The Line-Identification Option
RFC 6788

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Internet Engineering Task Force (IETF)                       S. Krishnan
Request for Comments: 6788                                   A. Kavanagh
Category: Standards Track                                       B. Varga
ISSN: 2070-1721                                                 Ericsson
                                                                S. Ooghe
                                                          Alcatel-Lucent
                                                             E. Nordmark
                                                                   Cisco
                                                           November 2012

                     The Line-Identification Option

Abstract

   In Ethernet-based aggregation networks, several subscriber premises
   may be logically connected to the same interface of an Edge Router.
   This document proposes a method for the Edge Router to identify the
   subscriber premises using the contents of the received Router
   Solicitation messages.  The applicability is limited to broadband
   network deployment scenarios in which multiple user ports are mapped
   to the same virtual interface on the Edge Router.

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/rfc6788.

Krishnan, et al.             Standards Track                    [Page 1]
RFC 6788                     Line-ID Option                November 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   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 ....................................................3
      1.1. Terminology ................................................4
      1.2. Conventions Used in This Document ..........................6
   2. Applicability Statement .........................................6
   3. Issues with Identifying the Subscriber Premises in an
      N:1 VLAN Model ..................................................7
   4. Basic Operation .................................................7
   5. AN Behavior .....................................................8
      5.1. On Initialization ..........................................8
      5.2. On Receiving a Router Solicitation from the End-Device .....8
      5.3. On Receiving a Router Advertisement from the Edge Router ...9
           5.3.1. Identifying Tunneled Router Advertisements ..........9
      5.4. On Detecting a Subscriber Circuit Coming Up ................9
      5.5. On Detecting Edge Router Failure ..........................10
      5.6. RS Retransmission Algorithm ...............................10
   6. Edge Router Behavior ...........................................10
      6.1. On Receiving a Tunneled Router Solicitation from the AN ...10
      6.2. On Sending a Router Advertisement Towards the End-Device ..10
      6.3. Sending Periodic Unsolicited Router Advertisements
           Towards the End-Device ....................................11
   7. Line-Identification Option (LIO) ...............................12
      7.1. Encoding of Line ID .......................................13
   8. Garbage Collection of Unused Prefixes ..........................14
   9. Interactions with Secure Neighbor Discovery ....................14
   10. Acknowledgements ..............................................14
   11. Security Considerations .......................................14
   12. IANA Considerations ...........................................14
   13. References ....................................................15
      13.1. Normative References .....................................15
      13.2. Informative References ...................................16

Krishnan, et al.             Standards Track                    [Page 2]
RFC 6788                     Line-ID Option                November 2012

1.  Introduction

   Digital Subscriber Line (DSL) is a widely deployed access technology