draft-ietf-dhc-leasequery-by-remote-id-07.txt   draft-ietf-dhc-leasequery-by-remote-id-08.txt 
DHC Working Group P. Kurapati DHC Working Group P. Kurapati
Internet-Draft Juniper Networks Ltd. Internet-Draft Juniper Networks Ltd.
Updates: 4388 (if approved) R. Desetti Updates: 4388 (if approved) R. Desetti
Expires: April 11, 2011 B. Joshi Intended status: Standards Track B. Joshi
Infosys Technologies Ltd. Expires: May 20, 2011 Infosys Technologies Ltd.
October 8, 2010 November 16, 2010
DHCPv4 lease query by Relay Agent Remote ID DHCPv4 lease query by Relay Agent Remote ID
draft-ietf-dhc-leasequery-by-remote-id-07.txt draft-ietf-dhc-leasequery-by-remote-id-08.txt
Abstract Abstract
Some Relay Agents extract lease information from the DHCP messages Some Relay Agents extract lease information from the DHCP messages
exchanged between the client and DHCP server. This lease information exchanged between the client and DHCP server. This lease information
is used by relay agents for various purposes like antispoofing and is used by relay agents for various purposes like antispoofing and
prevention of flooding. RFC 4388 defines a mechanism for relay prevention of flooding. RFC 4388 defines a mechanism for relay
agents to retrieve the lease information from the DHCP server as and agents to retrieve the lease information from the DHCP server as and
when this information is lost. The existing lease query mechanism is when this information is lost. The existing lease query mechanism is
data driven, which means that a relay agent can initiate the lease data driven, which means that a relay agent can initiate the lease
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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."
This Internet-Draft will expire on April 11, 2011. This Internet-Draft will expire on May 20, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 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 Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Server. In this process, some relay agents also glean the lease Server. In this process, some relay agents also glean the lease
information sent by the server and maintain this locally. This information sent by the server and maintain this locally. This
information is used to prevent spoofing attempts from clients and information is used to prevent spoofing attempts from clients and
also sometimes to install routing information. When a relay agent also sometimes to install routing information. When a relay agent
reboots, this information is lost. RFC 4388 [RFC4388] has defined a reboots, this information is lost. RFC 4388 [RFC4388] has defined a
mechanism to retrieve this lease information from the DHCP server. mechanism to retrieve this lease information from the DHCP server.
The existing query types defined by RFC 4388 [RFC4388] are data- The existing query types defined by RFC 4388 [RFC4388] are data-
driven. When a client sends data upstream, the relay agent can query driven. When a client sends data upstream, the relay agent can query
the server about the related lease information, based on the source the server about the related lease information, based on the source
MAC/IP address. These mechanisms do not scale well when there are MAC/IP address. These mechanisms do not scale well when there are
thousands of clients connected to the relay agent. In the data- thousands of clients connected to the relay agent. In the data
driven model, lease query does not provide the full and consolidated driven model, lease query does not provide the full and consolidated
active lease informations associated with a given connection/circuit, active lease informations associated with a given connection/circuit,
which will result in inefficient anti-spoofing. The relay agent also which will result in inefficient anti-spoofing. The relay agent also
has to contend with considerable resources for negative caching has to contend with considerable resources for negative caching
specially under spoofing attacks. specially under spoofing attacks.
We need a mechanism for a relay agent to retrieve the consolidated We need a mechanism for a relay agent to retrieve the consolidated
lease information for a given connection/circuit before upstream lease information for a given connection/circuit before upstream
traffic is sent by the clients. traffic is sent by the clients.
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complete understanding of the protocol. complete understanding of the protocol.
When used in this document, the unqualified term "DHCPLEASEQUERY" When used in this document, the unqualified term "DHCPLEASEQUERY"
indicates a lease query by Remote ID, unless otherwise specified. indicates a lease query by Remote ID, unless otherwise specified.
RFC 3046 [RFC3046] defines two sub-options for the Relay Agent RFC 3046 [RFC3046] defines two sub-options for the Relay Agent
Information option. Sub-option 1 corresponds to the Circuit ID that Information option. Sub-option 1 corresponds to the Circuit ID that
identifies the local circuit of the access concentrator. This sub- identifies the local circuit of the access concentrator. This sub-
option is unique to the relay agent. Sub-option 2 corresponds to the option is unique to the relay agent. Sub-option 2 corresponds to the
Remote ID that identifies the remote node connected to the access Remote ID that identifies the remote node connected to the access
concentrator. This is globally unique in the network. concentrator. The Remote ID is globally unique in the network and is
configured per circuit/connection in the relay agent.
This document defines a new query type based on the Remote ID sub- This document defines a new query type based on the Remote ID sub-
option. Suppose that the access concentrator (e.g., DSLAM) lost the option. Suppose that the access concentrator (e.g., DSLAM) lost the
lease information when it was rebooted. When the access concentrator lease information when it was rebooted. When the access concentrator
comes up, it initiates (for each connection/circuit) a DHCP lease comes up, it initiates (for each connection/circuit) a DHCP lease
query by Remote ID as defined in this section. For this query, the query by Remote ID as defined in this section. For this query, the
requester supplies an option 82 that includes only a Remote ID sub- requester supplies an option 82 that includes only a Remote ID sub-
option in the DHCPLEASEQUERY message. option in the DHCPLEASEQUERY message. The Remote ID is normally pre-
provisioned in the access concentrator per circuit/connection and
hence the same will remain available to the access concentrator after
reboot.
The DHCP server MUST reply with a DHCPLEASEACTIVE message if there is The DHCP server MUST reply with a DHCPLEASEACTIVE message if there is
an active lease corresponding to the Remote ID that is present in the an active lease corresponding to the Remote ID that is present in the
DHCPLEASEQUERY message. Otherwise, the server MUST reply with a DHCPLEASEQUERY message. Otherwise, the server MUST reply with a
DHCPLEASEUNKNOWN message. Servers that do not implement DHCP lease DHCPLEASEUNKNOWN message. Servers that do not implement DHCP lease
query based on Remote ID SHOULD simply not respond. query based on Remote ID SHOULD simply not respond.
4.1. Sending the DHCPLEASEQUERY Message 4.1. Sending the DHCPLEASEQUERY Message
The DHCPLEASEQUERY message is typically sent by an access The DHCPLEASEQUERY message is typically sent by an access
concentrator. The DHCPLEASEQUERY message uses the DHCP message concentrator. The DHCPLEASEQUERY message uses the DHCP message
format as described in RFC 2131 [RFC2131], and uses message number 10 format as described in RFC 2131 [RFC2131], and uses message number 10
in the DHCP Message Type option (option 53). The DHCPLEASEQUERY in the DHCP Message Type option (option 53). The DHCPLEASEQUERY
message has the following pertinent message contents: message has the following pertinent message contents:
o There MUST be a Relay Agent Information option (option 82) with o There MUST be a Relay Agent Information option (option 82) with
only a Remote ID sub-option (sub-option 2) in the DHCPLEASEQUERY only a Remote ID sub-option (sub-option 2) in the DHCPLEASEQUERY
message. message.
o Parameter Request List option MUST be populated by the access o The Parameter Request List option [RFC2132] MUST be populated by
concentrator with Associated-IP option. The giaddr and other the access concentrator with the Associated-IP option code. The
options listed in Parameter Request List option are set as giaddr field and other option codes listed in Parameter Request
explained in section 6.2 of RFC 4388 [RFC4388]. List option are set as explained in section 6.2 of RFC 4388
[RFC4388].
o The ciaddr field MUST be set to zero. o The ciaddr field MUST be set to zero.
o The values of htype, hlen, and chaddr MUST be set to zero. o The values of htype, hlen, and chaddr MUST be set to zero.
o The Client Identifier option (option 61) MUST NOT appear in the o The Client Identifier option (option 61) MUST NOT appear in the
packet. packet.
The DHCPLEASEQUERY message SHOULD be sent to a DHCP server that is The DHCPLEASEQUERY message SHOULD be sent to a DHCP server that is
known to possess authoritative information concerning the Remote ID. known to possess authoritative information concerning the Remote ID.
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pertaining to the client associated with the IP address specified in pertaining to the client associated with the IP address specified in
the ciaddr field. the ciaddr field.
In the case where more than one IP address has been involved in a In the case where more than one IP address has been involved in a
DHCP message exchange with the client specified by the Remote ID, DHCP message exchange with the client specified by the Remote ID,
then the list of all those IP addresses MUST be returned in the then the list of all those IP addresses MUST be returned in the
Associated-IP option, whether or not that option was requested as Associated-IP option, whether or not that option was requested as
part of the Parameter Request List option. This is intended for part of the Parameter Request List option. This is intended for
maintaining backwards compatibility with RFC 4388 [RFC4388]. maintaining backwards compatibility with RFC 4388 [RFC4388].
For all other options that are specified in Parameter Request List, All other options specified in the Parameter Request List [RFC2132]
the processing is same as mentioned in section 6.4.2 of RFC 4388 are processed as mentioned in section 6.4.2 of RFC 4388 [RFC4388].
[RFC4388].
In a DHCPLEASEUNKNOWN response message, the DHCP server MUST echo the In a DHCPLEASEUNKNOWN response message, the DHCP server MUST echo the
Option 82 received in the DHCPLEASEQUERY message. No other option is Option 82 received in the DHCPLEASEQUERY message. No other option is
included in the message. included in the message.
4.4. Determining the IP address to be used in response 4.4. Determining the IP address to be used in response
The IP address placed in the ciaddr field of a DHCPLEASEACTIVE The IP address placed in the ciaddr field of a DHCPLEASEACTIVE
message MUST be the IP address with the latest client-last- message MUST be the IP address with the latest client-last-
transaction-time associated with the client described by the Remote transaction-time associated with the client described by the Remote
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The server unicasts the DHCPLEASEACTIVE or DHCPLEASEUNKNOWN message The server unicasts the DHCPLEASEACTIVE or DHCPLEASEUNKNOWN message
to the address specified in the giaddr field of the DHCPLEASEQUERY to the address specified in the giaddr field of the DHCPLEASEQUERY
message. message.
4.6. Receiving a DHCPLEASEACTIVE or DHCPLEASEUNKNOWN Message 4.6. Receiving a DHCPLEASEACTIVE or DHCPLEASEUNKNOWN Message
When a DHCPLEASEACTIVE message is received in response to the When a DHCPLEASEACTIVE message is received in response to the
DHCPLEASEQUERY message, it means that there is currently an active DHCPLEASEQUERY message, it means that there is currently an active
lease associated with the Remote ID in the DHCP server. The access lease associated with the Remote ID in the DHCP server. The access
concentrator SHOULD use the information in the htype, hlen, and concentrator SHOULD use the information in the htype, hlen, and
chaddr fields of the DHCPLEASEACTIVE as well as Relay Agent chaddr fields of the DHCPLEASEACTIVE as well as the Relay Agent
Information option included in the packet to refresh its location Information option included in the packet to refresh its location
information for this IP address. An access concentrator is likely to information for this IP address. An access concentrator is likely to
query by IP address for all the IP addresses specified in the query by IP address for all the IP addresses specified in the
Associated-IP option in the response, if any, at this point in time. Associated-IP option in the response, if any, at this point in time.
When a DHCPLEASEUNKNOWN message is received by an access concentrator When a DHCPLEASEUNKNOWN message is received by an access concentrator
that had sent out a DHCPLEASEQUERY message, it means that the DHCP that had sent out a DHCPLEASEQUERY message, it means that the DHCP
server does not have definitive information concerning the DHCP server does not have definitive information concerning the DHCP
client specified in the Remote ID sub-option of the DHCPLEASEQUERY client specified in the Remote ID sub-option of the DHCPLEASEQUERY
message. The access concentrator MAY store this information for message. The access concentrator MAY store this information for
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the data-driven approach [RFC4388], a node spoofing several IP the data-driven approach [RFC4388], a node spoofing several IP
addresses can lead to negative caching of greater magnitude. Another addresses can lead to negative caching of greater magnitude. Another
important change that this draft brings is the removal of periodic important change that this draft brings is the removal of periodic
lease queries generated from negative caching caused by lease queries generated from negative caching caused by
DHCPLEASEUNKNOWN. Since the information obtained through query by DHCPLEASEUNKNOWN. Since the information obtained through query by
Remote ID is complete, there is no need of attempting lease query Remote ID is complete, there is no need of attempting lease query
again for the same connection. again for the same connection.
4.7. Receiving No Response to the DHCPLEASEQUERY Message 4.7. Receiving No Response to the DHCPLEASEQUERY Message
The condition of access concentrator receiving no response to a The condition of an access concentrator receiving no response to a
DHCPLEASEQUERY message should be handled in the same manner as DHCPLEASEQUERY message should be handled in the same manner as
suggested in RFC 4388 [RFC4388]. suggested in RFC 4388 [RFC4388].
4.8. Lease Binding Data Storage Requirements 4.8. Lease Binding Data Storage Requirements
Implementation Note: Implementation Note:
To generate replies for a lease query by Remote ID effeciently, a To generate replies for a lease query by Remote ID effeciently, a
DHCP server should index the lease binding data structures using DHCP server should index the lease binding data structures using
Remote ID. Remote ID.
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[RFC4388] specifications. [RFC4388] specifications.
7. IANA Considerations 7. IANA Considerations
This document does not introduce any new namespaces for the IANA to This document does not introduce any new namespaces for the IANA to
manage. manage.
8. Acknowledgments 8. Acknowledgments
Copious amounts of text in this document are derived from RFC 4388 Copious amounts of text in this document are derived from RFC 4388
[RFC4388]. Kim Kinnear, Damien Neil, Stephen Jacob, Ted Lemon and [RFC4388]. Kim Kinnear, Damien Neil, Stephen Jacob, Ted Lemon, Ralph
Alfred Hoenes provided valuable feedback on this document. Droms and Alfred Hoenes provided valuable feedback on this document.
9. References 9. References
9.1. Normative Reference 9.1. Normative Reference
[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.
[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.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997. RFC 2131, March 1997.
[RFC2132] Droms, R. and S. Alexander, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, 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.
9.2. Informative Reference 9.2. Informative Reference
[RFC951] Croft, B. and J. Gilmore, "Bootstrap Protocol (BOOTP)", [RFC951] Croft, B. and J. Gilmore, "Bootstrap Protocol (BOOTP)",
RFC 951, September 1985. RFC 951, September 1985.
[RFC1542] Wimer, W., "Clarifications and Extensions for the [RFC1542] Wimer, W., "Clarifications and Extensions for the
Bootstrap Protocol", RFC 1542, October 1993. Bootstrap Protocol", RFC 1542, October 1993.
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