Client Hardware Address Option in DHCPv6
draft-halwasia-dhc-dhcpv6-hardware-addr-opt-00

Network Working Group                                        G. Halwasia
Internet-Draft                                               S. Bhandari
Intended status: Standards Track                                  W. Dec
Expires: March 28, 2012                                    Cisco Systems
                                                      September 25, 2011

                Client Hardware Address Option in DHCPv6
             draft-halwasia-dhc-dhcpv6-hardware-addr-opt-00

Abstract

   This document specifies the format and mechanism that is to be used
   for encoding client hardware address in DHCPv6 messages by defining a
   new DHCPv6 Client Hardware Address option.

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].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on March 28, 2012.

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Problem Background and Scenario . . . . . . . . . . . . . . . . 3
   3.  DHCPv6 Client Hardware Address Option . . . . . . . . . . . . . 4
   4.  DHCPv6 Client Behavior  . . . . . . . . . . . . . . . . . . . . 4
   5.  DHCPv6 Relay Agent Behavior . . . . . . . . . . . . . . . . . . 4
   6.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . . . . . 5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 5
   10. Normative References  . . . . . . . . . . . . . . . . . . . . . 5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Introduction

   This specification defines an optional mechanism and the related
   DHCPv6 option to allow DHCPv6 client or first hop DHCPv6 relay agent
   directly connected to the client to populate client hardware address
   in the DHCPv6 messages being sent towards the server.

2.  Problem Background and Scenario

   DHCPv4 protocol specification [RFC2131] provides a way to specify the
   client hardware address in the DHCPv4 message header.  DHCPv4 message
   header has 'htype' and 'chaddr' fields to specify client hardware
   address type and hardware address respectively.  The client hardware
   address thus learnt can be used by DHCPv4 server and relay 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,
   effectievly an enablement of dual-stack, there will be devices that
   act as both DHCPv4 and DHCPv6 clients.  In service provider
   deployments, a typical DHCPv4 implemention will use the client
   hardware address as one of the keys to build DHCP client lease
   database.  In dual stack scenarios it is desirable for the operator
   to associate DHCPv4 and DHCPv6 messages as belonging to the same
   client interface based on an identifier that is already used by that
   operator such as the client hardware address.

   Currently, the DHCPv6 protocol specification [RFC3315] does not
   define a way for DHCP clients to specify client hardware address in
   the DHCPv6 message sent towards DHCPv6 Server.  Similarly DHCPv6
   Relay or Server cannot glean client hardware address from the
   contents of DHCPv6 message received.  DHCPv6 protocol specification
   mandates all clients to prepare and send DUID as the client
   identifier option in all the DHCPv6 message exchange.  However none
   of these methods provide a simple way to extract client's hardware
   address.This presents a problem to an operator who is using an
   existing DHCPv4 system with the client hardware address as the
   customer identifier, and desires to correlate DHCPv6 assignments
   using the same identifier.  Modifying the system to use DUID based
   correlation across DHCPv4 and DHCPv6 is possible, but it requires a
   modification of the DHCPv4 system and associated back-ends.

   Providing an option in DHCPv6 messages to carry client hardware
   address explicitly will help above mentioned scenarios.  For e.g. it
   can be used along with other identifiers to associate DHCPv4 and
   DHCPv6 messages from a dual stack client.  Further, having client

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   hardware address in DHCPv6 will help in proving additional
   information in event debugging and logging related to the client at
   relay and server.

3.  DHCPv6 Client Hardware Address Option

   The format of the DHCPv6 Client Hardware Address option is shown
   below.
    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | OPTION_CLIENT_HARDWARE_ADDR   |           option-length       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  chtype       |                                               |
   +-+-+-+-+-+-+-+-+             chaddr                            +
   |                        (variable length)                      |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code:    OPTION_CLIENT_HARDWARE_ADDR (TBD)
   option-length:  1 + length of chaddr
   chtype:         Client Hardware address type, see ARP section in "Assigned
                    Numbers" RFC; e.g., '1' = 10mb ethernet.
   chaddr:         Client hardware address.

4.  DHCPv6 Client Behavior

   All hosts or clients MAY include DHCPv6 Client hardware address
   option in all the upstream DHCPv6 messages like SOCILIT, REQUEST,
   RENEW, REBIND, CONFIRM, RELEASE and DELCINE.

5.  DHCPv6 Relay Agent Behavior

   DHCPv6 Relay agents which are directly connected to clients/hosts MAY
   look for Client Hardware Address option in the incoming DHCPv6 client
   message.  In absence of client hardware option, DHCPv6 Relay agents
   MAY include client hardware address option in relayed DHCPv6 (RELAY-
   FORW) message.  The DHCPv6 Relay agent behaviour can depend on
   configuration that decides whether Client Hardware Address option
   needs to be processed and included.

   In Relay chaining scenarios, any other relay agent other than first

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   hop DHCPv6 Relay agent or DHCPv6 LDRA [RFC6221] MUST not add this
   option.

6.  DHCPv6 Server Behavior

   If DHCPv6 Server is configured to store or use client hardware
   address, it MUST first look for the client hardware address option in
   the client DHCP message.  In case it is not found, Server SHOULD look
   for client hardware option in the RELAY-FORW message of the DHCPv6
   Relay agent closest to the client.

   There is no requirement that a server return this option and its data
   in a downstream DHCP message.

7.  IANA Considerations

   IANA is requested to assign an option code to
   OPTION_CLIENT_HARDWARE_ADDR from the "DHCPv6 and DHCPv6 options"
   registry (http://www.iana.org/assignments/dhcpv6-parameters/dhcpv6-
   parameters.xml).

8.  Security Considerations

   Security issues related DHCPv6 are described in section 23 of
   [RFC3315].

9.  Acknowledgements

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC4361]  Lemon, T. and B. Sommerfeld, "Node-specific Client
              Identifiers for Dynamic Host Configuration Protocol
              Version Four (DHCPv4)", RFC 4361, February 2006.

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   [RFC4580]  Volz, B., "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6) Relay Agent Subscriber-ID Option", RFC 4580,
              June 2006.

   [RFC6221]  Miles, D., Ooghe, S., Dec, W., Krishnan, S., and A.
              Kavanagh, "Lightweight DHCPv6 Relay Agent", RFC 6221,
              May 2011.

Authors' Addresses

   Gaurav Halwasia
   Cisco Systems
   Cessna Business Park, Sarjapura Marathalli Outer Ring Road
   Bangalore, KARNATAKA  560 087
   India

   Phone: +91 80 4426 1321
   Email: ghalwasi@cisco.com

   Shwetha Bhandari
   Cisco Systems
   Cessna Business Park, Sarjapura Marathalli Outer Ring Road
   Bangalore, KARNATAKA  560 087
   India

   Phone: +91 80 4426 0474
   Email: shwethab@cisco.com

   Wojciech Dec
   Cisco Systems
   Haarlerbergweg 13-19
   1101 CH Amsterdam, Amsterdam  560 087
   The Netherlands

   Email: wdec@cisco.com

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