draft-ietf-dhc-duid-uuid-03.txt   rfc6355.txt 
Internet Engineering Task Force T. Narten Internet Engineering Task Force (IETF) T. Narten
Internet-Draft J. Johnson Request for Comments: 6355 J. Johnson
Intended status: Standards Track IBM Category: Standards Track IBM
Expires: August 8, 2011 February 4, 2011 ISSN: 2070-1721 August 2011
Definition of the UUID-based DHCPv6 Unique Identifier (DUID-UUID) Definition of the UUID-Based DHCPv6 Unique Identifier (DUID-UUID)
draft-ietf-dhc-duid-uuid-03
Abstract Abstract
This document defines a new DHCPv6 Unique Identifier (DUID) type, This document defines a new DHCPv6 Unique Identifier (DUID) type
called DUID-UUID. DUID-UUIDs are derived from the already called DUID-UUID. DUID-UUIDs are derived from the already-
standardized UUID format. DUID-UUID makes it possible for devices to standardized Universally Unique IDentifier (UUID) format. DUID-UUID
use UUIDs to identify themselves to DHC servers and vice versa. makes it possible for devices to use UUIDs to identify themselves to
UUIDs are globally unique and readily available on many systems, DHC servers and vice versa. UUIDs are globally unique and readily
making them convenient identifiers to leverage within DHCP. available on many systems, making them convenient identifiers to
leverage within DHCP.
Status of this Memo
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
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Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on August 8, 2011. Information about the current status of this document, any errata,
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Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. UUID Considerations . . . . . . . . . . . . . . . . . . . . . . 4 3. UUID Considerations . . . . . . . . . . . . . . . . . . . . . . 3
4. DUID-UUID Format . . . . . . . . . . . . . . . . . . . . . . . 5 4. DUID-UUID Format . . . . . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 6 8.2. Informative Reference . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
DHCP Unique Identifiers (DUIDs) are used in DHCPv6 to identify DHCP Unique Identifiers (DUIDs) are used in DHCPv6 to identify
clients and servers. This document defines a new DHCP Unique clients and servers. This document defines a new DHCP Unique
Identifier (DUID) type that embeds a Universally Unique IDentifier Identifier (DUID) type that embeds a Universally Unique IDentifier
(UUID) [RFC4122]. UUIDs are already in wide spread use and serve as (UUID) [RFC4122]. UUIDs are already in widespread use and serve as
an existing identifier that could be leveraged by DHCPv6. For an existing identifier that could be leveraged by DHCPv6. For
example, x86 based systems ship with an embedded UUID in firmware example, x86-based systems ship with an embedded UUID in firmware
that is readily available to the software running on the device. that is readily available to the software running on the device.
Although DUIDs are new to DHCPv6, identifying clients in DHCP via a Although DUIDs are new to DHCPv6, identifying clients in DHCP via a
UUID is not. DHCPv4 [RFC2132] defines a Client Machine Identifier UUID is not. DHCPv4 [RFC2132] defines a Client Machine Identifier
Option (option 97) that embeds a UUID (aka GUID) [RFC4578]. This Option (option 97) that embeds a UUID (aka a Globally Unique
document extends that capability to DHCPv6. Identifier (GUID)) [RFC4578]. This document extends that capability
to DHCPv6.
Terminology specific to IPv6 and DHCPv6 are used in the same way as Terminology specific to IPv6 and DHCPv6 is used as defined in the
is defined in the "Terminology" sections of [RFC3315]. "Terminology" sections of [RFC3315].
2. Background 2. Background
In DHCPv6, clients identify themselves to servers via DHCP Unique In DHCPv6, clients identify themselves to servers via DHCP Unique
Identifiers (DUIDs) [RFC3315]. DUIDs are identifiers that DHCP Identifiers (DUIDs) [RFC3315]. DUIDs are identifiers that DHCP
servers treat as opaque objects with no internal structure. DUIDs servers treat as opaque objects with no internal structure. DUIDs
are intended to be globally unique, with no two devices using the are intended to be globally unique, with no two devices using the
same DUID. Three DUIDs types have been defined previously: same DUID. Three DUIDs types have been defined previously:
DUID-LLT - the Link-Layer address of one of the device's network DUID-LLT - the Link-Layer address of one of the device's network
interfaces, concatenated with a timestamp interfaces, concatenated with a timestamp
DUID-EN - an Enterprise Number plus additional information specific DUID-EN - an Enterprise Number plus additional information specific
to the enterprise to the enterprise
DUID-LL - the Link-Layer address of one of the device's network DUID-LL - the Link-Layer address of one of the device's network
interfaces interfaces
DUIDs are intended to remain constant over time, so that they can be DUIDs are intended to remain constant over time, so that they can be
used as permanent identifiers for a device. In the case of DUID- used as permanent identifiers for a device. In the case of DUID-
LLTs, they are intended to be generated once, and then stored in LLTs, they are intended to be generated once, stored in stable
stable storage and reused from that point forward. storage, and reused from that point forward.
One issue that has arisen concerns devices that employ multi-step One issue that has arisen concerns devices that employ multi-step
network boot loading. An initial step (typically run out of network boot loading. An initial step (typically run out of
firmware) loads a small image that in turn loads a second image, and firmware) loads a small image that, in turn, loads a second image and
so forth, until the actual target system is loaded. Each step in the so forth until the actual target system is loaded. Each step in the
booting process may invoke DHCP. In some operational environments, booting process may invoke DHCP. In some operational environments,
it is important that each step in the sequence use the same DUID, so it is important that each step in the sequence use the same DUID, so
that the server knows it is getting requests from the same device and that the server knows it is getting requests from the same device and
can return the proper configuration information (including the can return the proper configuration information (including the
pointer to the correct image to load). pointer to the correct image to load).
Unfortunately, none of the previously defined DUIDs are ideal for Unfortunately, none of the previously defined DUIDs are ideal for
multi-step network booting. The DUID-LLT and DUID-LL identifiers multi-step network booting. The DUID-LLT and DUID-LL identifiers
that a given device may use are not guaranteed to remain constant that a given device may use are not guaranteed to remain constant
across each booting step. Even if the different stages used DUID-LL across each booting step. Even if the different stages used DUID-LL
or DUID-LLT, on devices with multiple interfaces, there is no way to or DUID-LLT, on devices with multiple interfaces, there is no way to
guarantee that the same interface (and hence DUID) will be selected. guarantee that the same interface (and hence DUID) will be selected.
Finally, in the case of DUID-LLT, even if the same interface were Finally, in the case of DUID-LLT, even if the same interface is
chosen, it can be difficult to ensure that each stage uses the same chosen, it can be difficult to ensure that each stage uses the same
timestamp value. While a DUID-EN could be defined and used, such timestamp value. While a DUID-EN could be defined and used, such
usage is proprietary by definition. usage is proprietary by definition.
This document defines a new DUID type, based on the Universally This document defines a new DUID type, based on the Universally
Unique IDentifier (UUID) [RFC4122]. UUIDs are already used in Unique IDentifier (UUID) [RFC4122]. UUIDs are already used in
practice and serve as an existing identifier that could be leveraged practice and serve as an existing identifier that could be leveraged
by DHCP. In some environments, a UUID-based DUID is preferable to by DHCP. In some environments, a UUID-based DUID is preferable to
the other existing DUID types. the other existing DUID types.
It should be noted that use of a DUID-UUID will not by itself solve It should be noted that use of a DUID-UUID will not, by itself, solve
all the network boot problems described in this document. Given the all the network boot problems described in this document. Given the
availablility of a suitable DUID-UUID, implementations will still availability of a suitable DUID-UUID, implementations will still need
need to take steps to ensure that all boot stages use the same DUID- to take steps to ensure that all boot stages use the same DUID-UUID
UUID as appropriate. Given that DHCP has already defined multiple as appropriate. Given that DHCP has already defined multiple DUID
DUID types, the question of which of several DUIDs to select from types, the question of which of several DUIDs to select from already
already exists -- and defining a new DUID type doesn't by itself exists, and defining a new DUID type does not, by itself, help. It
help. It is believed, however, that network boot services can be is believed, however, that network boot services can be configured to
configured to use a DUID-UUID and that other software can do so as use a DUID-UUID and that other software can do so as well. Ensuring
well. Ensuring this happens in general is beyond the scope of this this happens in general is beyond the scope of this document.
document.
3. UUID Considerations 3. UUID Considerations
Although many UUIDs are in use today, not all UUIDs meet DHCP's Although many UUIDs are in use today, not all UUIDs meet DHCP's
requirements (see Section 9 of [RFC3315]). DHCP UUIDs should be requirements (see Section 9 of [RFC3315]). DHCP UUIDs should be
persistant across system restarts, across system reconfiguration persistent across system restarts, system reconfiguration events,
events, system software and operating system upgrades or system software and operating system upgrades or reinstallation as
reinstallation, and be easily available to any part of the boot well as be easily available to any part of the boot process that
process that requires access to the DHCP UUID. For example, UUIDs requires access to the DHCP UUID. For example, UUIDs used in
used in Microsoft's Component Object Module (COM), and for labeling Microsoft's Component Object Module (COM), and for labeling
partitions in filesystems, are likely not appropriate as they may not partitions in filesystems, are likely not appropriate as they may not
be accessible to firmware boot loaders, and can change over time. be accessible to firmware boot loaders and can change over time.
Implementations of this specification using DUID-UUID must select a Implementations of this specification using DUID-UUID must select a
UUID that is persistent across system restart and reconfiguration UUID that is persistent across system restart and reconfiguration
events, and that is available to all DHCP protocol agents that may events and that is available to all DHCP protocol agents that may
need to identify themselves. For instance, a UUID that is part of need to identify themselves. For instance, a UUID that is part of
the system firmware, or managed by the system firmware, satisfies the system firmware, or managed by the system firmware, satisfies
this requirement. this requirement.
4. DUID-UUID Format 4. DUID-UUID Format
The DUID-UUID is carried within Client Identifier or Server The DUID-UUID is carried within Client Identifier or Server
Identifier options. It has the following format: Identifier options. It has the following format:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID-Type (4) | UUID (128 bits) | | DUID-Type (4) | UUID (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| | | |
| -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
DUID-UUID format. Figure 1: DUID-UUID Format
Figure 1
DUID-Type - DUID-UUID (4) - (16 bits) DUID-Type - DUID-UUID (4) - (16 bits)
UUID - An RFC4122 UUID (128 bits) UUID - An [RFC4122] UUID (128 bits)
5. Acknowledgements 5. Acknowledgements
This document was inspired by a discussion on the DHC mailing list in This document was inspired by a discussion on the DHC mailing list in
November, 2009 on the topic of netboot for IPv6. Specifically, some November 2009 on the topic of netboot for IPv6. Specifically, some
scenarios were described where it was difficult to do something in scenarios were described where it was difficult to do something in
DHCPv6 that had worked well in DHCPv4. DHCPv6 that had worked well in DHCPv4.
We would like to thank the following individuals in particular for We would like to thank the following individuals in particular for
their specific comments and suggestions on this draft: Thomas Huth, their specific comments and suggestions on this document: Thomas
Andre Kostur, Suresh Krishnan, Ted Lemon, Bernie Volz & Vincent Huth, Andre Kostur, Stephen Jacob, Suresh Krishnan, Ted Lemon, Bernie
Zimmer. Volz, and Vincent Zimmer.
6. IANA Considerations 6. IANA Considerations
IANA has assigned the value 4 for use by the DHCPv6 DUID-UUID type. IANA has assigned the value 4 for use by the DHCPv6 DUID-UUID type.
[TO BE REMOVED UPON PUBLICATION: IANA should update the registry
entry for the DUID-UUID DUID-Type and mark the assignment permanent.]
7. Security Considerations 7. Security Considerations
DHCP traffic between a client and server is sent in the clear. An DHCP traffic between a client and server is sent in the clear. An
eavesdroppper residing on the path between the client and server eavesdropper residing on the path between the client and server could
could see DHCP traffic and obtain the UUID for a particular machine. see DHCP traffic and obtain the UUID for a particular machine. This
This may raise some privacy issues, but is not a new issue brought on may raise some privacy issues but is not a new issue brought on by
by the use of DUID type defined in this document. the use of the DUID type defined in this document.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122, Unique IDentifier (UUID) URN Namespace", RFC 4122,
July 2005. July 2005.
8.2. Informative References 8.2. Informative Reference
[RFC4578] Johnston, M. and S. Venaas, "Dynamic Host Configuration [RFC4578] Johnston, M. and S. Venaas, "Dynamic Host Configuration
Protocol (DHCP) Options for the Intel Preboot eXecution Protocol (DHCP) Options for the Intel Preboot eXecution
Environment (PXE)", RFC 4578, November 2006. Environment (PXE)", RFC 4578, November 2006.
Authors' Addresses Authors' Addresses
Thomas Narten Thomas Narten
IBM IBM
Email: narten@us.ibm.com EMail: narten@us.ibm.com
Jarrod B. Johnson Jarrod B. Johnson
IBM IBM
Email: jarrod.b.johnson@gmail.com EMail: jarrod.b.johnson@gmail.com
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