draft-ietf-dhc-relay-id-suboption-07.txt   draft-ietf-dhc-relay-id-suboption-08.txt 
DHC M. Stapp DHC B. Joshi
Internet-Draft Cisco Systems, Inc. Internet-Draft R. Rao
Intended status: Standards Track July 7, 2009 Intended status: Standards Track Infosys Technologies Ltd.
Expires: January 8, 2010 Expires: December 6, 2011 M. Stapp
Cisco Systems, Inc.
June 4, 2011
The DHCPv4 Relay Agent Identifier Suboption The DHCPv4 Relay Agent Identifier Suboption
draft-ietf-dhc-relay-id-suboption-07.txt draft-ietf-dhc-relay-id-suboption-08.txt
Abstract
This draft defines a new Relay Agent Identifier suboption for the
Dynamic Host Configuration Protocol's (DHCP) Relay Agent Information
option. The suboption carries a value that uniquely identifies the
relay agent device within the administrative domain. The value is
typically administratively-configured in the relay agent. The
suboption allows a DHCP relay agent to include the identifier in the
DHCP messages it sends.
Status of this Memo Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of Provisions Relating to IETF Documents
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Abstract include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
This memo defines a new Relay Agent Identifier suboption for the described in the Simplified BSD License.
Dynamic Host Configuration Protocol's (DHCP) Relay Agent Information
option. The suboption carries a value that uniquely identifies the
relay agent device. The value may be administratively-configured or
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. Example Use-Cases . . . . . . . . . . . . . . . . . . . . . . . 3 3. Example Use-Cases . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Industrial Ethernet . . . . . . . . . . . . . . . . . . . . 3 3.1. Industrial Ethernet . . . . . . . . . . . . . . . . . . . . 3
3.2. Bulk Leasequery . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Bulk Leasequery . . . . . . . . . . . . . . . . . . . . . . 4
4. Suboption Format . . . . . . . . . . . . . . . . . . . . . . . 4 4. Suboption Format . . . . . . . . . . . . . . . . . . . . . . . 4
5. Relay Identifier Types . . . . . . . . . . . . . . . . . . . . 5 5. Relay Identifier Types . . . . . . . . . . . . . . . . . . . . 4
6. Generating a Relay Identifier . . . . . . . . . . . . . . . . . 5 6. Identifier Stability . . . . . . . . . . . . . . . . . . . . . 5
7. Identifier Stability . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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 agent information option echo it back in their
replies.
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 a the Relay Agent Information option. The Relay-Id suboption carries a
sequence of octets that is intended to identify the relay agent sequence of octets that is intended to uniquely identify the relay
uniquely within the administrative domain. The identifier may be agent within the administrative domain.
administratively configured: in some networks it may be adequate to
assign ASCII strings such as "switch1" and "switch2". Alternatively,
the identifier may be generated by the relay agent itself, and we
specify use of DUIDs [RFC3315] 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].
[RFC3315].
3. Example Use-Cases 3. Example Use-Cases
3.1. Industrial Ethernet 3.1. Industrial Ethernet
DHCP typically identifies clients based on information in their DHCP DHCP typically identifies clients based on information in their DHCP
messages - such as the Client-Identifier option, or the value of the messages - such as the Client-Identifier option, or the value of the
chaddr field. In some networks, however, the location of a client - chaddr field. In some networks, however, the location of a client -
its point of attachment to the network - is a more useful identifier. its point of attachment to the network - is a more useful identifier.
In factory-floor networks (commonly called 'Industrial' networks), In factory-floor networks (commonly called 'Industrial' networks),
skipping to change at page 4, line 14 skipping to change at page 4, line 10
supply information that a DHCP server could use as a client supply information that a DHCP server could use as a client
identifier. A straightforward way to form identifier information is identifier. A straightforward way to form identifier information is
to combine something that is unique within the scope of the network to combine something that is unique within the scope of the network
element, such as a port/slot value, with something that uniquely element, such as a port/slot value, with something that uniquely
identifies that network element, such as a Relay Agent Identifier. identifies that network element, such as a Relay Agent Identifier.
3.2. Bulk Leasequery 3.2. Bulk Leasequery
There has been quite a bit of recent interest in extending the DHCP There has been quite a bit of recent interest in extending the DHCP
Leasequery protocol [RFC4388] to accommodate some additional Leasequery protocol [RFC4388] to accommodate some additional
situations. There is a recent draft ([draft-kinnear]) proposing a situations. There is a recent draft
variety of enhancements to the existing Leasequery protocol. The ([I-D.ietf-dhc-dhcpv4-bulk-leasequery]) proposing a variety of
draft describes a use-case where a relay agent queries DHCP servers enhancements to the existing Leasequery protocol. The draft
using the Relay Identifier to retrieve all the leases allocated describes a use-case where a relay agent queries DHCP servers using
through the relay device. the Relay Identifier to retrieve all the leases allocated through the
relay agent.
4. Suboption Format 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 | type | | |SUBOPT_RELAY_ID| length | type | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. . . .
. identifier (variable) . . identifier (variable) .
. . . .
+---------------------------------------------------------------+ +---------------------------------------------------------------+
Where: Where:
SUBOPT_RELAY_ID [TBA] SUBOPT_RELAY_ID [TBA]
length the number of octets in the suboption length the number of octets in the suboption
(excluding the suboption ID and length fields); (excluding the suboption ID and length fields);
the minimum length is two. the minimum length is two.
type a single octet describing the type of type a single octet describing the type of
identifier that is present. identifier that is present.
identifier the identifying data. identifier the identifying data.
5. Relay Identifier Types 5. Relay Identifier Types
For clarity, the suboption specified here includes a type octet that For clarity, the suboption specified here includes a type octet that
describes the data used in the identifier field. The type value zero 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: is reserved and MUST NOT be used. One type value is defined here:
RELAY_IDENTIFIER_DUID and RELAY_IDENTIFIER_ASCII. RELAY_IDENTIFIER_OPAQUE. RELAY_IDENTIFIER_OPAQUE is used when the
RELAY_IDENTIFIER_DUID is used when the identifier field contains a identifier field contains a series of octets.
DUID [RFC3315]. 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
network devices to generate identifiers themselves. Relay agents who
send the Relay Agent Identifier suboption using identifiers that are
not administratively-configured MUST be generated following the
procedures in the DUID section of [RFC3315]. Relay agents who use
generated identifiers SHOULD make the generated value visible to
their administrators via their user interface, through a log entry,
or through some other mechanism.
7. Identifier Stability 6. Identifier Stability
If the relay identifier is to be meaningful it has to be stable. A If the relay identifier is to be meaningful it has to be stable. A
relay agent SHOULD use a single identifier type and value relay agent SHOULD use a single identifier type and value
consistently. The identifier used by a relay device SHOULD be consistently. The identifier used by a relay device SHOULD be
committed to stable storage, unless the relay device can regenerate committed to stable storage, unless the relay device can regenerate
the value upon reboot. the value upon reboot.
Relay agents SHOULD make their relay identifiers visible to their
administrators via their user interface, through a log entry, or
through some other mechanism. Among other uses, this is expected to
be useful to administrators in detecting misconfiguration of relay
identifiers (for example, multiple relay agents configured with the
same relay identifier).
Implementors should note that the identifier needs to be present in Implementors should note that the identifier needs to be present in
all DHCP message types where its value is being used by the DHCP all DHCP message types where its value is being used by the DHCP
server. The relay agent may not be able to add the Relay Agent server. The relay agent may not be able to add the Relay Agent
Information option to all messages - such as RENEW messages sent as Information option to all messages - such as RENEW messages sent as
IP unicasts. In some deployments that might mean that the server has IP unicasts. In some deployments that might mean that the server has
to be willing to continue to associate the relay identifier it has to be willing to continue to associate the relay identifier it has
last seen with a lease that is being RENEWed. Other deployments may last seen with a lease that is being RENEWed. Other deployments may
prefer to use the Server Identifier Override suboption [RFC5107] to prefer to use the Server Identifier Override suboption [RFC5107] to
permit the relay device to insert the Information option into all permit the relay device to insert the Relay Agent Information option
relayed messages. into all relayed messages.
Handling situations where a relay agent device is replaced is another Handling situations where a relay agent device is replaced is another
aspect of "stability". One of the use-cases for the relay identifier aspect of "stability". One of the use-cases for the relay identifier
is to permit a server to associate clients' lease bindings with the is to permit a server to associate clients' lease bindings with the
relay device connected to the clients. If the relay device is relay device connected to the clients. If the relay device is
replaced, because it has failed or been upgraded, it may be desirable replaced, because it has failed or been upgraded, it may be desirable
for the new device to continue to provide the same relay identifier for the new device to continue to provide the same relay identifier
as the old device. Implementors should be aware of this possibility, as the old device. Implementors should be aware of this possibility,
and consider making it possible for administrators to configure the and consider making it possible for administrators to configure the
identifier. identifier.
8. 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.
9. IANA Considerations [RFC4030] to provide integrity protection and to avoid duplication of
relay identifiers by malicious entities.
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 [TBA] Relay Agent Identifier Suboption [TBA]
We request that IANA establish a new registry of DHCP Relay Agent We request that IANA establish a new registry of DHCP Relay Agent
Identifier Sub-Option Types, to be maintained in Identifier Sub-Option Types, to be maintained in
http://www.iana.org/assignments/bootp-dhcp-parameters. The http://www.iana.org/assignments/bootp-dhcp-parameters. The
Identifier Type is a single octet. The initial values assigned in Identifier Type is a single octet. The initial values assigned in
this document are: this document are:
Reserved 0 Reserved 0
RELAY_IDENTIFIER_DUID 1 RELAY_IDENTIFIER_OPAQUE 1
RELAY_IDENTIFIER_ASCII 2
Additional Identifier Type values will be allocated and assigned Additional Identifier Type values will be allocated and assigned
through IETF Review, as defined in [RFC5226]. through IETF Review, as defined in [RFC5226].
9. Acknowledgments
Thanks to Ted Lemon, David W. Hankins and Bernie Volz for providing
valuable suggestions.
10. References 10. References
10.1. Normative References 10.1. Normative References
[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.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[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.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[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.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
10.2. Informative References 10.2. Informative References
[RFC4388] Woundy, R. and K. Kinnear, "Dynamic Host Configuration [RFC4388] Woundy, R. and K. Kinnear, "Dynamic Host Configuration
Protocol (DHCP) Leasequery", RFC 4388, February 2006. Protocol (DHCP) Leasequery", RFC 4388, February 2006.
[RFC5107] Johnson, R., Kumarasamy, J., Kinnear, K., and M. Stapp, [RFC5107] Johnson, R., Kumarasamy, J., Kinnear, K., and M. Stapp,
"DHCP Server Identifier Override Suboption", RFC 5107, "DHCP Server Identifier Override Suboption", RFC 5107,
February 2008. February 2008.
[draft-kinnear] [I-D.ietf-dhc-dhcpv4-bulk-leasequery]
Kinnear, K., Volz, B., Russell, N., and M. Stapp, "Bulk Kinnear, K., Volz, B., Russell, N., Stapp, M., Rao, D.,
DHCPv4 Lease Query Joshi, B., and P. Kurapati, "Bulk DHCPv4 Lease Query",
(draft-kinnear-dhc-dhcpv4-bulk-leasequery-*)", July 2008. draft-ietf-dhc-dhcpv4-bulk-leasequery-04 (work in
progress), May 2011.
Author's Address Authors' Addresses
Bharat Joshi
Infosys Technologies Ltd.
44 Electronics City, Hosur Road
Bangalore 560 100
India
Email: bharat_joshi@infosys.com
URI: http://www.infosys.com/
D.T.V Ramakrishna Rao
Infosys Technologies Ltd.
44 Electronics City, Hosur Road
Bangalore 560 100
India
Email: ramakrishnadtv@infosys.com
URI: http://www.infosys.com/
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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