Interworking LISP with IPv4 and IPv6
draft-ietf-lisp-interworking-05

Network Working Group                                           D. Lewis
Internet-Draft                                                  D. Meyer
Intended status: Experimental                               D. Farinacci
Expires: September 1, 2012                                     V. Fuller
                                                     Cisco Systems, Inc.
                                                       February 29, 2012

                  Interworking LISP with IPv4 and IPv6
                  draft-ietf-lisp-interworking-05.txt

Abstract

   This document describes techniques for allowing sites running the
   Locator/ID Separation Protocol (LISP) to interoperate with Internet
   sites (which may be using either IPv4, IPv6, or both) but which are
   not running LISP.  A fundamental property of LISP speaking sites is
   that they use Endpoint Identifiers (EIDs), rather than traditional IP
   addresses, in the source and destination fields of all traffic they
   emit or receive.  While EIDs are syntactically identical to IPv4 or
   IPv6 addresses, normally routes to them are not carried in the global
   routing system so an interoperability mechanism is needed for non-
   LISP-speaking sites to exchange traffic with LISP-speaking sites.
   This document introduces three such mechanisms.  The first uses a new
   network element, the LISP Proxy Ingress Tunnel Routers (Proxy-ITRs)
   (Section 5) to act as a intermediate LISP Ingress Tunnel Router (ITR)
   for non-LISP-speaking hosts.  Second the document adds Network
   Address Translation (NAT) functionality to LISP Ingress and LISP
   Egress Tunnel Routers (xTRs) to substitute routable IP addresses for
   non-routable EIDs.  Finally, this document introduces the Proxy
   Egress Tunnel Router (Proxy ETR) to handle cases where a LISP ITR
   cannot send packets to non-LISP sites without encapsulation.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 1, 2012.

Copyright Notice

   Copyright (c) 2012 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
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   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Definition of Terms  . . . . . . . . . . . . . . . . . . . . .  6
   3.  LISP Interworking Models . . . . . . . . . . . . . . . . . . .  7
   4.  Routable EIDs  . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.1.  Impact on Routing Table  . . . . . . . . . . . . . . . . .  8
     4.2.  Requirement for sites to use BGP . . . . . . . . . . . . .  8
     4.3.  Limiting the Impact of Routable EIDs . . . . . . . . . . .  8
     4.4.  Use of Routable EIDs for sites transitioning to LISP . . .  8
   5.  Proxy Ingress Tunnel Routers . . . . . . . . . . . . . . . . . 10
     5.1.  Proxy-ITR EID announcements  . . . . . . . . . . . . . . . 10
     5.2.  Packet Flow with Proxy-ITRs  . . . . . . . . . . . . . . . 10
     5.3.  Scaling Proxy-ITRs . . . . . . . . . . . . . . . . . . . . 11
     5.4.  Impact of the Proxy-ITRs placement in the network  . . . . 12
     5.5.  Benefit to Networks Deploying Proxy-ITRs . . . . . . . . . 12
   6.  Proxy Egress Tunnel Routers  . . . . . . . . . . . . . . . . . 13
     6.1.  Packet Flow with Proxy Egress Tunnel Routers . . . . . . . 13
   7.  LISP-NAT . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     7.1.  Using LISP-NAT with LISP-NR EIDs . . . . . . . . . . . . . 15
     7.2.  LISP Sites with Hosts using RFC 1918 Addresses Sending
           to non-LISP Sites  . . . . . . . . . . . . . . . . . . . . 16
     7.3.  LISP Sites with Hosts using RFC 1918 Addresses
           Sending Packets to Other LISP Sites  . . . . . . . . . . . 16
     7.4.  LISP-NAT and multiple EIDs . . . . . . . . . . . . . . . . 17
   8.  Discussion of Proxy-ITRs (Proxy-ITRs), LISP-NAT, and
       Proxy-ETRs (Proxy-ETRs)  . . . . . . . . . . . . . . . . . . . 18
     8.1.  How Proxy-ITRs and Proxy-ETRs Interact . . . . . . . . . . 18
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 20
   11. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 21
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 22
     12.2. Informative References . . . . . . . . . . . . . . . . . . 22
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24

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1.  Introduction

   This document describes interoperation mechanisms between LISP [LISP]
   sites which use non-globally-routed EIDs, and non-LISP sites.  A key
   behavior of the separation of Locators and Endpoint IDs is that EID
   prefixes are normally not advertised into the Internet's Default Free
   Zone (DFZ).  Specifically, only Routing Locators (RLOCs) are carried
   in the Internet's DFZ.  Existing Internet sites (and their hosts)
   which do not run in the LISP protocol must still be able to reach
   sites numbered from LISP EID space.  This draft describes three
   mechanisms that can be used to provide reachability between sites
   that are LISP-capable and those that are not.

   The first mechanism uses a new network element, the LISP Proxy
   Ingress Tunnel Router (Proxy-ITR) to act as a intermediate LISP
   Ingress Tunnel Router (ITR) for non-LISP-speaking hosts.  The second
   mechanism adds a form of Network Address Translation (NAT)
   functionality to Tunnel Routers (xTRs), to substitute routable IP
   addresses for non-routable EIDs.  The final network element is the
   LISP Proxy Egress Tunnel Routers (Proxy-ETR), which act as an
   intermediate Egress Tunnel Router (ETR) for LISP sites which need to
   encapsulate LISP packets destined to non-LISP sites.

   More detailed descriptions of these mechanisms and the network
   elements involved may be found in the following sections:

   - Section 2 defines terms used throughout the document

   - Section 2 describes the different cases where interworking
   mechanisms are needed

   - Section 4 describes the relationship between the new EID prefix
   space and the IP address space used by the current Internet

   - Section 5 introduces and describes the operation of Proxy Ingress
   tunnel Routerss

   - Section 6 introduces and describes the operations of Proxy-ETRs

   - Section 7 defines how NAT is used by ETRs to translate non-routable
   EIDs into routable IP addresses.

   - Section 8 describes the relationship between asymmetric and
   symmetric interworking mechanisms (Proxy-ITRs and Proxy-ETRs vs LISP-
   NAT)

   Note that any successful interworking model should be independent of
   any particular EID-to-RLOC mapping algorithm.  This document does not

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   comment on the value of any of the particular LISP mapping systems.

   Several areas concerning the Interworking of LISP and non-LISP sites
   remain open for further study.  These areas include an examination of
   the impact of LISP-NAT on Internet traffic and applications,
   understanding the deployment motivations for the deployment and
   operation of Proxy Tunnel Routers, the impact of EID routes
   originated into the Internet's Default Free Zone,and the effects of
   Proxy Tunnel Routers or LISP-NAT on Internet traffic and
   applications.  Until these issues are fully understood, it is
   possible that the interworking mechanisms described in this document
   are hard to deploy, or may have unintended consequences to
   applications.

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