IPv6 Unicast Address Assignment Considerations
RFC 5375
Network Working Group G. Van de Velde
Request for Comments: 5375 C. Popoviciu
Category: Informational Cisco Systems
T. Chown
University of Southampton
O. Bonness
C. Hahn
T-Systems Enterprise Services GmbH
December 2008
IPv6 Unicast Address Assignment Considerations
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
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Abstract
One fundamental aspect of any IP communications infrastructure is its
addressing plan. With its new address architecture and allocation
policies, the introduction of IPv6 into a network means that network
designers and operators need to reconsider their existing approaches
to network addressing. Lack of guidelines on handling this aspect of
network design could slow down the deployment and integration of
IPv6. This document aims to provide the information and
recommendations relevant to planning the addressing aspects of IPv6
deployments. The document also provides IPv6 addressing case studies
for both an enterprise and an ISP network.
Van de Velde, et al. Informational [Page 1]
RFC 5375 IPv6 Addressing Considerations December 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Network-Level Addressing Design Considerations . . . . . . . . 4
2.1. Globally Unique Addresses . . . . . . . . . . . . . . . . 4
2.2. Unique Local IPv6 Addresses . . . . . . . . . . . . . . . 5
2.3. 6bone Address Space . . . . . . . . . . . . . . . . . . . 6
2.4. Network-Level Design Considerations . . . . . . . . . . . 6
2.4.1. Sizing the Network Allocation . . . . . . . . . . . . 8
2.4.2. Address Space Conservation . . . . . . . . . . . . . . 8
3. Subnet Prefix Considerations . . . . . . . . . . . . . . . . . 8
3.1. Considerations for /64 Prefixes . . . . . . . . . . . . . 10
4. Allocation of the IID of an IPv6 Address . . . . . . . . . . . 10
4.1. Automatic EUI-64 Format Option . . . . . . . . . . . . . . 10
4.2. Using Privacy Extensions . . . . . . . . . . . . . . . . . 10
4.3. Manual/Dynamic Assignment Option . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
7. Informative References . . . . . . . . . . . . . . . . . . . . 12
Appendix A. Case Studies . . . . . . . . . . . . . . . . . . . . 16
A.1. Enterprise Considerations . . . . . . . . . . . . . . . . 16
A.1.1. Obtaining General IPv6 Network Prefixes . . . . . . . 16
A.1.2. Forming an Address (Subnet) Allocation Plan . . . . . 17
A.1.3. Other Considerations . . . . . . . . . . . . . . . . . 18
A.1.4. Node Configuration Considerations . . . . . . . . . . 18
A.2. Service Provider Considerations . . . . . . . . . . . . . 19
A.2.1. Investigation of Objective Requirements for an
IPv6 Addressing Schema of a Service Provider . . . . . 19
A.2.2. Exemplary IPv6 Address Allocation Plan for a
Service Provider . . . . . . . . . . . . . . . . . . . 23
A.2.3. Additional Remarks . . . . . . . . . . . . . . . . . . 28
Appendix B. Considerations for Subnet Prefixes Different than
/64 . . . . . . . . . . . . . . . . . . . . . . . . . 30
B.1. Considerations for Subnet Prefixes Shorter than /64 . . . 30
B.2. Considerations for Subnet Prefixes Longer than /64 . . . . 31
B.2.1. /126 Addresses . . . . . . . . . . . . . . . . . . . . 31
B.2.2. /127 Addresses . . . . . . . . . . . . . . . . . . . . 31
B.2.3. /128 Addresses . . . . . . . . . . . . . . . . . . . . 31
B.2.4. EUI-64 'u' and 'g' Bits . . . . . . . . . . . . . . . 31
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