 1 where ITR A.1
of domain A is sending unidirectional traffic to the xTR B of domain of domain A is sending unidirectional traffic to the domain B, while
B, while xTR A.2 of domain A and xTR B of domain B exchange A.2 of domain A exchange bidirectional traffic with domain B. In
bidirectional traffic. particular, ITR A.2 send traffic to ETR B and ETR A.2 receives
traffic from ITR B.
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| Domain A | | Domain B | | Domain A | | Domain B |
| +---------+ | | | +---------+ | |
| | xTR A.1 |--- | | | | ITR A.1 |--- | |
| +---------+ \ +---------+ | | +---------+ \ +---------+ |
| | -------->| xTR B | | | | ------->| ETR B | |
| | -------->| | | | | ------->| | |
| +---------+ / +---------+ | | +---------+ / | | |
| | xTR A.2 |<-- | | | | ITR A.2 |--- -----| ITR B | |
| | | / +---------+ |
| | ETR A.2 |<----- | |
| +---------+ | | | +---------+ | |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 1 Figure 1
Obviously in the case of Map-Versioning both xTRs of domain A must Obviously in the case of Map-Versioning both ITR A.1 and ITR A.2 of
use the same value otherwise the xTR of domain B will start to send domain A must use the same value otherwise the ETR of domain B will
Map-Requests. start to send Map-Requests.
The same problem can, however, arise without Map-Versioning. For The same problem can, however, arise without Map-Versioning. For
instance if the two xTRs of domain A send different Loc Status Bits. instance, if the two ITRs of domain A send different Loc Status Bits.
In this case either the traffic is disrupted, if the xTR B trusts the In this case either the traffic is disrupted, if the ETR B trusts the
Locator Status Bits, or if xTR B does not trusts the Locator Status Locator Status Bits, or if ETR B does not trusts the Locator Status
Bits it will start sending Map-Requests to confirm the each change in Bits it will start sending Map-Requests to confirm the each change in
the reachability. the reachability.
So far, LISP does not provide any specific synchronization mechanism, So far, LISP does not provide any specific synchronization mechanism,
but assumes that synchronization is provided by configuring the but assumes that synchronization is provided by configuring the
different xTRs consistently. The same applies for Map-Versioning. different xTRs consistently. The same applies for Map-Versioning.
If in the future any synchronization mechanism is provided, Map- If in the future any synchronization mechanism is provided, Map-
Versioning will take advantage of it automatically since it is Versioning will take advantage of it automatically since it is
included in the Record format, as described in Section 7. included in the Record format, as described in Section 7.
skipping to change at page 13, line 7 skipping to change at page 13, line 44
destination version number in the LISP header since the Source Map- destination version number in the LISP header since the Source Map-
Version number is in ITR's database, while the Destination Map- Version number is in ITR's database, while the Destination Map-
Version number is in ITR's cache. Version number is in ITR's cache.
For what concerns the ETR, it simply checks only the Destination Map- For what concerns the ETR, it simply checks only the Destination Map-
Version number in the same way as described in Section 5, ignoring Version number in the same way as described in Section 5, ignoring
the Source Map-Version number. the Source Map-Version number.
8.3. Map-Versioning and interworking 8.3. Map-Versioning and interworking
Map-Versioning works in the context of interworking between LISP and Map-Versioning is compatible with the LISP interworking between LISP
IPv4 and IPv6 ([I-D.ietf-lisp-interworking]) in the following way. and non-LISP sites as defined in [I-D.ietf-lisp-interworking]. LISP
interworking defines three techniques to make LISP sites and non-LISP
sites, namely Proxy-ITR, LISP-NAT, and Proxy-ETR. Hereafter it is
described how Map-Versioning relates to these three mechanisms.
The case of proxy-ITR encapsulating packet for LISP sites is 8.3.1. Map-Versioning and Proxy-ITRs
basically the same as the unidirectional traffic case presented in
the previous section. The same rules can be applied. The only The purpose of the Proxy-ITR (PITR) is to encapsulate traffic
difference that arises is the fact that a proxy-ITR does not have any originating in a non-LISP site in order to deliver the packet to one
mapping, since it just encapsulate packets arriving from non-LISP of the ETRs of the LISP site (cf. Figure 3). This case is very
site, thus it has no Source Map-Version. In this case, the proxy-ITR similar to the unidirectional traffic case described in Section 8.2,
will just put the special value 0 (zero) as Source Map-Version hence similar rules apply.
+----------+ +-------------+
| LISP | | non-LISP |
| Domain A | | Domain B |
| +-------+ +-----------+ | |
| | ETR A |<-------| Proxy ITR |<-------| |
| +-------+ +-----------+ | |
| | | |
+----------+ +-------------+
Figure 3
The main difference is that a Proxy-ITR does not have any mapping,
since it just encapsulate packets arriving from non-LISP site, thus
cannot provide a Source Map-Version. In this case, the proxy-ITR
will just put the Null Map-Version value as Source Map-Version
number, while the receiving ETR will ignore the field. number, while the receiving ETR will ignore the field.
8.4. Graceful RLOC shutdown/withdraw With this setup the LISP Domain A is able to check whether or not the
PITR is using the latest mapping. If this is not the case the
mapping for LISP Domain A on the PITR can be updated using one of the
mechanisms defined in [I-D.ietf-lisp] and
[I-D.ietf-lisp-interworking].
8.3.2. Map-Versioning and LISP-NAT
The LISP-NAT mechanism is based on address translation from non-
routable EIDs to routable EIDs and does not involve any form of
encapsulation. As such Map-Versioning does not apply in this case.
8.3.3. 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 the non-
LISP site (cf. Figure 4). One of the main reasons of 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 ETR |------->| |
| +-------+ +-----------+ | |
| | | |
+----------+ +-------------+
Figure 4
A Proxy-ETR does not have any mapping, since it just decapsulate
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 receiving Proxy-ETR will ignore the field.
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
A on the PETR can be updated using one of the mechanisms defined in
[I-D.ietf-lisp] and [I-D.ietf-lisp-interworking].
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, because all sites have
updated the mapping, it can be shut down safely. updated the mapping, it can be shut down safely.
It should be pointed out that for frequent up/down changes such a
mechanism should not be used since this can generate excessive load
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.
In the current LISP specifications the set of RLOCs must always be In the current LISP specifications the set of RLOCs must always be
maintained ordered and consistent with the content of the Loc Status maintained ordered and consistent with the content of the Loc Status
Bits (see section 6.5 of [I-D.ietf-lisp]). With Map-Versioning such Bits (see section 6.5 of [I-D.ietf-lisp]). With Map-Versioning such
type of mechanisms can be avoided. When a new RLOC is added to a type of mechanisms can be avoided. When a new RLOC is added to a
skipping to change at page 15, line 8 skipping to change at page 17, line 20
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-
Request. The assumption is that the mapping distribution system is Request. The assumption is that the mapping distribution system is
sufficiently secure that Map-Request and Map-Reply messages and their sufficiently secure that Map-Request and Map-Reply messages and their
content can be trusted. Security issues concerning specific mapping content can be trusted. Security issues concerning specific mapping
distribution system are out of the scope of this document. Note also distribution system are out of the scope of this document. In the
that in the case of Map-Versioning the attacker should "guess" a case of Map-Versioning the attacker should "guess" a valid version
valid version number that triggers a Map-Request, as described in number that triggers a Map-Request, as described in Section 5,
Section 5, otherwise the packet is simply dropped. otherwise the packet is simply dropped. Nevertheless, guessing a
version number that generates a Map-Request is easy, hence it is
important to follow the rate limitations policies described in
[I-D.ietf-lisp] in order to avoid DoS attacks.
Note that a similar level of security can be obtained with Loc Status Note that a similar level of security can be obtained with Loc Status
Bits, by simply making mandatory to verify any change through a Map- Bits, by simply making mandatory to verify any change through a Map-
Request. However, in this case Locator Status Bits loose their Request. However, in this case Locator Status Bits loose their
meaning, because, it does not matter anymore which specific bits has meaning, because, it does not matter anymore which specific bits has
changed, the xTR will query the mapping system and trust the content changed, the xTR will query the mapping system and trust the content
of the received Map-Reply. Furthermore there is no way to perform of the received Map-Reply. Furthermore there is no way to perform
filtering as in the Map-Versioning in order to drop packets that do filtering as in the Map-Versioning in order to drop packets that do
not carry a valid Map-Version number. In the case of Locator Status not carry a valid Map-Version number. In the case of Locator Status
Bits, any random change can trigger a Map-Request (unless rate Bits, any random change can trigger a Map-Request (unless rate
skipping to change at page 16, line 16 skipping to change at page 18, line 29
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-08 (work in progress), August 2010. draft-ietf-lisp-10 (work in progress), March 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-04 Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-06
(work in progress), April 2010. (work in progress), March 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-01 (work in progress), draft-ietf-lisp-interworking-02 (work in progress),
August 2010. March 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-05 (work in progress), April 2010. draft-ietf-lisp-ms-07 (work in progress), March 2011.
[I-D.saucez-lisp-security] [I-D.saucez-lisp-security]
Saucez, D., Iannone, L., and O. Bonaventure, "LISP Saucez, D., Iannone, L., and O. Bonaventure, "LISP
Security Threats", draft-saucez-lisp-security-01 (work in Security Threats", draft-saucez-lisp-security-03 (work in
progress), July 2010. progress), March 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
granularity of seconds and assuming as worst-case that a new version granularity of seconds and assuming as worst-case that a new version
is issued each second, it takes slightly more than 1 hour before the is issued each second, it takes slightly more than 1 hour before the
version wraps around. Note that the granularity of seconds is in version wraps around. Note that the granularity of seconds is in
line with the rate limitation policy for Map-Request messages, as line with the rate limitation policy for Map-Request messages, as
proposed in the LISP main specifications ([I-D.ietf-lisp]). proposed in the LISP main specifications ([I-D.ietf-lisp]).
skipping to change at page 17, line 42 skipping to change at page 20, line 22
| 32 | 8171 Years | 136 Years | | 32 | 8171 Years | 136 Years |
| 30 | 2042 Years | 34 Years | | 30 | 2042 Years | 34 Years |
| 24 | 31 Years | 194 Days | | 24 | 31 Years | 194 Days |
| 16 | 45 Days | 18 Hours | | 16 | 45 Days | 18 Hours |
| 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 3: 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 Posted September 2010. o Version 01 Posted March 2011.
o Added Section "Definitions of Terms". * Changed the wording from "Map-Version number 0" to "Null Map-
Version.
o Editorial polishing of all sections. * Clarification of the use of the Null Map-Version value as
Source Map-Version Number and Destination Map-Version Number.
o Added clarifications in section "Dealing with Map-Version numbers" * Extended the section describing Map-Versioning and LISP
for the case of the special Map-Version number 0. Interworking co-existence.
o Rename of draft-iannone-mapping-versioning-02.txt. * 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.
Authors' Addresses Authors' Addresses
Luigi Iannone Luigi Iannone
TU Berlin - Deutsche Telekom Laboratories AG TU Berlin - Deutsche Telekom Laboratories AG
Ernst-Reuter Platz 7 Ernst-Reuter Platz 7
Berlin Berlin
Germany Germany
Email: luigi@net.t-labs.tu-berlin.de Email: luigi@net.t-labs.tu-berlin.de
 End of changes. 62 change blocks. 
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