Hiding Transit-Only Networks in OSPF
RFC 6860

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Internet Engineering Task Force (IETF)                           Y. Yang
Request for Comments: 6860                                     A. Retana
Updates: 2328, 5340                                               A. Roy
Category: Standards Track                            Cisco Systems, Inc.
ISSN: 2070-1721                                             January 2013

                  Hiding Transit-Only Networks in OSPF

Abstract

   A transit-only network is defined as a network connecting routers
   only.  In OSPF, transit-only networks are usually configured with
   routable IP addresses, which are advertised in Link State
   Advertisements (LSAs) but are not needed for data traffic.  In
   addition, remote attacks can be launched against routers by sending
   packets to these transit-only networks.  This document presents a
   mechanism to hide transit-only networks to speed up network
   convergence and reduce vulnerability to remote attacks.

   In the context of this document, 'hiding' implies that the prefixes
   are not installed in the routing tables on OSPF routers.  In some
   cases, IP addresses may still be visible when using OSPFv2.

   This document updates RFCs 2328 and 5340.

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/rfc6860.

Yang, et al.                 Standards Track                    [Page 1]
RFC 6860          Hiding Transit-Only Networks in OSPF      January 2013

Copyright Notice

   Copyright (c) 2013 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. Requirements Notation ......................................3
   2. Hiding IPv4 Transit-Only Networks in OSPFv2 .....................3
      2.1. Point-to-Point Networks ....................................3
           2.1.1. Advertising Point-to-Point Networks .................4
           2.1.2. Hiding Point-to-Point Networks ......................4
      2.2. Broadcast Networks .........................................5
           2.2.1. Advertising Broadcast Networks ......................5
           2.2.2. Hiding Broadcast Networks ...........................5
                  2.2.2.1. Sending Network-LSA ........................5
                  2.2.2.2. Receiving Network-LSA ......................6
                           2.2.2.2.1. Backward Compatibility ..........6
      2.3. Non-Broadcast Networks .....................................7
           2.3.1. NBMA ................................................7
           2.3.2. Point-to-Multipoint .................................7
                  2.3.2.1. Advertising Point-to-Multipoint Networks ...7
                  2.3.2.2. Hiding Point-to-Multipoint Networks ........8
   3. Hiding IPv6 Transit-Only Networks in OSPFv3 .....................9
      3.1. Hiding AF-Enabled Transit-Only Networks in OSPFv3 ..........9
   4. Operational Considerations ......................................9
      4.1. Forwarding Address ........................................10
      4.2. Virtual Links .............................................10
      4.3. Unnumbered Interfaces .....................................10
   5. Security Considerations ........................................11
   6. Acknowledgments ................................................11
   7. References .....................................................12
      7.1. Normative References ......................................12
      7.2. Informative References ....................................12

Yang, et al.                 Standards Track                    [Page 2]
RFC 6860          Hiding Transit-Only Networks in OSPF      January 2013

1.  Introduction

   A transit-only network is defined as a network connecting routers
   only.  In OSPF, transit-only networks are usually configured with