DHC                                                              T. Huth
Internet-Draft                                               J. Freimann
Intended status: Standards Track                  IBM Deutschland Germany Research &
Expires: May 22, August 8, 2009                                 Development GmbH
                                                       November 18, 2008
                                                               V. Zimmer
                                                                   Intel
                                                               D. Thaler
                                                               Microsoft
                                                        February 4, 2009

                     DHCPv6 option for network boot
                  draft-ietf-dhc-dhcpv6-opt-netboot-02
                  draft-ietf-dhc-dhcpv6-opt-netboot-03

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Abstract

   The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) provides a
   framework for passing configuration information to nodes on a
   network.  This document describes a new option options for DHCPv6 to convey
   information, which are
   required for network booting, to booting a node from the nodes. network.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Netboot option format  Options  . . . . . . . . . . . . . . . . . . . .  3
   4.  Suboptions . . . . . . .  4
     3.1.  Boot File Uniform Resource Locator (URL) Option  . . . . .  4
     3.2.  Boot File Parameters Option  . . . . . . . . . . . . . .  4
     4.1.  Suboption: Boot file Uniform Resource Locator (URL) .  5
     3.3.  Client System Architecture Type Option . . . .  4
     4.2.  Suboption: Vendor class extension . . . . . .  6
     3.4.  Client Network Interface Identifier Option . . . . . . . .  6
   5.
   4.  Appearance of the Netboot option options  . . . . . . . . . . . . . . . . . .  7
   6.
   5.  Boot protocol considerations . . . . . . . . . . . . . . . . .  8
   7.  7
   6.  IANA considerations  . . . . . . . . . . . . . . . . . . . . .  8
   8.
   7.  Security considerations  . . . . . . . . . . . . . . . . . . .  9
   9.
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   10.
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     10.1.
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     10.2.
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
   Intellectual Property and Copyright Statements . . . . . . . . . . 12

1.  Introduction

   Network booting means that a node which should be booted fetches the
   files required for booting via its network device from a server.
   Network booting is, for example, very useful in environments where
   the administrators have to maintain a large number of nodes.  Since
   all boot and configuration files are stored on a central server, the
   maintenance of all nodes can be kept simple this way.

   A typical boot file would be, for example, an operating system kernel
   or a boot loader program.  To be able to download execute such a file, the
   firmware (BIOS) running on the client node must be provided with perform the following
   two steps (see Figure 1): First get all information which are
   required for downloading and executing the boot file such as: the
   server on which the boot files can be found, the protocol to be used
   for the download (for example TFTP [RFC1350])
   and [RFC1350]), the name of the boot file.  Since some kernels or boot loaders
   need to be provided with
   file and additional parameters, there parameters which should also be
   the possibility passed to pass additional parameters along with the server
   address, OS
   kernel or boot loader program respectively.  As second step, download
   the protocol and boot file from the file name. server and execute it.

                                            +------+
                    _______________________\| DHCP |
                   / 1 Get boot file info  /|Server|
           +------+                         +------+
           | Host |
           +------+                         +------+
                   \_______________________\| File |
                     2 Download boot file  /|Server|
                                            +------+

                      Figure 1: Network Boot Sequence

   DHCPv6 allows client nodes to ask a DHCPv6 server for configuration
   parameters.  Contrary to its IPv4 predecessor, DHCPv6 does not yet
   define a way to query network boot options such as the IPv6 address
   of a boot file server and boot file names.  Therefore this document
   defines a new DHCPv6 option options which is are required for network booting
   clients.

2.  Conventions

   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].

   Terminology specific to IPv6 and DHCPv6 are used in the same way as
   defined in the "Terminology" sections of RFC 3315 [RFC3315].

3.  Netboot option format

   The netboot  Options

3.1.  Boot File Uniform Resource Locator (URL) Option

   This option consists of an ASCII string.  It is used as an encapsulation for suboptions which
   carry the actual information needed to boot a client.  This option
   will be used by clients convey an URL
   to request boot information from a server. boot file.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        OPT_NET_BOOT       OPT_BOOTFILE_URL        |            option-len         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      suboption-code 1         |          suboption-len        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    subopt-data 1 (variable length)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                       <multiple suboptions>               bootfile-url (variable length)                  .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      suboption-code n         |          suboption-len        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    subopt-data n (variable length)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Format description:

   option-code       OPT_NET_BOOT       OPT_BOOTFILE_URL (TBD1).

   option-len        Length of the netboot bootfile URL option in octets (not
                     including the size of the option-code and option-
                     len fields).

   suboption-code, suboption-len and subopt-data  together comprise

   bootfile-url      This ASCII string is the URL (conforming to
                     [RFC3986]) for a
                     suboption boot file.  This string starts
                     with the protocol which is used for downloading.
                     Separated by "://", the netboot option. hostname or IPv6 address of
                     the server hosting the boot file follows, and then
                     the path, file name and query parts of the URL.
                     The 16-bit
                     unsigned suboption-code values are drawn from string is not null-terminated.

   Note about the bootfile-url: This string can either contain a
                     private namespace of
   hostname or a literal IPv6 address to specify the server where the
   boot file should be downloaded from.  All clients which implement the netboot
   OPT_BOOTFILE_URL option managed by
                     IANA (cf. Section 8). MUST be able to handle IPv6 addresses here
   and SHOULD also be able to handle a hostname in the URL.  The 16-bit unsigned
                     suboption-len values indicate IPv6
   address in the length of URL then MUST be enclosed in "[" and "]" characters,
   conforming to [RFC3986].  Clients SHOULD also be able to handle
   hostnames in the
                     subopt-data field URLs.  However, in this case the firmware
   implementation on the client machine must support DNS, too.  Due to
   size limitations, this might not be possible in all firmware
   implementations, so support for hostnames in octets. the URLs is only
   optional.

   Multiple occurences occurrences of each suboption-type OPT_BOOTFILE_URL can occur within be present in a netboot
   option (for example when more than one boot server is available). single
   DHCP message.  Clients MUST process the suboptions them in the order in which they
   appear
   in the message sent by within the server.

   So far, only the suboptions in message.  The client starts with the following chapters have been
   defined.  Other suboptions might first file
   that should be defined in future RFCs.

4.  Suboptions

4.1.  Suboption: downloaded and executed.  In case of a failure the
   process should continue with the second one and so on.

3.2.  Boot file Uniform Resource Locator (URL) File Parameters Option

   This suboption option consists of multiple ASCII strings.  It is  They are used to
   convey an URL to a boot file together with additional
   specify parameters for the boot file (e.g. parameters for the kernel
   or boot loader program).

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       SUBOPT_BOOTFILE_URL     |          suboption-len        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | bootfile-len                  |           bootfile-url       OPT_BOOTFILE_PARAM      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+         (variable length)     .
   .            option-len         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | param-len 1                   |            parameter 1        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+         (variable length)     .
   .                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                       <multiple Parameters>                   .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | param-len n                   |            parameter n        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+         (variable length)     .
   .                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Format description:

   suboption-code    SUBOPT_BOOTFILE_URL (1).

   suboption-len

   option-code       OPT_BOOTFILE_PARAM (TBD2).

   option-len        Length of the bootfile suboption parameters option in octets
                     (not including the size of the suboption-code option-code and
                     suboption-len
                     option-len fields).

   bootfile-len      16-bit integer that specifies the length of the
                     bootfile-url in octets (not including the bootfile-
                     length field).

   bootfile-url      This ASCII string is the URL (conforming to
                     [RFC3986]) for a boot file.  This string starts
                     with the protocol which is used for downloading.
                     Separated by "://", the hostname or IPv6 address of
                     the server hosting the boot file (see also the note
                     below) follows, and then the path, file name and
                     query parts of the URL.  The string is not null-
                     terminated.

   param-len 1...n   This is a 16-bit integer which specifies the length
                     of the following parameter in octets (not including
                     the parameter-length field).

   parameters 1...n  These ASCII strings are parameters needed for
                     booting, e.g. kernel parameters.  The strings are
                     not null-terminated.

   The firmware should MUST pass these parameters in the order they appear in
   the
                     SUBOPT_BOOTFILE_URL suboption OPT_BOOTFILE_PARAM option to the boot file which has been
   specified in the bootfile-url field.
                     In cases where no parameters are needed, everything
                     but the boot file URL (including its length field)
                     can be omitted.

   Note about the bootfile-url: OPT_BOOTFILE_URL option.

3.3.  Client System Architecture Type Option

   This string can either contain a
   hostname or a literal IPv6 address to specify the server where the
   boot file should be downloaded from.  All clients which implement option provides parity with the
   SUBOPT_BOOTFILE_URL suboption MUST be able to handle IPv6 addresses
   here and SHOULD also be able to handle a hostname Client System Architecture Type
   Option defined for DHCPv4 in the URL. [RFC4578] section 2.1.

   The
   IPv6 address in format of the URL then MUST be enclosed in "[" and "]"
   characters, conforming to [RFC3986].  Clients SHOULD also be able to
   handle hostnames in the URLs.  However, in this case the firmware
   implementation on the client machine must support DNS, too.  Due to
   size limitations, this might not be possible in all firmware
   implementations, so support for hostnames in the URLs is only
   optional.

   Since multiple occurrences of SUBOPT_BOOTFILE_URL can be present in a
   single OPT_NETBOOT message, clients MUST process them in the order in
   which they appear within the message.  For example in the case of a
   boot file URL the first file should be downloaded and executed.  In
   case of a failure the process should continue with the second one and
   so on.

4.2.  Suboption: Vendor class extension

   With this suboption, vendors can define their own netboot suboptions:
   It can be used by clients and servers to exchange vendor-specific
   information which is related to network booting.

   This suboption can occur multiple times within a OPT_NET_BOOT option
   (also with different enterprise-numbers in case a server and client
   implementation supports different vendor extensions).  Clients MUST
   process them in the order in which they appear within the message.
   Unsupported vendor extensions MUST be ignored. is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      SUBOPT_NETBOOT_VENDOR    OPTION_CLIENT_ARCH_TYPE    |          suboption-len        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       enterprise-number         option-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                       vendor-class-data                       .
   .         Processor Architecture Type (variable length)         .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Format description:

   suboption-code     SUBOPT_NETBOOT_VENDOR (2).

   suboption-len      Length of the vendor class suboption in octets
                      (not including the size of the suboption-code and
                      suboption-len fields).

   enterprise-number  The enterprise number

   option-code       OPTION_CLIENT_ARCH_TYPE (TBD3).

   option-len        See below.  FIXME

   Processor Architecture Type  A list of the vendor one or more architecture
                     types, as registered
                      with IANA (see [VENDORIDS]).

   vendor-class-data  Vendor-specific information. specified in [RFC4578] section 2.1.

3.4.  Client Network Interface Identifier Option

   The meaning Client Network Interface Identifier option is
                      defined by the vendor identified sent by the
                      enterprise-number.  It is suggested that the
                      vendor-class-data SHOULD be composed of a series DHCP
   client to a DHCP server to provide information about its level of separate items
   Universal Network Device Interface (UNDI) support (see also [PXE21]
   and [UEFI22]).

   This option provides parity with a two-octets length field
                      at the beginning of each item, as it is described Client Network Interface
   Identifier Option defined for the vendor class option DHCPv4 in chapter 22.16 of
                      [RFC3315].

5.  Appearance [RFC4578] section 2.2.

   The format of the Netboot option

   The netboot option is:

    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_NII          |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |     Major     |      Minor      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code       OPTION_NII (TBD4).

   option-len        3

   Type              As specified in [RFC4578] section 2.2.

   Major             As specified in [RFC4578] section 2.2.

   Minor             As specified in [RFC4578] section 2.2.

4.  Appearance of the options

   These options MUST NOT appear in DHCPv6 messages other than the types
   Solicit, Advertise, Request, Renew, Rebind, Information-Request and
   Reply.

   The option-code option-codes of the netboot option these options MAY appear in the Option Request
   Option in the DHCPv6 message types Solicit, Request, Renew, Rebind,
   Information-Request and Reconfigure.

   The suboptions MUST appear only in the netboot option.

6.

5.  Boot protocol considerations

   RFC 906 [RFC906] suggests to use TFTP for bootstrap loading.  Because
   it  Since
   TFTP is easy to implement this protocol based on UDP, it has the advantage that it can also be used
   in firmware (where one has implementations which have to deal with size and
   complexity constraints), this constraints and thus can not include a full-blown TCP/IP
   stack.  It can also be used in multicast mode (see [RFC2090]) which
   is still useful when a lot of nodes boot the
   recommended protocol for network booting.  Every firmware
   implementation SHOULD same boot file at least support this protocol.  The the same
   time.  So if TFTP should be used as boot protocol, the boot file URLs
   then must be specified according to RFC 3617 [RFC3617].

   However, TFTP also has some severe limitations, for example
   performance limitations due to acknowledging each packet and size
   limitations due to using only 16-bit packet counters.  So this
   specification suggests to use now the well-known and established
   hypertext transfer protocol (HTTP, see [RFC2616]) as default for
   network booting instead.

   An alternative approach to TFTP network booting is to bootstrap the system
   with iSCSI.  In this case, the URL in the SUBOPT_BOOTFILE_URL
   suboption OPT_BOOTFILE_URL option
   MUST be specified according to the "iscsi:" string definition in
   chapter 5 of [RFC4173].  Note that [RFC4173] also suggests that the
   "iscsi:" string should be specified in the so-
   called so-called "Root Path"
   option.  However, this option does not exist for DHCPv6 yet, and with
   the SUBOPT_BOOTFILE_URL OPT_BOOTFILE_URL it is also not necessary anymore.  So for IPv6
   iSCSI booting, the "iscsi:" string MUST be specified as URL in the SUBOPT_BOOTFILE_URL suboption
   OPT_BOOTFILE_URL option instead.

   In some different scenarios,

   If multiple interfaces are available for booting, it might also be useful a good
   strategy to use other
   protocols like FTP or HTTP for network booting, so send out requests out on each interface in parallel to
   speed up the discovery.  However how to handle multiple replies, i.e.
   replies from more than one DHCP server is not a firmware
   implementation problem that can support these protocols, too.  Then it be
   easily solved on the protocol level.  It is up to the network administrator implementors to
   provide users with a possibility to either choose the appropriate boot protocol for
   the network, and a network interface
   to specify the right boot file URLs in the DHCPv6
   server configuration file.

7. from, or to assign a preference to interfaces or even known
   DHCP servers.

6.  IANA considerations

   The following option options needs to be assigned by the IANA from the
   option number space defined in the chapter 22 of the DHCPv6 RFC
   [RFC3315].

                  +--------------+-------+--------------+

            +-------------------------+-------+--------------+
            |       Option name       | Value | Specified in |
                  +--------------+-------+--------------+
            +-------------------------+-------+--------------+
            | OPT_NET_BOOT     OPT_BOOTFILE_URL    |  TBD1 |  Section 3 3.1 |
                  +--------------+-------+--------------+

   The OPT_NET_BOOT option
            |    OPT_BOOTFILE_PARAM   |  TBD2 |  Section 3.2 |
            | OPTION_CLIENT_ARCH_TYPE |  TBD3 |  Section 3.3 |
            |        OPTION_NII       |  TBD4 |  Section 3.4 |
            +-------------------------+-------+--------------+

   This document also defines introduces a new IANA registry for processor
   architecture types.  The name of this registry shall be "Processor
   Architecture Type".  Registry entries consist of a 16-bit integer suboption
   field, for which IANA is to create
   recorded in decimal format, and maintain a new sub-registry
   entitled "Netboot Suboptions" under the OPT_NET_BOOT option.  Initial descriptive name.  The initial
   values for the Netboot Suboptions of this registry are given below; future
   assignments are to can be found in [RFC4578] section 2.1.

   The assignment policy for values shall be made through IETF Expert Review (see [RFC5226]).
   Assignments consist of a suboption name
   [RFC5226]), and its associated value.

             +-----------------------+-------+--------------+
             |     Suboption any requests for values must supply the descriptive
   name    | Value | Specified in |
             +-----------------------+-------+--------------+
             |  SUBOPT_BOOTFILE_URL  |   1   |  Section 4.1 |
             | SUBOPT_NETBOOT_VENDOR |   2   |  Section 4.2 |
             +-----------------------+-------+--------------+

8. for the processor architecture type.

7.  Security considerations

   The new DHCPv6 option described in this document could be sent in
   untrusted networks by malicious people with a fake DHCPv6 server to
   confuse the booting clients.  The clients could be provided with a
   wrong URL so that the boot either fails, or even worse, the client
   boots the wrong operating system which has been provided by a
   malicious file server.  To prevent this kind of attack, clients
   SHOULD use authentication of DHCPv6 messages (see chapter 21. in RFC
   3315
   [RFC3315]).

   Note also that DHCPv6 messages are sent unencrypted by default.  So
   the boot file URL options are sent unencrypted over the network, too.
   This can become a security risk since the URLs can contain sensitive
   information like user names and passwords (for example a URL like
   "ftp://username:password@servername/path/file").  At the current
   point in time, there is no possibility to send encrypted DHCPv6
   messages, so it is strongly recommended not to use sensitive
   information in the URLs in untrusted networks.

9.

8.  Acknowledgements

   The authors would like to thank Ruth Li, Dong Wei, Kathryn Hampton,
   Phil Dorah, Richard Chan, and Fiona Jensen for discussions that led
   to this document.

   The authors would also like to thank Ketan P. Pancholi and Alfred
   Hoenes for corrections and suggestions.

   Vijayabhaskar Kalusivalingam and Senthil Balasubramanian published a
   similar draft for IPv6 network booting some years ago (available at
   http://tools.ietf.org/html/draft-ietf-dhc-dhcpv6-opt-rboot-00), which
   however was abandoned for unknown reasons.

10.

9.  References

10.1.

9.1.  Normative References

   [PXE21]    Johnston, M., "Preboot Execution Environment (PXE)
              Specification", September 1999,
              <http://www.pix.net/software/pxeboot/archive/pxespec.pdf>.

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

   [RFC3617]  Lear, E., "Uniform Resource Identifier (URI) Scheme and
              Applicability Statement for the Trivial File Transfer
              Protocol (TFTP)", RFC 3617, October 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4173]  Sarkar, P., Missimer, D., and C. Sapuntzakis,
              "Bootstrapping Clients using the Internet Small Computer
              System Interface (iSCSI) Protocol", RFC 4173,
              September 2005.

   [RFC4578]  Johnston, M. and S. Venaas, "Dynamic Host Configuration
              Protocol (DHCP) Options for the Intel Preboot eXecution
              Environment (PXE)", RFC 4578, November 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [VENDORIDS]
              IANA, "Private Enterprise Numbers",
              <http://www.iana.org/assignments/enterprise-numbers>.

10.2.

   [UEFI22]   UEFI Forum, "Unified Extensible Firmware Interface
              Specification, Version 2.2", September 2008,
              <http://www.uefi.org/>.

9.2.  Informative References

   [RFC1350]  Sollins, K., "The TFTP Protocol (Revision 2)", STD 33,
              RFC 1350, July 1992.

   [RFC2090]  Emberson, A., "TFTP Multicast Option", RFC 2090,
              February 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC906]   Finlayson, R., "Bootstrap Loading using TFTP", RFC 906,
              June 1984.

Authors' Addresses

   Thomas H. Huth
   IBM Deutschland Germany Research & Development GmbH
   Schoenaicher Strasse 220
   Boeblingen  71032
   Germany

   Phone: +49-7031-16-2183
   Email: thuth@de.ibm.com

   Jens T. Freimann
   IBM Deutschland Germany Research & Development GmbH
   Schoenaicher Strasse 220
   Boeblingen  71032
   Germany

   Phone: +49-7031-16-1122
   Email: jfrei@de.ibm.com

Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

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   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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