A Decent LISP Mapping System (LISP-Decent)
draft-farinacci-lisp-decent-21
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Dino Farinacci , Colin Cantrell | ||
| Last updated | 2025-11-04 (Latest revision 2025-11-03) | ||
| RFC stream | Independent Submission | ||
| Intended RFC status | Informational | ||
| Formats | |||
| IETF conflict review | conflict-review-farinacci-lisp-decent | ||
| Stream | ISE state | Sent to the RFC Editor | |
| Consensus boilerplate | Unknown | ||
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| Shepherd write-up | Show Last changed 2025-07-19 | ||
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| Send notices to | (None) | ||
| IANA | IANA review state | Version Changed - Review Needed | |
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| RFC Editor | RFC Editor state | EDIT | |
| Details |
draft-farinacci-lisp-decent-21
Network Working Group D. Farinacci
Internet-Draft lispers.net
Intended status: Informational C. Cantrell
Expires: 7 May 2026 Nexus
3 November 2025
A Decent LISP Mapping System (LISP-Decent)
draft-farinacci-lisp-decent-21
Abstract
This draft describes how the LISP mapping system can be distributed
for scale, decentralized for management and maintain trust among
data-plane nodes. The intended status for this document is
Informational RFC and should be used by LISP-Decent implementations
to interoperate with each other.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 7 May 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Decent-Push Based Mapping System . . . . . . . . . . . . . . 6
4.1. Components of a Decent-Pushed Based LISP-Decent xTR . . . 7
4.2. Implementation Considerations . . . . . . . . . . . . . . 8
4.3. Configuration and Authentication . . . . . . . . . . . . 8
4.4. Core Seed-Group . . . . . . . . . . . . . . . . . . . . . 8
5. Decent-Pull Based Mapping System . . . . . . . . . . . . . . 11
5.1. Components of a Decent-Pulled Based LISP-Decent xTR . . . 11
5.2. Deployment Example . . . . . . . . . . . . . . . . . . . 12
5.3. Management Considerations . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 16
Appendix B. Document Change Log . . . . . . . . . . . . . . . . 16
B.1. Changes to draft-farinacci-lisp-decent-21 . . . . . . . . 16
B.2. Changes to draft-farinacci-lisp-decent-20 . . . . . . . . 17
B.3. Changes to draft-farinacci-lisp-decent-19 . . . . . . . . 17
B.4. Changes to draft-farinacci-lisp-decent-18 . . . . . . . . 17
B.5. Changes to draft-farinacci-lisp-decent-17 . . . . . . . . 17
B.6. Changes to draft-farinacci-lisp-decent-16 . . . . . . . . 17
B.7. Changes to draft-farinacci-lisp-decent-15 . . . . . . . . 17
B.8. Changes to draft-farinacci-lisp-decent-14 . . . . . . . . 18
B.9. Changes to draft-farinacci-lisp-decent-13 . . . . . . . . 18
B.10. Changes to draft-farinacci-lisp-decent-12 . . . . . . . . 18
B.11. Changes to draft-farinacci-lisp-decent-11 . . . . . . . . 18
B.12. Changes to draft-farinacci-lisp-decent-10 . . . . . . . . 18
B.13. Changes to draft-farinacci-lisp-decent-09 . . . . . . . . 18
B.14. Changes to draft-farinacci-lisp-decent-08 . . . . . . . . 18
B.15. Changes to draft-farinacci-lisp-decent-07 . . . . . . . . 18
B.16. Changes to draft-farinacci-lisp-decent-06 . . . . . . . . 19
B.17. Changes to draft-farinacci-lisp-decent-05 . . . . . . . . 19
B.18. Changes to draft-farinacci-lisp-decent-04 . . . . . . . . 19
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B.19. Changes to draft-farinacci-lisp-decent-03 . . . . . . . . 19
B.20. Changes to draft-farinacci-lisp-decent-02 . . . . . . . . 19
B.21. Changes to draft-farinacci-lisp-decent-01 . . . . . . . . 20
B.22. Changes to draft-farinacci-lisp-decent-00 . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
The LISP architecture and protocols [RFC9300] introduces two new
numbering spaces, Endpoint Identifiers (EIDs) and Routing Locators
(RLOCs) that are intended to provide overlay network functionality.
To map from EID to a set of RLOCs, a control-plane mapping system is
used [RFC6836] [RFC8111]. These mapping systems are naturally
distributed in their deployment for scalability but are centrally
managed by a third-party entity, namely a Mapping System Provider
(MSP). The entities that use the mapping system, such as data-plane
LISP Tunnel Routers (xTRs), depend on and trust the MSP. They do not
participate in the mapping system other than to register and retrieve
information [RFC9301].
This document introduces a Decentralized Mapping System (DMS) so the
xTRs can participate in the mapping system as well as use it. They
can trust each other rather than rely on third-party infrastructure.
The xTRs act as Map-Servers to maintain distributed state for scale
and reduce the attack surface. The trust relationships between the
xTRs are established through authentication and authorization
procedures in [RFC9301] and [I-D.ietf-lisp-ecdsa-auth].
This design was first introduced to the LISP WG in January 2018. It
was presented in London March 2018 [MAR-WG-PRESO] and in Prague July
2019 [JUL-WG-PRESO]. This informational document is not a standard
and did not reach community consensus to make it IETF LISP working
group document.
The intended audience for this specification are protocol development
engineers who would implement this specification in products as well
network engineers who deploy the technology in operational
environments.
This design does not conflict with those designs or contradicts any
other LISP design principles produced by the working group. This
solution makes no fundamental LISP protocol changes and adheres to
the specifications documented in [RFC9301].
By the nature of this work, this document uses IP addresses as
examples. They should not be copied or used outside of a lab
environment. Deployments should use addresses appropriate for their
environment.
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2. Definition of Terms
Mapping System Provider (MSP): infrastructure service that deploys
LISP Map-Resolvers and Map-Servers [RFC9301] and possibly LISP-ALT
nodes [RFC6836] or LISP-DDT nodes [RFC8111]. ALT-nodes and DDT-
nodes use different algorithms for connecting together Map-
Resolvers and Map-Servers. The MSP can be managed by a separate
organization other than the one that manages xTRs. This model
provides a business separation between who manages and responsible
for the control-plane versus who manages the data-plane overlay
service.
Decentralized Mapping System (DMS): a mapping system entity that is
managed by the xTR nodes that use it and not third-party nodes/
operators. The xTRs themselves are part of the mapping system.
The state of the mapping system is fully distributed across xTRs,
decentralized, and the trust relies on the xTRs that use and
participate in their own mapping system.
Decent-Pull Based Mapping System: the mapping system is pull-based
meaning that xTRs will lookup and register mappings by algorithmic
transformation to locate which Map-Resolvers and Map-Servers are
used. It is required that the lookup and registration uses a
consistent algorithmic transformation function. Map-Registers are
sent to specific Map-Servers. Map-Requests are considered
external lookups when sent to Map-Resolvers on xTRs that do not
participate in the mapping system and the Map-Requests are
considered internal lookups when they are sent to Map-Resolvers on
xTRs that do participate in the mapping system.
Modulus Value: this value is used in the Pull-Based Mapping System.
It defines the number of map-server sets used for the mapping
system. The modulus value is used to produce a Name Index used
for a DNS lookup. The Modulus Value is chosen based on the
horizontal scale-out width of the map-server cluster the network
operator chooses to deploy.
Name Index: this index value <index> is used in the Pull-Based
Mapping System. For a mapping system that is configured with a
map-server set of DNS names in the form of <name>.example.com, the
name index is prepended to <name> to form the lookup name
<index>.<name>.example.com. If the Modulus Value is 8, then the
name indexes are 0 through 7.
Hash Mask: The Hash Mask is used in the Pull-Based Mapping System.
It is a mask value with 1 bits left justified. The mask is used
to select what high-order bits of an EID-prefix are used in the
hash function.
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Decent-Push Based Mapping System: the mapping system is push-based
meaning that xTRs will push registrations via IP multicast to a
group of Map-Servers and do local lookups acting as their own Map-
Resolvers.
Replication List Entry (RLE): an RLOC-record format that contains a
list of RLOCs that an Ingress Tunnel Router (ITR) replicates
multicast packets on a multicast overlay. The RLE format is
specified in [RFC8060]. RLEs are used with the Decent-Pushed
Based mapping system.
Group Address EID: an EID-record format that contains IPv4
(0.0.0.0/0, G) or IPv6 (0::/0, G) state. This state is encoded as
a Multicast Info Type LCAF specified in [RFC8060]. Members of a
seed-group send Map-Registers for (0.0.0.0/0, G) or (0::/0, G)
with an RLOC-record that RLE encodes its RLOC address. Details
are specified in [RFC8378].
Seed-Group: a set of Map-Servers joined to a multicast group for the
Decent-Push Based Mapping system or are mapped by DNS names in a
Pull-Based Mapping System. A core seed-group is used to bootstrap
a set of LISP-Decent xTRs so they can learn about each other and
use each other's mapping system service. A seed-group can be
pull-based to bootstrap the Decent-Push based mapping system.
That is, a set of DNS mapped map-servers can be used to join the
mapping system's IP multicast group.
3. Overview
The clients of the Decentralized Mapping System (DMS) are also the
providers of mapping state, see [RFC9301] for formal details.
Clients are typically Egress Tunnel Routers (ETRs) that Map-Register
EID-to-RLOC mapping state to the mapping database system. ITRs are
clients in that they send Map-Requests to the mapping database system
to obtain EID-to-RLOC mappings that are cached for data-plane use.
When xTRs participate in a DMS, they are also acting as Map-Resolvers
and Map-Servers using the protocol machinery defined in LISP control-
plane specifications [RFC9301], [RFC9303], and
[I-D.ietf-lisp-ecdsa-auth]. The xTRs are not required to run the
database mapping transport system protocols specified in [RFC6836] or
[RFC8111].
This document will describe two decentralized and distributed mapping
system mechanisms. A Decent-Push Based Mapping System uses IP
multicast so xTRs can find each other by locally joining an IP
multicast group. A Decent-Pull Based Mapping System uses DNS with an
algorithmic transformation function so xTRs can find each other.
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The document proposes two approaches to provide state/bandwidth, ease
of configurability, and robustness/complexity tradeoffs. When the
Decent-Push Based approach is used there is less messaging involved.
xTRs can multicast a single Map-Register message which goes to all
Map-Servers joined to the multicast group. When Map-Servers are
added to or removed from the Map-Server cluster group, the mapping
system updates quickly with little human intervention. In the push
model, all mapping state is stored in all Map-Servers so there is
robustness achieved through redundancy. However, this requires a
multicast underlay in nodes between all xTRs and Map-Servers. When a
multicast underlay is not available, the Decent-Pull Based approach
can be used with the help of the DNS system. This approach uses less
state overall among the Map-Servers (they each have different mapping
system state) and the ITRs know which Map-Server to ask by using the
hashing techniques described later in this document.
This document does not describe any compatibility with other mapping
systems. The design is intentional all xTRs and Map-Servers support
this specification. Moreover, all xTRs and Map-Servers MUST support
either the Pull-Based or Push-Based algorithms. They cannot be
mixed. When both are used, they are completely discrete mapping
systems just like they would be using one of the LISP Working Group
mapping system designs. An implementation can decide to implement
only the Pull-Based approach or the Push-Based approach and still be
compliant with this specification.
4. Decent-Push Based Mapping System
The xTRs are organized in a mapping-system group. The group is
identified by an IPv4 or IPv6 multicast group address or using a
Decent-Pull based approach described in Section 5. When using
multicast, the xTRs join the same multicast group and receive LISP
control-plane messages addressed to the group. Messages sent to the
multicast group are distributed when the underlay network supports IP
multicast [RFC6831] or via the overlay multicast mechanism described
in [RFC8378]. When overlay multicast is used and LISP Map-Register
messages are sent to the group, they are LISP data encapsulated with
a instance-ID set to 0xffffff in the LISP header. The inner header
of the encapsulated packet has the destination address set to the
multicast group address and the outer header that is prepended has
the destination address set to the RLOC of mapping system group
member. The members of the mapping system group are kept in the LISP
data-plane map-cache so packets for the group can be replicated to
each member RLOC.
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All xTRs in a mapping system group will store the same registered
mappings and maintain the state as Map-Servers normally do. The
members are not only receivers of the multicast group but also send
packets to the group.
4.1. Components of a Decent-Pushed Based LISP-Decent xTR
When an xTR is configured to be a LISP-Decent xTR (or PxTR
[RFC6832]), it runs the ITR, ETR, Map-Resolver, and Map-Server LISP
network functions.
The following diagram shows 3 LISP-Decent xTRs joined to mapping
system group 233.252.1.1. When the ETR function of xTR1 originates a
Map-Register, it is sent to all xTRs (including itself) synchronizing
all 3 Map-Servers in xTR1, xTR2, and xTR3. The ITR function can
populate its map-cache by sending a Map-Request locally to its Map-
Resolver so it can replicate packets to each RLOC for EID
233.252.1.1.
In this document, there is no special meaning for the multicast group
address 233.252.1.1. It is used for example purposes only.
xTR1
Map-Request +--------------------+
(always local) | +-----+ +-----+ |
+---------------| ITR | | ETR |-------------+
| | +-----+ +-----+ | |
| | | | Map-Register to EID
| | +-------+ | | 233.252.1.1 encapsulated to
+------------------>| MR/MS |<---------------+ RLOCs xTR1, xTR2, and xTR3
| +-------+ | |
+--------------------+ |
|
+--------------------+------------+
| |
| |
+----------v---------+ +----------v---------+
| +--------+ | | +--------+ |
| | MR/MS | | | | MR/MS | |
| +--------+ | | +--------+ |
| +-----+ +-----+ | | +-----+ +-----+ |
| | ITR | | ETR | | | | ITR | | ETR | |
| +-----+ +-----+ | | +-----+ +-----+ |
+--------------------+ +--------------------+
xTR2 xTR3
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Note if any external xTR would like to use a Map-Resolver from the
mapping system group, it only needs to have one of the LISP-Decent
Map-Resolvers configured. By doing a looking to this Map-Resolver
for EID 233.252.1.1, the external xTR could get the complete list of
members for the mapping system group.
For future study, an external xTR could multicast the Map-Request to
233.252.1.1 and either one of the LISP-Decent Map-Resolvers would
return a Map-Reply or the external xTR is prepared to receive
multiple Map-Replies.
4.2. Implementation Considerations
There are no LISP protocol changes required to support the Decent-
Push based LISP-Decent set of procedures. An implementation that
sends Map-Register messages to a multicast group versus a specific
Map-Server unicast address MUST change to call the data-plane
component so the ITR functionality in the node can encapsulate the
Map-Register as a unicast packet to each member of the mapping system
group.
An ITR SHOULD lookup its mapping system group address periodically to
determine if the membership has changed. The lookup interval is a
configuration parameter only needed when when the ITR does not use
the PubSub capability documented in [RFC9437] to be notified when a
new member joins or leaves the multicast group. When PubSub is not
used, there needs to be coordination (via configuration management)
among all xTRs so they rendezvous roughly at the same time and to the
same group address.
4.3. Configuration and Authentication
When xTRs are joined to a multicast group, they MUST have their site
registration configuration consistent. Any policy or authentication
key material MUST be configured consistently among all members. When
[I-D.ietf-lisp-ecdsa-auth] is used to sign Map-Register messages,
public-keys can be registered to the mapping system group using the
site authentication key mentioned above or using a different
authentication key from the one used for registering EID records. An
out-of-band registration controller, like an ETR dedicated for this
function, can send Map-Register messages for public-key encoded EIDs.
4.4. Core Seed-Group
A core seed-group can be discovered using a multicast group in a
Decent-Push based system or a Map-Server set of DNS names in a
Decent-Pull based system (see Section 5 for details).
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When using multicast for the mapping system group, a core seed-group
multicast group address can be preconfigured to bootstrap the
decentralized mapping system. The group address (or DNS name that
maps to a group address) can be explicitly configured in a few xTRs
to start building up the registrations. Then as other xTRs come
online, they can add themselves to the core seed-group by joining the
seed-group multicast group.
Alternatively or additionally, new xTRs can join a new mapping system
multicast group to form another layer of a decentralized mapping
system. The group address and members of this new layer seed-group
would be registered to the core seed-group address and stored in the
core seed-group mapping system. Note each mapping system layer could
have a specific function or a specific circle of trust.
This multi-layer mapping system can be illustrated:
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____________ -----------
/ core \ 233.252.2.2 / layer-1 \
| seed-group | ----------> | I |
| 233.252.1.1 | | / \ |
\____________/ | J---K |
| \___________/
| 233.252.3.3
|
v
---------
/ layer-2 \
| X |
| / \ |
| Y---Z |
\_________/
Configured in xTRs A, B, and C (they make up the core seed-group):
233.252.1.1 -> RLE: A, B, C
core seed-group DMS, mapping state in A, B, and C:
233.252.2.2 -> RLE: I, J, K
233.252.3.3 -> RLE: X, Y, Z
layer-1 seed-group DMS (inter-continental), mapping state in I, J, K:
EID1 -> RLOCs: i(1), j(2)
...
EIDn -> RLOCs: i(n), j(n)
layer-2 seed-group DMS (intra-continental), mapping sate in X, Y, Z::
EIDa -> RLOCs: x(1), y(2)
...
EIDz -> RLOCs: x(n), y(n)
The core seed-group multicast address 233.252.1.1 is configured in
xTRs A, B and C so when each of them send Map-Register messages, they
would all be able to maintain synchronized mapping state. Any EID
can be registered to this DMS but in this example, seed-group
multicast group EIDs are being registered only to find other mapping
system groups.
For example, lets say that xTR I boots up and it wants to find its
other peers in its mapping system group 233.252.2.2. Group address
233.252.2.2 is configured so xTR I knows what group to join for its
mapping system group. But xTR I needs a mapping system to register
to, so the core seed-group is used and available to receive Map-
Registers. The other xTRs J and K in the mapping system group do the
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same so when any of I, J or K needs to register EIDs, they can now
send their Map-Register messages to group 233.252.2.2. Examples of
EIDs being register are EID1 through EIDn shown above.
When Map-Registers are sent to group 233.252.2.2, they are
encapsulated by the LISP data-plane by looking up EID 233.252.2.2 in
the core seed-group mapping system. For the map-cache entry to be
populated for 233.252.2.2, the data-plane MUST send a Map-Request so
the RLOCs I, J, and K are cached for replication. To use the core
seed-group mapping system, the data-plane MUST know of at least one
of the RLOCs A, B, and/or C.
5. Decent-Pull Based Mapping System
5.1. Components of a Decent-Pulled Based LISP-Decent xTR
When an xTR is configured to be a LISP-Decent xTR (or PxTR
[RFC6832]), it runs the ITR, ETR, Map-Resolver, and Map-Server LISP
network functions.
Unlike the Decent-Push Based Mapping System, the xTRs do not need to
be organized by joining a multicast group. In a Decent-Pull Based
Mapping System, a hash function over an EID is used to identify which
xTR is used as the Map-Resolver and Map-Server. The Domain Name
System (DNS) [RFC1034] [RFC1035] is used as a resource discovery
mechanism.
The RLOC addresses of the xTRs will be A and AAAA records for DNS
names that map algorithmically from the hash of the EID. A SHA-256
hash function [RFC6234] over the following ASCII formatted EID string
is used:
[<iid>]<eid>/<ml>
[<iid>]<group>/<gml>-<source>/<sml>
In this section, where you see angle brackets, they are replaced with
values in ASCII characters. For example, a unicast EID of 1.1.1.1 in
instance-id 11 would be encoded as a string "[11]1.1.1.1/32".
Where <iid> is the instance-ID and <eid> is the EID of any EID-type
defined in [RFC8060]. And then the Modulus Value <mv> is used to
produce the Name Index <index> used to build the DNS lookup name:
eid = "[<iid>]<eid>/<ml>"
index = hash.sha_256(eid) MOD mv
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The Hash Mask is used to select what bits are used in the SHA-256
hash function. This is required to support longest match lookups in
the mapping system. The same map-server set needs to be selected
when looking up a more-specific EID found in the Map-Request message
with one that could match a less-specific EID-prefix registered and
found in the Map-Register message. For example, if an EID-prefix
[0]240.0.1.0/24 is registered to the mapping system and EID
[0]240.0.1.1/32 is looked up to match the registered prefix, a Hash
Mask of 8 bytes can be used to AND both the /32 or /24 entries to
produce the same hash string bits of "[0]240.0".
For (*,G) and (S,G) multicast entries in the mapping system, the hash
strings are:
sg-eid = "[<iid>]<group>/<gml>-<source>/<sml>"
index = hash.sha_256(sg-eid) MOD mv
starg-eid = "[<iid>]<group>/<gml>-0.0.0.0/0"
index = hash.sha_256(starg-eid) MOD mv
The Hash Mask MUST include the string "[<iid>]<group>" and not string
<source>. So when looking up [0](2.2.2.2, 233.252.1.1) that will
match a (*, 233.252.1.1/32), the hash string produced with a Hash
Mask of 12 bytes is "[0]233.252.1.1".
When the <index> is computed from a unicast or multicast EID, the DNS
lookup name becomes:
<index>.map-server.example.com
When an xTR does a DNS lookup on the lookup name, it will send Map-
Register messages to all A and AAAA records for EID registrations.
For Map-Request messages, xTRs MAY round robin EID lookup requests
among the A and AAAA records.
5.2. Deployment Example
Here is an example deployment of a Decent-Pull based model. Let's
say 4 map-server sets are provisioned for the mapping system.
Therefore 4 distinct DNS names are allocated and a Modulus Value 4 is
used. Each DNS name is allocated Name Index 0 through 3:
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0.map-server.lispers.net
1.map-server.lispers.net
2.map-server.lispers.net
3.map-server.lispers.net
The A records for each name can be assigned as:
0.map-server.lispers.net:
A <rloc1-att>
A <rloc2-verizon>
1.map-server.lispers.net:
A <rloc1-bt>
A <rloc2-dt>
2.map-server.lispers.net:
A <rloc1-cn>
A <rloc2-kr>
3.map-server.lispers.net:
A <rloc1-au>
A <rloc2-nz>
When an xTR wants to register "[1000]fd::2222", it hashes the EID
string to produce, for example, hash value 0x66. Using the modulus
value 4 (0x67 & 0x3) produces index 0x3, so the DNS name 3.map-
server.lispers.net is used and a Map-Register is sent to <rloc1-au>
and <rloc2-nz>.
Note that the Decent-Pull based method can be used for a core seed-
group for bootstrapping a Decent-Push based mapping system where
multicast groups are registered.
5.3. Management Considerations
An implementation SHOULD do periodic DNS lookups to determine if A
records have changed for a DNS entry. This is a configuration
parameter the network operator selects. This specification makes no
recommendation for an interval value.
When xTRs derive Map-Resolver and Map-Server names from the DNS, they
need to use the same Modulus Value otherwise some xTRs will lookup
EIDs to the wrong place they were registered.
The Modulus Value can be configured or pushed to the LISP-Decent
xTRs. A future version of this document will describe a push
mechanism so all xTRs use a consistent modulus value.
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6. Security Considerations
Refer to the Security Considerations section of [RFC9301] for a
complete list of security mechanisms as well as pointers to threat
analysis drafts.
It is recommended, where DNS is deployed for the Pull-Based Mapping
System, DNSSEC [RFC9364] be used to add more security to the DNS
lookup system.
Replay attacks, spoofing, and trust relationships are discussed in
detail in [RFC9301] and [RFC9303].
7. IANA Considerations
At this time there are no specific requests for IANA.
8. References
8.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The
Locator/ID Separation Protocol (LISP) for Multicast
Environments", RFC 6831, DOI 10.17487/RFC6831, January
2013, <https://www.rfc-editor.org/info/rfc6831>.
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[RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
"Interworking between Locator/ID Separation Protocol
(LISP) and Non-LISP Sites", RFC 6832,
DOI 10.17487/RFC6832, January 2013,
<https://www.rfc-editor.org/info/rfc6832>.
[RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol Alternative Logical
Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,
January 2013, <https://www.rfc-editor.org/info/rfc6836>.
[RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060,
February 2017, <https://www.rfc-editor.org/info/rfc8060>.
[RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A.
Smirnov, "Locator/ID Separation Protocol Delegated
Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111,
May 2017, <https://www.rfc-editor.org/info/rfc8111>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID
Separation Protocol (LISP) Multicast", RFC 8378,
DOI 10.17487/RFC8378, May 2018,
<https://www.rfc-editor.org/info/rfc8378>.
[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>.
[RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Ed., "Locator/ID Separation Protocol (LISP) Control
Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
<https://www.rfc-editor.org/info/rfc9301>.
[RFC9303] Maino, F., Ermagan, V., Cabellos, A., and D. Saucez,
"Locator/ID Separation Protocol Security (LISP-SEC)",
RFC 9303, DOI 10.17487/RFC9303, October 2022,
<https://www.rfc-editor.org/info/rfc9303>.
[RFC9364] Hoffman, P., "DNS Security Extensions (DNSSEC)", BCP 237,
RFC 9364, DOI 10.17487/RFC9364, February 2023,
<https://www.rfc-editor.org/info/rfc9364>.
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[RFC9437] Rodriguez-Natal, A., Ermagan, V., Cabellos, A., Barkai,
S., and M. Boucadair, "Publish/Subscribe Functionality for
the Locator/ID Separation Protocol (LISP)", RFC 9437,
DOI 10.17487/RFC9437, August 2023,
<https://www.rfc-editor.org/info/rfc9437>.
8.2. Informative References
[I-D.ietf-lisp-ecdsa-auth]
Farinacci, D. and E. Nordmark, "LISP Control-Plane ECDSA
Authentication and Authorization", Work in Progress,
Internet-Draft, draft-ietf-lisp-ecdsa-auth-15, 4 August
2025, <https://datatracker.ietf.org/doc/html/draft-ietf-
lisp-ecdsa-auth-15>.
[JUL-WG-PRESO]
Farinacci, D., "LISP WG July 2019 Presentation",
https://www.dropbox.com/scl/fi/3z7uichvi8x9940xlz6pm/lisp-
decent-ietf-prague.pdf?rlkey=4v1lup23zc0j6kpicqfr2npro,
July 2019.
[MAR-WG-PRESO]
Farinacci, D., "LISP WG March 2018 Presentation",
https://www.dropbox.com/scl/fi/eqoqestxsoc4w7zh2t8dr/lisp-
decent-ietf-london.pdf?rlkey=dw0c96xtbi4c5074a2i90g4qh,
March 2018.
Appendix A. Acknowledgments
The authors would like to thank the LISP WG for their review and
acceptance of this draft.
The authors would also like to give a special thanks to Roman
Shaposhnik for several discussions that occurred before the first
draft was published.
ISE Eliot Lear and Victor Moreno are appreciated for their efforts
proof reading the draft before Informational RFC publication.
Appendix B. Document Change Log
[RFC Editor: Please delete this section on publication as RFC.]
B.1. Changes to draft-farinacci-lisp-decent-21
* Posted November 2025.
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* Remove normative references to bis documents for RFC6831, RFC8378,
and RFC8060 but keep the original RFCs.
B.2. Changes to draft-farinacci-lisp-decent-20
* Posted October 2025.
* Made editorial changes suggested by Eliot.
B.3. Changes to draft-farinacci-lisp-decent-19
* Posted October 2025.
* Victor Moreno completed proof-read and submitted editorial
comments.
* Dino completed final proof-read.
* Updated references to latest working group drafts and RFCs.
B.4. Changes to draft-farinacci-lisp-decent-18
* Posted July 2025.
* Made suggested changes to reflect comments from Joel and Padma per
ISE (Eliot) distinguished review request. This should be final
review cycle.
B.5. Changes to draft-farinacci-lisp-decent-17
* Posted April 2025.
* Made suggested changes to reflect second review from ISE (Eliot
Lear).
B.6. Changes to draft-farinacci-lisp-decent-16
* Posted December 2024.
* Made suggested changes from ISE review.
B.7. Changes to draft-farinacci-lisp-decent-15
* Posted June 2024.
* Making draft an ISE submission as Informational RFC.
* Update references and document expiry timer.
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B.8. Changes to draft-farinacci-lisp-decent-14
* Posted April 2024.
* Update references and document expiry timer.
B.9. Changes to draft-farinacci-lisp-decent-13
* Posted October 2023.
* Make the general definitions of "pull-based" and "push-based" be
more specific to the way LISP-Decent uses them. Call them Decent-
Pull and Decent-Push.
B.10. Changes to draft-farinacci-lisp-decent-12
* Posted August 2023.
* Update references and document expiry timer.
B.11. Changes to draft-farinacci-lisp-decent-11
* Posted February 2023.
* Update references and document expiry timer.
B.12. Changes to draft-farinacci-lisp-decent-10
* Posted August 2022.
* Update references and document expiry timer.
B.13. Changes to draft-farinacci-lisp-decent-09
* Posted February 2022.
* Update references and document expiry timer.
B.14. Changes to draft-farinacci-lisp-decent-08
* Posted August 2021.
* Update references and document expiry timer.
B.15. Changes to draft-farinacci-lisp-decent-07
* Posted March 2021.
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* Update references and document expiry timer.
B.16. Changes to draft-farinacci-lisp-decent-06
* Posted September 2020.
* Update references and document expiry timer.
B.17. Changes to draft-farinacci-lisp-decent-05
* Posted March 2020.
* Update references and document expiry timer.
B.18. Changes to draft-farinacci-lisp-decent-04
* Posted September 2019.
* Update references and document expiry timer.
B.19. Changes to draft-farinacci-lisp-decent-03
* Posted March 2019.
* Introduce the Hash Mask which is used to grab common bits from a
registered prefix and a lookup prefix.
* Spec how multicast lookups are done in the pull-based mapping
system.
* Indicate the hash string includes the unicast EID mask-length and
multicast group and source mask-lengths.
B.20. Changes to draft-farinacci-lisp-decent-02
* Posted November 2018.
* Changed references from peer-group to seed-group to make the
algorithms in this document more like how blockchain networks
initialize the peer-to-peer network.
* Added pull mechanism to complement the push mechanism. The pull
mechanism could be used as a seed-group to bootstrap the push
mechanism.
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B.21. Changes to draft-farinacci-lisp-decent-01
* Posted July 2018.
* Document timer and reference update.
B.22. Changes to draft-farinacci-lisp-decent-00
* Initial draft posted January 2018.
Authors' Addresses
Dino Farinacci
lispers.net
San Jose, CA
United States of America
Email: farinacci@gmail.com
Colin Cantrell
Nexus
Tempe, AZ
United States of America
Email: colin@nexus.io
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