Client Link-Layer Address Option in DHCPv6
RFC 6939
Internet Engineering Task Force (IETF) G. Halwasia
Request for Comments: 6939 S. Bhandari
Category: Standards Track W. Dec
ISSN: 2070-1721 Cisco Systems
May 2013
Client Link-Layer Address Option in DHCPv6
Abstract
This document specifies the format and mechanism that is to be used
for encoding the client link-layer address in DHCPv6 Relay-Forward
messages by defining a new DHCPv6 Client Link-Layer Address option.
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/rfc6939.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Halwasia, et al. Standards Track [Page 1]
RFC 6939 DHCPv6 Client Link-Layer Address Option May 2013
Table of Contents
1. Introduction ....................................................2
2. Requirements Language ...........................................2
3. Problem Background and Scenario .................................2
4. DHCPv6 Client Link-Layer Address Option .........................4
5. DHCPv6 Relay Agent Behavior .....................................4
6. DHCPv6 Server Behavior ..........................................4
7. DHCPv6 Client Behavior ..........................................5
8. IANA Considerations .............................................5
9. Security Considerations .........................................5
10. Acknowledgements ...............................................6
11. References .....................................................6
11.1. Normative References ......................................6
11.2. Informative References ....................................6
1. Introduction
This specification defines an optional mechanism and the related
DHCPv6 option to allow first-hop DHCPv6 relay agents (relay agents
that are connected to the same link as the client) to provide the
client's link-layer address in the DHCPv6 messages being sent towards
the server.
2. 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 RFC 2119 [RFC2119].
3. Problem Background and Scenario
The DHCPv4 specification [RFC2131] provides a way to specify the
client link-layer address in the DHCPv4 message header. A DHCPv4
message header has 'htype' and 'chaddr' fields to specify the client
link-layer address type and the link-layer address, respectively.
The client link-layer address thus learned can be used by the DHCPv4
server and the relay agent in different ways. In some of the
deployments, DHCPv4 servers use 'chaddr' as a customer identifier and
a key for lookup in the client lease database.
With the incremental deployment of IPv6 to existing IPv4 networks,
which results in a dual-stack network environment, there will be
devices that act as both DHCPv4 and DHCPv6 clients. In service
provider deployments, a typical DHCPv4 implementation will use the
client link-layer address as one of the keys to build the DHCP client
lease database. In dual-stack scenarios, operators need to be able
Halwasia, et al. Standards Track [Page 2]
RFC 6939 DHCPv6 Client Link-Layer Address Option May 2013
to associate DHCPv4 and DHCPv6 messages with the same client
interface, based on an identifier that is common to the interface.
The client link-layer address is such an identifier.
Currently, the DHCPv6 specification [RFC3315] does not define a way
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