Internet Engineering Task Force (IETF) M. Ford, Ed.
Request for Comments: 6269 Internet Society
Category: Informational M. Boucadair
ISSN: 2070-1721 France Telecom
A. Durand
Juniper Networks
P. Levis
France Telecom
P. Roberts
Internet Society
June 2011
Issues with IP Address Sharing
Abstract
The completion of IPv4 address allocations from IANA and the Regional
Internet Registries (RIRs) is causing service providers around the
world to question how they will continue providing IPv4 connectivity
service to their subscribers when there are no longer sufficient IPv4
addresses to allocate them one per subscriber. Several possible
solutions to this problem are now emerging based around the idea of
shared IPv4 addressing. These solutions give rise to a number of
issues, and this memo identifies those common to all such address
sharing approaches. Such issues include application failures,
additional service monitoring complexity, new security
vulnerabilities, and so on. Solution-specific discussions are out of
scope.
Deploying IPv6 is the only perennial way to ease pressure on the
public IPv4 address pool without the need for address sharing
mechanisms that give rise to the issues identified herein.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
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). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Ford, et al. Informational [Page 1]RFC 6269 Issues with IP Address Sharing June 2011
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/rfc6269.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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described in the Simplified BSD License.
Ford, et al. Informational [Page 2]RFC 6269 Issues with IP Address Sharing June 2011Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Shared Addressing Solutions . . . . . . . . . . . . . . . . . 4
3. Analysis of Issues as They Relate to First and Third
Parties . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Content Provider Example . . . . . . . . . . . . . . . . . . . 8
5. Port Allocation . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Outgoing Ports . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Incoming Ports . . . . . . . . . . . . . . . . . . . . . . 10
5.2.1. Port Negotiation . . . . . . . . . . . . . . . . . . . 11
5.2.2. Connection to a Well-Known Port Number . . . . . . . . 12
5.2.3. Port Discovery Mechanisms . . . . . . . . . . . . . . 12
6. Impact on Applications . . . . . . . . . . . . . . . . . . . . 12
7. Geo-location and Geo-proximity . . . . . . . . . . . . . . . . 14
8. Tracking Service Usage . . . . . . . . . . . . . . . . . . . . 15
9. ICMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
10. MTU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
11. Fragmentation . . . . . . . . . . . . . . . . . . . . . . . . 16
12. Traceability . . . . . . . . . . . . . . . . . . . . . . . . . 17
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