





Internet Engineering Task Force (IETF)                         D. Saucez
Request for Comments: 7834                                         INRIA
Category: Informational                                       L. Iannone
ISSN: 2070-1721                                        Telecom ParisTech
                                                             A. Cabellos
                                                                F. Coras
                                       Technical University of Catalonia
                                                              April 2016


              Locator/ID Separation Protocol (LISP) Impact

Abstract

   The Locator/ID Separation Protocol (LISP) aims to improve the
   Internet routing scalability properties by leveraging three
   principles: address role separation, encapsulation, and mapping.  In
   this document, based on implementation work, deployment experiences,
   and theoretical studies, we discuss the impact that the deployment of
   LISP can have on both the routing infrastructure and the end user.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7834.















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Copyright Notice

   Copyright (c) 2016 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
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   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  LISP in a Nutshell  . . . . . . . . . . . . . . . . . . . . .   4
   3.  LISP for Scaling the Internet Routing Architecture  . . . . .   5
   4.  Beyond Scaling the Internet Routing Architecture  . . . . . .   6
     4.1.  Traffic Engineering . . . . . . . . . . . . . . . . . . .   8
     4.2.  LISP for IPv6 Co-existence  . . . . . . . . . . . . . . .   8
     4.3.  Inter-domain Multicast  . . . . . . . . . . . . . . . . .   9
   5.  Impact of LISP on Operations and Business Models  . . . . . .  10
     5.1.  Impact on Non-LISP Traffic and Sites  . . . . . . . . . .  10
     5.2.  Impact on LISP Traffic and Sites  . . . . . . . . . . . .  11
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  14
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18


















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1.  Introduction

   The Locator/ID Separation Protocol (LISP) relies on three principles
   to improve the scalability properties of Internet routing: address
   role separation, encapsulation, and mapping.  When invented, LISP was
   targeted at solving the Internet routing scaling problem [RFC4984].
   There have now been years of implementations and experiments
   examining the impact and open questions of using LISP to improve
   inter-domain routing scalability.  Experience has shown that because
   LISP utilizes mapping and encapsulation technologies, it can be
   deployed and used for purposes that go beyond routing scalability.
   For example, LISP provides a mean for a LISP site to precisely
   control its inter-domain outgoing and incoming traffic, with the
   possibility to apply different policies to different domains
   exchanging traffic with it.  LISP can also be used to ease the
   transition from IPv4 to IPv6 as it allows the transport of IPv4 over
   IPv6 or IPv6 over IPv4.  Furthermore, LISP also supports inter-domain
   multicast.

   Leveraging implementation and deployment experience, as well as
   research work, this document describes, at a high level, the impacts
   and open questions still seen in LISP.  This information is
   particularly useful for considering future approaches and to support
   further experimentation to clarify some large open questions (e.g.,
   around the operations).  LISP utilizes a tunnel-based data plane and
   a distributed control plane.  LISP requires some new functionalities,
   such as reachability mechanisms.  Because LISP is more than a simple
   encapsulation technology and is a new technology, until even more
   deployment experience is gained, some open questions related to LISP
   deployment and operations remain.  As an encapsulation technology,
   there may be concerns on reduced Maximum Transmission Unit (MTU) size
   in some deployments.  An important impact of LISP is on network
   operations related to resiliency and troubleshooting.  As LISP relies
   on cached mappings and on encapsulation, resiliency during failures
   and troubleshooting may be more difficult.  Also, the use of
   encapsulation may make failure detection and recovery slower, and it
   will require more coordination than with a single, non-encapsulated,
   routing domain solution.













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2.  LISP in a Nutshell

   LISP relies on three principles: address role separation,
   encapsulation, and mapping.

   The address space is divided into two sets that have different
   semantic meanings: the Routing Locators (RLOCs) and the Endpoint
   Identifiers (EIDs).  RLOCs are addresses typically assigned from the
   Provider Aggregatable (PA) address space.  The EIDs are attributed to
   the nodes in the edge networks, by a block of contiguous addresses,
   which are typically Provider Independent (PI).  To limit the
   scalability problem, LISP only requires the PA routes towards the
   RLOCs to be announced in the provider infrastructure.  Whereas for
   non-LISP deployments, the EIDs need to be propagated as well.

   LISP routers are used at the boundary between the EID and the RLOC
   spaces.  Routers used to exit the EID space (towards the provider
   domain) are called Ingress Tunnel Routers (ITRs), and those used to
   enter the EID space (from the provider domain) are called the Egress
   Tunnel Routers (ETRs).  When a host sends a packet to a remote
   destination, it sends it as in the non-LISP Internet.  The packet
   arrives at the border of its site at an ITR.  Because EIDs are not
   routable on the Internet, the packet is encapsulated with the source
   address set to the ITR RLOC and the destination address set to the
   ETR RLOC.  The encapsulated packet is then forwarded in the provider
   domain until it reaches the selected ETR.  The ETR de-encapsulates
   the packet and forwards it to its final destination.  The acronym xTR
   stands for Ingress/Egress Tunnel Router and is used for a router
   playing these two roles.

   The correspondence between EIDs and RLOCs is given by the mappings.
   When an ITR needs to find ETR RLOCs that serve an EID, it queries a
   mapping system.  With the LISP Canonical Address Format (LCAF)
   [LISP-LCAF], LISP is not restricted to the Internet protocol for the
   EID addresses.  With LCAF, any address type can be used as EID (the
   address is only the key for the mapping lookup).  LISP can transport,
   for example, Ethernet frames over the Internet.

   An introduction to LISP can be found in [RFC7215].  The LISP
   specifications are given in [RFC6830], [RFC6833], [LISP-DDT],
   [RFC6836], [RFC6832], and [RFC6834].










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3.  LISP for Scaling the Internet Routing Architecture

   The original goal of LISP was to improve the scalability properties
   of the Internet routing architecture.  LISP utilizes traffic
   engineering and stub Autonomous System (AS) prefixes (not announced
   anymore in the Default-Free Zone (DFZ)), so that routing tables are
   smaller and more stable (i.e., they experience less churn).
   Furthermore, at the edge of the network, information necessary to
   forward packets (i.e., the mappings) is obtained on demand using a
   pull model (whereas the current Internet BGP model uses a push
   model).  Therefore, the scalability of edge networks is less
   dependent on the Internet's size and more related to its traffic
   matrix.  This scaling improvement has been proven by several studies
   (see below).  The research studies cited hereafter are based on the
   following assumptions:

   o  EID-to-RLOC mappings follow the same prefix size as the current
      BGP routing infrastructure (current PI addresses only);

   o  EIDs are used only at the stub ASes, not in the transit ASes; and

   o  the RLOCs of an EID prefix are deployed at the edge between the
      stubs owning the EID prefix and the providers, allocating the
      RLOCs in a PA mode.

   The above assumptions are inline with [RFC7215] and current LISP
   deployments.  It is recognized these assumptions may change in the
   longer term.  [KIF13] and [CDLC] explore different EID prefix space
   sizes and still show results that are consistent and equivalent to
   the above assumptions.

   Quoitin et al. [QIdLB07] show that the separation between locator and
   identifier roles at the network level improves the routing
   scalability by reducing the Routing Information Base (RIB) size (up
   to one order of magnitude) and increases path diversity and thus the
   traffic engineering capabilities.  [IB07] and [KIF13] show, based on
   real Internet traffic traces, that the number of mapping entries that
   must be handled by an ITR of a network with up to 20,000 users is
   limited to few tens of thousands; the signaling traffic (i.e.,
   Map-Request/Map-Reply packets) is in the same order of magnitude
   similar to DNS request/reply traffic; and the encapsulation overhead,
   while not negligible, is very limited (in the order of few percentage
   points of the total traffic volume).

   Previous studies consider the case of a timer-based cache eviction
   policy (i.e., mappings are deleted from the cache upon timeout),
   while [CDLC] has a more general approach based on the Least Recently
   Used (LRU) eviction policy, proposing an analytic model for the EID-



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   to-RLOC cache size when prefix-level traffic has a stationary
   generating process.  The model shows that miss rate can be accurately
   predicted from the EID-to-RLOC cache size and a small set of easily
   measurable traffic parameters.  The model was validated using four
   one-day-long packet traces collected at egress points of a campus
   network and an academic exchange point considering EID prefixes as
   being of the same size as BGP prefixes.  Consequently, operators can
   provision the EID-to-RLOC cache of their ITRs according to the miss
   rate they want to achieve for their given traffic.

   Results in [CDLC] indicate that for a given target miss ratio, the
   size of the cache depends only on the parameters of the popularity
   distribution; the size of the cache is independent of the number of
   users (the size of the LISP site) and the number of destinations (the
   size of the EID prefix space).  Assuming that the popularity
   distribution remains constant, this means that as the number of users
   and the number of destinations grow, the cache size needed to obtain
   a given miss rate remains constant O(1).

   LISP usually populates its EID-to-RLOC cache in a pull mode, which
   means that mappings are retrieved on demand by the ITR.  The main
   advantage of this mode is that the EID-to-RLOC cache size only
   depends on the traffic characteristics at the ITR and is independent
   of the size of the provider domain.  This benefit comes at the cost
   of some delay to transmit the packets that do not hit an entry in the
   cache (for which a mapping has to be learned).  This delay is bound
   by the time necessary to retrieve the mapping from the mapping
   system.  Moreover, similarly to a push model (e.g., BGP), the pull
   model induces signaling messages that correspond to the retrieval of
   mappings upon cache miss.  The difference being that the signaling
   load only depends on the traffic at the ITR and is not triggered by
   external events such as in BGP.  [CDLC] shows that the miss rate is a
   function of the EID-to-RLOC cache size and traffic generation
   process, and [CDLC], [SDIB08], and [SDIB08] show from traffic traces
   that, in practice, the cache miss rate, and thus the signaling rate,
   remain low.

4.  Beyond Scaling the Internet Routing Architecture

   LISP is more than just a scalability solution; it is also a tool to
   provide both incoming and outgoing traffic engineering [S11]
   [LISP-TE], it can be used as an IPv6 transition at the routing level,
   and it can be used for inter-domain multicast [RFC6831] [LISP-RE].
   Also, LISP has been identified for use to support devices' Internet
   mobility [LISP-MN] and to support virtual machines' mobility in data
   centers and multi-tenant VPNs.  These last two uses are not discussed
   further as they are out of the scope of the current LISP Working
   Group charter.



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   A key advantage of the LISP architecture is that it facilitates
   routing in environments where there is little to no correlation
   between network endpoints and topological location.  In service-
   provider environments, this application is needed in a range of
   consumer use cases that require an inline anchor to deliver a service
   to subscribers.  Inline anchors provide one of three types of
   capabilities:

   o  enable mobility of subscriber endpoints

   o  enable chaining of middlebox functions and services

   o  enable functions to be scaled out seamlessly

   Without LISP, the approach commonly used by operators is to aggregate
   service anchors in custom-built boxes.  This limits deployments as
   endpoints can only move on the same mobile gateway, functions can be
   chained only if traffic traverses the same wire or the same Deep
   Packet Inspection (DPI) box, and capacity can be scaled out only if
   traffic fans out to/from a specific load balancer.

   With LISP, service providers are able to distribute, virtualize, and
   instantiate subscriber-service anchors anywhere in the network.
   Typical use cases for virtualized inline anchors and network
   functions include Distributed Mobility and Virtualized Evolved Packet
   Core (vEPC), Virtualized Customer Premise Equipment (vCPE), where
   functionality previously anchored at a customer premise is now
   dynamically allocated in the network, Virtualized SGi LAN, Virtual IP
   Multimedia Subsystems (IMSs), Virtual Session Border Controller
   (SBC), etc.

   ConteXtream [ConteXtream] has been deploying map-assisted overlay
   networks since 2006, first with a proprietary solution, then evolving
   to standard LISP.  The solution has been deployed in production in
   three tier-1 operators spanning hundreds of millions of subscribers.
   Map-assisted overlays had been primarily used to map subscriber flows
   to services resources dynamically based on profiles and conditions.
   Specifically, it has been used to map mobile subscribers to value-
   added/optimization services, broadband subscribers to telephony
   services, and fixed-mobile subscribers to Broadband Network Gateway
   (BNG) functions and Internet access services.  The LISP map-assisted
   overlay architecture is used to optimally resolve subscriber to
   services, functions, instances, and IP overlay aggregation locations
   on a per-flow basis and just in time.







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4.1.  Traffic Engineering

   In the current (non-LISP) routing infrastructure, addresses used by
   stub networks are globally routable, and the routing system
   distributes the routes to reach these stubs.  With LISP, the EID
   prefixes of a LISP site are not routable in the DFZ; mappings are
   needed in order to determine the list of LISP routers to contact to
   forward packets.  This difference is significant for two reasons.
   First, packets are not forwarded to a site but to a specific router.
   Second, a site can control the entry points for its traffic by
   controlling its mappings.

   For traffic engineering purposes, a mapping associates an EID prefix
   to a list of RLOCs.  Each RLOC is annotated with a priority and a
   weight.  When there are several RLOCs, the ITR selects the one with
   the highest priority and sends the encapsulated packet to this RLOC.
   If several RLOCs with the highest priority exist, then the traffic is
   balanced proportionally to their weight among such RLOCs.  Traffic
   engineering in LISP thus allows the mapping owner to have a fine-
   grained control on the primary and backup path for its incoming and
   outgoing packet use.  In addition, it can share the load among its
   links.  An example of the use of such a feature is described by
   Saucez et al. [SDIB08], which shows how to use LISP to direct
   different types of traffic on different links having different
   capacity.

   Traffic engineering in LISP goes one step further, as every Map-
   Request contains the source EID address of the packet that caused a
   cache miss and triggered the Map-Request.  It is thus possible for a
   mapping owner to differentiate the answer (Map-Reply) it gives to
   Map-Requests based on the requester.  This functionality is not
   available today with BGP because a domain cannot control exactly the
   routes that will be received by domains that are not in the direct
   neighborhood.

4.2.  LISP for IPv6 Co-existence

   The LISP encapsulation mechanism is designed to support any
   combination of address families for locators and identifiers.  It is
   then possible to bind IPv6 EIDs with IPv4 RLOCs and vice versa.  This
   allows transporting IPv6 packets over an IPv4 network (or IPv4
   packets over an IPv6 network), making LISP a valuable mechanism to
   ease the transition to IPv6.

   An example is the case of the network infrastructure of a data center
   being IPv4 only while dual-stack front-end load balancers are used.
   In this scenario, LISP can be used to provide IPv6 access to servers
   even though the network and the servers only support IPv4.  Assuming



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   that the data center's ISP offers IPv6 connectivity, the data center
   only needs to deploy one (or more) xTR(s) at its border with the ISP
   and one (or more) xTR(s) directly connected to the load balancers.
   The xTR(s) at the ISP's border tunnels IPv6 packets over IPv4 to the
   xTR(s) directly attached to the load balancer.  The load balancer's
   xTR de-encapsulates the packets and forwards them to the load
   balancer, which act as a proxy, translating each IPv6 packet into an
   IPv4 packet.  IPv4 packets are then sent to the appropriate servers.
   Similarly, when the server's response arrives at the load balancer,
   the packet is translated back into an IPv6 packet and forwarded to
   its xTR(s), which in turn will tunnel it back, over the IPv4-only
   infrastructure, to an xTR connected to the ISP.  The packet is then
   de-encapsulated and forwarded to the ISP natively in IPv6.

4.3.  Inter-domain Multicast

   LISP has native support for multicast [RFC6831].  From the data-plane
   perspective, at a multicast-enabled xTR, an EID-sourced multicast
   packet is encapsulated in another multicast packet and subsequently
   forwarded in an RLOC-level distribution tree.  Therefore, xTRs must
   participate in both EID and RLOC-level distribution trees.  Control-
   plane wise, since group addresses have no topological significance,
   they need not be mapped.  It is worth noting that, to properly
   function, LISP-Multicast requires that inter-domain multicast be
   available.

   LISP Replication Engineering (LISP-RE) [LISP-RE] [CDM12] leverages
   LISP messages [LISP-MULTI-SIGNALING] for multicast state distribution
   to construct xTR-based inter-domain multicast distribution trees when
   inter-domain multicast support is not available.  Simulations of
   three different management strategies for low-latency content
   delivery show that such overlays can support thousands of member
   xTRs, support hundreds of thousands of end hosts, and deliver content
   at latencies close to unicast ones [CDM12].  It was also observed
   that high client churn has a limited impact on performance and
   management overhead.

   Similar to LISP-RE, "Signal-Free LISP Multicast" [LISP-SFM] can be
   used when the core network does not provide multicast support.  But
   instead of using signaling to build inter-domain multicast trees,
   signal-free exclusively leverages the map server for multicast state
   storage and distribution.  As a result, the source ITR generally
   performs head-end replication, but it might also be used to emulate
   LISP-RE distribution trees.







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5.  Impact of LISP on Operations and Business Models

   Numerous implementation efforts ([IOSNXOS], [OpenLISP], [LISPmob],
   [LISPClick], [LISPcp], and [LISPfritz]) have been made to assess the
   specifications, and additionally, interoperability tests [Was09] have
   been successful.  A worldwide large deployment in the international
   lisp4.net testbed, which is currently composed of nodes running at
   least three different implementations, will allow us to learn further
   operational aspects related to LISP.

   The following sections distinguish the impact of LISP on LISP sites
   from the impact on non-LISP sites.

5.1.  Impact on Non-LISP Traffic and Sites

   LISP has no impact on traffic that has neither LISP origin nor LISP
   destination.  However, LISP can have a significant impact on traffic
   between a LISP site and a non-LISP site.  Traffic between a non-LISP
   site and a LISP site is subject to the same issues as those observed
   for LISP-to-LISP traffic but also has issues specific to the
   transition mechanism that allow the LISP site to exchange packets
   with a non-LISP site [RFC6832] [RFC7215].

   The transition requires setup of proxy tunnel routers (PxTRs).
   Proxies cause what is referred to as path stretch (i.e., a
   lengthening of the path compared to the topological shortest path)
   and make troubleshooting harder.  There are still questions related
   to PxTRs that need to be answered:

   o  Where to deploy PxTRs?  The placement in the topology has an
      important impact on the path stretch.

   o  How many PxTRs?  The number of PxTRs has a direct impact on the
      load and the impact of the failure of a PxTR on the traffic.

   o  What part of the EID space?  Will all the PxTRs be proxies for the
      whole EID space, or will it be segmented between different PxTRs?

   o  Who operates PxTRs?  An important question to answer is related to
      the entities that will deploy PxTRs: how will they manage their
      additional Capital Expenditure (CAPEX) / Operating Expenses (OPEX)
      associated with PxTRs?  How will the traffic be carried with
      respect to security and privacy?

   A PxTR will also normally advertise in BGP the EID prefix for which
   they are proxies.  However, if proxies are managed by different
   entities, they will belong to different ASes.  In this case, we need
   to be sure that this will not cause Multi-Origin AS (MOAS) issues



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   that could negatively influence routing.  Moreover, it is important
   to ensure that the way EID prefixes will be de-aggregated by the
   proxies will remain reasonable so as not to contribute to BGP
   scalability issues.

5.2.  Impact on LISP Traffic and Sites

   LISP is a protocol based on the map-and-encap paradigm, which has the
   positive impacts that we have summarized in the above sections.
   However, LISP also has impacts on operations:

   MTU issue:  As LISP uses encapsulation, the MTU is reduced; this has
      implications on potentially all of the traffic.  However, in
      practice, on the lisp4.net network, no major issue due to the MTU
      has been observed.  This is probably due to the fact that current
      end-host stacks are well designed to deal with the problem of MTU.

   Resiliency issue:  The advantage of flexibility and control offered
      by the Locator/ID separation comes at the cost of increasing the
      complexity of the reachability detection.  Indeed, identifiers are
      not directly routable and have to be mapped to locators, but a
      locator may be unreachable while others are still reachable.  This
      is an important problem for any tunnel-based solution.  In the
      current Internet, packets are forwarded independently of the
      border router of the network meaning that, in case of the failure
      of a border router, another one can be used.  With LISP, the
      destination RLOC specifically designates one particular ETR;
      hence, if this ETR fails, the traffic is dropped, even though
      other ETRs are available for the destination site.  Another
      resiliency issue is linked to the fact that mappings are learned
      on demand.  When an ITR fails, all its traffic is redirected to
      other ITRs that might not have the mappings requested by the
      redirected traffic.  Existing studies [SKI12] [SD12] show, based
      on measurements and traffic traces, that failure of ITRs and RLOC
      are infrequent but that when such failure happens, a critical
      number of packets can be dropped.  Unfortunately, the current
      techniques for LISP resiliency, based on monitoring or probing,
      are not rapid enough (failure recovery on the order of a few
      seconds).  To tackle this issue, [LISP-PRESERVE] and
      [LISP-ITR-GRACEFUL] propose techniques based on local failure
      detection and recovery.

   Middleboxes/filters:  Because of the increasingly common use of
      encryption as a response to pervasive monitoring [RFC7258] with
      LISP providing the option to encrypt traffic between xTRs
      [LISP-CRYPTO], middleboxes are increasingly likely to be unable to
      understand encapsulated traffic, which can cause them to drop
      legitimate packets.  In addition, LISP allows triangular or even



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      rectangular routing, so it is difficult to maintain a correct
      state even if the middlebox understands LISP.  Finally, filtering
      may also have problems because they may think only one host is
      generating the traffic (the ITR), as long as it is not
      de-encapsulated.  To deal with LISP encapsulation, LISP-aware
      firewalls that inspect inner LISP packets are proposed
      [lispfirewall].

   Troubleshooting/debugging:  The major issue that LISP experimentation
      has shown is the difficulty of troubleshooting.  When there is a
      problem in the network, it is hard to pinpoint the reason as the
      operator only has a partial view of the network.  The operator can
      see what is in its EID-to-RLOC cache/database and can try to
      obtain what is potentially elsewhere by querying the Map
      Resolvers, but the knowledge remains partial.  On top of that,
      ICMP packets only carry the first few tens of bytes of the
      original packet, which means that when an ICMP arrives at the ITR,
      it might not contain enough information to allow correct
      troubleshooting.  Deployment in the beta network has shown that
      LISP+ALT [RFC6836] was not easy to maintain and control [CCR13],
      which explains the migration to LISP-DDT [LISP-DDT], based on a
      massively distributed and hierarchical approach [CCR13].

   Business/operational related:  Iannone et al. [IL10] have shown that
      there are economical incentives to migrate to LISP; however, some
      questions remain.  For example, how will the EIDs be allocated to
      allow aggregation and hence scalability of the mapping system?
      Who will operate the mapping system infrastructure and for what
      benefits?  What if several operators run different mapping
      systems?  How will they interoperate or share mapping information?

   Reachability:  The overhead related to RLOC reachability mechanisms
      is not known.

6.  Security Considerations

   A thorough security and threat analysis of LISP is carried out in
   detail in [RFC7835].  For LISP and other Internet technologies, most
   of the threats can be mitigated using Best Current Practices, meaning
   with careful deployment and configuration (e.g., filter), by
   activating only features that are really necessary in the deployment,
   and by verifying all the information obtained from third parties.
   Unless gleaning (Section 6 of [RFC6830] and Section 3.1 of [RFC7835])
   features are used, the LISP data plane shows the same level of
   security as other IP-over-IP technologies.  From a security
   perspective, the control plane remains the critical part of the LISP
   architecture.  To mitigate the threats on the mapping system,
   authentication should be used for all control-plane messages.  The



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   current specification defines security mechanisms [RFC6836]
   [LISP-SEC] that can reduce threats in open network environments.  The
   LISP specification defines a generic authentication data field for
   control-plane messages [RFC6836], which could be used for a general
   authentication mechanism for the LISP control plane while staying
   backward compatible.

7.  References

7.1.  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,
              <http://www.rfc-editor.org/info/rfc6830>.

   [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, <http://www.rfc-editor.org/info/rfc6831>.

   [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,
              <http://www.rfc-editor.org/info/rfc6832>.

   [RFC6833]  Fuller, V. and D. Farinacci, "Locator/ID Separation
              Protocol (LISP) Map-Server Interface", RFC 6833,
              DOI 10.17487/RFC6833, January 2013,
              <http://www.rfc-editor.org/info/rfc6833>.

   [RFC6834]  Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID
              Separation Protocol (LISP) Map-Versioning", RFC 6834,
              DOI 10.17487/RFC6834, January 2013,
              <http://www.rfc-editor.org/info/rfc6834>.

   [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, <http://www.rfc-editor.org/info/rfc6836>.

   [RFC7215]  Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo-
              Pascual, J., and D. Lewis, "Locator/Identifier Separation
              Protocol (LISP) Network Element Deployment
              Considerations", RFC 7215, DOI 10.17487/RFC7215, April
              2014, <http://www.rfc-editor.org/info/rfc7215>.




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   [RFC7835]  Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID
              Separation Protocol (LISP) Threat Analysis", RFC 7835,
              DOI 10.17487/RFC7835, April 2016,
              <http://www.rfc-editor.org/info/rfc7835>.

7.2.  Informative References

   [CCR13]    Saucez, D., Iannone, L., and B. Donnet, "A First
              Measurement Look at the Deployment and Evolution of the
              Locator/ID Separation Protocol", ACM SIGCOMM Computer
              Communication Review, Vol. 43, Issue 2, pp. 37-43,
              DOI 10.1145/2479957.2479963, April 2013.

   [CDLC]     Coras, F., Domingo, J., Lewis, D., and A. Cabellos, "An
              Analytical Model for Loc/ID Mappings Caches", IEEE/ACM
              Transactions on Networking, Vol. 24, Issue 1, pp. 506-516,
              DOI 10.1109/TNET.2014.2373398, February 2014.

   [CDM12]    Coras, F., Domingo-Pascual, J., Maino, F., Farinacci, D.,
              and A. Cabellos-Aparicio, "Lcast: Software-defined Inter-
              Domain Multicast", Computer Networks, Vol. 59, pp.
              153-170, DOI 10.1016/j.bjp.2013.10.010, February 2014.

   [ConteXtream]
              ConteXtream Software Company, , "SDN and NFV solutions for
              carrier networks.  (Further details on LISP only through
              private inquiry.)", <http://www.contextream.com>.

   [IB07]     Iannone, L. and O. Bonaventure, "On the cost of caching
              locator/ID mappings", in Proceedings of ACM CoNEXT 2007,
              DOI 0.1145/1364654.1364663, December 2007.

   [IL10]     Iannone, L. and T. Leva, "Modeling the economics of Loc/ID
              Split for the Future Internet", IOS Press, pp. 11-20,
              DOI 10.3233/978-1-60750-539-6-11, May 2010.

   [IOSNXOS]  Cisco Systems Inc., "Locator/ID Separation Protocol
              (LISP)", 2015, <http://lisp4.cisco.com>.

   [KIF13]    Kim, J., Iannone, L., and A. Feldmann, "Caching Locator/ID
              mappings: An experimental scalability analysis and its
              implications", Computer Networks, Vol. 57, Issue 4,
              DOI 10.1016/j.comnet.2012.11.007, March 2013.

   [LISP-CRYPTO]
              Farinacci, D. and B. Weis, "LISP Data-Plane
              Confidentiality", Work in Progress,
              draft-ietf-lisp-crypto-03, September 2015.



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   [LISP-DDT] Fuller, V., Lewis, D., Ermagan, V., and A. Jain, "LISP
              Delegated Database Tree", Work in Progress,
              draft-ietf-lisp-ddt-03, April 2015.

   [LISP-ITR-GRACEFUL]
              Saucez, D., Bonaventure, O., Iannone, L., and C. Filsfils,
              "LISP ITR Graceful Restart", Work in Progress,
              draft-saucez-lisp-itr-graceful-03, December 2013.

   [LISP-LCAF]
              Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
              Address Format (LCAF)", Work in Progress,
              draft-ietf-lisp-lcaf-12, September 2015.

   [LISP-MN]  Farinacci, D., Lewis, D., Meyer, D., and C. White, "LISP
              Mobile Node", Work in Progress, draft-meyer-lisp-mn-14,
              July 2015.

   [LISP-MULTI-SIGNALING]
              Farinacci, D. and M. Napierala, "LISP Control-Plane
              Multicast Signaling", Work in Progress, draft-farinacci-
              lisp-mr-signaling-06, February 2015.

   [LISP-PRESERVE]
              Bonaventure, O., Francois, P., and D. Saucez, "Preserving
              the reachability of LISP ETRs in case of failures", Work
              in Progress, draft-bonaventure-lisp-preserve-00, July
              2009.

   [LISP-RE]  Coras, F., Cabellos-Aparicio, A., Domingo-Pascual, J.,
              Maino, F., and D. Farinacci, "LISP Replication
              Engineering", Work in Progress, draft-coras-lisp-re-08,
              November 2015.

   [LISP-SEC] Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D.
              Saucez, "LISP-Security (LISP-SEC)", Work in Progress,
              draft-ietf-lisp-sec-10, October 2015.

   [LISP-SFM] Moreno, V. and D. Farinacci, "Signal-Free LISP Multicast",
              Work in Progress, draft-ietf-lisp-signal-free-
              multicast-01, April 2016.

   [LISP-TE]  Farinacci, D., Kowal, M., and P. Lahiri, "LISP Traffic
              Engineering Use-Cases", Work in Progress,
              draft-farinacci-lisp-te-10, September 2015.






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   [LISPClick]
              Saucez, D. and V. Nguyen, "LISP-Click: A Click
              implementation of the Locator/ID Separation Protocol", 1st
              Symposium on Click Modular Router, November 2009,
              <http://hdl.handle.net/2078.1/79067>.

   [LISPcp]   "LIP6-LISP open source project", 2014,
              <https://github.com/lip6-lisp>.

   [lispfirewall]
              "LISP and Zone-Based Firewalls Integration and
              Interoperability", 2014,
              <http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/
              sec_data_zbf/configuration/xe-3s/sec-data-zbf-xe-book/
              sec-zbf-lisp-inner-pac-insp.html>.

   [LISPfritz]
              "Unsere FRITZ!Box-Produkte", 2014,
              <http://avm.de/produkte/fritzbox/>.

   [LISPmob]  "An open-source LISP implementation for Linux, Android and
              OpenWRT", 2015, <http://lispmob.org>.

   [OpenLISP] "The OpenLISP Project", 2013, <http://www.openlisp.org>.

   [QIdLB07]  Quoitin, B., Iannone, L., de Launois, C., and O.
              Bonaventure, "Evaluating the Benefits of the Locator/
              Identifier Separation", in Proceedings of MobiArch,
              Article No. 5, DOI 10.1145/1366919.1366926, August 2007.

   [RFC4984]  Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report
              from the IAB Workshop on Routing and Addressing",
              RFC 4984, DOI 10.17487/RFC4984, September 2007,
              <http://www.rfc-editor.org/info/rfc4984>.

   [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
              Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
              2014, <http://www.rfc-editor.org/info/rfc7258>.

   [S11]      Saucez, D., "Mechanisms for Interdomain Traffic
              Engineering with LISP", PhD Thesis, Universite catholique
              de Louvain, September 2011,
              <http://hdl.handle.net/2078.1/92231>.

   [SD12]     Saucez, D. and B. Donnet, "On the Dynamics of Locators in
              LISP", in Proceedings of IFIP/TC6 Networking, pp. 385-396,
              DOI 10.1007/978-3-642-30045-5_29, May 2012.




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   [SDIB08]   Saucez, D., Donnet, B., Iannone, L., and O. Bonaventure,
              "Interdomain Traffic Engineering in a Locator/Identifier
              Separation Context", in Proceedings of Internet Network
              Management Workshop, DOI 10.1109/INETMW.2008.4660330,
              October 2008.

   [SKI12]    Saucez, D., Kim, J., Iannone, L., Bonaventure, O., and C.
              Filsfils, "A Local Approach to Fast Failure Recovery of
              LISP Ingress Tunnel Routers", in Proceedings of IFIP
              Networking 2012, pp. 397-408,
              DOI 10.1007/978-3-642-30045-5_30, May 2012.

   [Was09]    Wasserman, M., "LISP Interoperability Testing", IETF
              76, LISP WG Presentation, November 2009.

Acknowledgments

   Thanks to Deborah Brungard, Ben Campbell, Spencer Dawkins, Stephen
   Farrel, Wassim Haddad, Kathleen Moriarty, and Hilarie Orman for their
   thorough reviews, comments, and suggestions.

   The people that contributed to this document are Alia Atlas, Sharon
   Barkai, Ron Bonica, Ross Callon, Vince Fuller, Joel Halpern, Terry
   Manderson, and Gregg Schudel.

   The work of Luigi Iannone has been partially supported by the
   ANR 13 INFR 0009 LISP-Lab Project <http://www.lisp-lab.org>.
























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Authors' Addresses

   Damien Saucez
   INRIA
   2004 route des Lucioles BP 93
   06902 Sophia Antipolis Cedex
   France

   Email: damien.saucez@inria.fr


   Luigi Iannone
   Telecom ParisTech
   23, Avenue d'Italie, CS 51327
   75214 Paris Cedex 13
   France

   Email: ggx@gigix.net


   Albert Cabellos
   Technical University of Catalonia
   C/Jordi Girona, s/n
   08034 Barcelona
   Spain

   Email: acabello@ac.upc.edu


   Florin Coras
   Technical University of Catalonia
   C/Jordi Girona, s/n
   08034 Barcelona
   Spain

   Email: fcoras@ac.upc.edu















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