Client Identifier Option in DHCP Server Replies
RFC 6842
| Document | Type |
RFC - Proposed Standard
(January 2013; No errata)
Updates RFC 2131
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | WG Document | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6842 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Ralph Droms | ||
| IESG note | Ted Lemon (Ted.Lemon@nominum.com) is the Document Shepherd. | ||
| Send notices to | (None) | ||
Internet Engineering Task Force (IETF) N. Swamy
Request for Comments: 6842 Samsung India
Updates: 2131 G. Halwasia
Category: Standards Track P. Jhingran
ISSN: 2070-1721 Cisco Systems
January 2013
Client Identifier Option in DHCP Server Replies
Abstract
This document updates RFC 2131 "Dynamic Host Configuration Protocol"
by addressing the issues arising from that document's specification
that the server MUST NOT return the 'client identifier' option to the
client.
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 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/rfc6842.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Swamy, et al. Standards Track [Page 1]
RFC 6842 Client Identifier Option January 2013
Table of Contents
1. Introduction ....................................................2
1.1. Requirements Language ......................................2
2. Problem Statement ...............................................2
3. Modification to RFC 2131 ........................................3
4. Security Considerations .........................................4
5. Acknowledgments .................................................4
6. Normative References ............................................4
1. Introduction
The Dynamic Host Configuration Protocol (DHCP) defined in [RFC2131]
provides configuration parameters to hosts on an IP-based network.
DHCP is built on a client-server model, where designated DHCP servers
allocate network addresses and deliver configuration parameters to
dynamically configured hosts.
The changes to [RFC2131] defined in this document clarify the use of
the 'client identifier' option by the DHCP servers. The
clarification addresses the issues (as mentioned in Problem
Statement) arising out of the point specified by [RFC2131] that the
server MUST NOT return the 'client identifier' option to the client.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Problem Statement
[RFC2131] specifies that a combination of 'client identifier' or
'chaddr' and assigned network address constitute a unique identifier
for the client's lease and are used by both the client and server to
identify a lease referred in any DHCP messages. [RFC2131] also
specifies that the server MUST NOT return the 'client identifier'
option in DHCPOFFER and DHCPACK messages. Furthermore, DHCP relay
agents and servers implementing [RFC2131] MAY drop the DHCP packets
in the absence of both the 'client identifier' and 'chaddr' option.
In some cases, a client may not have a valid hardware address to
populate the 'chaddr' field and may set the field to all zeroes. One
such example is when DHCP is used to assign an IP address to a mobile
phone or a tablet and where the 'chaddr' field is set to zero in DHCP
request packets. In such cases, the client usually sets the 'client
Swamy, et al. Standards Track [Page 2]
RFC 6842 Client Identifier Option January 2013
identifier' option field (to a value as permitted in [RFC2131]), and
both the client and server use this field to uniquely identify the
client with in a subnet.
Note that due to aforementioned recommendations in [RFC2131], valid
downstream DHCP packets (DHCPOFFER, DHCPACK, and DHCPNAK) from the
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