DHC B. Volz
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track January 12, 2009
Expires: July 16, 2009
DHCPv4 Vendor-specific Message
<draft-ietf-dhc-dhcpv4-vendor-message-00.txt>
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Abstract
This document requests a vendor-specific DHCPv4 message assignment.
This message can be used for vendor specific and experimental
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purposes.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Vendor-specific Message . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The DHCPv4 [RFC2131] protocol specifies a mechanism for the
assignment of addresses and configuration information to nodes. The
protocol provides for 256 possible message codes, of which a small
number are assigned ([DHCPv4Params]). Each of the assigned message
codes have specific purposes. New message codes are assigned through
IETF Standards Action.
There may be a need for vendors of DHCPv4 clients, relay agents, or
servers to experiment with new capabilities that require new messages
to be exchanged between these elements. Thus, this document defines
the format for and requests that a new message code be reserved for
vendor-specific and experimental purposes.
2. Terminology
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].
3. Vendor-specific Message
The vendor-specific message may be exchanged between clients, relay
agents, and/or servers and allows multiple vendors to make use of the
message for completely different and independent purposes.
Clients and servers MAY chose to support this message; those that do
not, MUST discard the message. Relay agents SHOULD relay these
messages as they would other DHCPv4 messages unless the relay agent
understands the specific message and knows that the message was
directed at it.
Applications using these messages MUST NOT assume that all DHCPv4
clients, relay agents, and servers support them and MUST use good
networking practices when transmitting and retransmitting these
messages. For some applications, it may be appropriate to use
Vendor-Identifying Vendor Options [RFC3925] in a standard DHCPv4
exchange to negotiate whether the end-points support the vendor-
specific message.
A vendor-specifc message is constructed by placing the Vendor-
Specific Message number (254) into the DHCP Message Type option
[RFC2132] and including the Vendor Message Option defined below. A
Vendor-Specific Message that does not contain the Vendor Message
Option MUST be ignored. A Vendor Message Option in a DHCPv4 message
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other than the Vendor-Specific Message MUST be ignored.
The format of the Vendor Message Option is shown below:
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ enterprise-number +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| vendor | |
| msg-type | |
+-+-+-+-+-+-+-+-+ |
/ vendor-option-data /
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_VENDOR_MESSAGE (TBD)
option-len 5 plus the length of the vendor-option-data.
enterprise-number The vendor's 32-bit Enterprise Number as
registered with [EID], in network octet order.
vendor-msg-type The vendor's message-type. The values are
defined by the vendor identified in the
enterprise-number field and are not managed by
IANA.
vendor-option-data Vendor specific data (of length option-len
minus 5 octets). This is optional.
The vendor-option-data field MUST be encoded as a sequence of code/
length/value fields of identical format to the DHCP options field.
The option codes are defined by the vendor identified in the
enterprise-number field and are not managed by IANA. Option codes 0
and 255 have no pre-defined interpretation or format. Each of the
encapsulated options is formatted as follows:
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1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subopt-code | subopt-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ sub-option-data /
~ ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
subopt-code The code for the encapsulated option.
subopt-len An unsigned integer giving the length of the
option-data field in this encapsulated option in
octets.
sub-option-data Data area for the encapsulated option.
Clients, relay agents, and/or servers supporting the Vendor Message
Option MUST support [RFC3396].
Note: Vendor-Identifying Vendor Options [RFC3925] are not used to
convey the vendor identification (enterprise-number) for the vendor-
specific message as the message may contain instances of those
options for other reasons.
4. Security Considerations
The Security Considerations of [RFC2131] apply.
This new message does potentially open up new avenues of attacking
clients, relay agents, or servers. The exact nature of these attacks
will depend on what functions and capabilities the message exposes
and are thus not possible to describe in this document. Clients and
servers that have no use for these messages SHOULD discard them and
thus the threat is no different than before this message was
assigned.
Vendors using this new message should use the DHCPv4 security
mechanisms (such as [RFC3118] as appropriate) and carefully consider
the security implications of the functions and capabilities exposed.
5. IANA Considerations
IANA is requested to assign DHCPv4 Message type 254 to the Vendor-
specific Message in the registry maintained in [DHCPv4Params]:
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254 VENDOR-SPECIFIC
IANA is requested to assign a DHCPv4 option number to the Vendor
Message Option in the registry maintained in [DHCPv4Params]:
TBD OPTION_VENDOR_MESSAGE
6. References
6.1. 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.
[EID] IANA, "Private Enterprise Numbers.
http://www.iana.org/assignments/enterprise-numbers".
6.2. Informative References
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
Messages", RFC 3118, June 2001.
[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the
Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
November 2002.
[RFC3925] Littlefield, J., "Vendor-Identifying Vendor Options for
Dynamic Host Configuration Protocol version 4 (DHCPv4)",
RFC 3925, October 2004.
[DHCPv4Params]
IANA, "Dynamic Host Configuration Protocol (DHCP) and
Bootstrap Protocol (BOOTP) Parameters.
http://www.iana.org/assignments/bootp-dhcp-parameters".
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Author's Address
Bernard Volz
Cisco Systems, Inc.
1414 Massachusetts Ave.
Boxborough, MA 01719
USA
Phone: +1 978 936 0000
Email: volz@cisco.com
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