Network Working Group                                       D. Farinacci
Intended status: Experimental                                C. Cantrell
Expires: July 14, 2018                                             Nexus
                                                        January 10, 2018

               A Decent LISP Mapping System (LISP-Decent)


   This draft describes how the LISP mapping system designed to be
   distributed for scale can also be decentralized for management and

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on July 14, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definition of Terms . . . . . . . . . . . . . . . . . . . . .   2
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Components of a LISP-Decent xTR . . . . . . . . . . . . . . .   5
   5.  No LISP Protocol Changes  . . . . . . . . . . . . . . . . . .   6
   6.  Configuration and Authentication  . . . . . . . . . . . . . .   6
   7.  Core Peer-Group . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  10
   Appendix B.  Document Change Log  . . . . . . . . . . . . . . . .  10
     B.1.  Changes to draft-farinacci-lisp-decent  . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The LISP architecture and protocols [RFC6830] introduces two new
   numbering spaces, Endpoint Identifiers (EIDs) and Routing Locators
   (RLOCs) which is intended to provide overlay network functionality.
   To map from EID to a set or RLOCs, a control-plane mapping system are
   used [RFC6836] [RFC8111].  These mapping systems are distributed in
   nature 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 xTRs,
   depend on and trust the MSP.  They do not participate in the mapping
   system other than to register and retrieve information to/from the
   mapping system [RFC6833].

   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 reducing attack surface.

2.  Definition of Terms

   Decentralized Mapping System (DMS):  is a mapping system entity that
      is not third-party to the xTR nodes that use it.  The xTRs
      themselves are part of the mapping system.  The state of the
      mapping system is fully distributed, decentralized, and the trust
      relies on the xTRs that use and participate in their own mapping

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   Mapping System Provider (MSP):  is an infrastructure service that
      deploys LISP Map-Resolvers and Map-Servers [RFC6833] and possibly
      ALT-nodes [RFC6836] or DDT-nodes [RFC8111].  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 is responsible for the control-plane versus who
      manages the data-plane overlay service.

   Peer-Group:  is a set of Map-Servers which are joined to the same
      multicast group that send and receive Map-Register messages
      addressed to the multicast group.  Map-Resolvers can use the peer-
      group to resolve mappings by sending Map-Requests to the multicast
      group or to any member of the peer-group.  Map-Resolvers can do a
      mapping system lookup for the peer-group multicast address to
      obtain members of the peer-group.

   Core Peer-Group:  is a set of Map-Servers and Map-Resolvers who are
      joined to a multicast group to bootstrap a multi-layer
      decentralized mapping system.

   Replication List Entry (RLE):  is an RLOC-record format that contains
      a list of RLOCs that an ITR replicates multicast packets on a
      multicast overlay.  The RLE format is specified in [RFC8060].

   Group Address EID:  is an EID-record format that contains IPv4
      (, G) or IPv6 (0::/0, G) state.  This state is encoded as
      a Multicast Info Type LCAF specified in [RFC8060].  Members of a
      peer-group send Map-Registers for (, G) or (0::/0, G)
      with an RLOC-record that RLE encodes its RLOC address.  Details
      are specified in [I-D.ietf-lisp-signal-free-multicast].

3.  Overview

   The clients of the Decentralized Mapping System (DMS) are also the
   providers of mapping state.  Clients are typically 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 [RFC6833], [I-D.ietf-lisp-sec],
   and [I-D.farinacci-lisp-ecdsa-auth].  The xTRs are not required to
   run the database mapping transport system protocols specified in
   [RFC6836] or [RFC8111].

   The xTRs are organized in a peer-group.  The peer-group is identified
   by an IPv4 or IPv6 multicast group address.  The xTRs join the same
   multicast group and receive LISP control-plane messages addressed to

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   the group.  Messages sent to the multicast group are distributed when
   the underlay network supports IP multicast [RFC6831] or is achieved
   with the overlay multicast mechanism described in
   [I-D.ietf-lisp-signal-free-multicast].  When overlay multicast is
   used and LISP Map-Register messages are sent to a peer-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 peer-group multicast group address and
   the outer header that is prepended has the destination address set to
   the RLOC of peer-group member.  The members of the peer-group are
   kept in the LISP data-plane map-cache so packets for the peer-group
   can be replicated to each member RLOC.

   All xTRs in a peer-group will store the same registered mappings and
   maintain the state as Map-Servers normally do.  The peer-group
   members are not only receivers of the multicast group but also send
   packets to the group.

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4.  Components of a 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 peer-group  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

 Map-Request    +--------------------+
(always local)  |  +-----+  +-----+  |
   +---------------| ITR |  | ETR |-------------+
   |            |  +-----+  +-----+  |          |
   |            |                    |          |    Map-Register to EID
   |            |      +-------+     |          | encapsulated to
   +------------------>| MR/MS |<---------------+  RLOCs xTR1, xTR2, and xTR3
                |      +-------+     |          |
                +--------------------+          |
                           |                                 |
                           |                                 |
                +----------v---------+            +----------v---------+
                |     +--------+     |            |     +--------+     |
                |     |  MR/MS |     |            |     |  MR/MS |     |
                |     +--------+     |            |     +--------+     |
                |  +-----+  +-----+  |            |  +-----+  +-----+  |
                |  | ITR |  | ETR |  |            |  | ITR |  | ETR |  |
                |  +-----+  +-----+  |            |  +-----+  +-----+  |
                +--------------------+            +--------------------+
                         xTR2                              xTR3

   Note if any external xTR would like to use a Map-Resolver from the
   peer-group, it only needs to have one of the LISP-Decent Map-
   Resolvers configured.  By doing a looking to this Map-Resolver for
   EID 224.1.1,1, the external xTR could get the complete list of
   members for the peer-group.

   For future study, an external xTR could multicast the Map-Request to and either one of the LISP-Decent Map-Resolvers would

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   return a Map-Reply or the external xTR is prepared to receive
   multiple Map-Replies.

5.  No LISP Protocol Changes

   There are no LISP protocol changes required to support this LISP-
   Decent specification.  However, 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 peer-group.

   An ITR SHOULD lookup its peer-group address periodically to determine
   if the membership has changed.  The ITR can also use the pubsub
   capability documented in [I-D.rodrigueznatal-lisp-pubsub] to be
   notified when a new member joins or leaves the peer-group.

6.  Configuration and Authentication

   When xTRs are joined to a multicast peer-group, they must have their
   site registration configuration consistent.  Any policy or
   authentication key material must be configured correctly and
   consistently among all members.  When [I-D.farinacci-lisp-ecdsa-auth]
   is used to sign Map-Register messages, public-keys can be registered
   to the peer-group using the site authentication key mentioned above
   or using a different authentication key from the one used for
   registering EID records.

7.  Core Peer-Group

   A core peer-group multicast 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 mappings.  Then as other xTRs come
   online, they can add themselves to the core peer-group by joining the
   peer-group multicast group.

   Alternatively or additionally, new xTRs can join a new peer-group
   multicast group to form another layer of a decentralized mapping
   system.  The group address and members of this new layer peer-group
   would be registered to the core peer-group address and stored in the
   core peer-group mapping system.  Note each mapping system layer could
   have a specific function or a specific circle of trust.

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   This multi-layer mapping system can be illustrated:

              __________               ---------
             /   core   \  / layer-1 \
            | peer-group | --------> |     I     |
            | |           |    / \    |
             \__________/            |   J---K   |
                  |                   \_________/
             / layer-2 \
            |     X     |
            |    / \    |
            |   Y---Z   |

   Configured in xTRs A, B, and C (they make up the core peer-group): -> RLE: A, B, C

   core peer-group DMS, mapping state in A, B, and C: -> RLE: I, J, K -> RLE: X, Y, Z

   layer-1 peer-group DMS (inter-continental), mapping state in I, J, K:
      EID1 -> RLOCs: i(1), j(2)
      EIDn -> RLOCs: i(n), j(n)

   layer-2 peer-group DMS (intra-continental), mapping sate in X, Y, Z::
      EIDa -> RLOCs: x(1), y(2)
      EIDz -> RLOCs: x(n), y(n)

   The core peer-group multicast address 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, peer-group
   multicast group EIDs are being registered only to find other peer-

   For example, lets say that xTR I boots up and it wants to find its
   other peers in its peer-group  Group address is
   configured so xTR I knows what group to join for its peer-group.  But
   xTR I needs a mapping system to register to, so the core peer-group
   is used and available to receive Map-Registers.  The other xTRs J and

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   K in the peer-group do the same so when any of I, J or K needs to
   register EIDs, they can now send their Map-Register messages to group  Examples of EIDs being register are EID1 through EIDn
   shown above.

   When Map-Registers are sent to group, they are encapsulated
   by the LISP data-plane by looking up EID in the core peer-
   group mapping system.  For the map-cache entry to be populated for, the data-plane must send a Map-Request so the RLOCs I, J,
   and K are cached for replication.  To use the core peer-group mapping
   system, the data-plane must know of at least one of the RLOCs A, B,
   and/or C.

8.  Security Considerations

   Refer to the Security Considerations section of
   [I-D.ietf-lisp-rfc6833bis] for a complete list of security mechanisms
   as well as pointers to threat analysis drafts.

9.  IANA Considerations

   At this time there are no specific requests for IANA.

10.  References

10.1.  Normative References

   [RFC6830]  Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
              Locator/ID Separation Protocol (LISP)", RFC 6830,
              DOI 10.17487/RFC6830, January 2013,

   [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, <>.

   [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,

   [RFC6833]  Fuller, V. and D. Farinacci, "Locator/ID Separation
              Protocol (LISP) Map-Server Interface", RFC 6833,
              DOI 10.17487/RFC6833, January 2013,

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   [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, <>.

   [RFC8060]  Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
              Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060,
              February 2017, <>.

   [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, <>.

10.2.  Informative References

              Farinacci, D. and E. Nordmark, "LISP Control-Plane ECDSA
              Authentication and Authorization", draft-farinacci-lisp-
              ecdsa-auth-01 (work in progress), October 2017.

              Fuller, V., Farinacci, D., and A. Cabellos-Aparicio,
              "Locator/ID Separation Protocol (LISP) Control-Plane",
              draft-ietf-lisp-rfc6833bis-07 (work in progress), December

              Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D.
              Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-14
              (work in progress), October 2017.

              Moreno, V. and D. Farinacci, "Signal-Free LISP Multicast",
              draft-ietf-lisp-signal-free-multicast-07 (work in
              progress), November 2017.

              Rodriguez-Natal, A., Ermagan, V., Leong, J., Maino, F.,
              Cabellos-Aparicio, A., Barkai, S., Farinacci, D.,
              Boucadair, M., Jacquenet, C., and s.
    , "Publish/Subscribe Functionality
              for LISP", draft-rodrigueznatal-lisp-pubsub-01 (work in
              progress), October 2017.

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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 occured before the first
   draft was published.

Appendix B.  Document Change Log

   [RFC Editor: Please delete this section on publication as RFC.]

B.1.  Changes to draft-farinacci-lisp-decent

   o  Initial draft posted January 2018.

Authors' Addresses

   Dino Farinacci
   San Jose, CA


   Colin Cantrell
   Scottsdale, AZ


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