Analysis of the 64-bit Boundary in IPv6 Addressing (RFC7421)
Original Publication Date: 2015-Jan-01
Included in the Prior Art Database: 2015-Jan-15
Internet Society Requests For Comment (RFCs)
B. Carpenter: AUTHOR [+7]
Rather than simply overcoming the IPv4 address shortage by doubling the address size to 64 bits, IPv6 addresses were originally chosen to be 128 bits long to provide flexibility and new possibilities. In particular, the notion of a well-defined interface identifier was added to the IP addressing model. The IPv6 addressing architecture [RFC4291] specifies that a unicast address is divided into n bits of subnet prefix followed by (128-n) bits of interface identifier (IID). The bits in the IID may have significance only in the process of deriving the IID; once it is derived, the entire identifier should be treated as an opaque value [RFC7136]. Also, since IPv6 routing is entirely based on variable length prefixes (also known as variable length subnet masks), there is no basic architectural assumption that n has any particular fixed value. All IPv6 routing protocols support prefixes of any length up to /128.
Internet Engineering Task Force (IETF) B. Carpenter, Ed. Request for Comments: 7421 Univ. of Auckland Category: Informational T. Chown ISSN: 2070-1721 Univ. of Southampton F. Gont SI6 Networks / UTN-FRH S. Jiang Huawei Technologies Co., Ltd A. Petrescu CEA, LIST A. Yourtchenko Cisco January 2015
Analysis of the 64-bit Boundary in IPv6 Addressing
The IPv6 unicast addressing format includes a separation between the prefix used to route packets to a subnet and the interface identifier used to specify a given interface connected to that subnet. Currently, the interface identifier is defined as 64 bits long for almost every case, leaving 64 bits for the subnet prefix. This document describes the advantages of this fixed boundary and analyzes the issues that would be involved in treating it as a variable boundary.
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.
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/rfc7421.
Carpenter, et al. Informational ...