Address Resolution Protocol (ARP) Mediation for IP Interworking of Layer 2 VPNs
RFC 6575

Internet Engineering Task Force (IETF)                      H. Shah, Ed.
Request for Comments: 6575                                         Ciena
Category: Standards Track                                  E. Rosen, Ed.
ISSN: 2070-1721                                            G. Heron, Ed.
                                                                   Cisco
                                                        V. Kompella, Ed.
                                                          Alcatel-Lucent
                                                               June 2012

            Address Resolution Protocol (ARP) Mediation for
                    IP Interworking of Layer 2 VPNs

Abstract

   The Virtual Private Wire Service (VPWS), detailed in RFC 4664,
   provides point-to-point connections between pairs of Customer Edge
   (CE) devices.  It does so by binding two Attachment Circuits (each
   connecting a CE device with a Provider Edge (PE) device) to a
   pseudowire (connecting the two PEs).  In general, the Attachment
   Circuits must be of the same technology (e.g., both Ethernet or both
   ATM), and the pseudowire must carry the frames of that technology.
   However, if it is known that the frames' payload consists solely of
   IP datagrams, it is possible to provide a point-to-point connection
   in which the pseudowire connects Attachment Circuits of different
   technologies.  This requires the PEs to perform a function known as
   "Address Resolution Protocol (ARP) Mediation".  ARP Mediation refers
   to the process of resolving Layer 2 addresses when different
   resolution protocols are used on either Attachment Circuit.  The
   methods described in this document are applicable even when the CEs
   run a routing protocol between them, as long as the routing protocol
   runs over IP.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc6575.

Shah, et al.                 Standards Track                    [Page 1]
RFC 6575       ARP Mediation for IP Interworking of L2VPNs     June 2012

Copyright Notice

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................3
      1.1. Conventions Used in This Document ..........................4
   2. ARP Mediation (AM) Function .....................................5
   3. IP Layer 2 Interworking Circuit .................................6
   4. IP Address Discovery Mechanisms .................................6
      4.1. Discovery of IP Addresses of Locally Attached IPv4 CE ......7
           4.1.1. Monitoring Local Traffic ............................7
           4.1.2. CE Devices Using ARP ................................7
           4.1.3. CE Devices Using Inverse ARP ........................8
           4.1.4. CE Devices Using PPP ................................9
           4.1.5. Router Discovery Method ............................10
           4.1.6. Manual Configuration ...............................10
      4.2. How a CE Learns the IPv4 Address of a Remote CE ...........10
           4.2.1. CE Devices Using ARP ...............................11
           4.2.2. CE Devices Using Inverse ARP .......................11
           4.2.3. CE Devices Using PPP ...............................11
      4.3. Discovery of IP Addresses of IPv6 CE Devices ..............11
           4.3.1. Distinguishing Factors between IPv4 and IPv6 .......11
           4.3.2. Requirements for PEs ...............................12
           4.3.3. Processing of Neighbor Solicitations ...............12
           4.3.4. Processing of Neighbor Advertisements ..............13
           4.3.5. Processing Inverse Neighbor Solicitations (INSs) ...14