DHCPv6 Prefix-Length Hint Issues (RFC8168)
Original Publication Date: 2017-May-01
Included in the Prior Art Database: 2017-Jun-01
Internet Society Requests For Comment (RFCs)
T. Li: AUTHOR [+3]
DHCPv6 Prefix Delegation [RFC3633] allows a client to include a prefix-length hint value in the message sent to the server to indicate a preference for the size of the prefix to be delegated. A prefix-length hint is communicated by a client to the server by including an IA_PD Prefix Option (IAPREFIX option), encapsulated in an IA_PD option, with the "IPv6 prefix" field set to zero and the "prefix-length" field set to a non-zero value. The servers are free to ignore the prefix-length hint values depending on server policy. However, some clients may not be able to function (or only in a degraded state) when they're provided with a prefix whose length is different from what they requested. For example, if the client is asking for a /56 and the server returns a /64, the functionality of the client might be limited because it might not be able to split the prefix for all its interfaces. For other hints, such as requesting for an explicit address, this might be less critical, as it just helps a client that wishes to continue using what it used last time. The prefix-length hint directly impacts the operational capability of the client; thus, it should be given more consideration.
Internet Engineering Task Force (IETF) T. Li Request for Comments: 8168 C. Liu Category: Standards Track Y. Cui ISSN: 2070-1721 Tsinghua University May 2017
DHCPv6 Prefix-Length Hint Issues
DHCPv6 Prefix Delegation allows a client to include a prefix-length hint value in the IA_PD option to indicate a preference for the size of the prefix to be delegated, but it is unclear about how the client and server should act in different situations involving the prefix- length hint. This document provides a summary of the existing problems with the prefix-length hint and guidance on what the client and server could do in different situations.
Status of This Memo
This is an Internet Standards Track document.
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). Further information on Internet Standards is available in Section 2 of RFC 7841.
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/rfc8168.
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Li, et al. Standards Track [Page 1]
RFC 8168 DHCPv6 Prefix-Length Hint Issues May 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Problem Description and Proposed Solutions . . . . . . . . . 3
3.1. Creation of Solicit Message . . ....