IAB/IESG Recommendations on IPv6 Address Allocations to Sites
RFC 3177
Document | Type |
RFC - Informational
(September 2001; No errata)
Obsoleted by RFC 6177
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Author | IAB | ||
Last updated | 2013-03-02 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 3177 (Informational) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group IAB Request for Comments: 3177 IESG Category: Informational September 2001 IAB/IESG Recommendations on IPv6 Address Allocations to Sites 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. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract This document provides recommendations to the addressing registries (APNIC, ARIN and RIPE-NCC) on policies for assigning IPv6 address blocks to end sites. In particular, it recommends the assignment of /48 in the general case, /64 when it is known that one and only one subnet is needed and /128 when it is absolutely known that one and only one device is connecting. The original recommendations were made in an IAB/IESG statement mailed to the registries on September 1, 2000. This document refines the original recommendation and documents it for the historical record. 1. Introduction There have been many discussions between IETF and RIR experts on the topic of IPv6 address allocation policy. This memo addresses the issue of the boundary in between the public and the private topology in the Internet, that is, how much address space should an ISP allocate to homes, small and large enterprises, mobile networks and transient customers. This document does not address the issue of the other boundaries in the public topology, that is, between the RIRs and the LIRs. This document was developed by the IPv6 Directorate, IAB and IESG, and is a recommendation from the IAB and IESG to the RIRs. IAB & IESG Informational [Page 1] RFC 3177 IAB/IESG Recommendations on IPv6 Addresses September 2001 2. Background The technical principles that apply to address allocation seek to balance healthy conservation practices and wisdom with a certain ease of access. On one hand, when managing a potentially limited resource, one must conserve wisely to prevent exhaustion within an expected lifetime. On the other hand, the IPv6 address space is in no sense as limited a resource as the IPv4 address space, and unwarranted conservatism acts as a disincentive in a marketplace already dampened by other factors. So from a market development perspective, we would like to see it be very easy for a user or an ISP to obtain as many IPv6 addresses as they really need without a prospect of immediate renumbering or of scaling inefficiencies. The IETF makes no comment on business issues or relationships. However, in general, we observe that technical delegation policy can have strong business impacts. A strong requirement of the address delegation plan is that it not be predicated on or unduly bias business relationships or models. The IPv6 address, as currently defined, consists of 64 bits of "network number" and 64 bits of "host number". The technical reasons for this are several. The requirements for IPv6 agreed to in 1993 included a plan to be able to address approximately 2^40 networks and 2^50 hosts; the 64/64 split effectively accomplishes this. Procedures used in host address assignment, such as the router advertisement of a network's prefix to hosts [RFC2462], which in turn place a locally unique number in the host portion, depend on this split. Subnet numbers must be assumed to come from the network part. This is not to preclude routing protocols such as IS-IS level 1 (intra-area) routing, which routes individual host addresses, but says that it may not be depended upon in the world outside that zone. The 64-bit host field can also be used with EUI-64 for a flat, uniquely allocated space, and therefore it may not be globally treated as a subnetting resource. Those concerned with privacy issues linked to the presence of a globally unique identifier may note that 64 bits makes a large enough field to maintain excellent random-number-draw properties for self-configured End System Designators. That alternative construction of this 64-bit host part of an IPv6 address is documented in [RFC3041]. While the IETF has also gone to a great deal of effort to minimize the impacts of network renumbering, renumbering of IPv6 networks is neither invisible nor completely painless. Therefore, renumbering should be considered a tolerable event, but to be avoided if reasonably feasible. IAB & IESG Informational [Page 2] RFC 3177 IAB/IESG Recommendations on IPv6 Addresses September 2001 In [RFC2374] and [RFC2450], the IETF's IPNG working group has recommended that the address block given to a single edge networkShow full document text