rfc9302.original   rfc9302.txt 
Network Working Group L. Iannone Internet Engineering Task Force (IETF) L. Iannone
Internet-Draft Huawei Technologies France Request for Comments: 9302 Huawei Technologies France
Obsoletes: 6834 (if approved) D. Saucez Obsoletes: 6834 D. Saucez
Intended status: Standards Track INRIA Category: Standards Track Inria
Expires: December 23, 2022 O. Bonaventure ISSN: 2070-1721 O. Bonaventure
Universite catholique de Louvain Universite catholique de Louvain
June 21, 2022 October 2022
Locator/ID Separation Protocol (LISP) Map-Versioning Locator/ID Separation Protocol (LISP) Map-Versioning
draft-ietf-lisp-6834bis-14
Abstract Abstract
This document describes the LISP (Locator/ID Separation Protocol) This document describes the Locator/ID Separation Protocol (LISP)
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. This approach is based on associating encapsulate LISP data packets. This approach is based on associating
a version number to EID-to-RLOC mappings and the transport of such a a version number to EID-to-RLOC mappings and transporting such a
version number in the LISP-specific header of LISP-encapsulated version number in the LISP-specific header of LISP-encapsulated
packets. LISP Map-Versioning is particularly useful to inform packets. LISP Map-Versioning is particularly useful to inform
communicating Ingress Tunnel Routers (ITRs) and Egress Tunnel Routers communicating Ingress Tunnel Routers (ITRs) and Egress Tunnel Routers
(ETRs) about modifications of the mappings used to encapsulate (ETRs) about modifications of the mappings used to encapsulate
packets. The mechanism is optional and transparent to packets. The mechanism is optional and transparent to
implementations not supporting this feature, since in the LISP- implementations not supporting this feature, since in the LISP-
specific header and in the Map Records, bits used for Map-Versioning specific header and in the Map Records, bits used for Map-Versioning
can be safely ignored by ITRs and ETRs that do not support or do not can be safely ignored by ITRs and ETRs that do not support or do not
want to use the mechanism. want to use the mechanism.
This document obsoletes RFC 6834 "Locator/ID Separation Protocol This document obsoletes RFC 6834, which is the initial experimental
(LISP) Map-Versioning", which is the initial experimental
specifications of the mechanisms updated by this document. specifications of the mechanisms updated by this document.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This document is a product of the Internet Engineering Task Force
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working documents as Internet-Drafts. The list of current Internet- received public review and has been approved for publication by the
Drafts is at https://datatracker.ietf.org/drafts/current/. Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Internet-Drafts are draft documents valid for a maximum of six months Information about the current status of this document, any errata,
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time. It is inappropriate to use Internet-Drafts as reference https://www.rfc-editor.org/info/rfc9302.
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This Internet-Draft will expire on December 23, 2022.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Notation
3. Definitions of Terms . . . . . . . . . . . . . . . . . . . . 4 3. Definitions of Terms
4. LISP-specific Header and Map-Version Numbers . . . . . . . . 4 4. LISP-Specific Header and Map-Version Numbers
5. Map Record and Map-Version . . . . . . . . . . . . . . . . . 5 5. Map Record and Map-Version
6. EID-to-RLOC Map-Version Number . . . . . . . . . . . . . . . 6 6. EID-to-RLOC Map-Version Number
6.1. The Null Map-Version . . . . . . . . . . . . . . . . . . 7 6.1. The Null Map-Version
7. Dealing with Map-Version Numbers . . . . . . . . . . . . . . 7 7. Dealing with Map-Version Numbers
7.1. Handling Destination Map-Version Number . . . . . . . . . 8 7.1. Handling Dest Map-Version Number
7.2. Handling Source Map-Version Number . . . . . . . . . . . 9 7.2. Handling Source Map-Version Number
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. Security Considerations
9. Deployment Considerations . . . . . . . . . . . . . . . . . . 11 9. Deployment Considerations
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 10. IANA Considerations
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 11. References
11.1. Normative References . . . . . . . . . . . . . . . . . . 12 11.1. Normative References
11.2. Informative References . . . . . . . . . . . . . . . . . 12 11.2. Informative References
Appendix A. Benefits and Case Studies for Map-Versioning . . . . 14 Appendix A. Benefits and Case Studies for Map-Versioning
A.1. Map-Versioning and Unidirectional Traffic . . . . . . . . 14 A.1. Map-Versioning and Unidirectional Traffic
A.2. Map-Versioning and Interworking . . . . . . . . . . . . . 14 A.2. Map-Versioning and Interworking
A.2.1. Map-Versioning and Proxy-ITRs . . . . . . . . . . . . 14 A.2.1. Map-Versioning and Proxy-ITRs
A.2.2. Map-Versioning and LISP-NAT . . . . . . . . . . . . . 15 A.2.2. Map-Versioning and LISP-NAT
A.2.3. Map-Versioning and Proxy-ETRs . . . . . . . . . . . . 15 A.2.3. Map-Versioning and Proxy-ETRs
A.3. RLOC Shutdown/Withdraw . . . . . . . . . . . . . . . . . 16 A.3. RLOC Shutdown/Withdraw
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses
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 (Endpoint ID to Routing information on changes in the Endpoint-ID-to-Routing-Locator (EID-to-
Locator) mappings used in the LISP (Locator/ID Separation Protocol RLOC) mappings used in the Locator/ID Separation Protocol (LISP)
[I-D.ietf-lisp-rfc6830bis][I-D.ietf-lisp-rfc6833bis]) context to [RFC9300] [RFC9301] context to perform packet encapsulation. The
perform packet encapsulation. The mechanism is totally transparent mechanism is totally transparent to Ingress and Egress Tunnel Routers
to xTRs (Ingress and Egress Tunnel Routers) not supporting or not (xTRs) not supporting or not using such functionality. The
using such functionality. [I-D.ietf-lisp-introduction] describes the architecture of LISP is described in [RFC9299]. The reader is
architecture of the Locator/ID Separation Protocol. It is expected expected to be familiar with this introductory document.
that the reader is familiar with this introductory document.
This document obsoletes [RFC6834], which is the initial experimental This document obsoletes [RFC6834], which is the initial experimental
specifications of the mechanisms updated by this document. specification that describes the mechanisms updated by this 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 modification in the RLOCs set such as addition, removal, or can be a modification in the RLOCs set, such as addition of, removal
change in priority or weight of one or more RLOCs. of, or change in the priority or weight of one 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 RLOCs). This the outer header (i.e., both source and destination RLOCs). This
information has two uses. On the one hand, it enables the ETR information has two uses:
(Egress Tunnel Router) receiving the packet to know if the ITR
(Ingress Tunnel Router) is using the latest mapping version for the 1. Map-Versioning enables the Egress Tunnel Router (ETR) receiving
destination EID. If this is not the case, the ETR can directly send the packet to know if the Ingress Tunnel Router (ITR) is using
a Map-Request containing the updated mapping to the ITR, to notify it the latest mapping version for the destination EID. If this is
of the latest version. The ETR can also solicit the ITR to trigger a not the case, the ETR can directly send a Map-Request containing
Map-Request to obtain the latest mapping by sending it a Solicit Map- the updated mapping to the ITR to notify it of the latest
Request (SMR) message. Both cases are defined in version. The ETR can also solicit the ITR to trigger a Map-
[I-D.ietf-lisp-rfc6833bis]. On the other hand, it enables an ETR Request to obtain the latest mapping by sending a Solicit Map-
receiving such a packet to know if it has in its EID-to-RLOC Map- Request (SMR) message. Both options are defined in [RFC9301].
Cache the latest mapping for the source EID. If this is not the
case, a Map-Request can be sent. 2. Map-Versioning enables an ETR receiving the packet to know if it
has in its EID-to-RLOC Map-Cache the latest mapping for the
source EID. If this is not the case, a Map-Request can be sent.
Considerations about the deployment of LISP Map-Versioning are Considerations about the deployment of LISP Map-Versioning are
discussed in Section 9. discussed in Section 9.
Benefits brought by Map-Versioning in some common LISP-related use The benefits of Map-Versioning in some common LISP-related use cases
cases are discussed in Appendix A. are discussed in Appendix A.
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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Definitions of Terms 3. Definitions of Terms
This document uses terms already defined in the main LISP This document uses terms already defined in the main LISP
specification ([I-D.ietf-lisp-rfc6830bis], specifications ([RFC9300] and [RFC9301]). Here, we define the terms
[I-D.ietf-lisp-rfc6833bis]). Here, we define the terms that are that are specific to the Map-Versioning mechanism. Throughout the
specific to the Map-Versioning mechanism. Throughout the whole whole document, big-endian bit ordering is used.
document, Big Endian bit ordering is used.
Map-Version number: An unsigned 12-bit integer is assigned to an Map-Version number: An unsigned 12-bit integer is assigned to an
EID-to-RLOC mapping, indicating its version number (Section 6). EID-to-RLOC mapping, indicating its version number (Section 6).
Null Map-Version: A Map-Version number with a value of 0x000 (zero), Null Map-Version: A Map-Version number with a value of 0x000 (zero),
used to signal that the Map-Version feature is not used and no Map- which is used to signal that the Map-Version feature is not used
Version number is assigned to the EID-to-RLOC mapping and no Map-Version number is assigned to the EID-to-RLOC mapping
(Section 6.1). (Section 6.1).
Dest Map-Version number: Map-Version of the mapping in the EID-to- Dest Map-Version number: Map-Version of the mapping in the EID-to-
RLOC Map-Cache used by the ITR to select the RLOC present in the RLOC Map-Cache used by the ITR to select the RLOC present in the
"Destination Routing Locator" field of the outer IP header of LISP- 'Destination Routing Locator' field of the outer IP header of LISP-
encapsulated packets (Section 7.1). encapsulated packets (Section 7.1).
Source Map-Version number: Map-Version of the mapping in the EID-to- Source Map-Version number: Map-Version of the mapping in the EID-to-
RLOC Database used by the ITR to select the RLOC present in the RLOC Database used by the ITR to select the RLOC present in the
"Source Routing Locator" field of the outer IP header of LISP- 'Source Routing Locator' field of the outer IP header of LISP-
encapsulated packets (Section 7.2). encapsulated packets (Section 7.2).
4. LISP-specific Header and Map-Version Numbers 4. LISP-Specific 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 the Source Map-Version number and Dest Map- header has to carry both the Source Map-Version number and Dest Map-
Version number. This is done by setting the V-bit in the LISP- Version number. This is done by setting the V-bit in the LISP-
specific header as specified in [I-D.ietf-lisp-rfc6830bis] and shown specific header as specified in [RFC9300] and shown in the example in
in the example in Figure 1. All permissible combinations of the Figure 1. All permissible combinations of the flags when the V-bit
flags when the V-bit is set to 1 are described in is set to 1 are described in [RFC9300]. Not all of the LISP-
[I-D.ietf-lisp-rfc6830bis]. Not all of the LISP-encapsulated packets encapsulated packets need to carry version numbers. When the V-bit
need to carry version numbers. When the V-bit is set, the LISP- is set, the LISP-specific header has the following encoding:
specific header has the following encoding:
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|R|K|K| Source Map-Version | Dest Map-Version | |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance ID/Locator-Status-Bits | | Instance ID/Locator-Status-Bits |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: LISP-Specific header example when Map-Versioning is in use. Figure 1: LISP-Specific Header Example When Map-Versioning Is in Use
Source Map-Version number (12 bits): See Section 3. Source Map-Version number (12 bits): See Section 3.
Dest Map-Version number (12 bits): See Section 3. Dest Map-Version number (12 bits): See Section 3.
5. Map Record and Map-Version 5. Map Record and Map-Version
To accommodate the mechanism, the Map Records that are transported in To accommodate the mechanism, the Map Records that are transported in
Map-Request/Map-Reply/Map-Register messages need to carry the Map- Map-Request/Map-Reply/Map-Register messages need to carry the Map-
Version number as well. For reference, the Map Record (specified in Version number as well. For reference, the Map Record (specified in
[I-D.ietf-lisp-rfc6833bis]) is reported here as an example in [RFC9301]) is reported here as an example in Figure 2. This memo
Figure 2. This memo does not change the operation of Map-Request/ does not change the operation of Map-Request/Map-Reply/Map-Register
Map-Reply/Map-Register messages, they continue to be used as messages; they continue to be used as specified in [RFC9301].
specified in [I-D.ietf-lisp-rfc6833bis].
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 |
+-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Map-Record format example. Figure 2: Map-Record Format Example
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 6.1, this field can be zero (0), Record. As explained in Section 6.1, this field can be zero (0),
meaning that no Map-Version is associated to the mapping. meaning that no Map-Version is associated to the mapping.
This packet format is backward compatible with xTRs that do not This packet format is backward compatible with xTRs that do not
support Map-Versioning, since they can simply ignore those bits. support Map-Versioning, since they can simply ignore those bits.
A Map-Server receiving a message with an unexpected Map-Version A Map-Server receiving a message with an unexpected Map-Version
number, like for instance an old one, MUST silently drop the message number, for instance an old one, MUST silently drop the message and
and an appropriate log action SHOULD be taken. an appropriate log action SHOULD be taken.
6. EID-to-RLOC Map-Version Number 6. EID-to-RLOC Map-Version Number
The EID-to-RLOC Map-Version number consists of an unsigned 12-bit 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 different version numbers, which
which is also updated independently. An update in the version number are updated independently. An update in the version number (i.e., a
(i.e., a newer version) MUST consist of an increment of the older newer version) MUST consist of an increment of the older version
version number (only exception is for the Null Map-Version as number (the only exception is for the Null Map-Version as explained
explained in at the end of Section 6.1). in at the end of Section 6.1).
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 are considered greater (i.e., newer) than the current version numbers are considered greater (i.e., newer) than the current
Map-Version number and the other half of the version numbers are Map-Version number and the other half of the version numbers are
considered smaller (i.e., older) than the current Map-Version number. considered smaller (i.e., older) than the current Map-Version number.
This is basically a serial number on which the arithmetic described This is basically a serial number on which the arithmetic described
in [RFC1982] applies. The ordering enables reacting differently to in [RFC1982] applies. The ordering enables different reactions to
"older" and "newer" Map-Version number, discarding the packet in the "older" and "newer" Map-Version numbers, whereby "older" numbers are
former case and triggering a Map-Request in the latter (see Section 7 discarded and "newer" numbers trigger Map-Requests (see Section 7 for
for further details). In a formal way, assuming that we have two further details). In a formal way, assuming that we have two version
version numbers V1 and V2, both different from the special value Null numbers (V1 and V2), both different from the special value Null Map-
Map-Version (see Section 6.1), and that the numbers are expressed on Version (see Section 6.1), and that the numbers are expressed on 12
12 bits, the following steps MUST be performed (in the same order as bits, the following steps MUST be performed (in the same order shown
shown below) to strictly define their order: below) to strictly define their order:
1. V1 = V2 : The Map-Version numbers 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**(12-1) V2 > V1 AND (V2 - V1) <= 2^(12-1)
OR OR
V1 > V2 AND (V1 - V2) > 2**(12-1) V1 > V2 AND (V1 - V2) > 2^(12-1)
3. V1 > V2 : otherwise. 3. V1 > V2 : otherwise.
Using 12 bits and assuming a Map-Version value of 69, Map-Version Using 12 bits and assuming a Map-Version value of 69, Map-Version
numbers in the range [70; 69 + 2048] are greater than 69, while Map- numbers in the range [70; 69 + 2048] are greater than 69, while Map-
Version numbers in the range [69 + 2049; (69 + 4095) mod 4096] are Version numbers in the range [69 + 2049; (69 + 4095) mod 4096] are
smaller than 69. smaller than 69.
The initial Map-Version number of a new EID-to-RLOC mapping SHOULD be The initial Map-Version number of a new EID-to-RLOC mapping SHOULD be
assigned randomly, but it MUST NOT be set to the Null Map-Version assigned randomly, but it MUST NOT be set to the Null Map-Version
skipping to change at page 7, line 27 skipping to change at line 294
6.1. The Null Map-Version 6.1. The Null Map-Version
The value 0x000 (zero) is a special Map-Version number indicating The value 0x000 (zero) is a special Map-Version number indicating
that there is actually no version number associated to the EID-to- that there is actually no version number associated to the EID-to-
RLOC mapping. Such a value is used for special purposes and is named RLOC mapping. Such a value is used for special purposes and is named
the Null Map-Version number. the Null Map-Version number.
Map Records that have a Null Map-Version number indicate that there Map Records that have a Null Map-Version number indicate that there
is no Map-Version number associated with the mapping. This means is no Map-Version number associated with the mapping. This means
that LISP-encapsulated packets destined to the EID-Prefix referred to that LISP-encapsulated packets destined to the EID-Prefix referred to
by the Map Record MUST NOT contain any Map-Version numbers (V bit set by the Map Record MUST NOT contain any Map-Version numbers (V-bit set
to 0). If an ETR receives LISP-encapsulated packets with the V-bit to 0). If an ETR receives LISP-encapsulated packets with the V-bit
set, when the original mapping in the EID-to-RLOC Database has the set, when the original mapping in the EID-to-RLOC Database has the
version number set to the Null Map-Version value, then those packets version number set to the Null Map-Version value, then those packets
MUST be silently dropped. MUST be silently dropped.
The Null Map-Version may appear in the LISP-specific header as a The Null Map-Version may appear in the LISP-specific header as a
Source Map-Version number (Section 7.2). When the Source Map-Version Source Map-Version number (Section 7.2). When the Source Map-Version
number is set to the Null Map-Version value, it means that no map number is set to the Null Map-Version value, it means that no map
version information is conveyed for the source site. This means that version information is conveyed for the source site. This means that
if a mapping exists for the source EID in the EID-to-RLOC Map-Cache, if a mapping exists for the source EID in the EID-to-RLOC Map-Cache,
skipping to change at page 8, line 4 skipping to change at line 320
change in the mapping, if the next value is 0, then the Map-Version change in the mapping, if the next value is 0, then the Map-Version
number MUST be incremented by 2 (i.e., set to 1 (0x001), which is the number MUST be incremented by 2 (i.e., set to 1 (0x001), which is the
next valid value). next valid value).
7. Dealing with Map-Version Numbers 7. 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 Traffic Engineering policies, or a change in the weights due to Traffic Engineering policies, or a change in the
priorities) or a LISP site realizes that one or more of its own RLOCs priorities) or a LISP site realizes that one or more of its own RLOCs
are not reachable anymore from a local perspective (e.g., through are no longer reachable from a local perspective (e.g., through IGP
IGP, or policy changes) the LISP site updates the mapping, also or policy changes), the LISP site updates the mapping and also
assigning a new Map-Version number. Only the latest Map-Version assigns a new Map-Version number. Only the latest Map-Version number
number has to be considered valid. Mapping updates, and their has to be considered valid. Mapping updates and their corresponding
corresponding Map Version Number must be managed so that a very old Map-Version Number must be managed so that a very old version number
version number will not be confused as a new version number (because will not be confused as a new version number (because of the circular
of the circular numbering space). To this end simple measures can be numbering space). To this end, simple measures can be taken, like
taken, like updating a mapping only when all active traffic is using updating a mapping only when all active traffic is using the latest
the latest version, or waiting sufficient time to be sure that version, or waiting a sufficient amount of time to be sure that the
mapping in LISP caches expire, which means waiting at least as much mapping in LISP caches expires, which means waiting at least as long
as the mapping Time-To-Live (as defined in as the mapping Time To Live (TTL) (as defined in [RFC9301]).
[I-D.ietf-lisp-rfc6833bis]).
An ETR receiving a LISP packet with Map-Version numbers checks the An ETR receiving a LISP packet with Map-Version numbers checks the
following predicates: following predicates:
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 Map-Cache for the destination EID and is performing EID-to-RLOC Map-Cache for the destination EID and is performing
encapsulation correctly. See Section 7.1 for details. encapsulation correctly. See Section 7.1 for details.
2. In the case of bidirectional traffic, the mapping in the local 2. In the case of bidirectional traffic, the mapping in the local
ETR EID-to-RLOC Map-Cache for the source EID is up-to-date. See ETR EID-to-RLOC Map-Cache for the source EID is up to date. See
Section 7.2 for details. Section 7.2 for details.
7.1. Handling Destination Map-Version Number 7.1. Handling Dest Map-Version Number
When an ETR receives a packet, the Dest Map-Version number relates to When an ETR receives a packet, the Dest Map-Version number relates to
the mapping for the destination EID for which the ETR is an RLOC. the mapping for the destination EID for which the ETR is an RLOC.
This mapping is part of the ETR EID-to-RLOC Database. Since the ETR This mapping is part of the ETR EID-to-RLOC Database. Since the ETR
is authoritative for the mapping, it has the correct and up-to-date is authoritative for the mapping, it has the correct and up-to-date
Dest Map-Version number. A check on this version number MUST be Dest Map-Version number. A check on this version number MUST be
done, where the following cases can arise: done, where the following cases can arise:
1. The packet arrives with the same Dest Map-Version number stored 1. The packet arrives with the same Dest Map-Version number stored
in the EID-to-RLOC Database. This is the regular case. The ITR in the EID-to-RLOC Database. This is the regular case. The ITR
sending the packet has in its EID-to-RLOC Map-Cache an up-to-date sending the packet has, in its EID-to-RLOC Map-Cache, an up-to-
mapping. No further actions are needed. date mapping. No further actions are needed.
2. The packet arrives with a Dest Map-Version number newer (as 2. The packet arrives with a Dest Map-Version number newer (as
defined in Section 6) than the one stored in the EID-to-RLOC defined in Section 6) than the one stored in the EID-to-RLOC
Database. Since the ETR is authoritative on the mapping, meaning Database. Since the ETR is authoritative on the mapping, meaning
that the Map-Version number of its mapping is the correct one, that the Map-Version number of its mapping is the correct one,
the packet carries a version number that is not considered valid the packet carries a version number that is not considered valid.
and packet MUST be silently dropped and an appropriate log action Therefore, the packet MUST be silently dropped and an appropriate
SHOULD be taken. log action SHOULD be taken.
3. The packet arrives with a Dest Map-Version number older (as 3. The packet arrives with a Dest Map-Version number older (as
defined in Section 6) than the one stored in the EID-to-RLOC defined in Section 6) than the one stored in the EID-to-RLOC
Database. This means that the ITR sending the packet has an old Database. This means that the ITR sending the packet has an old
mapping in its EID-to-RLOC Map-Cache containing stale mapping in its EID-to-RLOC Map-Cache containing stale
information. The ETR MAY choose to normally process the information. The ETR MAY choose to normally process the
encapsulated datagram according to [I-D.ietf-lisp-rfc6830bis]; encapsulated datagram according to [RFC9300]; however, the ITR
however, the ITR sending the packet MUST be informed that a newer sending the packet MUST be informed that a newer mapping is
mapping is available, respecting rate-limitation policies available, respecting rate-limitation policies described in
described in [I-D.ietf-lisp-rfc6833bis]. This is done with a [RFC9301]. This is done with a Map-Request message sent back to
Map-Request message sent back to the ITR, as specified in the ITR, as specified in [RFC9301]. One feature introduced by
[I-D.ietf-lisp-rfc6833bis]. One feature introduced by Map- Map-Version numbers is the possibility of blocking traffic not
Version numbers is the possibility of blocking traffic not using using the latest mapping. This can happen if an ITR is not
the latest mapping. This can happen if an ITR is not updating updating the mapping for which the ETR is authoritative, or it
the mapping for which the ETR is authoritative, or it might be might be some form of attack. According to the rate-limitation
some form of attack. According to rate limitation policy defined policy defined in [RFC9301] for Map-Request messages, after 10
in [I-D.ietf-lisp-rfc6833bis] for Map-Request messages, after 10 retries, Map-Requests are sent every 30 seconds; if after the
retries Map-Requests are sent every 30 seconds, if after the
first 10 retries the Dest Map-Version number in the packets is first 10 retries the Dest Map-Version number in the packets is
not updated, the ETR SHOULD drop packets with a stale Map-Version not updated, the ETR SHOULD drop packets with a stale Map-Version
number. Operators can configure exceptions to this number. Operators can configure exceptions to this
recommendation, which are outside the scope of this document. recommendation, which are outside the scope of this document.
The rule in the third case MAY be more restrictive. If the Record The rule in the third case MAY be more restrictive. If the Record
TTL of the previous mapping has already expired, all packets arriving TTL of the previous mapping has already expired, all packets arriving
with an old Map-Version MUST be silently dropped right away without with an old Map-Version MUST be silently dropped right away without
issuing any Map-Request. Such action is permitted because if the new issuing any Map-Request. Such action is permitted because, if the
mapping with the updated version number has been unchanged for at new mapping with the updated version number has been unchanged for at
least the same time as the Record TTL of the older mapping, all the least the same amount of time as the Record TTL of the older mapping,
entries in the EID-to-RLOC Map-Caches of ITRs must have expired. all the entries in the EID-to-RLOC Map-Caches of ITRs must have
Indeed, all ITRs sending traffic should have refreshed the mapping expired. Indeed, all ITRs sending traffic should have refreshed the
according to [I-D.ietf-lisp-rfc6833bis]. mapping according to [RFC9301].
It is a protocol violation for LISP-encapsulated packets to contain a It is a protocol violation for LISP-encapsulated packets to contain a
Dest Map-Version number equal to the Null Map-Version number, see Dest Map-Version number equal to the Null Map-Version number (see
Section 6.1. Section 6.1).
7.2. Handling Source Map-Version Number 7.2. 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
Map-Cache for the source EID, then a check MUST be performed and the Map-Cache for the source EID, then a check MUST be performed, and the
following cases can arise: following cases can arise:
1. The packet arrives with the same Source Map-Version number as 1. The packet arrives with the same Source Map-Version number as
that stored in the EID-to-RLOC Map-Cache. This is the regular that stored in the EID-to-RLOC Map-Cache. This is the regular
case. The ETR has in its EID-to-RLOC Map-Cache an up-to-date case. The ETR has in its EID-to-RLOC Map-Cache an up-to-date
copy of the 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 newer (as 2. The packet arrives with a Source Map-Version number newer (as
defined in Section 6) than the one stored in the local EID-to- defined in Section 6) than the one stored in the local EID-to-
RLOC Map-Cache. This means that the ETR has in its EID-to-RLOC RLOC Map-Cache. This means that the ETR has in its EID-to-RLOC
Map-Cache a mapping that is stale and needs to be updated. A Map-Cache a mapping that is stale and needs to be updated. A
Map-Request MUST be sent to get the new mapping for the source Map-Request MUST be sent to get the new mapping for the source
EID, respecting rate-limitation policies described in EID, respecting rate-limitation policies described in [RFC9301].
[I-D.ietf-lisp-rfc6833bis].
3. The packet arrives with a Source Map-Version number older (as 3. The packet arrives with a Source Map-Version number older (as
defined in Section 6) than the one stored in the local EID-to- defined in Section 6) than the one stored in the local EID-to-
RLOC Map-Cache. Note that if the mapping is already present in RLOC Map-Cache. Note that if the mapping is already present in
the EID-to-RLOC Map-Cache, this means that an explicit Map- the EID-to-RLOC Map-Cache, this means that an explicit Map-
Request has been sent and a Map-Reply has been received from an Request has been sent and a Map-Reply has been received from an
authoritative source. In this situation, the packet SHOULD be authoritative source. In this situation, the packet SHOULD be
silently dropped. Operators can configure exceptions to this silently dropped. Operators can configure exceptions to this
recommendation, which are outside the scope of this document. recommendation, which are outside the scope of this document.
If the ETR does not have an entry in the EID-to-RLOC Map-Cache for If the ETR does not have an entry in the EID-to-RLOC Map-Cache for
the source EID, then the Source Map-Version number MUST be ignored. the source EID, then the Source Map-Version number MUST be ignored.
See Appendix A.1 for an example of when this situation can arise. See Appendix A.1 for an example of when this situation can arise.
8. Security Considerations 8. Security Considerations
This document builds on the specification and operation of the LISP This document builds on the specification and operation of the LISP
control and data planes. The Security Considerations of control and data planes. The Security Considerations of [RFC9300]
[I-D.ietf-lisp-rfc6830bis] and [I-D.ietf-lisp-rfc6833bis] apply and, and [RFC9301] apply. As such, Map-Versioning MUST NOT be used over
as such, Map-Versioning MUST NOT be used over the public Internet and the public Internet and MUST only be used in trusted and closed
MUST only be used in trusted and closed deployments. A thorough deployments. A thorough security analysis of LISP is documented in
security analysis of LISP is documented in [RFC7835]. [RFC7835].
Attackers can try to trigger a large number of Map-Requests by simply Attackers can try to trigger a large number of Map-Requests by simply
forging packets with random Map-Versions. The Map-Requests are rate- forging packets with random Map-Versions. The Map-Requests are rate
limited as described in [I-D.ietf-lisp-rfc6833bis]. With Map- limited as described in [RFC9301]. With Map-Versioning, it is
Versioning it is possible to filter packet carrying invalid version possible to filter packets carrying invalid version numbers before
numbers before triggering a Map-Request, thus helping to reduce the triggering a Map-Request, thus helping to reduce the effects of DoS
effects of DoS attacks. However, it might not be enough to really attacks. However, it might not be enough to really protect against a
protect from a DDoS attack. DDoS attack.
The present memo includes log action to be taken upon certains event. The present memo includes log action to be taken upon certain events.
It is recommended that implementations include mechanisms (which are It is recommended that implementations include mechanisms (which are
beyond the scope of this document) to avoid log resource exhaustion beyond the scope of this document) to avoid log resource exhaustion
attacks. attacks.
The specifications in the present memo are relatively conservative in The specifications in the present memo are relatively conservative in
the sense that in several cases the packets are dropped. Such an the sense that, in several cases, the packets are dropped. Such an
approach is the outcome of considerations made about the possible approach is the outcome of considerations made about the possible
risks that data-plane-triggered control-plane actions can be used to risks that control plane actions that are triggered by the data plane
carry out attacks. There exists corner cases where, even with an can be used to carry out attacks. There exists corner cases where,
invalid Map-Version number, forwarding the packet might be even with an invalid Map-Version number, forwarding the packet might
potentially considered safe, however, system manageability has been be potentially considered safe; however, system manageability has
given priority with respect to having to put in place more machinery been given priority with respect to having to put in place more
to be able to identify leggitimate traffic. machinery to be able to identify legitimate traffic.
9. Deployment Considerations 9. Deployment Considerations
LISP requires multiple ETRs within the same site to provide identical LISP requires multiple ETRs within the same site to provide identical
mappings for a given EID-Prefix. Map-Versioning does not require mappings for a given EID-Prefix. Map-Versioning does not require
additional synchronization mechanisms. Clearly, all the ETRs have to additional synchronization mechanisms. Clearly, all the ETRs have to
reply with the same mapping including same Map-Version number; reply with the same mapping, including 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, and traffic disruptions. control traffic, instabilities, and traffic disruptions.
There are two ways Map-Versioning is helpful with respect to There are two ways Map-Versioning is helpful with respect to
synchronization. On the one hand, assigning version numbers to synchronization. On the one hand, assigning version numbers to
mappings helps in debugging, since quick checks on the consistency of mappings helps in debugging, since quick checks on the consistency of
the mappings on different ETRs can be done by looking at the Map- the mappings on different ETRs can be done by looking at the Map-
Version number. On the other hand, Map-Versioning can be used to 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.
skipping to change at page 11, line 46 skipping to change at line 502
| | ------->| ETR B | | | | ------->| ETR B | |
| | ------->| | | | | ------->| | |
| +---------+ / | | | | +---------+ / | | |
| | ITR A.2 |--- -----| ITR B | | | | ITR A.2 |--- -----| ITR B | |
| | | / +---------+ | | | | / +---------+ |
| | ETR A.2 |<----- | | | | ETR A.2 |<----- | |
| +---------+ | | | +---------+ | |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 3: Example topology. Figure 3: 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 Locator-Status-
Bits. In this case, either the traffic is disrupted if ETR B does Bits. In this case, either the traffic is disrupted if ETR B does
not verify reachability, or if ETR B will start sending Map-Requests not verify reachability or if ETR B will start sending Map-Requests
to confirm each change in reachability. to confirm 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. 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 Map Record format, as described in Section 5. included in the Map Record format, as described in Section 5.
10. IANA Considerations 10. IANA Considerations
This document includes no request to IANA. This document has no IANA actions.
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-lisp-rfc6830bis]
Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos-Aparicio, "The Locator/ID Separation Protocol
(LISP)", draft-ietf-lisp-rfc6830bis-38 (work in progress),
May 2022.
[I-D.ietf-lisp-rfc6833bis]
Farinacci, D., Maino, F., Fuller, V., and A. Cabellos-
Aparicio, "Locator/ID Separation Protocol (LISP) Control-
Plane", draft-ietf-lisp-rfc6833bis-31 (work in progress),
May 2022.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
11.2. Informative References [RFC9300] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos, Ed., "The Locator/ID Separation Protocol
(LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022,
<https://www.rfc-editor.org/info/rfc9300>.
[I-D.ietf-lisp-introduction] [RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Cabellos-Aparicio, A. and D. Saucez, "An Architectural Ed., "Locator/ID Separation Protocol (LISP) Control
Introduction to the Locator/ID Separation Protocol Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
(LISP)", draft-ietf-lisp-introduction-15 (work in <https://www.rfc-editor.org/info/rfc9301>.
progress), September 2021.
11.2. Informative References
[RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982, [RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
DOI 10.17487/RFC1982, August 1996, DOI 10.17487/RFC1982, August 1996,
<https://www.rfc-editor.org/info/rfc1982>. <https://www.rfc-editor.org/info/rfc1982>.
[RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
"Interworking between Locator/ID Separation Protocol "Interworking between Locator/ID Separation Protocol
(LISP) and Non-LISP Sites", RFC 6832, (LISP) and Non-LISP Sites", RFC 6832,
DOI 10.17487/RFC6832, January 2013, DOI 10.17487/RFC6832, January 2013,
<https://www.rfc-editor.org/info/rfc6832>. <https://www.rfc-editor.org/info/rfc6832>.
skipping to change at page 14, line 5 skipping to change at line 570
[RFC6834] Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID [RFC6834] Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Map-Versioning", RFC 6834, Separation Protocol (LISP) Map-Versioning", RFC 6834,
DOI 10.17487/RFC6834, January 2013, DOI 10.17487/RFC6834, January 2013,
<https://www.rfc-editor.org/info/rfc6834>. <https://www.rfc-editor.org/info/rfc6834>.
[RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID [RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Threat Analysis", RFC 7835, Separation Protocol (LISP) Threat Analysis", RFC 7835,
DOI 10.17487/RFC7835, April 2016, DOI 10.17487/RFC7835, April 2016,
<https://www.rfc-editor.org/info/rfc7835>. <https://www.rfc-editor.org/info/rfc7835>.
[RFC9299] Cabellos, A. and D. Saucez, Ed., "An Architectural
Introduction to the Locator/ID Separation Protocol
(LISP)", RFC 9299, DOI 10.17487/RFC9299, October 2022,
<https://www.rfc-editor.org/info/rfc9299>.
Appendix A. Benefits and Case Studies for Map-Versioning Appendix A. 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 uses of Map-Versioning. Security observations are aspects and uses of Map-Versioning. Security observations are
grouped in Section 8. grouped in Section 8.
A.1. Map-Versioning and Unidirectional Traffic A.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 Map-
Version numbers, for both source and destination mappings. This can Version numbers for both source and destination mappings. This can
raise the question on what will happen in the case of unidirectional raise the question on what will happen in the case of unidirectional
flows, for instance, in the case presented in Figure 4, since the flows, for instance, in the case presented in Figure 4, since the
LISP specifications do not mandate that the ETR have a mapping from LISP specifications do not mandate that the ETR have a mapping from
the source EID. the source EID.
+-----------------+ +-----------------+ +-----------------+ +-----------------+
| Domain A | | Domain B | | Domain A | | Domain B |
| +---------+ +---------+ | | +---------+ +---------+ |
| | ITR A |----------->| ETR B | | | | ITR A |----------->| ETR B | |
| +---------+ +---------+ | | +---------+ +---------+ |
| | | | | | | |
+-----------------+ +-----------------+ +-----------------+ +-----------------+
Figure 4: Unidirectional traffic between LISP domains. Figure 4: Unidirectional Traffic between LISP Domains
An ITR is able to put both the source and destination version numbers An ITR is able to put both the source and destination version numbers
in the LISP-specific header since the Source Map-Version number is in in the LISP-specific header since the Source Map-Version number is in
its database while the Destination Map-Version number is in its its database, while the Dest Map-Version number is in its cache.
cache.
The ETR checks only the Dest Map-Version number, ignoring the Source The ETR checks only the Dest Map-Version number, ignoring the Source
Map-Version number as specified in the final sentence of Section 7.2, Map-Version number as specified in the final sentence of Section 7.2.
ignoring the Source Map-Version number.
A.2. Map-Versioning and Interworking A.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 [RFC6832]. LISP interworking and non-LISP sites as defined in [RFC6832]. LISP interworking
defines three techniques to allow communication LISP sites and non- defines three techniques to allow communication LISP sites and non-
LISP sites, namely: Proxy-ITR, LISP-NAT, and Proxy-ETR. The LISP sites, namely: Proxy-ITR, LISP-NAT, and Proxy-ETR. The
following text describes how Map-Versioning relates to these three following text describes how Map-Versioning relates to these three
mechanisms. mechanisms.
A.2.1. Map-Versioning and Proxy-ITRs A.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 5). This case is very of the ETRs of the LISP site (cf. Figure 5). This case is very
similar to the unidirectional traffic case described in Appendix A.1; similar to the unidirectional traffic case described in Appendix A.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 5: Unidirectional traffic from non-LISP domain to LISP domain. Figure 5: 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 encapsulates packets arriving from the non-LISP site, since it just encapsulates packets arriving from the non-LISP site,
and thus cannot provide a Source Map-Version. In this case, the and thus cannot provide a Source Map-Version. In this case, the
proxy-ITR will just put the Null Map-Version value as the Source Map- Proxy-ITR will just put the Null Map-Version value as the Source Map-
Version number, while the receiving ETR will ignore the field. Version number, while the receiving ETR will ignore the field.
With this setup, LISP Domain A is able to check whether the PITR is With this setup, LISP Domain A is able to check whether the PITR is
using the latest mapping. The Proxy ITR will put in the Dest Map- using the latest mapping. In the Dest Map-Version Number of the
Version Number, of the LISP-specific header, the version number of LISP-specific header, the Proxy-ITR will put the version number of
the mapping it is using for encapsulation, the ETR A can use such the mapping it is using for encapsulation; the ETR A can use such
value as defined in Section 7.1. value as defined in Section 7.1.
A.2.2. Map-Versioning and LISP-NAT A.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 non-
routable EIDs to routable EIDs and does not involve any form of 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.
A.2.3. Map-Versioning and Proxy-ETRs A.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 non-
LISP site (cf. Figure 6). One of the main reasons to deploy PETRs LISP site (cf. Figure 6). One of the main reasons to deploy PETRs
is to bypass Unicast Reverse Path Forwarding checks on the domain. is to bypass Unicast Reverse Path Forwarding checks on the domain.
+----------+ +-------------+ +----------+ +-------------+
| LISP | | non-LISP | | LISP | | non-LISP |
| Domain A | | Domain B | | Domain A | | Domain B |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | ITR A |------->| Proxy ETR |------->| | | | ITR A |------->| Proxy-ETR |------->| |
| +-------+ +-----------+ | | | +-------+ +-----------+ | |
| | | | | | | |
+----------+ +-------------+ +----------+ +-------------+
Figure 6: Unidirectional traffic from LISP domain to non-LISP domain. Figure 6: 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 the LISP site. In this case, the ITR can packets arriving from the LISP site. In this case, the ITR can
interchangeably put a Map-Version value or the Null Map-Version value interchangeably put a Map-Version value or the Null Map-Version value
as the Dest Map-Version number since the receiving Proxy-ETR will as the Dest Map-Version number, since the receiving Proxy-ETR will
ignore the field. ignore the field.
With this setup, the Proxy-ETR, by looking at the Source Map-Version With this setup, the Proxy-ETR, by looking at the Source Map-Version
Number, is able to check whether the mapping of the source EID has Number, is able to check whether the mapping of the source EID has
changed. This is useful to perform source RLOC validation. In the changed. This is useful to perform source RLOC validation. In the
example above, traffic coming from LISP domain has to be LISP- example above, traffic coming from the LISP domain has to be LISP
encapsulated with a source address being an RLOC of the domain. The encapsulated with a source address being an RLOC of the domain. The
Proxy ETR can retrieve the mapping associated to the LISP domain and Proxy-ETR can retrieve the mapping associated to the LISP domain and
check if incoming LISP-encapsulated traffic is arriving from a valid check if incoming LISP-encapsulated traffic is arriving from a valid
RLOC. A change in the RLOC set that can be used as source addresses RLOC. A change in the RLOC-Set that can be used as source addresses
can be signaled via the version number, with the Proxy ETR able to can be signaled via the version number, with the Proxy-ETR able to
request the latest mapping if necessary as described in Section 7.2. request the latest mapping if necessary as described in Section 7.2.
A.3. RLOC Shutdown/Withdraw A.3. RLOC Shutdown/Withdraw
Map-Versioning can also be used to perform a graceful shutdown or Map-Versioning can also be used to perform a graceful shutdown or to
withdraw of a specific RLOC. This is achieved by simply issuing a withdraw a specific RLOC. This is achieved by simply issuing a new
new mapping, with an updated Map-Version number where the specific mapping, with an updated Map-Version number where the specific RLOC
RLOC to be shut down is withdrawn or announced as unreachable (via to be shut down is withdrawn or announced as unreachable (via the
the R bit in the Map Record; see [I-D.ietf-lisp-rfc6833bis]), but R-bit in the Map Record; see [RFC9301]) but without actually turning
without actually turning it off. it off.
Upon updating the mapping, the RLOC will receive less and less Upon updating the mapping, the RLOC will receive less and less
traffic because remote LISP sites will request the updated mapping traffic because remote LISP sites will request the updated mapping
and see that it is disabled. At least one TTL, plus a little time and see that it is disabled. At least one TTL, plus a little time
for traffic transit, after the mapping is updated, it should be safe for traffic transit, after the mapping is updated, it should be safe
to shut down the RLOC gracefully, because all sites actively using to shut down the RLOC gracefully, because all sites actively using
the mapping should have been updated. the mapping should have been updated.
Note that a change in ETR for a flow can result in the re-ordering of Note that a change in ETR for a flow can result in the reordering of
the packet in the flow just as any other routing change could cause the packet in the flow just as any other routing change could cause
re-ordering. reordering.
Authors' Addresses Authors' Addresses
Luigi Iannone Luigi Iannone
Huawei Technologies France Huawei Technologies France
Email: luigi.iannone@huawei.com
EMail: luigi.iannone@huawei.com
Damien Saucez Damien Saucez
INRIA Inria
2004 route des Lucioles - BP 93
EMail: damien.saucez@inria.fr Sophia Antipolis
France
Email: damien.saucez@inria.fr
Olivier Bonaventure Olivier Bonaventure
Universite catholique de Louvain Universite catholique de Louvain
Email: olivier.bonaventure@uclouvain.be
EMail: olivier.bonaventure@uclouvain.be
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