Network Working Group                                         L. Iannone
Internet-Draft                             Deutsche Telekom Laboratories
Intended status: Informational                                  D. Lewis
Expires: January 3, 2012                                        D. Meyer
                                                               V. Fuller
                                                     Cisco Systems, Inc.
                                                            July 2, 2011

                             LISP EID Block


   This is a direction to IANA to allocate a /16 IPv6 prefix for use
   with the Locator/ID Separation Protocol (LISP).  The prefix will be
   used by sites deploying LISP as EID (Endpoint IDentifier) addressing
   space for local intra-domain routing and global endpoint

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
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   This Internet-Draft will expire on January 3, 2012.

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   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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.  Requirements Notation . . . . . . . . . . . . . . . . . . . . . 3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Definition of Terms . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Rationale and Intent  . . . . . . . . . . . . . . . . . . . . . 5
   5.  Expected use  . . . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Action Plan . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Routing Considerations  . . . . . . . . . . . . . . . . . . . . 7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   11. Normative References  . . . . . . . . . . . . . . . . . . . . . 8
   Appendix A.  Document Change Log  . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9

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1.  Requirements Notation

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

2.  Introduction

   This document directs the IANA to allocate a /16 IPv6 prefix for use
   with the Locator/ID Separation Protocol (LISP - [I-D.ietf-lisp]),
   LISP Map Server ([I-D.ietf-lisp-ms]), LISP Alternative Topology
   (LISP+ALT - [I-D.ietf-lisp-alt]) (or other) mapping system, and LISP
   Interworking ([I-D.ietf-lisp-interworking]).

   This block will be used as global Endpoint IDentifier (EID) space
   (Section 3).

3.  Definition of Terms

   LISP operates on two name spaces and introduces several new network
   elements.  This section provides high-level definitions of the LISP
   name spaces and network elements and as such, it MUST NOT be
   considered as an authoritative source.  The reference to the
   authoritative document for each term is included in every term

   Legacy Internet:  The portion of the Internet which does not run LISP
      and does not participate in LISP+ALT or any other mapping system.

   LISP site:  A LISP site is a set of routers in an edge network that
      are under a single technical administration.  LISP routers that
      reside in the edge network are the demarcation points to separate
      the edge network from the core network.  See [I-D.ietf-lisp] for
      more details.

    Endpoint ID (EID):  An EID is a 32-bit (for IPv4) or 128-bit (for
      IPv6) value used in the source and destination address fields of
      the first (most inner) LISP header of a packet.  A packet that is
      emitted by a system contains EIDs in its headers and LISP headers
      are prepended only when the packet reaches an Ingress Tunnel
      Router (ITR) on the data path to the destination EID.  The source
      EID is obtained via existing mechanisms used to set a host's
      "local" IP address.  An EID is allocated to a host from an EID-
      prefix block associated with the site where the host is located.
      See [I-D.ietf-lisp] for more details.

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   EID-prefix:  A power-of-two block of EIDs that are allocated to a
      site by an address allocation authority.  See [I-D.ietf-lisp] for
      more details.

   EID-Prefix Aggregate:  A set of EID-prefixes said to be aggregatable
      in the [RFC4632] sense.  That is, an EID-Prefix aggregate is
      defined to be a single contiguous power-of-two EID-prefix block.
      Such a block is characterized by a prefix and a length.  See
      [I-D.ietf-lisp] for more details.

   Routing LOCator (RLOC):  A RLOC is an IPv4 or IPv6 address of an
      egress tunnel router (ETR).  A RLOC is the output of an EID-to-
      RLOC mapping lookup.  An EID maps to one or more RLOCs.
      Typically, RLOCs are numbered from topologically aggregatable
      blocks that are assigned to a site at each point to which it
      attaches to the global Internet; where the topology is defined by
      the connectivity of provider networks, RLOCs can be thought of as
      Provider Aggregatable (PA) addresses.  See [I-D.ietf-lisp] for
      more details.

    EID-to-RLOC Mapping:  A binding between an EID-Prefix and the RLOC-
      set that can be used to reach the EID-Prefix.  The general term
      "mapping" always refers to an EID-to-RLOC mapping.  See
      [I-D.ietf-lisp] for more details.

   Ingress Tunnel Router (ITR):  An Ingress Tunnel Router (ITR) is a
      router that accepts receives IP packets from site end-systems on
      one side and sends LISP-encapsulated IP packets toward the
      Internet on the other side.  The router treats the "inner" IP
      destination address as an EID and performs an EID-to-RLOC mapping
      lookup.  The router then prepends an "outer" IP header with one of
      its globally-routable RLOCs in the source address field and the
      result of the mapping lookup in the destination address field.
      See [I-D.ietf-lisp] for more details.

   Egress Tunnel Router (ETR):  An Egress Tunnel Router (ETR) receives
      LISP-encapsulated IP packets from the Internet on one side and
      sends decapsulated IP packets to site end-systems on the other
      side.  An ETR router accepts an IP packet where the destination
      address in the "outer" IP header is one of its own RLOCs.  The
      router strips the "outer" header and forwards the packet based on
      the next IP header found.  See [I-D.ietf-lisp] for more details.

   Proxy ITR (PITR):  A Proxy-ITR (PITR) acts like an ITR but does so on
      behalf of non-LISP sites which send packets to destinations at
      LISP sites.  See [I-D.ietf-lisp-interworking] for more details.

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   Proxy ETR (PETR):  A Proxy-ETR (PETR) acts like an ETR but does so on
      behalf of LISP sites which send packets to destinations at non-
      LISP sites.  See [I-D.ietf-lisp-interworking] for more details.

   Map Server (MS):  A network infrastructure component that learns EID-
      to-RLOC mapping entries from an authoritative source (typically an
      ETR).  A Map-Server publishes these mappings in the distributed
      mapping system.  See [I-D.ietf-lisp-ms] for more details.

   Map Resolver (MR):  A network infrastructure component that accepts
      LISP Encapsulated Map-Requests, typically from an ITR, quickly
      determines whether or not the destination IP address is part of
      the EID namespace; if it is not, a Negative Map-Reply is
      immediately returned.  Otherwise, the Map-Resolver finds the
      appropriate EID-to-RLOC mapping by consulting the distributed
      mapping database system.  See [I-D.ietf-lisp-ms] for more details.

   The LISP Alternative Logical Topology (ALT):  The virtual overlay
      network made up of tunnels between LISP+ALT Routers.  The Border
      Gateway Protocol (BGP) runs between ALT Routers and is used to
      carry reachability information for EID-prefixes.  The ALT provides
      a way to forward Map-Requests toward the ETR that "owns" an EID-
      prefix.  See [I-D.ietf-lisp-alt] for more details.

   ALT Router:  The device on which runs the ALT.  The ALT is a static
      network built using tunnels between ALT Routers.  These routers
      are deployed in a roughly-hierarchical mesh in which routers at
      each level in the topology are responsible for aggregating EID-
      Prefixes learned from those logically "below" them and advertising
      summary prefixes to those logically "above" them.  Prefix learning
      and propagation between ALT Routers is done using BGP.  When an
      ALT Router receives an ALT Datagram, it looks up the destination
      EID in its forwarding table (composed of EID-Prefix routes it
      learned from neighboring ALT Routers) and forwards it to the
      logical next-hop on the overlay network.  The primary function of
      LISP+ALT routers is to provide a lightweight forwarding
      infrastructure for LISP control-plane messages (Map-Request and
      Map-Reply), and to transport data packets when the packet has the
      same destination address in both the inner (encapsulating)
      destination and outer destination addresses ((i.e., a Data Probe
      packet).  See [I-D.ietf-lisp-alt] for more details.

4.  Rationale and Intent

   With the current specifications, if an ITR is sending to all types of
   destinations (i.e., non-LISP destinations, LISP destinations not in
   the IPv6 EID Block, and LISP destinations in the IPv6 EID Block) the

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   only way to understand whether or not to encapsulate the traffic is
   to perform a cache lookup and, in case of cache-miss, send a Map-
   Request to the mapping system.  In the meanwhile, packets can be

   By defining an IPv6 EID Block is possible to configure the router so
   to natively forward all packets that have not a destination address
   in the block, without performing any lookup whatsoever.  This will
   give a tighter control over the traffic in the initial experimental
   phase, while facilitating its large-scale deployment.

   The EID Block will be used only at configuration level, it is
   RECOMMENDED not to hard-code in any way the IPv6 EID Block in the
   router hardware.  This allows to avoid locking out sites that may
   want to switch to LISP while keeping their own IPv6 prefix, which is
   not in the IPv6 EID Block.

5.  Expected use

   Sites planning to deploy LISP may request a prefix in the IPv6 EID
   Block.  Such prefix will be used for routing and endpoint
   identification inside the site requesting it.  Mappings related to
   such prefix, or part of it, will be made available through the
   mapping system in use or registered to one or more Map-Server(s).
   Too guarantee reachability from the Legacy Internet the prefix could
   be announced in the BGP routing infrastructure by one or more
   PITR(s), possibly as part of a larger prefix, aggregating several
   prefixes of several sites.

6.  Action Plan

   This document requests IANA to initially allocate a /16 prefix out of
   the IPv6 addressing space for use as EID in LISP (Locator/ID
   Separation protocol).  It is suggested to IANA to temporarily avoid
   allocating any other address block the same /12 prefix the EID /16
   prefix belongs to.  This is to accommodate future requests of EID
   space without fragmenting the EID addressing space.  This will also
   help from an operational point of view, since it will be sufficient
   to change the subnet mask length in existing deployments.

   If in the future there will be need for a larger EID Block the
   address space adjacent the EID Block could be allocate by IANA
   according to the current policies.

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7.  Routing Considerations

   In order to provide connectivity between the Legacy Internet and LISP
   sites, PITRs announcing large aggregates of the IPv6 EID Block could
   be deployed.  By doing so, PITRs will attract traffic destined to
   LISP sites in order to encapsulate and forward it toward the specific
   destination LISP site.  Routers in the Legacy Internet MUST treat
   announcements of prefixes from the IPv6 EID Block as normal
   announcements, applying best current practice for traffic engineering
   and security.

   Even in a LISP site, not all routers need to run LISP elements.  In
   particular, routers that are not at the border of the local domain,
   used only for intra-domain routing, do not need to provide any
   specific LISP functionality but MUST be able to route traffic using
   addresses in the IPv6 EID Block.

   For the above-mentioned reasons, routers that do not run any LISP
   element, MUST NOT include any special handling code or hardware for
   addresses in the IPv6 EID Block.  In particular, it is RECOMMENDED
   that the default router configuration does not handle such addresses
   in any special way.  Doing differently could prevent communication
   between the Legacy Internet and LISP sites or even break local intra-
   domain connectivity.

8.  Security Considerations

   This document does not introduce new security threats in the LISP
   architecture nor in the Legacy Internet architecture.

9.  Acknowledgments

   Marla Azinger, Chris Morrow, Peter Schoenmaker all made insightful
   comments on early versions of this draft.

10.  IANA Considerations

   This document instructs the IANA to assign a /16 IPv6 prefix for use
   as the global LISP EID space using an hierarchical allocation as
   outlined in [RFC2434].  During the discussion related to this
   document, the LISP Working Group agreed in suggesting to IANA to
   reserve adjacent addressing space for future use as EID space if
   needs come.  Following the policies outlined in [RFC2434], such space
   will be assigned only upon IETF Consensus.  This document does not
   specify any specific value for the requested address block.

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11.  Normative References

              Farinacci, D., Fuller, V., Meyer, D., and D. Lewis,
              "Locator/ID Separation Protocol (LISP)",
              draft-ietf-lisp-14 (work in progress), June 2011.

              Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, "LISP
              Alternative Topology (LISP+ALT)", draft-ietf-lisp-alt-07
              (work in progress), June 2011.

              Lewis, D., Meyer, D., Farinacci, D., and V. Fuller,
              "Interworking LISP with IPv4 and IPv6",
              draft-ietf-lisp-interworking-02 (work in progress),
              June 2011.

              Fuller, V. and D. Farinacci, "LISP Map Server",
              draft-ietf-lisp-ms-09 (work in progress), June 2011.

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

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC4632]  Fuller, V. and T. Li, "Classless Inter-domain Routing
              (CIDR): The Internet Address Assignment and Aggregation
              Plan", BCP 122, RFC 4632, August 2006.

Appendix A.  Document Change Log

   Version 00 Posted July 2011.

   o  Updated section "IANA Considerations"

   o  Added section "Rationale and Intent" explaining why the EID block
      allocation is useful.

   o  Added section "Expected Use" explaining how sites can request and
      use a prefix in the IPv6 EID Block.

   o  Added section "Action Plan" suggesting IANA to avoid allocating
      address space adjacent the allocated EID block in order to

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      accommodate future EID space requests.

   o  Added section "Routing Consideration" describing how routers not
      running LISP deal with the requested address block.

   o  Added the present section to keep track of changes.

   o  Rename of draft-meyer-lisp-eid-block-02.txt.

Authors' Addresses

   Luigi Iannone
   Deutsche Telekom Laboratories


   Darrel Lewis
   Cisco Systems, Inc.


   David Meyer
   Cisco Systems, Inc.


   Vince Fuller
   Cisco Systems, Inc.


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