IANA Reserved IPv4 Prefix for Shared Transition Space
draft-weil-shared-transition-space-request-02

Abstract

This document requests a reserved IANA IPv4 address allocation as Shared Transition Space to support the deployment of IPv4 address sharing technologies post IPv4 exhaustion.

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 working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on January 10, 2012.

Copyright Notice

Copyright (c) 2011 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
• 2. Requirements Language
• 3. Motivation
• 4. Shared Transition Space
• 5. Security Considerations
• 6. IANA Considerations
• 7. References
• Appendix A. Acknowledgements
• Authors' Addresses

1. Introduction

Many operators are currently implementing their IPv6 transition plans. During the transition, continued support for heritage IPv4 only devices will be required. While most operators are well aware of the limitations of Carrier Grade NAT, particularly NAT444 [I-D.shirasaki-nat444] (see [I-D.donley-nat444-impacts]), it is the transition mechanism that has the least customer impact for many carriers.

To deploy Carrier Grade NAT, it becomes necessary for a provider to create an inside address pool that will not conflict with its customer address space. This document requests that IANA reserve a /10 of IPv4 addresses to use as Shared Transition Space. As IANA has exhausted its pool of addresses, one or more RIR(s) or legacy address holder(s) will need to supply IANA with such addresses (e.g. per ARIN Draft Policy 2011-5 [ARIN]).

2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

3. Motivation

The Internet community is rapidly consuming the remaining supply of unallocated IPv4 addresses. During the transition period to IPv6, it is imperative that Service Providers maintain IPv4 service for devices and networks that are currently incapable of upgrading to IPv6.

In order to provide IPv4 service to customers and/or devices once the IPv4 address space is exhausted, Service Providers must multiplex several subscribers behind a single IPv4 address using one of several techniques including NAT444 or Carrier Grade NAT. Providers need sufficient non-[RFC1918] address space to deploy such technologies and avoid overlap with customer use of private address space.

Many CPE router devices used to provide residential or small-medium business services have been optimized for IPv4 operation, and typically require replacement in order to fully support the transition to IPv6 (either natively or via one of many transition technologies). In addition, various consumer devices including IP-enabled televisions, gaming consoles, medical and family monitoring devices, etc. are IPv4-only, and cannot be upgraded. While these will eventually be replaced with dual-stack or IPv6 capable devices, this transition will take many years. As these are typically consumer-owned devices, service providers do not have control over the speed of their replacement cycle. However, consumers have an expectation that they will continue to receive IPv4 service, and that such devices will continue to have IPv4 Internet connectivity after the IPv4 pool is exhausted, even if the customer contracts for new service with a new provider.

Until such customers replace their Home Gateways and all IPv4-only CPE devices with IPv6-capable devices, Service Providers will be required to continue to offer IPv4 services through the use of an IPv4 address sharing technology such as NAT444 [I-D.shirasaki-nat444]. The challenges associated with these deployments are identified in [I-D.shirasaki-nat444-isp-shared-addr], [I-D.donley-nat444-impacts], and [I-D.ietf-intarea-shared-addressing-issues].

Addressing solutions for dealing with the depletion of the IPv4 public address space and the lack of available private addresses within large providers are presented in [I-D.azinger-additional-private-ipv4-space-issues] as well as [I-D.shirasaki-nat444-isp-shared-addr]. For infrastructure providers whose customers are already using [RFC1918] space, as described in [I-D.bdgks-arin-shared-transition-space] and [ARIN], the preferred method for addressing the problems presented in both documents is to direct IANA to reserve address space for Shared Transition Space.

4. Shared Transition Space

This document proposes the assignment of a /10 as Shared Transition Space. Shared Transition Space is IPv4 address space reserved for Infrastructure provider use with the purpose of facilitating IPv6 transition and IPv4 coexistence deployment. The requested block SHOULD NOT be utilized for any purpose other than as "inside" addresses in a carrier NAT environment (e.g. between the CGN and customer CPE devices) or for other IPv4 to IPv6 transition infrastructure. Network equipment manufacturers MUST NOT use the assigned block in default or example device configurations.

Because Shared Transition addresses have no meaning outside of the Infrastructure Provider, routing information about shared transition space networks MUST NOT be propagated on interdomain links, and packets with shared transition source or destination addresses SHOULD NOT be forwarded across such links. Internet service providers SHOULD filter out routing information about shared transition space networks on ingress links.

5. Security Considerations

This memo does not define any protocol, and raises no security issues. Any addresses allocated as Shared Transition Space would not be routable on the Internet.

6. IANA Considerations

IANA is asked to reserve an IPv4 /10 for use as Shared Transition Space. This prefix is intended to be non-routable. As IANA has exhausted its pool of IPv4 address space, it may be necessary for one or more RIRs and/or legacy address holders to provide such addresses for IANA reservation (e.g. per ARIN Draft Policy 2011-5 [ARIN]).

7. References

Appendix A. Acknowledgements

Thanks to the following people (in alphabetical order) for their guidance and feedback:

John Brzozowski

Isaiah Connell

Greg Davies

Kirk Erichsen

Wes George

Tony Hain

Philip Matthews

John Pomeroy

Barbara Stark

Jean-Francois Tremblay

Leo Vegoda

Steven Wright

Ikuhei Yamagata

Authors' Addresses