draft-ietf-lisp-map-versioning-09.txt   rfc6834.txt 
Network Working Group L. Iannone Internet Engineering Task Force (IETF) L. Iannone
Internet-Draft Telekom Innovation Laboratories Request for Comments: 6834 Telecom ParisTech
Intended status: Experimental D. Saucez Category: Experimental D. Saucez
Expires: September 2, 2012 INRIA Sophia Antipolis ISSN: 2070-1721 INRIA Sophia Antipolis
O. Bonaventure O. Bonaventure
Universite catholique de Louvain Universite catholique de Louvain
March 1, 2012 January 2013
LISP Map-Versioning Locator/ID Separation Protocol (LISP) Map-Versioning
draft-ietf-lisp-map-versioning-09.txt
Abstract Abstract
This document describes the LISP (Locator/ID Separation Protocol) This document describes the LISP (Locator/ID Separation Protocol)
Map-Versioning mechanism, which provides in-packet information about Map-Versioning mechanism, which provides in-packet information about
Endpoint-ID to Routing Locator (EID-to-RLOC) mappings used to Endpoint ID to Routing Locator (EID-to-RLOC) mappings used to
encapsulate LISP data packets. The proposed approach is based on encapsulate LISP data packets. The proposed approach is based on
associating a version number to EID-to-RLOC mappings and transport associating a version number to EID-to-RLOC mappings and the
such a version number in the LISP specific header of LISP- transport of such a version number in the LISP-specific header of
encapsulated packets. LISP Map-Versioning is particularly useful to LISP-encapsulated packets. LISP Map-Versioning is particularly
inform communicating Ingress Tunnel Routers (ITRs) and Egress Tunnel useful to inform communicating Ingress Tunnel Routers (ITRs) and
Routers (ETRs) about modifications of the mappings used to Egress Tunnel Routers (ETRs) about modifications of the mappings used
encapsulate packets. The mechanism is transparent to implementations to encapsulate packets. The mechanism is transparent to
not supporting this feature, since in the LISP-specific header and in implementations not supporting this feature, since in the LISP-
the Map Records, bits used for Map-Versioning can be safely ignored specific header and in the Map Records, bits used for Map-Versioning
by ITRs and ETRs that do not support the mechanism. can be safely ignored by ITRs and ETRs that do not support the
mechanism.
Status of this Memo
This Internet-Draft is submitted in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is not an Internet Standards Track specification; it is
Task Force (IETF). Note that other groups may also distribute published for examination, experimental implementation, and
working documents as Internet-Drafts. The list of current Internet- evaluation.
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document defines an Experimental Protocol for the Internet
and may be updated, replaced, or obsoleted by other documents at any community. This document is a product of the Internet Engineering
time. It is inappropriate to use Internet-Drafts as reference Task Force (IETF). It represents the consensus of the IETF
material or to cite them other than as "work in progress." 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 a candidate for any level of
Internet Standard; see Section 2 of RFC 5741.
This Internet-Draft will expire on September 2, 2012. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6834.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Notation ...........................................4
3. Definitions of Terms . . . . . . . . . . . . . . . . . . . . . 4 3. Definitions of Terms ............................................4
4. EID-to-RLOC Map-Version number . . . . . . . . . . . . . . . . 4 4. EID-to-RLOC Map-Version Number ..................................4
4.1. The Null Map-Version . . . . . . . . . . . . . . . . . . . 5 4.1. The Null Map-Version .......................................5
5. Dealing with Map-Version numbers . . . . . . . . . . . . . . . 6 5. Dealing with Map-Version Numbers ................................6
5.1. Handling Destination Map-Version number . . . . . . . . . 7 5.1. Handling Destination Map-Version Number ....................7
5.2. Handling Source Map-Version number . . . . . . . . . . . . 9 5.2. Handling Source Map-Version Number .........................9
6. LISP header and Map-Version numbers . . . . . . . . . . . . . 10 6. LISP Header and Map-Version Numbers ............................10
7. Map Record and Map-Version . . . . . . . . . . . . . . . . . . 11 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. Map-Versioning and unidirectional traffic . . . . . . . . 12 8.1. Map-Versioning and Unidirectional Traffic .................12
8.2. Map-Versioning and interworking . . . . . . . . . . . . . 12 8.2. Map-Versioning and Interworking ...........................12
8.2.1. Map-Versioning and Proxy-ITRs . . . . . . . . . . . . 12 8.2.1. Map-Versioning and Proxy-ITRs ......................13
8.2.2. Map-Versioning and LISP-NAT . . . . . . . . . . . . . 13 8.2.2. Map-Versioning and LISP-NAT ........................13
8.2.3. Map-Versioning and Proxy-ETRs . . . . . . . . . . . . 13 8.2.3. Map-Versioning and Proxy-ETRs ......................14
8.3. RLOC shutdown/withdraw . . . . . . . . . . . . . . . . . . 14 8.3. RLOC Shutdown/Withdraw ....................................14
8.4. Map-Version for lightweight LISP implementation . . . . . 14 8.4. Map-Version for Lightweight LISP Implementation ...........15
9. Incremental deployment and implementation status . . . . . . . 15 9. Incremental Deployment and Implementation Status ...............15
10. Security Considerations . . . . . . . . . . . . . . . . . . . 15 10. Security Considerations .......................................16
10.1. Map-Versioning against traffic disruption . . . . . . . . 15 10.1. Map-Versioning against Traffic Disruption ................16
10.2. Map-Versioning against reachability information DoS . . . 16 10.2. Map-Versioning against Reachability Information DoS ......17
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 11. Open Issues and Considerations ................................17
12. Open Issues and Considerations . . . . . . . . . . . . . . . . 17 11.1. Lack of Synchronization among ETRs .......................17
12.1. Lack of Synchronization among ETRs . . . . . . . . . . . . 17 12. Acknowledgments ...............................................19
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 13. References ....................................................19
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 13.1. Normative References .....................................19
14.1. Normative References . . . . . . . . . . . . . . . . . . . 19 13.2. Informative References ...................................19
14.2. Informative References . . . . . . . . . . . . . . . . . . 19 Appendix A. Estimation of Time before Map-Version Wrap-Around .....21
Appendix A. Estimation of time before Map-Version wrap-around . . 19
Appendix B. Document Change Log . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
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 (Endsystem ID to Routing information on changes in the EID-to-RLOC (Endpoint ID to Routing
LOCator) mappings used in the LISP (Locator/Id Separation Protocol Locator) mappings used in the LISP (Locator/ID Separation Protocol
[I-D.ietf-lisp]) context to perform packet encapsulation. The [RFC6830]) context to perform packet encapsulation. The mechanism is
mechanism is totally transparent to xTRs (Ingress and Egress Tunnel totally transparent to xTRs (Ingress and Egress Tunnel Routers) not
Routers) not supporting such functionality. It is not meant to supporting such functionality. It is not meant to replace any
replace any existing LISP mechanism, but rather to extend them existing LISP mechanisms but rather to extend them by providing new
providing new functionalities. If for any unforseen reason a functionalities. If for any unforeseen reason a normative conflict
normative conflict between the present document and the LISP main between this document and the LISP main specifications is found, the
specifications is found, the latter ([I-D.ietf-lisp]) has precedence latter ([RFC6830]) has precedence over this document.
on the present document.
The basic mechanism is to associate a Map-Version number to each LISP The basic mechanism is to associate a Map-Version number to each LISP
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
skipping to change at page 3, line 39 skipping to change at page 3, line 38
the outer header (i.e., both source and destination). These version 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 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 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 high-order bits of the first longword of the LISP header). Note that
not all packets need to carry version numbers. not all packets need to carry version numbers.
When an ITR (Ingress Tunnel Router) encapsulates a data packet, with When an ITR (Ingress Tunnel Router) encapsulates a data packet, with
a LISP header containing the Map-Version numbers, it puts in the a LISP header containing the Map-Version numbers, it puts in the
LISP-specific header two version numbers: LISP-specific header two 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
to-RLOC Database) used to select the source RLOC. EID-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
to-RLOC Cache) used to select the destination RLOC. EID-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
(Egress Tunnel Router) receiving the packet to know if the ITR has (Egress Tunnel Router) receiving the packet to know if the ITR has
the latest version number that any ETR at the destination EID site the latest version number that any ETR at the destination EID site
has provided to the ITR in a Map-Reply. If it is not the case the has provided to the ITR in a Map-Reply. If this is not the case, the
ETR can send to the ITR a Map-Request containing the updated mapping ETR can send to the ITR a Map-Request containing the updated mapping
or soliciting a Map-Request from the ITR (both cases are already or solicit a Map-Request from the ITR (both cases are already defined
defined in [I-D.ietf-lisp]). In this way the ITR can update its EID- in [RFC6830]). In this way, the ITR can update its EID-to-RLOC
to-RLOC Cache. On the other hand, it enables an ETR receiving such a Cache. On the other hand, it enables an ETR receiving such a packet
packet to know if it has in its EID-to-RLOC Cache the latest mapping to know if it has in its EID-to-RLOC Cache the latest mapping for the
for the source EID (in case of bidirectional traffic). If it is not source EID (in the case of bidirectional traffic). If this is not
the case a Map-Request can be sent. the case, a Map-Request can be sent.
Issues and concerns about the deployment of LISP for Internet traffic Issues and concerns about the deployment of LISP for Internet traffic
are discussed in [I-D.ietf-lisp]. Section 12 provides additional are discussed in [RFC6830]. Section 11 provides additional issues
issues and concerns raised by this document. In particular, and concerns raised by this document. In particular, Section 11.1
Section 12.1 provides details about the ETRs' synchronization issue provides details about the ETRs' synchronization issue in the context
in the context of Map-Versioning. of Map-Versioning.
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 This document uses terms already defined in the main LISP
specification [I-D.ietf-lisp]. Hereafter are defined only the terms specification [RFC6830]. Here, we define the terms that are specific
that are specific to the Map-Versioning mechanism. Throughout the to the Map-Versioning mechanism. Throughout the whole document, Big
whole document Big Endian bit ordering is used. Endian bit ordering is used.
Map-Version number: An unsigned 12-bits assigned to an EID-to-RLOC Map-Version number: An unsigned 12-bit integer is assigned to an
mapping, not including the value 0 (0x000). EID-to-RLOC mapping, not including the value 0 (0x000).
Null Map-Version: The 12-bits null value of 0 (0x000) is not used as Null Map-Version: The 12-bit null value of 0 (0x000) is not used as
Map-Version number. It is used to signal that no Map-Version a Map-Version number. It is used to signal that no Map-Version
number 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: This Map-Version number of the
mapping used to select the source address (RLOC) of the outer IP EID-to-RLOC mapping is used to select the source address (RLOC)
header of LISP-encapsulated packets. of the outer IP header of LISP-encapsulated packets.
Destination Map-Version number: Map-Version number of the EID-to- Destination Map-Version number: This Map-Version number of the
RLOC mapping used to select the destination address (RLOC) of the EID-to-RLOC mapping is used to select the destination address
outer IP header of LISP-encapsulated packets. (RLOC) of the 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 of an unsigned 12-bit
integer. The version number is assigned on a per-mapping basis, integer. The version number is assigned on a per-mapping basis,
meaning that different mappings have a different version number, meaning that different mappings have a different version number,
which is also updated independently. An update in the version number which is also updated independently. An update in the version number
(i.e., a newer version) consists in incrementing by one the older (i.e., a newer version) consists of incrementing by one the older
version number. Appendix A contains a rough estimation of the wrap- version number. Appendix A contains a rough estimation of the
around time for the Map-Version number. wrap-around time for the Map-Version number.
The space of version numbers has a circular order where half of the The space of version numbers has a circular order where half of the
version numbers is greater(i.e., newer) than the current Map-Version version numbers are greater (i.e., newer) than the current
number and the other half is smaller (i.e., older) than current Map- Map-Version number and the other half of the version numbers are
Version number. In a more formal way, assuming we have two version smaller (i.e., older) than the current Map-Version number. In a more
numbers V1 and V2 and that the numbers are expressed on N bits, the formal way, assuming that we have two version numbers V1 and V2 and
following steps MUST be performed (in the same order as hereafter) to that the numbers are expressed in N bits, the following steps MUST be
strictly define their order: performed (in the same order as shown below) to strictly define their
order:
1. V1 = V2 : The map-version number are the same. 1. V1 = V2 : The Map-Version numbers are the same.
2. V2 > V1 : if and only if 2. V2 > V1 : if and only if
V2 > V1 AND (V2 - V1) <= 2**(N-1) V2 > V1 AND (V2 - V1) <= 2**(N-1)
OR OR
V1 > V2 AND (V1 - V2) > 2**(N-1) V1 > V2 AND (V1 - V2) > 2**(N-1)
3. V1 > V2 : otherwise. 3. V1 > V2 : otherwise.
Using 12 bits, as defined in this document, and assuming a Map- Using 12 bits, as defined in this document, and assuming a
Version value of 69, Map-Version numbers in the range [70; 69 + 2048] Map-Version value of 69, Map-Version numbers in the range
are greater than 69, while Map-Version numbers in the range [69 + [70; 69 + 2048] are greater than 69, while Map-Version numbers in the
2049; (69 + 4096) mod 4096] are smaller than 69. range [69 + 2049; (69 + 4096) mod 4096] are smaller than 69.
Map-version number are assigned to mappings by configuration. The Map-Version numbers are assigned to mappings by configuration. The
initial Map-Version number of a new EID-to-RLOC mapping SHOULD be 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 assigned randomly, but it MUST NOT be set to the Null Map-Version
value (0x000), because it has a special meaning (see Section 4.1). value (0x000), because the 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 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 Database. If those mappings have a Map-Version number, it will be
used according to the mechnisms described in this document. ETRs used according to the mechanisms described in this document. ETRs
MUST NOT automatically generate and assign Map-Version numbers to MUST NOT automatically generate and assign Map-Version numbers to
mappings in the EID-to-RLOC Database. mappings in the EID-to-RLOC Database.
4.1. The Null Map-Version 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. Such a value is used for the version of the EID-to-RLOC mapping. Such a value is used for
special purposes and is named the Null Map-Version number. special purposes and is named the Null Map-Version number.
The Null Map-Version MAY appear in the LISP specific header as either The Null Map-Version MAY appear in the LISP-specific header as either
Source Map-Version number (cf. Section 5.2) or Destination Map- a Source Map-Version number (cf. Section 5.2) or a Destination
Version number (cf. Section 5.1). When the Source Map-Version number Map-Version number (cf. Section 5.1). When the Source Map-Version
is set to the Null Map-version value it means that no map version number is set to the Null Map-Version value, it means that no map
information is conveyed for the source site. This means that if a version information is conveyed for the source site. This means that
mapping exists for the source EID in the EID-to-RLOC Cache, then the if a mapping exists for the source EID in the EID-to-RLOC Cache, then
ETR MUST NOT compare the received Null Map-Version with the content the ETR MUST NOT compare the received Null Map-Version with the
of the EID-to-RLOC Cache. When the Destination Map-version number is content of the EID-to-RLOC Cache. When the Destination Map-Version
set to the Null Map-version value it means that no map version number is set to the Null Map-Version value, it means that no map
information is conveyed for the destination site. This means that version information is conveyed for the destination site. This means
the ETR MUST NOT compare the value with the Map-Version number of the that the ETR MUST NOT compare the value with the Map-Version number
mapping for the destination EID present in the EID-to-RLOC Database. 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, 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 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 messages (defined in [RFC6830]). Map Records that have a Null
Map-Version number indicate that there is no Map-Version number Map-Version number indicate that there is no Map-Version number
associated with the mapping. This means that LISP encapsulated associated with the mapping. This means that LISP-encapsulated
packets, destined to the EID-Prefix the Map Record refers to, MUST packets destined to the EID-Prefix referred to by the Map Record MUST
either not contain any Map-Version numbers (V bit set to 0), or if it either not contain any Map-Version numbers (V-bit set to 0) or, if
contains Map-Version numbers (V bit set to 1) then the destination they contain Map-Version numbers (V-bit set to 1), then the
Map-Version number MUST be set to the Null Map-Version number. Any destination Map-Version number MUST be set to the Null Map-Version
value different from zero means that Map-Versioning is supported and number. Any value different from zero means that Map-Versioning is
MAY be used. 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 the Map-Version
MUST be incremented by 2 (i.e., set to 1, which is the next valid number MUST be incremented by 2 (i.e., set to 1, which is the next
value). valid 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
a change in the mapping (e.g., adding/removing RLOCs, a change in the a change in the mapping (e.g., adding/removing RLOCs, a change in the
weights due to TE policies, or a change in the priorities) or a LISP weights due to Traffic Engineering policies, or a change in the
site realizes that one or more of its own RLOCs are not reachable priorities) or a LISP site realizes that one or more of its own RLOCs
anymore from a local perspective (e.g., through IGP, or policy are not reachable anymore from a local perspective (e.g., through
changes) the LISP site updates the mapping also assigning a new Map- IGP, or policy changes) the LISP site updates the mapping, also
Version number. assigning a new Map-Version number.
To each mapping, a version number is associated and changes each time To each mapping, a version number is associated and changes each time
the mapping is changed. Note that map-versioning does not introduce the mapping is changed. Note that Map-Versioning does not introduce
new problems concerning the coordination of different ETRs of a new problems concerning the coordination of different ETRs of a
domain. Indeed, ETRs belonging to the same LISP site must return for domain. Indeed, ETRs belonging to the same LISP site must return for
a specific EID-prefix the same mapping, including the same Map- a specific EID-Prefix the same mapping, including the same
Version number. In principle this is orthogonal to whether or not Map-Version number. In principle, this is orthogonal to whether or
map-versioning is used. The synchronization problem and its not Map-Versioning is used. The synchronization problem and its
implication on the traffic is out of the scope of this document (see implication on the traffic are out of the scope of this document (see
Section 12). Section 11).
In order to announce in a data-driven fashion that the mapping has In order to announce in a data-driven fashion that the mapping has
been updated, Map-Version numbers used to create the outer IP header been updated, Map-Version numbers used to create the outer IP header
of the LISP-encapsulated packet are embedded in the LISP-specific of the LISP-encapsulated packet are embedded in the LISP-specific
header. This means that the header needs to contain two Map-Version header. This means that the header needs to contain two Map-Version
numbers: numbers:
o The Source Map-Version number of the EID-to-RLOC mapping in the o The Source Map-Version number of the EID-to-RLOC mapping in the
EID-to-RLOC Database used to select the source RLOC. EID-to-RLOC Database used to select the source RLOC.
o The Destination Map-Version number of the EID-to-RLOC mapping in o The Destination Map-Version number of the EID-to-RLOC mapping in
the EID-to-RLOC Cache used to select the destination RLOC. the EID-to-RLOC Cache used to select the destination RLOC.
By embedding both Source Map-Version number and Destination Map- By embedding both the Source Map-Version number and the Destination
Version number an ETR receiving a LISP packet with Map-Version Map-Version number, an ETR receiving a LISP packet with Map-Version
numbers, 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
EID-to-RLOC Cache for the destination EID and is performing EID-to-RLOC Cache for the destination EID and is performing
encapsulation correctly. encapsulation correctly.
2. In case of bidirectional traffic, the mapping in the local ETR 2. In the case of bidirectional traffic, the mapping in the local
EID-to-RLOC Cache for the source EID is up-to-date. ETR EID-to-RLOC Cache for the source EID is up to date.
If one or both of the above conditions do not hold, the ETR 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
EID-to-RLOC Cache (see Section 5.2). EID-to-RLOC 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
RLOC. This mapping is part of the ETR EID-to-RLOC Database. Since an RLOC. This mapping is part of the ETR EID-to-RLOC Database.
the ETR is authoritative for the mapping, it has the correct and up- Since the ETR is authoritative for the mapping, it has the correct
to-date Destination Map-Version number. A check on this version and up-to-date Destination Map-Version number. A check on this
number can be done, where the following cases can arise: version number can be done, where the following cases can arise:
1. The packets arrive with the same Destination Map-Version number 1. The packet arrives 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
date mapping. No further actions are needed. up-to-date mapping. No further actions are needed.
2. The packet arrives with a Destination Map-Version number greater 2. The packet arrives with a Destination Map-Version number greater
(i.e., newer) than the one stored in the EID-to-RLOC Database. (i.e., newer) than the one stored in the EID-to-RLOC Database.
Since the ETR is authoritative on the mapping, meaning that the Since the ETR is authoritative on the mapping, meaning that the
Map-Version number of its mapping is the correct one, this Map-Version number of its mapping is the correct one, this
implies that someone is not behaving correctly with respect to implies that someone is not behaving correctly with respect to
the specifications. In this case the packet carries a version the specifications. In this case, the packet carries a version
number that is not valid, otherwise the ETR would have the same, number that is not valid; otherwise, the ETR would have the same
and SHOULD be silently dropped. number, and the packet SHOULD be silently dropped.
3. The packets arrive with a Destination Map-Version number smaller 3. The packets arrive with a Destination Map-Version number smaller
(i.e., older) than the one stored in the EID-to-RLOC Database. (i.e., older) than the one stored in the EID-to-RLOC Database.
This means that the ITR sending the packet has an old mapping in This means that the ITR sending the packet has an old mapping in
its EID-to-RLOC Cache containing stale information. The ETR MAY its EID-to-RLOC Cache containing stale information. The ETR MAY
choose to normally process the encapsulated datagram according to choose to normally process the encapsulated datagram according to
[I-D.ietf-lisp], however, the ITR sending the packet has to be [RFC6830]; however, the ITR sending the packet has to be informed
informed that a newer mapping is available. This is done with a that a newer mapping is available. This is done with a
Map-Request message sent back to the ITR. The Map-Request will Map-Request message sent back to the ITR. The Map-Request will
either trigger a Map-Request back using the Solicit-Map-Request either trigger a Map-Request back using the Solicit-Map-Request
(SMR) bit or it will piggyback the newer mapping. These are not (SMR) bit or it will piggyback the newer mapping. These are not
new mechanisms; how to SMR or piggyback mappings in Map-Request new mechanisms; how to use the SMR bit or how to piggyback
messages is already described in [I-D.ietf-lisp], while their mappings in Map-Request messages is already described in
security is discussed in [I-D.ietf-lisp-threats]. These Map- [RFC6830], while their security is discussed in [LISP-THREATS].
Request messages should be rate limited (rate limitation policies These Map-Request messages should be rate-limited
are also described in [I-D.ietf-lisp]). The feature introduced (rate-limitation policies are also described in [RFC6830]). The
by Map-Version numbers is the possibility of blocking traffic not feature introduced by Map-Version numbers is the possibility of
using the latest mapping. Indeed, after a certain number of blocking traffic not using the latest mapping. Indeed, after a
retries, if the Destination Map-Version number in the packets is certain number of retries, if the Destination Map-Version number
not updated, the ETR MAY drop packets with a stale Map-Version in the packets is not updated, the ETR MAY drop packets with a
number while strongly reducing the rate of Map-Request messages. stale Map-Version number while strongly reducing the rate of
This because either the ITR is refusing to use the mapping for Map-Request messages. This is because either the ITR is refusing
which the ETR is authoritative or (worse) it might be some form to use the mapping for which the ETR is authoritative, or (worse)
of attack. Another case might be that the control-plane is it might be some form of attack. Another case might be that the
experiencing transient failures so the Map-Requests cannot reach control plane is experiencing transient failures, so the
that ITR. By keeping sending Map-Requests at very low rate it is Map-Requests cannot reach that ITR. By continually sending
possible to recover from this situation. Map-Requests at a very low rate, it is possible to recover from
this situation.
The rule in the third case MAY be more restrictive. If the mapping The rule in the third case MAY be more restrictive. If the mapping
has been the same for a period of time as long as the TTL (defined in has been the same for a period of time as long as the Time to Live
[I-D.ietf-lisp]) of the previous version of the mapping, all packets (TTL) (defined in [RFC6830]) of the previous version of the mapping,
arriving with an old Map-Version SHOULD be silently dropped right all packets arriving with an old Map-Version SHOULD be silently
away without issuing any Map-Request. The reason that allows such dropped right away without issuing any Map-Request. Such action is
action is the fact that if the new mapping with the updated version permitted because if the new mapping with the updated version number
number has been unchanged for at least the same time as the TTL of has been unchanged for at least the same time as the TTL of the older
the older mapping, all the entries in the EID-to-RLOC Caches of ITRs mapping, all the entries in the EID-to-RLOC Caches of ITRs must have
must have expired. Hence, all ITRs sending traffic should have expired. Hence, all ITRs sending traffic should have refreshed the
refreshed the mapping according to [I-D.ietf-lisp]. If packets with mapping according to [RFC6830]. If packets with old Map-Version
old Map-Version number are still received, then either someone has numbers are still received, then either someone has not respected the
not respected the TTL, or it is a form of spoof/attack. In both TTL or it is a form of spoof/attack. In both cases, this is not
cases this is not valid behavior with respect to the specifications valid behavior with respect to the specifications and the packet
and the packet SHOULD be silently dropped. SHOULD be silently dropped.
LISP-encapsulated packets with the V-bit set, when the original LISP-encapsulated packets with the V-bit set, when the original
mapping in the EID-to-RLOC Database has version number set to the mapping in the EID-to-RLOC Database has the version number set to the
Null Map-Version value, MAY be silently dropped. As explained in Null Map-Version value, MAY be silently dropped. As explained in
Section 4.1, if an EID-to-RLOC mapping has a Null Map-Version, it Section 4.1, if an EID-to-RLOC mapping has a Null Map-Version, it
means that ITRs, using the mapping for encapsulation, MUST NOT use means that ITRs, using the mapping for encapsulation, MUST NOT use a
Map-Version number in the LISP-specific header. Map-Version number in the LISP-specific header.
For LISP-encapsulated packets with the V-bit set, when the original For LISP-encapsulated packets with the V-bit set, when the original
mapping in the EID-to-RLOC Database has version number set to a value mapping in the EID-to-RLOC Database has the version number set to a
different from the Null Map-Version value, a Destination Map-Version value different from the Null Map-Version value, a Destination
number equal to the Null Map-Version value means that the Destination Map-Version number equal to the Null Map-Version value means that the
Map-Version number MUST be ignored. Destination Map-Version number MUST be ignored.
5.2. Handling Source Map-Version number 5.2. Handling Source Map-Version Number
When an ETR 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 ETR has an entry in its EID-to-RLOC 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 Cache for the source EID, then a check can be performed and the
following cases can arise: 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 as
in the EID-to-RLOC Cache. This is the correct regular case. The that stored in the EID-to-RLOC Cache. This is the correct
ITR has in its EID-to-RLOC Cache an up-to-date copy of the regular case. The ITR has in its EID-to-RLOC Cache an up-to-date
mapping. No further actions are needed. copy of the mapping. No 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 EID-to-RLOC Cache. (i.e., newer) than the one stored in the local EID-to-RLOC Cache.
This means that ETR has in its EID-to-RLOC Cache a mapping that This means that the ETR has in its EID-to-RLOC Cache a mapping
is stale and needs to be updated. A Map-Request SHOULD be sent that is stale and needs to be updated. A Map-Request SHOULD be
to get the new mapping for the source EID. This is a normal Map- sent to get the new mapping for the source EID. This is a normal
Request message sent through the mapping system and MUST respect Map-Request message sent through the mapping system and MUST
the specifications in [I-D.ietf-lisp], including rate limitation respect the specifications in [RFC6830], including rate-
policies. limitation policies.
3. The packet arrives with a Source Map-Version number smaller 3. The packet arrives with a Source Map-Version number smaller
(i.e., older) than the one stored in the local EID-to-RLOC Cache. (i.e., older) than the one stored in the local EID-to-RLOC Cache.
Such a case is not valid with respect to the specifications. Such a case is not valid with respect to the specifications.
Indeed, if the mapping is already present in the EID-to-RLOC Indeed, if the mapping is already present in the EID-to-RLOC
Cache, this means that an explicit Map-Request has been sent and Cache, this means that an explicit Map-Request has been sent and
a Map-Reply has been received from an authoritative source. a Map-Reply has been received from an authoritative source.
Assuming that the mapping system is not corrupted anyhow, the Assuming that the mapping system is not corrupted, the
Map-Version in the EID-to-RLOC Cache is the correct one, while Map-Version in the EID-to-RLOC Cache is the correct one, while
the one carried by the packet is stale. In this situation the the one carried by the packet is stale. In this situation, the
packet MAY be silently dropped. packet MAY be silently dropped.
If the ETR does not have an entry in the EID-to-RLOC Cache for the If the ETR does not have an entry in the EID-to-RLOC Cache for the
source EID (e.g., in case of unidirectional traffic) then the Source source EID (e.g., in the case of unidirectional traffic), then the
Map-Version number can be safely ignored. 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
Version number is the Null Map-Version value, it means that the Map-Version number is the Null Map-Version value, it means that the
Source Map-Version number MUST be ignored. Source Map-Version number MUST be ignored.
6. LISP header and Map-Version numbers 6. LISP Header and Map-Version Numbers
In order for the versioning approach to work, the LISP specific In order for the versioning approach to work, the LISP-specific
header has to carry both Source Map-Version number and Destination header has to carry both the Source Map-Version number and
Map-Version number. This is done by setting the V-bit in the LISP Destination Map-Version number. This is done by setting the V-bit in
specific header as defined in [I-D.ietf-lisp] Section 5.3. When the the LISP-specific header as defined in [RFC6830] Section 5.3. When
V-bit is set the low-order 24-bits of the first longword are used to the V-bit is set, the low-order 24 bits of the first longword are
transport both source and destination Map-Version numbers. In used to transport both the source and destination Map-Version
particular the first 12 bits are used for Source Map-Version number numbers. In particular, the first 12 bits are used for the Source
and the second 12 bits for the Destination Map-Version number. 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 Below is an example of a LISP header carrying version numbers in the
the case of IPv4-in-IPv4 encapsulation. The same setting can be used case of IPv4-in-IPv4 encapsulation. The same setting can be used for
for any other case (IPv4-in-IPv6, IPv6-in-IPv4, and IPv6-in-IPv6). any other case (IPv4-in-IPv6, IPv6-in-IPv4, and IPv6-in-IPv6).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ |N|L|E|V|I|flags| Source Map-Version |Destination Map-Version| / |N|L|E|V|I|flags| Source Map-Version |Destination Map-Version|
LISP+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ LISP+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | Instance ID/Locator Status Bits | \ | Instance ID/Locator-Status-Bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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. How to set on transmission and handle on Locator' field. Section 5.2 describes how to set this value on
reception this value is described in Section 5.2. transmission and handle it on reception.
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. How to set on transmission and handle on Routing Locator' field. Section 5.1 describes how to set this
reception this value is described in Section 5.1. value on transmission and handle it on reception.
The present document just specifies how to use the low-order 24-bits This document only specifies how to use the low-order 24 bits of the
of the first longword of the LISP-specific header when the V-bit is first longword of the LISP-specific header when the V-bit is set to
set to 1. All other cases, including the bit fields of the rest of 1. All other cases, including the bit fields of the rest of the
the LISP-specific header and the whole LISP packet format are LISP-specific header and the whole LISP packet format, are specified
specified in [I-D.ietf-lisp]. Not all of the LISP encapsulated in [RFC6830]. Not all of the LISP-encapsulated packets need to carry
packets need to carry version numbers. When Map-Version numbers are version numbers. When Map-Version numbers are carried in these
carried the V-bit MUST be set to 1. All legal combinations of the packets, the V-bit MUST be set to 1. All permissible combinations of
flags, when the V-bit is set to 1, are described in [I-D.ietf-lisp]. the flags when the V-bit is set to 1 are described in [RFC6830].
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/Map-Register messages need to transported in Map-Request/Map-Reply/Map-Register messages need to
carry the Map-Version number as well. For this purpose the 12-bits carry the Map-Version number as well. For this purpose, the 12 bits
before the EID-AFI field in the Record that describe a mapping is before the 'EID-Prefix-AFI' field in the Record that describes a
used. This is defined in Section 6.1.4 of [I-D.ietf-lisp] and mapping are used. This is defined in Section 6.1.4 of [RFC6830] and
reported here as example. reported here as an 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-prefix-AFI | c | Rsvd | Map-Version Number | EID-Prefix-AFI |
o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
r | EID-prefix | r | EID-Prefix |
d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| /| Priority | Weight | M Priority | M Weight | | /| Priority | Weight | M Priority | M Weight |
| L +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | L +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| o | Unused Flags |L|p|R| Loc-AFI | | o | Unused Flags |L|p|R| Loc-AFI |
| c +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | c +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| \| Locator | | \| Locator |
+-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Map-Version Number: Map-Version of the mapping contained in the Map-Version Number: Map-Version of the mapping contained in the
Record. As explained in Section 4.1 this field can be zero (0), Record. As explained in Section 4.1, this field can be zero (0),
meaning that no Map-Version is associated to the mapping, hence meaning that no Map-Version is associated to the mapping; hence,
packets that are LISP-encapsulated using this mapping MUST NOT packets that are LISP encapsulated using this mapping MUST NOT
contain Map-Version numbers in the LISP specific header and the contain Map-Version numbers in the LISP-specific header, and the
V-bit MUST be set to 0. V-bit MUST be set to 0.
This packet format works perfectly with xTRs that do not support Map- This packet format works perfectly with xTRs that do not support
Versioning, since they can simply ignore those bits. Map-Versioning, since they can simply ignore those bits.
8. Benefits and case studies for Map-Versioning 8. Benefits and Case Studies for Map-Versioning
In the following sections we provide more discussion on various In the following sections, we provide more discussion on various
aspects and use of the Map-Versioning. Security observations are aspects and uses of Map-Versioning. Security observations are
instead grouped in Section 10. grouped in Section 10.
8.1. Map-Versioning and unidirectional traffic 8.1. Map-Versioning and Unidirectional Traffic
When using Map-Versioning the LISP specific header carries two Map- When using Map-Versioning, the LISP-specific header carries two
Version numbers, for both source and destination mappings. This can Map-Version numbers, for both source and destination mappings. This
raise the question on what will happen in the case of unidirectional can raise the question on what will happen in the case of
flows, like for instance in the case presented in Figure 1, since unidirectional flows, for instance, in the case presented in
LISP specification do not mandate for ETR to have a mapping for the Figure 1, since the LISP specification does not mandate that the ETR
source EID. have a mapping for the source EID.
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| Domain A | | Domain B | | Domain A | | Domain B |
| +---------+ +---------+ | | +---------+ +---------+ |
| | ITR A |----------->| ETR B | | | | ITR A |----------->| ETR B | |
| +---------+ +---------+ | | +---------+ +---------+ |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 1 Figure 1: Unidirectional Traffic between LISP Domains
For what concerns the ITR, it is able to put both source and In the case of the ITR, the ITR is able to put both the source and
destination version number in the LISP header since the Source Map- destination version number in the LISP header, since the Source
Version number is in ITR's database, while the Destination Map- Map-Version number is in the ITR's database, while the Destination
Version number is in ITR's cache. Map-Version number is in the ITR's cache.
For what concerns the ETR, it simply checks only the Destination Map- In the case of the ETR, the ETR simply checks only the Destination
Version number in the same way as described in Section 5, ignoring Map-Version number in the same way as that described in Section 5,
the Source Map-Version number. ignoring the Source Map-Version number.
8.2. Map-Versioning and interworking 8.2. Map-Versioning and Interworking
Map-Versioning is compatible with the LISP interworking between LISP Map-Versioning is compatible with the LISP interworking between LISP
and non-LISP sites as defined in [I-D.ietf-lisp-interworking]. LISP and non-LISP sites as defined in [RFC6832]. LISP interworking
interworking defines three techniques to make LISP sites and non-LISP defines three techniques to make LISP sites and non-LISP sites,
sites, namely Proxy-ITR, LISP-NAT, and Proxy-ETR. Hereafter it is namely Proxy-ITR, LISP-NAT, and Proxy-ETR. The following text
described how Map-Versioning relates to these three mechanisms. describes how Map-Versioning relates to these three mechanisms.
8.2.1. Map-Versioning and Proxy-ITRs 8.2.1. Map-Versioning and Proxy-ITRs
The purpose of the Proxy-ITR (PITR) is to encapsulate traffic 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 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 of the ETRs of the LISP site (cf. Figure 2). This case is very
similar to the unidirectional traffic case described in Section 8.1, similar to the unidirectional traffic case described in Section 8.1;
hence similar rules apply. hence, similar rules apply.
+----------+ +-------------+ +----------+ +-------------+
| LISP | | non-LISP | | LISP | | non-LISP |
| Domain A | | Domain B | | Domain A | | Domain B |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | ETR A |<-------| Proxy ITR |<-------| | | | ETR A |<-------| Proxy-ITR |<-------| |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | | | | | | |
+----------+ +-------------+ +----------+ +-------------+
Figure 2 Figure 2: Unidirectional Traffic from Non-LISP Domain to LISP Domain
The main difference is that a Proxy-ITR does not have any mapping, The main difference is that a Proxy-ITR does not have any mapping,
since it just encapsulate packets arriving from non-LISP site, thus since it just encapsulates packets arriving from the non-LISP site
cannot provide a Source Map-Version. In this case, the proxy-ITR and thus cannot provide a Source Map-Version. In this case, the
will just put the Null Map-Version value as Source Map-Version Proxy-ITR will just put the Null Map-Version value as the Source
number, while the receiving ETR will ignore the field. Map-Version number, while the receiving ETR will ignore the field.
With this setup the LISP Domain A is able to check whether or not the With this setup, LISP Domain A is able to check whether or not the
PITR is using the latest mapping. If this is not the case 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 mapping for LISP Domain A on the PITR can be updated using one of the
mechanisms defined in [I-D.ietf-lisp] and mechanisms defined in [RFC6830] and [RFC6832].
[I-D.ietf-lisp-interworking].
8.2.2. Map-Versioning and LISP-NAT 8.2.2. Map-Versioning and LISP-NAT
The LISP-NAT mechanism is based on address translation from non- The LISP-NAT mechanism is based on address translation from
routable EIDs to routable EIDs and does not involve any form of non-routable EIDs to routable EIDs and does not involve any form of
encapsulation. As such Map-Versioning does not apply in this case. encapsulation. As such, Map-Versioning does not apply in this case.
8.2.3. Map-Versioning and Proxy-ETRs 8.2.3. Map-Versioning and Proxy-ETRs
The purpose of the Proxy-ETR (PETR) is to decapsulate traffic 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- originating in a LISP site in order to deliver the packet to the
LISP site (cf. Figure 3). One of the main reasons of deploy PETRs is non-LISP site (cf. Figure 3). One of the main reasons to deploy
to bypass uRPF (Unicast Reverse Path Forwarding) checks on the PETRs is to bypass uRPF (Unicast Reverse Path Forwarding) checks on
provider edge. the provider edge.
+----------+ +-------------+ +----------+ +-------------+
| LISP | | non-LISP | | LISP | | non-LISP |
| Domain A | | Domain B | | Domain A | | Domain B |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | ITR A |------->| Proxy ETR |------->| | | | ITR A |------->| Proxy-ETR |------->| |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | | | | | | |
+----------+ +-------------+ +----------+ +-------------+
Figure 3 Figure 3: Unidirectional Traffic from LISP Domain to Non-LISP Domain
A Proxy-ETR does not have any mapping, since it just decapsulates A Proxy-ETR does not have any mapping, since it just decapsulates
packets arriving from LISP site. In this case, the ITR will just put packets arriving from the LISP site. In this case, the ITR will just
the Null Map-Version value as Destination Map-Version number, while put the Null Map-Version value as the Destination Map-Version number,
the receiving Proxy-ETR will ignore the field. while the receiving Proxy-ETR will ignore the field.
With this setup the Proxy-ETR is able to check whether or not the With this setup, the Proxy-ETR is able to check whether or not the
mapping has changed. If this is the case the mapping for LISP Domain mapping has changed. If this is the case, the mapping for LISP
A on the PETR can be updated using one of the mechanisms defined in Domain A on the PETR can be updated using one of the mechanisms
[I-D.ietf-lisp] and [I-D.ietf-lisp-interworking]. defined in [RFC6830] and [RFC6832].
8.3. RLOC shutdown/withdraw 8.3. RLOC Shutdown/Withdraw
Map-Versioning can be even used to perform a graceful shutdown or Map-Versioning can also be 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 (via
in the Map Record, see [I-D.ietf-lisp]), but without actually turning the R-bit in the Map Record; see [RFC6830]), but without actually
it off. turning it off.
Once no more traffic is received by the RLOC, it can be shut down Once no more traffic is received by the RLOC, it can be shut down
gracefully, because at least all sites actively using the mapping gracefully, because all sites actively using the mapping have
have updated it. updated it.
It should be pointed out that for frequent up/down changes such a It should be pointed out that for frequent up/down changes such a
mechanism should not be used since this can generate excessive load mechanism should not be used, since this can generate excessive load
on the Mapping System. on the mapping system.
8.4. Map-Version for lightweight LISP implementation 8.4. 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. However, this comes with the price of not
Loc-Status-Bit, which are useful in some contexts. supporting the Locator-Status-Bit, which is 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
Bits (see section 6.5 of [I-D.ietf-lisp]). With Map-Versioning such Locator-Status-Bits (see Section 6.5 of [RFC6830]). With
type of mechanisms can be avoided. When a new RLOC is added to a Map-Versioning, such types of mechanisms can be avoided. When a new
mapping, it is not necessary to "append" new locators to the existing RLOC is added to a mapping, it is not necessary to "append" new
ones as explained in Section 6.5 of [I-D.ietf-lisp]. A new mapping Locators to the existing ones as explained in Section 6.5 of
with a new Map-Version number will be issued, and since the old [RFC6830]. A new mapping with a new Map-Version number will be
locators are still valid the transition will be with no disruptions. issued, and since the old Locators are still valid, the transition
The same applies for the case a RLOC is withdrawn. There is no need will occur with no disruptions. The same applies for the case where
to maintain holes in the list of locators, as is the case when using an RLOC is withdrawn. There is no need to maintain holes in the list
Locator Status Bits, for sites that are not using the RLOC that has of Locators, as is the case when using Locator-Status-Bits, for sites
been withdrawn the transition will be with no disruptions. that are not using the RLOC that has been withdrawn; in this case,
the transition will occur with no disruptions.
All of these operations, as already stated, do not need to maintain All of these operations, as already stated, do not need to maintain
any consistency among Locator Status Bits, and the way RLOC are any consistency among Locator-Status-Bits and in the way that the
stored in the EID-to-RLOC Cache. RLOCs are stored in the EID-to-RLOC Cache.
Further, Map-Version can be used to substitute the "clock sweep" Further, Map-Versioning can be used as a substitute for the "clock
operation described in Section 6.5.1 of [I-D.ietf-lisp]. Indeed, sweep" operation described in Section 6.6.1 of [RFC6830]. Indeed,
every LISP site communicating to a specific LISP site that has every LISP site communicating to a specific LISP site that has
updated the mapping will be informed of the available new mapping in updated the mapping will be informed of the available new mapping in
a data-driven manner. a data-driven manner.
Note that what is proposed in the present section is just an example Note that what is proposed in this section is just an example and
and MUST NOT be considered as specifications for a lightweight LISP MUST NOT be considered as specifications for a lightweight LISP
implementation. In case the IETF decides to undertake such a work, implementation. If the IETF decides to undertake such work, it will
it will be documented elsewhere. be documented elsewhere.
9. Incremental deployment and implementation status 9. Incremental Deployment and Implementation Status
Map-Versioning can be incrementally deployed without any negative Map-Versioning can be incrementally deployed without any negative
impact on existing LISP elements (e.g., xTRs, Map-Servers, Proxy- impact on existing LISP elements (e.g., xTRs, Map-Servers,
ITRs, etc). Any LISP element that does not support Map-Versioning Proxy-ITRs, etc.). Any LISP element that does not support
can safely ignore them. Further, there is no need of any specific Map-Versioning can safely ignore Map-Version numbers carried in the
mechanism to discover if an xTR supports or not Map-Versioning. This LISP header. Further, there is no need of any specific mechanism to
discover whether or not an xTR supports Map-Versioning. This
information is already included in the Map Record. information is already included in the Map Record.
Map-Versioning is currently implemented in OpenLISP Map-Versioning is currently implemented in OpenLISP [OPENLISP].
[I-D.iannone-openlisp-implementation].
Note that the reference document for LISP implementation and Note that the reference document for LISP implementations and
interoperability tests remains [I-D.ietf-lisp]. interoperability tests remains [RFC6830].
10. Security Considerations 10. Security Considerations
Map-Versioning does not introduce any security issue concerning both Map-Versioning does not introduce any security issues concerning both
the data-plane and the control-plane. On the contrary, as described the data plane and the control plane. On the contrary, as described
in the following, if Map-Versioning may be used also to update below, if Map-Versioning may also be used to update mappings in the
mappings in case of change in the reachability information (i.e., case of change in the reachability information (i.e., instead of the
instead of the Locator Status Bits) it is possible to reduce the Locator-Status-Bits), it is possible to reduce the effects of some
effects of some DoS or spoofing attacks that can happen in an DoS or spoofing attacks that can happen in an untrusted environment.
untrusted environment.
Robustness of the Map-Versioning mechanism leverages on a trusted Robustness of the Map-Versioning mechanism leverages on a trusted
Mapping Distribution System. A thorough security analysis of LISP is Mapping Distribution System. A thorough security analysis of LISP is
documented in [I-D.ietf-lisp-threats]. documented in [LISP-THREATS].
10.1. Map-Versioning against traffic disruption 10.1. Map-Versioning against Traffic Disruption
An attacker can try to disrupt ongoing communications by creating An attacker can try to disrupt ongoing communications by creating
LISP encapsulated packets with wrong Locator Status Bits. If the xTR LISP-encapsulated packets with wrong Locator-Status-Bits. If the xTR
blindly trusts the Locator Status Bits it will change the blindly trusts the Locator-Status-Bits, it will change the
encapsulation accordingly, which can result in traffic disruption. encapsulation accordingly, which can result in traffic disruption.
This does not happen in the case of Map-Versioning. As described in This does not happen in the case of Map-Versioning. As described in
Section 5, upon a version number change the xTR first issues a Map- Section 5, upon a version number change the xTR first issues a
Request. The assumption is that the mapping distribution system is Map-Request. The assumption is that the mapping distribution system
sufficiently secure that Map-Request and Map-Reply messages and their is sufficiently secure that Map-Request and Map-Reply messages and
content can be trusted. Security issues concerning specific mapping their content can be trusted. Security issues concerning specific
distribution system are out of the scope of this document. In the mapping distribution systems are out of the scope of this document.
case of Map-Versioning the attacker should "guess" a valid version In the case of Map-Versioning, the attacker should "guess" a valid
number that triggers a Map-Request, as described in Section 5, version number that triggers a Map-Request as described in Section 5;
otherwise the packet is simply dropped. Nevertheless, guessing a otherwise, the packet is simply dropped. Nevertheless, guessing a
version number that generates a Map-Request is easy, hence it is version number that generates a Map-Request is easy; hence, it is
important to follow the rate limitations policies described in important to follow the rate-limitation policies described in
[I-D.ietf-lisp] in order to avoid DoS attacks. [RFC6830] in order to avoid DoS attacks.
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-
Request. However, in this case Locator Status Bits loose their
meaning, because, it does not matter anymore which specific bits has
changed, the xTR will query the mapping system and trust the content
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
not carry a valid Map-Version number. In the case of Locator Status
Bits, any random change can trigger a Map-Request (unless rate
limitation is enabled which raise another type of attack discussed in
Section 10.2).
10.2. Map-Versioning against reachability information DoS
Attackers can try to trigger a large amount of Map-Request by simply Note that a similar level of security can be obtained with
forging packets with random Map-Version or random Locator Status Locator-Status-Bits by simply making it mandatory to verify any
Bits. In both cases the Map-Requests are rate limited as described change through a Map-Request. However, in this case
in [I-D.ietf-lisp]. However, differently from Locator Status Bit Locator-Status-Bits lose their meaning, because it does not matter
where there is no filtering possible, in the case of Map-Versioning anymore which specific bits have changed; the xTR will query the
is possible to filter not valid version numbers before triggering a mapping system and trust the content of the received Map-Reply.
Map-Request, thus helping in reducing the effects of DoS attacks. In Furthermore, there is no way to perform filtering as in
other words the use of Map-Versioning enables a fine control on when Map-Versioning in order to drop packets that do not carry a valid
to update a mapping or when to notify that a mapping has been Map-Version number. In the case of Locator-Status-Bits, any random
updated. change can trigger a Map-Request (unless rate limitation is enabled,
which raises another type of attack as discussed in Section 10.2).
It is clear, that Map-Versioning does not protect against DoS and 10.2. Map-Versioning against Reachability Information DoS
DDoS attacks, where an xTR looses processing power doing checks on
the LISP header of packets sent by attackers. This is independent
from Map-Versioning and is the same for Loc Status Bits.
11. IANA Considerations Attackers can try to trigger a large amount of Map-Requests by simply
forging packets with random Map-Versions or random
Locator-Status-Bits. In both cases, the Map-Requests are
rate-limited as described in [RFC6830]. However, in contrast to the
Locator-Status-Bit, where there is no filtering possible, in the case
of Map-Versioning it is possible to filter invalid version numbers
before triggering a Map-Request, thus helping to reduce the effects
of DoS attacks. In other words, 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.
This document has no actions for IANA. It is clear that Map-Versioning does not protect against DoS and DDoS
attacks, where an xTR loses processing power when doing checks on the
LISP header of packets sent by attackers. This is independent of
Map-Versioning and is the same for Locator-Status-Bits.
12. Open Issues and Considerations 11. Open Issues and Considerations
There are a number of implications of the use of Map-Versioning that There are a number of implications of the use of Map-Versioning that
are not yet completely explored. Among these are: are not yet completely explored. Among these are:
o Performance of the convergence time when an EID-to-RLOC mapping 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 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 EID-to-RLOC Cache of the ITRs currently sending traffic to ETRs
for the EID whose mapping has been changed. for the EID whose mapping has been changed.
o Support to ETR synchronization. The implications that a temporary o Support for ETR synchronization. The implications that a
lack of synchronization may have on the traffic is yet to be fully temporary lack of synchronization may have on the traffic are yet
explored. Details on how to keep synchronization are presented in to be fully explored. Details on how to maintain synchronization
Section 6.6 of [I-D.ietf-lisp]. Section 12.1 hereafter discusses are presented in Section 6.6 of [RFC6830]. Section 11.1 discusses
the issue in further details with respect to the Map-Versioning the issue in further detail with respect to the Map-Versioning
mechanism. mechanism.
The authors expect that experimentation will help assess the The authors expect that experimentation will help assess the
performance and the limitations of the Map-Versioning mechanism. performance and limitations of the Map-Versioning mechanism. Issues
Issues and concerns about the deployment of LISP for Internet traffic and concerns about the deployment of LISP for Internet traffic are
are discussed in [I-D.ietf-lisp]. discussed in [RFC6830].
12.1. Lack of Synchronization among ETRs 11.1. Lack of Synchronization among ETRs
Even without Map-Versioning, LISP ([I-D.ietf-lisp]) requires ETRs to Even without Map-Versioning, LISP ([RFC6830]) requires ETRs to
announce the same mapping for the same EID-Prefix to a requester. announce the same mapping for the same EID-Prefix to a requester.
The implications that a temporary lack of synchronization may have on The implications that a temporary lack of synchronization may have on
the traffic is yet to be fully explored. the traffic are yet to be fully explored.
Map-Versioning does not require additional synchronization mechanism Map-Versioning does not require additional synchronization mechanisms
compared to the normal functioning of LISP without Map-Versioning. as 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, and traffic disruptions. It is the
without Map-Versioning, with ETRs that have to reply with the same same without Map-Versioning, with ETRs that have to reply with the
mapping, otherwise the same problems can arise. same mapping; otherwise, the same problems can arise.
There are two ways Map-Versioning is helpful with respect to the There are two ways Map-Versioning is helpful with respect to the
synchronization problem. On the one hand, assigning version numbers synchronization problem. On the one hand, assigning version numbers
to mappings helps in debugging, since quick checks on the consistency to mappings helps in debugging, since quick checks on the consistency
of the mappings on different ETRs can be done by looking at the Map- of the mappings on different ETRs can be done by looking at the
Version number. On the other hand, Map-Versioning can be used to Map-Version number. On the other hand, Map-Versioning can be used to
control the traffic toward ETRs that announce the latest mapping. 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 As an example, let's consider the topology of Figure 4 where ITR A.1
of domain A is sending unidirectional traffic to the domain B, while of Domain A is sending unidirectional traffic to Domain B, while A.2
A.2 of domain A exchanges bidirectional traffic with domain B. In of Domain A exchanges bidirectional traffic with Domain B. In
particular, ITR A.2 sends traffic to ETR B and ETR A.2 receives particular, ITR A.2 sends traffic to ETR B, and ETR A.2 receives
traffic from ITR B. traffic from ITR B.
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| Domain A | | Domain B | | Domain A | | Domain B |
| +---------+ | | | +---------+ | |
| | ITR A.1 |--- | | | | ITR A.1 |--- | |
| +---------+ \ +---------+ | | +---------+ \ +---------+ |
| | ------->| ETR B | | | | ------->| ETR B | |
| | ------->| | | | | ------->| | |
| +---------+ / | | | | +---------+ / | | |
| | ITR A.2 |--- -----| ITR B | | | | ITR A.2 |--- -----| ITR B | |
| | | / +---------+ | | | | / +---------+ |
| | ETR A.2 |<----- | | | | ETR A.2 |<----- | |
| +---------+ | | | +---------+ | |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 4 Figure 4: Example Topology
Obviously in the case of Map-Versioning both ITR A.1 and ITR A.2 of Obviously, in the case of Map-Versioning, both ITR A.1 and ITR A.2 of
domain A must use the same value otherwise the ETR of domain B will Domain A must use the same value; otherwise, the ETR of Domain B will
start to send 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 ITRs of domain A send different Locator Status instance, if the two ITRs of Domain A send different
Bits. In this case either the traffic is disrupted, if the ETR B Locator-Status-Bits. In this case, either the traffic is disrupted
trusts the Locator Status Bits, or if ETR B does not trust the if ETR B trusts the Locator-Status-Bits, or if ETR B does not trust
Locator Status Bits it will start sending Map-Requests to confirm the the Locator-Status-Bits it will start sending Map-Requests to confirm
each change in the reachability. each change in 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 (see Section 6.6 in [I-D.ietf-lisp]). different xTRs consistently (see Section 6.6 in [RFC6830]). The same
The same applies for Map-Versioning. If in the future any applies for Map-Versioning. If in the future any synchronization
synchronization mechanism is provided, Map-Versioning will take mechanism is provided, Map-Versioning will take advantage of it
advantage of it automatically since it is included in the Record automatically, since it is included in the Record format, as
format, as described in Section 7. described in Section 7.
13. Acknowledgements 12. Acknowledgments
The authors would like to thank Alia Atlas, Jesper Skriver, Pierre The authors would like to thank Alia Atlas, Jesper Skriver, Pierre
Francois, Noel Chiappa, Dino Farinacci for their comments and review. Francois, Noel Chiappa, and Dino Farinacci for their comments and
review.
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 (http://www.trilogy-project.org).
14. References
14.1. Normative References
[I-D.ietf-lisp] 13. References
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] 13.1. Normative References
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 [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.
14.2. Informative References [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830,
[I-D.iannone-openlisp-implementation] January 2013.
Iannone, L., Saucez, D., and O. Bonaventure, "OpenLISP
Implementation Report",
draft-iannone-openlisp-implementation-01 (work in
progress), July 2008.
[I-D.ietf-lisp-alt] [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "LISP "Interworking between Locator/ID Separation Protocol
Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-10 (LISP) and Non-LISP Sites", RFC 6832, January 2013.
(work in progress), December 2011.
[I-D.ietf-lisp-ms] 13.2. Informative References
Fuller, V. and D. Farinacci, "LISP Map Server Interface",
draft-ietf-lisp-ms-15 (work in progress), January 2012.
[I-D.ietf-lisp-threats] [LISP-THREATS]
Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats
Analysis", draft-ietf-lisp-threats-00 (work in progress), Analysis", Work in Progress, October 2012.
July 2011.
Appendix A. Estimation of time before Map-Version wrap-around [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.
The present section proposes an estimation of the wrap-around time Appendix A. Estimation of Time before Map-Version Wrap-Around
for the 12 bits size of the Map-Version number.
Using a granularity of seconds and assuming as worst-case that a new This section proposes an estimation of the wrap-around time for the
12-bit size of the Map-Version number.
Using a granularity of seconds and assuming as worst case that a new
version is issued each second, it takes slightly more than 1 hour version is issued each second, it takes slightly more than 1 hour
before the version wraps around. Note that the granularity of before the version wraps around. Note that the granularity of
seconds is in line with the rate limitation policy for Map-Request seconds is in line with the rate-limitation policy for Map-Request
messages, as proposed in the LISP main specifications messages, as proposed in the LISP main specifications ([RFC6830]).
([I-D.ietf-lisp]).
Alternatively a granularity of minutes can also be used, as for the Alternatively, a granularity of minutes can also be used, as for the
TTL of the Map-Reply ([I-D.ietf-lisp]). In this case the worst TTL of the Map-Reply ([RFC6830]). In this case, the worst-case
scenario is when a new version is issued every minute, leading to a scenario is when a new version is issued every minute, leading to a
much longer time before wrap-around. In particular, when using 12 much longer time before wrap-around. In particular, when using
bits, the wrap-around time is almost 3 days. 12 bits, the wrap-around time is almost 3 days.
For general information, hereafter there is a table with a rough
estimation of the time before wrap-around in the worst-case scenario,
considering different sizes (bits length) of the Map-Version number
and different time granularity.
Since even in the case of high mapping change rate (1 per second) the
wrap around time using 12 bits is far larger then any reasonable
Round-Trip-Time (RTT), there is no risk of race conditions.
+---------------+--------------------------------------------+
|Version Number | Time before wrap around |
| Size (bits) +---------------------+----------------------+
| |Granularity: Minutes | Granularity: Seconds |
| | (mapping changes | (mapping changes |
| | every 1 minute) | every 1 second) |
+-------------------------------------+----------------------+
| 32 | 8171 Years | 136 Years |
| 30 | 2042 Years | 34 Years |
| 24 | 31 Years | 194 Days |
| 16 | 45 Days | 18 Hours |
| 15 | 22 Days | 9 Hours |
| 14 | 11 Days | 4 Hours |
| 13 | 5.6 Days | 2.2 Hours |
| 12 | 2.8 Days | 1.1 Hours |
+---------------+---------------------+----------------------+
Figure 5: Estimation of time before wrap-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". For general information, Figure 5 below provides a rough estimation
of the time before wrap-around in the worst-case scenario,
considering different sizes (length in bits) of the Map-Version
number and different time granularities.
* Editorial polishing of all sections. Since even in the case of a high mapping change rate (1 per second)
the wrap-around time using 12 bits is far larger than any reasonable
Round-Trip Time (RTT), there is no risk of race conditions.
* Added clarifications in section "Dealing with Map-Version +---------------+--------------------------------------------+
numbers" for the case of the special Map-Version number 0. |Version Number | Time before Wrap-Around |
| Size (bits) +---------------------+----------------------+
| |Granularity: Minutes | Granularity: Seconds |
| | (mapping changes | (mapping changes |
| | every 1 minute) | every 1 second) |
+-------------------------------------+----------------------+
| 32 | 8171 years | 136 years |
| 30 | 2042 years | 34 years |
| 24 | 31 years | 194 days |
| 16 | 45 days | 18 hours |
| 15 | 22 days | 9 hours |
| 14 | 11 days | 4 hours |
| 13 | 5.6 days | 2.2 hours |
| 12 | 2.8 days | 1.1 hours |
+---------------+---------------------+----------------------+
* Rename of draft-iannone-mapping-versioning-02.txt. Figure 5: Estimation of Time before Wrap-Around
Authors' Addresses Authors' Addresses
Luigi Iannone Luigi Iannone
Telekom Innovation Laboratories Telecom ParisTech
Ernst-Reuter Platz 7
Berlin
Germany
Email: luigi@net.t-labs.tu-berlin.de EMail: luigi.iannone@telecom-paristech.fr
Damien Saucez Damien Saucez
INRIA Sophia Antipolis INRIA Sophia Antipolis
2004 route des Lucioles - BP 93 2004 route des Lucioles - BP 93
Sophia Antipolis Sophia Antipolis
France France
Email: damien.saucez@inria.fr EMail: damien.saucez@inria.fr
Olivier Bonaventure Olivier Bonaventure
Universite catholique de Louvain Universite catholique de Louvain
Place St. Barbe 2 Place St. Barbe 2
Louvain-la-Neuve Louvain-la-Neuve
Belgium Belgium
Email: olivier.bonaventure@uclouvain.be EMail: olivier.bonaventure@uclouvain.be
 End of changes. 156 change blocks. 
687 lines changed or deleted 543 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/