draft-ietf-dhc-relay-id-suboption-02.txt   draft-ietf-dhc-relay-id-suboption-03.txt 
DHC M. Stapp DHC M. Stapp
Internet-Draft Cisco Systems, Inc. Internet-Draft Cisco Systems, Inc.
Expires: March 23, 2009 September 19, 2008 Expires: April 2, 2009 September 29, 2008
The DHCPv4 Relay Agent Identifier Suboption The DHCPv4 Relay Agent Identifier Suboption
draft-ietf-dhc-relay-id-suboption-02.txt draft-ietf-dhc-relay-id-suboption-03.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on March 23, 2009. This Internet-Draft will expire on April 2, 2009.
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 value that uniquely identifies the option. The suboption carries a value that uniquely identifies the
relay agent device. The value may be administratively-configured or relay agent device. The value may be administratively-configured or
may be generated by the relay agent. The suboption allows a DHCP may be generated by the relay agent. The suboption allows a DHCP
relay agent to include the identifier in the DHCP messages it sends. relay agent to include the identifier in the DHCP messages it sends.
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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.
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 a
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 ASCII strings such as "switch1" and "switch2". Alternatively, assign ASCII strings such as "switch1" and "switch2". Alternatively,
the identifier may be generated by the relay agent itself, and we the identifier may be generated by the relay agent itself, and we
specify use of [RFC3315] DUIDs 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",
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location. Using manual address configuration is possible (and is location. Using manual address configuration is possible (and is
common) but it would be beneficial if DHCP configuration could be common) but it would be beneficial if DHCP configuration could be
applied to these networks. applied to these networks.
One way to provide connection-based identifiers for industrial One way to provide connection-based identifiers for industrial
networks is to have the network elements acting as DHCP relay agents networks is to have the network elements acting as DHCP relay agents
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 unique 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 accomodate some additional Leasequery protocol [RFC4388] to accomodate some additional
situations. There are two recent drafts ([draft-kinnear] and situations. There are two recent drafts ([draft-kinnear] and
[draft-dtv]) proposing a variety of enhancements to the existing [draft-dtv]) proposing a variety of enhancements to the existing
Leasequery protocol. Both describe cases where identifying the DHCP Leasequery protocol. draft-dtv describes a use-case where a relay
relay agent would be helpful in restoring binding information agent queries DHCP servers using the Relay Identifier to retrieve all
associated with the client downstream from the device acting as a the leases allocated through the relay device.
relay.
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 [TBD] SUBOPT_RELAY_ID [TBD]
length the number of octets in the suboption; the length the number of octets in the suboption; the
minimum length is one. 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. Two type values are defined here:
RELAY_IDENTIFIER_DUID and RELAY_IDENTIFIER_ASCII. RELAY_IDENTIFIER_DUID and RELAY_IDENTIFIER_ASCII.
RELAY_IDENTIFIER_DUID is used when the identifier field contains an RELAY_IDENTIFIER_DUID is used when the identifier field contains a
[RFC3315] DUID. Administrators may want to assign human-friendly DUID [RFC3315]. Administrators may want to assign human-friendly
ASCII identifiers: RELAY_IDENTIFIER_ASCII is used when the identifier ASCII identifiers: RELAY_IDENTIFIER_ASCII is used when the identifier
field contains an ASCII string. field contains an ASCII string.
6. Generating a Relay Identifier 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 visible 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.
7. Identifier Stability 7. Identifier Stability
If the relay identifier is to be meaningful it has to be stable. The If the relay identifier is to be meaningful it has to be stable. A
identifier associated with a relay device SHOULD be committed to relay agent SHOULD use a single identifier type and value
stable storage. This applies to all identifier types. consistently. The identifier used by a relay device SHOULD be
committed to stable storage, unless the relay device can regenerate
the value upon reboot.
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 Information option into all
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