Network Working Group                                       D. Farinacci
Intended status: Experimental                          P. Pillay-Esnault
Expires: November 29, 2018                           Huawei Technologies
                                                            May 28, 2018

                         LISP Predictive RLOCs


   This specification describes a method to achieve near-zero packet
   loss when an EID is roaming quickly across RLOCs.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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

   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 November 29, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definition of Terms . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Design Details  . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  RLE Encoding  . . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Packet Delivery Optimizations . . . . . . . . . . . . . .   6
     4.3.  Trading Off Replication Cost  . . . . . . . . . . . . . .   8
   5.  Directional Paths with Intersections  . . . . . . . . . . . .   9
   6.  Multicast Considerations  . . . . . . . . . . . . . . . . . .  10
   7.  Multiple Address-Family Considerations  . . . . . . . . . . .  11
   8.  Scaling Considerations  . . . . . . . . . . . . . . . . . . .  11
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     11.2.  Informative References . . . . . . . . . . . . . . . . .  13
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  13
   Appendix B.  Document Change Log  . . . . . . . . . . . . . . . .  13
     B.1.  Changes to draft-ietf-lisp-predictive-rlocs-02  . . . . .  13
     B.2.  Changes to draft-ietf-lisp-predictive-rlocs-01  . . . . .  13
     B.3.  Changes to draft-ietf-lisp-predictive-rlocs-00  . . . . .  14
     B.4.  Changes to draft-farinacci-lisp-predictive-rlocs-02 . . .  14
     B.5.  Changes to draft-farinacci-lisp-predictive-rlocs-01 . . .  14
     B.6.  Changes to draft-farinacci-lisp-predictive-rlocs-00 . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The LISP architecture [RFC6830] specifies two namespaces, End-Point
   IDs (EIDs) and Routing Locators (RLOCs).  An EID identifies a node in
   the network and the RLOC indicates the EID's topological location.
   When an node roams in the network, its EID remains fixed and
   unchanged but the RLOCs associated with it change to reflect its new
   topological attachment point.  This specification will focus EIDs and
   RLOCs residing in separate nodes.  An EID is assigned to a host node
   that roams while the RLOCs are assigned to network nodes that stay
   stationary and are part of the network topology.  For example, a set
   of devices on an aircraft are assigned EIDs, and base stations on the
   ground attached to the Internet infrastructure are configured as LISP
   xTRs where their RLOCs are used for the bindings of the EIDs on the
   aircraft up in the air.

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   The scope of this specification will not emphasize general physical
   roaming as an aircraft would do in the sky but in a direction that is
   more predictable such as a train traveling on a track or vehicle that
   travels along a road.

2.  Definition of Terms

   Roaming-EID -  is a network node that moves from one topological
      location in the network to another.  The network node uses the
      same EID when it is roaming.  That is, the EID address does not
      change for reasons of mobility.  A roaming-EID can also be a
      roaming EID-prefix where a set of EIDs covered by the prefix are
      all roaming and fate-sharing the same set of RLOCs at the same

   Predictive RLOCs -  is a set of ordered RLOCs in a list each assigned
      to LISP xTRs where the next RLOC in the list has high probability
      it will be the next LISP xTR in a physical path going in a single
      predictable direction.

   Road-Side-Units (RSUs) -  is a network node that acts as a router,
      more specifically as a LISP xTR.  The xTR automatically discovers
      roaming-EIDs that come into network connectivity range and relays
      packets to and from the roaming-EID.  RSUs are typically deployed
      along a directional path like a train track or road and are in
      connectivity range of devices that travel along the directional

3.  Overview

   The goal of this specification is to describe a make-before-break
   EID-mobility mechanism that offers near-zero packet loss.  Offering
   minimal packet loss, not only allows transport layers to operate more
   efficiently, but because an EID does not change while moving,
   transport layer session continuity is maintained.  To achieve these
   requirements, a mechanism that reacts to the mobility event is
   necessary but not sufficient.  So the question is not that there
   isn't a reaction but when it happens.  By using some predictive
   algorithms, we can guess with high probability where the EID will
   roam to next.  We can achieve this to a point where packet data will
   be at the new location when the EID arrives.

   First we should examine both the send and receive directions with
   respect to the roaming-EID.  Refer to Figure 1 for discussion.  We
   show a network node with a fixed EID address assigned to a roaming-
   EID moving along a train track.  And there are LISP xTRs deployed as
   Road-Side-Units to support the connectivity between the roaming-EID
   and the infrastructure or to another roaming-EID.

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          Roaming-EID ---->

      //    //    //    //    //    //    //    //   //    //    //

       xTR         xTR         xTR         xTR        xTR         xTR
        A           B           C           D          E           F

                      Figure 1: Directional Mobility

   For the send direction from roaming-EID to any destination can be
   accomplish as a local decision.  As long as the roaming-EID is in
   signal range to any xTR along the path, it can use it to forward
   packets.  The LISP xTR, acting as an ITR, can forward packets to
   destinations in non-LISP sites as well as to stationary and roaming
   EIDs in LISP sites.  This is accomplished by using the LISP overlay
   via dynamic packet encapsulation.  When the roaming-EID sends
   packets, the LISP xTR must discover the EID and MAY register the EID
   with a set of RLOCs to the mapping system
   [I-D.ietf-lisp-eid-mobility].  The discovery process is important
   because the LISP xTR, acting as an ETR for decapsulating packets that
   arrive, needs to know what local ports or radios to send packets to
   the roaming-EID.

   Much of the focus of this design is on the packet direction to the
   roaming-EID.  And how remote LISP ITRs find the current location
   (RLOCs) quickly when the roaming-EID is moving at high speed.  This
   specification solves the fast roaming with the introduction of the
   Predictive-RLOCs algorithm.

   Since a safe assumption is that the roaming-EID is going in one
   direction and cannot deviate from it allows us to know a priori the
   next set of RLOCs the roaming-EID will pass by.  Referring to
   Figure 1, if the roaming-EID is in range near xTR-A, then as it
   moves, it will at some point pass by xTR-B and xTR-C, and so on.  As
   the roaming-EID moves, one could time when the EID is mapped to RLOC
   A, and when it should change to RLOC B and so on.  However, the speed
   of movement of the roaming-EID won't be constant and the variables
   involved in consistent timing cannot be relied on.  Furthermore,
   timing the move is not a make-before-break algorithm, meaning the
   reaction of the binding happens at the time the roaming-EID is
   discovered by an xTR.  One cannot achieve fast hand-offs when message
   signaling will be required to inform remote ITRs of the new binding.

   The Predictive RLOCs algorithm allows a set of RLOCs, in an ordered
   list, to be provided to remote ITRs so they have the information

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   available and local for when they need to use it.  Therefore, no
   control-plane message signaling occurs when the roaming-EID is
   discovered by LISP xTRs.

4.  Design Details

   Predictive RLOCs accommodates for encapsulated packets to be
   delivered to Road-Side-Unit LISP xTRs regardless where the roaming-
   EID is currently positioned.

   Referring to Figure 1, the following sequence is performed:

   1.  The Predictive RLOCs are registered to the mapping system as a
       LCAF encoded Replication List Entry (RLE) Type [RFC8060].  The
       registration can happen by one or more RSUs or by a third-party.
       When registered by an RSU, and when no coordination is desired,
       they each register their own RLOC with merge-semantics so the
       list can be created and maintained in the LISP Map-Server.  When
       registered by a third-party, the complete list of RLOCs can be
       included in the RLE.

   2.  There can be multiple RLEs present each as different RLOC-
       records so a remote ITR can select one RLOC-record versus the
       other based in priority and weight policy [RFC6830].

   3.  When a remote ITR receives a packet destined for a roaming-EID,
       it encapsulates and replicates to each RLOC in the RLE thereby
       delivering the packet to the locations the roaming-EID is about
       to appear.  There are some cases where packets will go to
       locations where the roaming-EID has already been, but see
       Section 4.2 for packet delivery optimizations.

   4.  When the ETR resident RSU receives an encapsulated packet, it
       decapsulates the packet and then determines if the roaming-EID
       had been previously discovered.  If the EID has not been
       discovered, the ETR drops the packet.  Otherwise, the ETR
       delivers the decapsulated packet on the port interface the
       roaming-EID was discovered on.

4.1.  RLE Encoding

   The LCAF [RFC8060] Replication List Entry (RLE) will be used to
   encode the Predictive RLOCs in an RLOC-record for Map-Registers, Map-
   Reply, and Map-Notify messages [RFC6830].

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     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
    |           AFI = 16387         |     Rsvd1     |     Flags     |
    |   Type = 13   |    Rsvd2      |             4 + n             |
    |              Rsvd3            |     Rsvd4     |  Level Value  |
    |              AFI = x          |           RTR/ETR #1 ...      |
    |              Rsvd3            |     Rsvd4     |  Level Value  |
    |              AFI = x          |           RTR/ETR  #n ...     |

   When the RLOC-record contains an RLE with RLOC entries all with the
   same level value, it means the physical order listed is the
   directional path of the RSUs.  This will typically be the result of a
   third-party doing the registration where it knows ahead of time the
   RSU deployment.

   When each RSU is registering with merge-semantics on their own, the
   level number is used to place them in an ordered list.  Since the
   registrations come at different times and therefore arrive in
   different order than the physical RSU path, the level number creates
   the necessary sequencing.  Each RSU needs to know its position in the
   path relative to other RSUs.  For example, in xTR-B, it would
   register with level 1 since it is after xTR-A (and before xTR-C).  So
   if the registration order was xTR-B with level 1, xTR-C with level 2,
   and xTR-A with level 0, the RLE list stored in the mapping system
   would be (xTR-A, xTR-B, xTR-C).  It is recommended that level numbers
   be assigned in increments of 10 so latter insertion is possible.

   The use of Geo-Prefixes and Geo-Points [I-D.farinacci-lisp-geo] can
   be used to compare the physical presence of each RSU with respect to
   each other, so they can choose level numbers to sequence themselves.
   Also if the xTRs register with a Geo-Point in an RLOC-record, then
   perhaps the Map-Server could sequence the RLE list.

4.2.  Packet Delivery Optimizations

   Since the remote ITR will replicate to all RLOCs in the RLE, a
   situation is created where packets go to RLOCs that don't need to.
   For instance, if the roaming-EID is along side of xTR-B and the RLE
   is (xTR-A, xTR-B, xTR-C), there is no reason to replicate to xTR-A
   since the roaming-EID has passed it and the the signal range is weak
   or lost.  However, replicating to xTR-B and xTR-C is important to

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   deliver packets to where the roaming-EID resides and where it is
   about to go to.

   A simple data-plane option, which converges fairly quickly is to have
   the remote xTR, acting as an ETR, when packets are sent from the
   roaming-EID, examine the source RLOC in the outer header of the
   encapsulated packet.  If the source RLOC is xTR-B, the remote xTR can
   determine that the roaming-EID has moved past xTR-A and no longer
   needs to encapsulate packets to xTR-A's RLOC.

   In addition, the remote ITR can use RLOC-probing to determine if each
   RLOC in the RLE is reachable.  And if not reachable, exclude from the
   list of RLOCs to replicate to.

   This solution also handles the case where xTR-A and xTR-B may overlap
   in radio signal range, but the signal is weak from the roaming-EID to
   xTR-A but stronger to xTR-B.  In this case, the roaming-EID selects
   xTR-B to send packets that inform the remote xTR that return packets
   should not be encapsulated to xTR-A.

   There are also situations where the RSUs are in signal range of each
   other in which case they could report reachability status of each
   other.  The use of the Locator-Status-Bits of the LISP encapsulation
   header could be used to convey this information to the remote xTR.
   This would only occur when the roaming-EID was discovered by both
   xTR-A and xTR-B so it was possible for either xTR to reach the
   roaming-EID.  Either an IGP like routing protocol would be required
   to allow each xTR to know the other could reach the roaming-EID or a
   path trace tool (i.e. traceroute) could be originated by one xTR
   targeted for the roaming-EID but MAC-forwarded through the other xTR.
   These and other roaming-EID reachability mechanisms are work in
   progress and for further study.

   When a remote ITR is doing "Directional Mobility" and replicating to
   the last RLOC in the RLE list, it has a decision to guess where the
   roaming-EID will move to next.  Conservatively, an ITR can replicate
   to the entire set of RLOCs in the RLE list and wait to see if the
   roaming-EID moves to one of the RLOCs in the RLE list.

   Or more liberally, the remote ITR can assume the new roaming
   direction.  For example, with an RLE list of (xTR-A, xTR-B, xTR-C,
   xTR-D) and the roaming-EID is at D, the remote ITR can replicate to
   all of A, B, C and D to determine where the roaming-EID will move to
   next.  If the roaming-EID moves to C after it was at D, it is
   possible that the EID is moving in the opposite direction from C to B
   to A.  This would be known as "Back-n-Forth Mobility".  If an
   implementation is configured to support this for a particluar EID,
   the remote ITR could replicate in this sequence as the roaming-EID

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   moves from A to D and back to A: (A, B, C, D), (B, C, D), (C, D), (D,
   C, B, A), (C, B, A), (B, A), and again (A, B, C, D).

   The roaming-EID could be doing "Circular Mobility" where it moves
   from A to D directionally, next from D-to-A, and then back to A to D
   directionally again.  This form of mobility is just as predicatable
   as "Back-n-Forth Mobility" since a consistent pattern can be relied
   on.  Both of these mobility forms can be achieved with near-zero
   packet loss.

   On the other hand, the roaming-EID can be roaming arbitrarily using
   "Random Mobility" where it could roam in the following combinations:
   A-to-B, A-to-C, A-to-D, B-to-A, B-to-C, B-to-D, C-to-A, C-to-B, C-to-
   D, D-to-A, D-to-B, or D-to-C.  In this situation, when a return
   packet arrives at the ITR, it could then just replicate to where the
   roaming-EID is at rest and do so for a short period of time before it
   replciates to the entire RLE list again.  Using the wrong time period
   could lead to packet loss.  All these types of mobility can be
   supported by the remote ITR in a local manner without consulting or
   depending on any other LISP system.  It is left for further study, if
   any of the mobility types above should be encoded in the mapping

4.3.  Trading Off Replication Cost

   If RLE lists are large, packet replication can occur to locations
   well before the roaming-EID arrives.  Making RLE lists small is
   useful without sacrificing hand-off issues or incurring packet loss
   to the application.  By having overlapping RLEs in separate RLOC-
   records we a simple mechanism to solve this problem.  Here is an
   example mapping entry to illustrate the point:

   EID = <roaming-EID>, RLOC-records:
     RLOC = (RLE: xTR-A, xTR-B)
     RLOC = (RLE: xTR-B, xTR-C, xTR-D, xTR-E)
     RLOC = (RLE: xTR-E, xTR-F)

   When the remote ITR is encapsulating to xTR-B as a decision to use
   the first RLOC-record, it can decide to move to use the second RLOC-
   record because xTR-B is the last entry in the first RLOC-record and
   the first entry in the second RLOC-record.  When there are
   overlapping RLEs, the remote ITR can decide when it is more efficient
   to switch over.  For example, when the roaming-EID is in range of
   xTR-A, the remote ITR uses the first RLOC-record so the wasted
   replication cost is to xTR-B only versus a worse cost when using the
   second RLOC-record.  But when the roaming-EID is in range of xTR-B,
   then replicating to the other xTRs in the second RLOC-record may be
   crucial if the roaming-EID has increased speed.  And when the

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   roaming-EID may be at rest in a parked mode, then the remote ITR
   encapsulates to only xTR-F using the third RLOC-record since the
   roaming-EID has moved past xTR-E.

   In addition, to eliminate unnecessary replication to xTRs further
   down a directional path, GEO-prefixes [I-D.farinacci-lisp-geo] can be
   used so only nearby xTRs that the roaming-EID is about to come in
   contact with are the only ones to receive encapsulated packets.

   Even when replication lists are not large, we can reduce the cost of
   replication that the entire network bears by moving the replicator
   away from the the source (i.e. the ITR) and closer to the RSUs (i.e.
   the ETRs).  See the use of RTRs for Replication Engineering
   techniques in [RFC8378].

5.  Directional Paths with Intersections

   A roaming-EID could be registered to the mapping system with the
   following nested RLE mapping:

   EID = <roaming-EID>, RLOC-records:
     RLOC = (RLE: xTR-A, xTR-B, xTR-C, (RLE: xTR-X, xTR-Y, xTR-Z),
                  (RLE: xTR-I, xTR-J, xTR-K), xTR-D, xTR-E)

   The mapping entry above describes 3 directional paths where the
   ordered list has encoded one-level of two nested RLEs to denote
   intersections in a horizontal path.  Which is drawn as:

                                       | |  xTR-K
                                       | |
                                       | |
                                       | |  xTR-J
                                       | |
                                       | |
                         Roaming       | |  xTR-I
                           EID ---->   | |
---------------------------------------   ------------------------------
---------------------------------------   ------------------------------
    xTR-A        xTR-B        xTR-C    | |          xTR-D      xTR-E
                                       | |
                                       | |  xTR-X
                                       | |
                                       | |
                                       | |  xTR-Y
                                       | |
                                       | |
                                       | |  xTR-Z

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   When the roaming-EID is on the horizontal path, the remote-ITRs
   typically replicate to the rest the of the xTRs in the ordered list.
   When a list has nested RLEs, the replication should occur to at least
   the first RLOC in a nested RLE list.  So if the remote-ITR is
   replicating to xTR-C, xTR-D, and xTR-E, it should also replicate to
   xTR-X and xTR-I anticipating a possible turn at the intersection.
   But when the roaming-EID is known to be at xTR-D (a left or right
   hand turn was not taken), replication should only occur to xTR-D and
   xTR-E.  Once either xTR-I or xTR-X is determined to be where the
   roaming-EID resides, then the replication occurs on the respective
   directional path only.

   When nested RLEs are used it may be difficult to get merge-semantics
   to work when each xTR registers itself.  So it is suggested a third-
   party registers nested RLEs.  It is left to further study to
   understand better how to automate this.

6.  Multicast Considerations

   In this design, the remote ITR is receiving a unicast packet from an
   EID and replicating and encapsulating to each RLOC in an RLE list.
   This form of replication is no different than a traditional multicast
   replication function.  So replicating multicast packets in the same
   fashion is a fallout from this design.

   If there are multiple roaming-EIDs joined to the same multicast group
   but reside at different RSUs, a merge has to be done of any pruned
   RLEs used for forwarding.  So if roaming-EID-1 resides at xTR-A and
   roaming-EID-2 resides at xTR-B and the RLE list is (xTR-A, xTR-B,
   xTR-C), and they are joined to the same multicast group, then
   replication occurs to all of xTR-A, xTR-B, and xTR-C.  Even since
   roaming-EID-2 is past xTR-A, packets need to be delivered to xTR-A
   for roaming-EID-1.  In addition, packets need to be delivered to
   xTR-C because roaming-EID-1 and roaming-EID-2 will get to xTR-C (and
   roaming-EID-1 may get there sooner if it is traveling faster than

   When a roaming-EID is a multicast source, procedures from [RFC8378]
   are used to deliver packets to multicast group members anywhere in
   the network.  The solution requires no signaling to the RSUs.  When
   RSUs receive multicast packets from a roaming-EID, they do a
   (roaming-EID,G) mapping database lookup to find the replication list
   of ETRs to encapsulate to.

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7.  Multiple Address-Family Considerations

   Note that roaming-EIDs can be assigned IPv6 EID addresses while the
   RSU xTRs could be using IPv4 RLOC addresses.  Any combination of
   address-families can be supported as well as for multicast packet
   forwarding, where (S,G) are IPv6 addresses entries and replication is
   done with IPv4 RLOCs in the outer header.

8.  Scaling Considerations

   One can imagine there will be a large number of roaming-EIDs.  So
   there is a strong desire to efficiently store state in the mapping
   database and the in remote ITRs map-caches.  It is likely, that
   roaming-EIDs may share the same path and move at the same speed (EID
   devices on a train) and therefore share the same Predictive RLOCs.
   And since EIDs are not reassigned for mobility purposes or may be
   temporal , they will not be topologically aggregatable, so they
   cannot compress into a single EID-prefix mapping entry that share the
   same RLOC-set.

   By using a level of indirection with the mapping system this problem
   can be solved.  The following mapping entries could exist in the
   mapping database:

   EID = <eid1>, RLOC-records:
     RLOC = (afi=<dist-name>: "am-train-to-paris")
   EID = <eid2>, RLOC-records:
     RLOC = (afi=<dist-name>: "am-train-to-paris")
   EID = <eid3>, RLOC-records:
     RLOC = (afi=<dist-name>: "am-train-to-paris")

   EID = "am-train-to-paris", RLOC-records:
     RLOC = (afi=lcaf/RLE-type: xTR-A, xTR-B, xTR-C)

   EID = "am-train-to-paris-passengers", RLOC-records:
     RLOC = (afi=lcaf/afi-list-type: <eid1>, <eid2>, <eid3>)

   Each passenger that boards a train has their EID registered to point
   to the name of the train "am-train-to-paris".  And then the train
   with EID "am-train-to-paris" stores the Predictive RLOC-set.  When a
   remote-ITR wants to encapsulate packets for an EID, it looks up the
   EID in the mapping database gets the name "am-train-to-paris"
   returned.  Then the remote-ITR does another lookup for the name "am-
   train-to-paris" to get the RLE list returned.

   When new EIDs board the train, the RLE mapping entry does not need to
   be modified.  Only an EID-to-name mapping is registered for the
   specific new EID.  Optionally, another name "am-train-to-paris-

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   passengers" can be registered as an EID to allow mapping to all
   specific EIDs which are on the train.  This can be used for
   inventory, billing, or security purposes.

   This optimization comes at a cost of a 2-stage lookup.  However, if
   both sets of mapping entries are registered to the same Map-Server, a
   combined RLOC-set could be returned.  This idea is for further study.

9.  Security Considerations

   LISP has procedures for supporting both control-plane security
   [I-D.ietf-lisp-sec] and data-plane security [RFC8061].

10.  IANA Considerations

   At this time there are no requests for IANA.

11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

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

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

   [RFC8061]  Farinacci, D. and B. Weis, "Locator/ID Separation Protocol
              (LISP) Data-Plane Confidentiality", RFC 8061,
              DOI 10.17487/RFC8061, February 2017,

   [RFC8378]  Moreno, V. and D. Farinacci, "Signal-Free Locator/ID
              Separation Protocol (LISP) Multicast", RFC 8378,
              DOI 10.17487/RFC8378, May 2018,

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11.2.  Informative References

              Farinacci, D., "LISP Geo-Coordinate Use-Cases", draft-
              farinacci-lisp-geo-05 (work in progress), April 2018.

              Farinacci, D., Pillay-Esnault, P., and W. Haddad, "LISP
              EID Anonymity", draft-ietf-lisp-eid-anonymity-02 (work in
              progress), April 2018.

              Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino,
              F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a
              Unified Control Plane", draft-ietf-lisp-eid-mobility-02
              (work in progress), May 2018.

              Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D.
              Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-15
              (work in progress), April 2018.

Appendix A.  Acknowledgments

   The author would like to thank the LISP WG for their review and
   acceptance of this draft.

Appendix B.  Document Change Log

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

B.1.  Changes to draft-ietf-lisp-predictive-rlocs-02

   o  Posted May 2018.

   o  Update document timer and references.

B.2.  Changes to draft-ietf-lisp-predictive-rlocs-01

   o  Posted November 2017.

   o  Update document timer and references.

   o  Reflect comments from Prague meeting presentation.  There is no
      need for "RLE Usage Types" as suggested.  The ITR can treat what
      RLOCs it replicates to as a local matter via implementation
      configuration.  RLE Directional is default.  Circular rotation,
      back-n-forth, and random selection of RLOCs is up to the ITR.

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B.3.  Changes to draft-ietf-lisp-predictive-rlocs-00

   o  Posted June 2017.

   o  Make this specification a working group document.  It is a copy of

B.4.  Changes to draft-farinacci-lisp-predictive-rlocs-02

   o  Posted May 2017 to update document timer.

B.5.  Changes to draft-farinacci-lisp-predictive-rlocs-01

   o  Posted November 2016 to update document timer.

B.6.  Changes to draft-farinacci-lisp-predictive-rlocs-00

   o  Initial post April 2016.

Authors' Addresses

   Dino Farinacci
   San Jose, CA


   Padma Pillay-Esnault
   Huawei Technologies
   San Clara, CA


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