Issues with Private IP Addressing in the Internet
draft-ietf-grow-private-ip-sp-cores-03

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Network Working Group                                         A. Kirkham
Internet-Draft                                        Palo Alto Networks
Obsoletes:  None (if approved)                               May 7, 2012
Intended status:  Informational
Expires:  November 8, 2012

           Issues with Private IP Addressing in the Internet
                 draft-ietf-grow-private-ip-sp-cores-03

Abstract

   The purpose of this document is to provide a discussion of the
   potential problems of using private, RFC1918, or non-globally-
   routable addressing within the core of an SP network.  The discussion
   focuses on link addresses and to a small extent loopback addresses.
   While many of the issues are well recognised within the ISP
   community, there appears to be no document that collectively
   describes the issues.

Legal

   This documents and the information contained therein are provided on
   an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
   REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
   IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
   WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
   WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE
   ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
   FOR A PARTICULAR PURPOSE.

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
   Task Force (IETF).  Note that other groups may also distribute
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 8, 2012.

Kirkham                 Expires November 8, 2012                [Page 1]
Internet-Draft             private-ip-sp-cores                  May 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
   2.  Conservation of Address Space  . . . . . . . . . . . . . . . .  3
   3.  Effects on Traceroute  . . . . . . . . . . . . . . . . . . . .  4
   4.  Effects on Path MTU Discovery  . . . . . . . . . . . . . . . .  7
   5.  Unexpected interactions with some NAT implementations  . . . .  8
   6.  Interactions with edge anti-spoofing techniques  . . . . . . . 10
   7.  Peering using loopbacks  . . . . . . . . . . . . . . . . . . . 10
   8.  DNS Interaction  . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  Operational and Troubleshooting issues . . . . . . . . . . . . 11
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   11. Alternate approaches to core network security  . . . . . . . . 13
   12. Normative References . . . . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . . 14
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14

Kirkham                 Expires November 8, 2012                [Page 2]
Internet-Draft             private-ip-sp-cores                  May 2012

1.  Introduction

   In the mid to late 90's, some Internet Service Providers (ISPs)
   adopted the practice of utilising private (or non-globally unique) IP
   (i.e.  RFC1918) addresses for the infrastructure links and in some
   cases the loopback interfaces within their networks.  The reasons for
   this approach centered on conservation of address space (i.e.
   scarcity of public IPv4 address space), and security of the core
   network (also known as core hiding).

   However, a number of technical and operational issues occurred as a
   result of using private (or non-globally unique) IP addresses, and
   virtually all these ISPs moved away from the practice.  Tier 1 ISPs
   are considered the benchmark of the industry and as of the time of
   writing, there is no known tier 1 ISP that utilises the practice of
   private addressing within their core network.