draft-ietf-dhc-relay-id-suboption-00.txt   draft-ietf-dhc-relay-id-suboption-01.txt 
DHC M. Stapp DHC M. Stapp
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Expires: December 15, 2008 June 13, 2008 Expires: March 23, 2009 September 19, 2008
The DHCPv4 Relay Agent Identifier Suboption The DHCPv4 Relay Agent Identifier Suboption
draft-ietf-dhc-relay-id-suboption-00.txt draft-ietf-dhc-relay-id-suboption-01.txt
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Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract Abstract
This memo defines a new Relay Agent Identifier suboption for the This memo defines a new Relay Agent Identifier suboption for the
Dynamic Host Configuration Protocol's (DHCP) Relay Agent Information Dynamic Host Configuration Protocol's (DHCP) Relay Agent Information
option. The suboption carries a unique identifier configured or option. The suboption carries a value that uniquely identifies the
generated at the relay agent. The suboption allows a DHCP relay relay agent device. The value may be administratively-configured or
agent to include the unique identifier in the DHCP messages it sends. may be generated by the relay agent. The suboption allows a DHCP
relay agent to include the identifier in the DHCP messages it sends.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Suboption Format . . . . . . . . . . . . . . . . . . . . . . . 4 3. Example Use-Cases . . . . . . . . . . . . . . . . . . . . . . . 3
4. Generating a Relay Identifier . . . . . . . . . . . . . . . . . 4 3.1. Industrial Ethernet . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 3.2. Bulk Leasequery . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 4. Suboption Format . . . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . . 5 5. Relay Identifier Types . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Generating a Relay Identifier . . . . . . . . . . . . . . . . . 5
Intellectual Property and Copyright Statements . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8
1. Introduction 1. Introduction
The Dynamic Host Configuration Protocol for IPv4 (DHCPv4) [RFC2131] The Dynamic Host Configuration Protocol for IPv4 (DHCPv4) [RFC2131]
provides IP addresses and configuration information for IPv4 clients. provides IP addresses and configuration information for IPv4 clients.
It includes a relay agent capability, in which network elements It includes a relay agent capability, in which network elements
receive broadcast messages from clients and forward them to DHCP receive broadcast messages from clients and forward them to DHCP
servers as unicast messages. In many network environments, relay servers as unicast messages. In many network environments, relay
agents add information to the DHCP messages before forwarding them, agents add information to the DHCP messages before forwarding them,
using the Relay Agent Information option [RFC3046]. Servers that using the Relay Agent Information option [RFC3046]. Servers that
recognize the relay information option echo it back in their replies. recognize the relay information option echo it back in their replies.
DHCP typically identifies clients based on information in their DHCP
messages - such as the Client-Identifier option, or the value of the
chaddr field. In some networks, however, the location of a client,
its point of attachment to the network, is a more useful identifier.
In factory-floor networks (commonly called 'Industrial' networks),
for example, the role a device plays is often fixed and based on its
location. Using manual address configuration is possible (and is
common), but it would be beneficial if DHCP configuration could be
applied to these networks.
One way to provide connection-based identifiers for industrial
networks is to have the network elements acting as DHCP relay agents
supply information that the DHCP server can use as a client
identifier. A straightforward way to form identifier information is
to combine something that is unique within the scope of the network
element with something that uniquely identifies that network element.
There are several possibilities, but to improve interoperability we
describe a dedicated identifier that can be associated with the
network element and conveyed in a consistent way.
This specification introduces a Relay Agent Identifier suboption for This specification introduces a Relay Agent Identifier suboption for
the Relay Information option. The Relay-Id suboption carries an the Relay Information option. The Relay-Id suboption carries an
sequence of octets that is intended to identify the relay agent sequence of octets that is intended to identify the relay agent
uniquely within the administrative domain. The identifier may be uniquely within the administrative domain. The identifier may be
administratively configured: in some networks it may be adequate to administratively configured: in some networks it may be adequate to
assign strings such as "switch1" and "switch2". Alternatively, the assign ASCII strings such as "switch1" and "switch2". Alternatively,
identifier may be generated by the relay agent itself, and we specify the identifier may be generated by the relay agent itself, and we
an algorithm from [RFC3315] for this purpose. specify use of [RFC3315] DUIDs for this purpose.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
DHCPv4 terminology is defined in [RFC2131], and the DHCPv4 Relay DHCPv4 terminology is defined in [RFC2131], and the DHCPv4 Relay
Agent Information Option in [RFC3046]. DUID terminology is in Agent Information Option in [RFC3046]. DUID terminology is in
[RFC3315]. [RFC3315].
3. Suboption Format 3. Example Use-Cases
3.1. Industrial Ethernet
DHCP typically identifies clients based on information in their DHCP
messages - such as the Client-Identifier option, or the value of the
chaddr field. In some networks, however, the location of a client -
its point of attachment to the network - is a more useful identifier.
In factory-floor networks (commonly called 'Industrial' networks),
for example, the role a device plays is often fixed and based on its
location. Using manual address configuration is possible (and is
common) but it would be beneficial if DHCP configuration could be
applied to these networks.
One way to provide connection-based identifiers for industrial
networks is to have the network elements acting as DHCP relay agents
supply information that a DHCP server could use as a client
identifier. A straightforward way to form identifier information is
to combine something that is unique within the scope of the network
element, such as a port/slot value, with something that uniquely
identifies that network element, such as a unique identifier.
3.2. Bulk Leasequery
There has been quite a bit of recent interest in extending the DHCP
Leasequery protocol [RFC4388] to accomodate some additional
situations. There are two recent drafts ([draft-kinnear] and
[draft-dtv]) proposing a variety of enhancements to the existing
Leasequery protocol. Both describe cases where identifying the DHCP
relay agent would be helpful in restoring binding information
associated with the client downstream from the device acting as a
relay.
4. Suboption Format
Format of the Relay Agent Identifier suboption: Format of the Relay Agent Identifier suboption:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|SUBOPT_RELAY_ID| length | | |SUBOPT_RELAY_ID| length | type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ id (variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. . . .
. identifier (variable) .
. . . .
+---------------------------------------------------------------+ +---------------------------------------------------------------+
Where: Where:
SUBOPT_RELAY_ID [TBD] SUBOPT_RELAY_ID [TBD]
length the number of octets in the identifier; the
length the number of octets in the suboption; the
minimum length is one. minimum length is one.
id 'length' octets of identifier
4. Generating a Relay Identifier type a single octet describing the type of
identifier that is present.
identifier the identifying data.
5. Relay Identifier Types
For clarity, the suboption specified here includes a type octet that
describes the data used in the identifier field. The type value zero
is reserved and MUST NOT be used. Two type values are defined here:
RELAY_IDENTIFIER_DUID and RELAY_IDENTIFIER_ASCII.
RELAY_IDENTIFIER_DUID is used when the identifier field contains an
[RFC3315] DUID. Administrators may want to assign human-friendly
ASCII identifiers: RELAY_IDENTIFIER_ASCII is used when the identifier
field contains an ASCII string.
6. Generating a Relay Identifier
As described in Section 1, in some situations it may be useful for As described in Section 1, in some situations it may be useful for
network devices to generate identifiers themselves. Relay agents who network devices to generate identifiers themselves. Relay agents who
send the Relay Agent Identifier suboption using identifiers that are send the Relay Agent Identifier suboption using identifiers that are
not administratively-configured MUST be generated following the not administratively-configured MUST be generated following the
procedures in the DUID section of [RFC3315]. Relay agents who use procedures in the DUID section of [RFC3315]. Relay agents who use
generated identifiers should make the generated value available to generated identifiers SHOULD make the generated value visible to
their administrators via their user-interface, through a log entry, their administrators via their user-interface, through a log entry,
or through some other mechanism. or through some other mechanism.
5. Security Considerations 7. Security Considerations
Security issues with the Relay Agent Information option and its use Security issues with the Relay Agent Information option and its use
by servers in address assignment are discussed in [RFC3046] and by servers in address assignment are discussed in [RFC3046] and
[RFC4030]. Relay agents who send the Relay Agent Identifier [RFC4030]. Relay agents who send the Relay Agent Identifier
suboption SHOULD use the Relay Agent Authentication suboption suboption SHOULD use the Relay Agent Authentication suboption
[RFC4030] to provide integrity protection. [RFC4030] to provide integrity protection.
6. IANA Considerations 8. IANA Considerations
We request that IANA assign a new suboption code from the registry of We request that IANA assign a new suboption code from the registry of
DHCP Agent Sub-Option Codes maintained in DHCP Agent Sub-Option Codes maintained in
http://www.iana.org/assignments/bootp-dhcp-parameters. http://www.iana.org/assignments/bootp-dhcp-parameters.
Relay Agent Identifier Suboption [TBD] Relay Agent Identifier Suboption [TBD]
7. Normative References We request that IANA establish a new registry of DHCP Relay Agent
Identifier Sub-Option Types, to be maintained in
http://www.iana.org/assignments/bootp-dhcp-parameters. The
Identifier Type is a single octet. The initial values assigned in
this document are:
RELAY_IDENTIFIER_NULL 0
RELAY_IDENTIFIER_DUID 1
RELAY_IDENTIFIER_ASCII 2
Additional Identifier Type values will be allocated and assigned
through IETF consensus, as defined in [RFC2434].
9. References
9.1. Normative References
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", [RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC 3046, January 2001. RFC 3046, January 2001.
[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.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4030] Stapp, M. and T. Lemon, "The Authentication Suboption for [RFC4030] Stapp, M. and T. Lemon, "The Authentication Suboption for
the Dynamic Host Configuration Protocol (DHCP) Relay Agent the Dynamic Host Configuration Protocol (DHCP) Relay Agent
Option", RFC 4030, March 2005. Option", RFC 4030, March 2005.
9.2. Informative References
[RFC4388] Woundy, R. and K. Kinnear, "Dynamic Host Configuration
Protocol (DHCP) Leasequery", RFC 4388, February 2006.
[draft-kinnear]
Kinnear, K., Volz, B., Russell, N., and M. Stapp, "Bulk
DHCPv4 Lease Query
(draft-kinnear-dhc-dhcpv4-bulk-leasequery-*)", July 2008.
[draft-dtv]
Rao, D., Joshi, B., and P. Kurapati, "DHCPv4 bulk lease
query (draft-dtv-dhc-dhcpv4-bulk-leasequery-*)",
July 2008.
Author's Address Author's Address
Mark Stapp Mark Stapp
Cisco Systems, Inc. Cisco Systems, Inc.
1414 Massachusetts Ave. 1414 Massachusetts Ave.
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Phone: +1 978 936 0000 Phone: +1 978 936 0000
Email: mjs@cisco.com Email: mjs@cisco.com
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Acknowledgment
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Administrative Support Activity (IASA).
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