Network Working Group S. Miyakawa
Request for Comments: 3769 NTT Communications Corporation
Category: Informational R. Droms
Requirements for IPv6 Prefix Delegation
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 (C) The Internet Society (2004).
This document describes requirements for how IPv6 address prefixes
should be delegated to an IPv6 subscriber's network (or "site").
With the deployment of IPv6 , several Internet Service Providers
are ready to offer IPv6 access to the public. In conjunction with
widely deployed "always on" media such as ADSL and the expectation
that customers will be assigned a /48 IPv6 unicast address prefix
(see RFC 3513  and section 3 of RFC 3177 ), an efficient
mechanism for delegating address prefixes to the customer's sites is
needed. The delegation mechanism will be intended to automate the
process of informing the customer's networking equipment of the
prefixes to be used at the customer's site.
This document clarifies the requirements for IPv6 address prefix
delegation from the ISP to the site.
Miyakawa & Droms Informational [Page 1]RFC 3769 Requirements IPv6 Prefix Delegation June 20042. Scenario and terminology
The following figure illustrates a likely example for the
organization of a network providing subscription IPv6 service:
/ \ /
+---------------+ +--------+/ \------/
|ISP Edge Router|Point-to-point|Customer+
| +--------------+ Router | Customer networks
| (PE) | link | (CPE) +
+---------------+ +--------+\ /------\
\ / \
Figure 1: Illustration of ISP-customer network architecture
PE: Provider edge device; the device connected to the service
provider's network infrastructure at which the link to the
customer site is terminated
CPE: Customer premises equipment; the device at the customer site at
which the link to the ISP is terminated
3. Requirements for Prefix Delegation
The purpose of the prefix delegation mechanism is to delegate and
manage prefixes to the CPE automatically.
3.1. Number and Length of Delegated Prefixes
The prefix delegation mechanism should allow for delegation of
prefixes of lengths between /48 and /64, inclusively. Other lengths
should also be supported. The mechanism should allow for delegation
of more than one prefix to the customer.
Miyakawa & Droms Informational [Page 2]RFC 3769 Requirements IPv6 Prefix Delegation June 20043.2. Use of Delegated Prefixes in Customer Network
The prefix delegation mechanism must not prohibit or inhibit the
assignment of longer prefixes, created from the delegated prefixes,
to links within the customer network. The prefix delegation
mechanism is not required to report any prefix delegations within the
customer's network back to the ISP.
3.3. Static and Dynamic Assignment
The prefix delegation mechanism should allow for long-lived static
pre-assignment of prefixes and for automated, possibly short-lived,
on-demand, dynamic assignment of prefixes to a customer.
3.4. Policy-based Assignment
The prefix delegation mechanism should allow for the use of policy in
assigning prefixes to a customer. For example, the customer's
identity and type of subscribed service may be used to determine the
address block from which the customer's prefix is selected, and the
length of the prefix assigned to the customer.