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Versions: 00 01

dhc Working Group                                           S. Gandhewar
Internet-Draft                                    Juniper Networks, Inc.
Intended status: Standards Track                         October 1, 2015
Expires: April 3, 2016


                     DHCPv6 Relay Initiated Release
           draft-gandhewar-dhc-v6-relay-initiated-release-01

Abstract

   The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) is
   initiated by a DHCPv6 client.  A DHCPv6 server can force DHCPv6
   client to send RENEW or INFORMATION-REQUEST by sending a RECONFIGURE
   message.  There may be multiple DHCPv6 network devices connected in
   between a DHCPv6 client and a server, each one reserving resources
   for the DHCPv6 client.  There are no DHCPv6 messages that a relay can
   initiate in order to control the client binding.

   A DHCPv6 client may not always send a RELEASE message when it no
   longer needs the IPv6 address or prefix and network resources for the
   associated services it is using.  This document specifies a way to
   request release to be initiated by an intermediate DHCPv6 network
   device, e.g.  DHCPv6 relay, on behalf of DHCPv6 client.  This helps
   to relinquish network resources sooner than the lease expiration
   time.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 3, 2016.








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Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Problem Description . . . . . . . . . . . . . . . . . . .   3
     1.2.  Relay Initiated Release . . . . . . . . . . . . . . . . .   4
     1.3.  Applicability . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   7
   3.  Protocol Details  . . . . . . . . . . . . . . . . . . . . . .   7
     3.1.  Message Definitions . . . . . . . . . . . . . . . . . . .   7
       3.1.1.  RELEASE-REQUEST . . . . . . . . . . . . . . . . . . .   7
       3.1.2.  RELEASE-REQUEST-REPLY . . . . . . . . . . . . . . . .   8
     3.2.  Message Validation  . . . . . . . . . . . . . . . . . . .   8
       3.2.1.  RELEASE-REQUEST . . . . . . . . . . . . . . . . . . .   8
       3.2.2.  RELEASE-REQUEST-REPLY . . . . . . . . . . . . . . . .   9
   4.  Functionality . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  First DHCPv6 Network Device Behavior  . . . . . . . . . .   9
       4.1.1.  Generation and Transmission of RELEASE-REQUEST
               Message . . . . . . . . . . . . . . . . . . . . . . .  10
       4.1.2.  Receipt of RELEASE-REQUEST Message  . . . . . . . . .  11
     4.2.  Intermediate DHCPv6 Network Device Behavior . . . . . . .  11
     4.3.  DHCPv6 Server Behavior  . . . . . . . . . . . . . . . . .  11
     4.4.  Receipt of RELEASE-REQUEST-REPLY  . . . . . . . . . . . .  12
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14







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1.  Introduction

   DHCPv6 [RFC3315] and [RFC3633] provides a framework for configuring
   clients with network addresses, address prefixes and other network
   parameters.  It includes a relay agent capability where DHCPv6 server
   may not be directly connected to the DHCPv6 client.  A relay agent is
   an intermediate node that passes DHCPv6 messages between DHCPv6
   clients and DHCPv6 servers.  As per [RFC3315], a relay agent cannot
   generate a message on its own which can control the client binding.
   Figure 1 below shows a typical network with multiple DHCPv6 devices.

   +---------+     +---------+       +---------+     +---------+
   | DHCPv6  |-----| DHCPv6  |--...--| DHCPv6  |-----|  DHCPv6 |
   | Server  |     | Relay n |       | Relay 1 |     |  Client |
   +---------+     +---------+       +---------+     +---------+

                     Figure 1: Typical DHCPv6 Network

1.1.  Problem Description

   While providing an IPv6 address or IPv6 Prefix to the DHCPv6 Client,
   Service Providers (e.g.  Broadband Service Providers), creates a
   logical interface per client, programs various routes (e.g. access
   routes, framed routes) for the client to access the network and
   services, attaches services (e.g. voice, video, data), maintains
   policy, applies QoS.  Along with these resources there is a need for
   memory and bandwidth per client.  Since all these resources are
   limited on a network device (e.g.  Broadband Network Gateway), it
   defines the scaling capacity of the device.  Since the availability
   of the IPv6 addresses is large, subscription rate for the Service
   Providers is thus limited by the availability of the resources on
   their network device.

   A DHCPv6 client may be connected to the DHCPv6 server through
   multiple DHCPv6 network devices, e.g. multiple DHCPv6 relays.  These
   network resources remain reserved for the client at all the DHCPv6
   network devices until the lease expires.

   In some situations, there might be need to clear the client binding
   administratively.  The process of administratively clearing the
   client binding is very cumbersome.  The administrator needs to access
   every single DHCPv6 network device (relay, relay-proxy) and also the
   DHCPv6 server, and clear the DHCPv6 client binding at each of these
   devices manually.

   In some situations when the DHCPv6 client is replaced (e.g. replacing
   the set-top-box) due to the device failure or upgrade, the older
   DHCPv6 client might not have sent the RELEASE message on its failure.



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   In this case, the previously assigned IPv6 address or prefix and
   network resources for the older (stale) client will stay reserved and
   unused until the lease expires.

   Same is the situation where clients move frequently without sending
   RELEASE e.g. in the case of mobile networks, network resources stay
   reserved and unused.  Similarly, network resources stay reserved and
   unused where DHCPv6 clients login and logout frequently without
   sending RELEASE e.g.  Wi-Fi access centers.

   As per DHCPv6 protocol it is not mandatory for the DHCPv6 client to
   send a RELEASE message while disconnecting.  As per the statistics
   from Service Providers, 95% of the cases DHCPv6 client does not send
   RELEASE message when it no longer needs the service.  It is also
   possible that the UDP datagram carrying a RELEASE message may get
   dropped due to network issues.

   All the resources including the IPv6 address or prefix remains
   reserved for the client at all the DHCPv6 network devices until the
   lease expires.  Service Providers needs to take into account such
   situations and are forced to lower the subscription rate.  Thus it
   reduces the scaling per network device.  Also it causes errors for
   the time based billing.

1.2.  Relay Initiated Release

   It is possible for the first DHCPv6 network device, i.e. "DHCPv6
   Relay 1" in Figure 1 which is closest to the DHCPv6 client, to detect
   that the DHCPv6 client is replaced, moved or is no longer present on
   the network.  In this scenario, the relay agent doesn't have any
   mechanism to inform the server to release the client's binding and
   subsequently relinquish network resources.

   With the relay initiated release message, when a DHCPv6 relay detects
   client's unavailability or needs to clear the client binding
   administratively, it can generate the release message on behalf of
   the client and send it to the server.  Thus, all the DHCPv6 network
   devices along the path will be in synchronization with respect to the
   client's binding information and network resources can be
   relinquished earlier than the lease expiry.  The server MAY choose to
   integrate some mechanism to confirm with the client, e.g. generate
   RECONFIGURE message before sending reply to the relay.  It is outside
   the scope of this document.

   Generation of the relay initiated release SHOULD be a configurable
   behavior at the first relay.  The configuration at Relay SHOULD be
   further granular to indicate the situation under which relay should




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   initiate the release e.g. administratively clearing DHCPv6 binding,
   client replaced, client moved, client unavailable, etc.

   Forwarding of the relay initiated release related messages SHOULD be
   a configurable behavior at the intermediate DHCPv6 network devices.

   Acceptance of relay initiated release SHOULD also be a configurable
   behavior at the server.

   The purpose of such configurable behavior is explained in
   Section 1.3.

1.3.  Applicability

   As per the statistics from Service Providers, 95% of the cases DHCPv6
   client does not send RELEASE message when it no longer needs the
   service.  This functionality is useful in order to relinquish network
   resources sooner than the lease expiry.  This allows Service
   Providers for higher subscription rate and accurate time based
   billing.

   This functionality described in Section 1.2 is useful for clearing
   the client binding administratively, client replacement, frequent
   client login and logout without sending RELEASE (e.g. at Wi-Fi
   centers) or where client moves frequently without sending RELEASE
   (e.g. mobile networks).  All these situations can be detected by the
   first DHCPv6 network device.  Thus this functionality is applicable
   to all these situations without any problems.

   This functionality is also useful where client unavailability can be
   detected.  Client unavailability could be because of multiple
   reasons.  Client may become unavailable due to powered-off,
   disconnect from the network or problems in the network itself.  Since
   it is difficult to identify the cause of client's absence, precaution
   must be taken in such situations.  With this functionality described
   in Section 1.2, the state of the binding is cleared and network
   resources are relinquished at DHCPv6 Relay, DHCPv6 Server and all the
   intermediate network devices.  However it is possible that the
   binding is still not cleared at the DHCPv6 client.  There may be a
   situation where client remembers the IPv6 address or prefix as well
   as the lease it received and continue to use when network comes back.
   This situation may happen when the network between Relay and client
   becomes unavailable and Relay may assume that the client is
   unavailable.

   When such a situation happens where all the DHCPv6 network devices
   cleared the binding but client still remembers and tries to use the
   address or prefix, at that moment there is no way to clear the



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   binding at the client.  The client's binding will get cleared at the
   client at the time of Renew or Rebind or when the lease expires or
   when client restarts DHCPv6 process.

   This may not be a problem in case of DSL based networks where DHCPv6
   is over PPP session.  The failed PPP session will cause the DHCPv6
   client to bring up the PPP session and restart the DHCPv6 discovery
   process.  However it may be a problem with an Ethernet based access
   network since there is no trigger event to the CPE (client) to
   restart the DHCPv6 binding process.

   In some provider networks, DHCPv6 Relay has liveness detection.  When
   the network between DHCPv6 Relay and client becomes unavailable,
   DHCPv6 Relay may initiate Release, whereas client is completely
   unaware.  It is not possible to differentiate between network
   unavailable and client unavailable.  This will very likely be the
   case with cable network configurations.  If the link between Cable
   Modem and the CMTS goes down, the Relay running on CMTS may initiate
   release for the Cable Modem as well as the devices behind the Cable
   Modem unless Cable Modem runs the DHCPv6 Relay.  The granular
   configuration to initiate Release on client unavailability should be
   turned off in such networks.

   However, there are some Service Provider networks where DHCPv6 client
   runs the liveness detection e.g.  BFD on the provider facing
   interface.  Such DHCPv6 clients can identify the network
   unavailability and may restart the DHCPv6 binding process.

   In some Service Provider networks, Relay takes up longer lease from
   the Server but gives out very small lease to the DHCPv6 client.  This
   forces DHCPv6 client to frequently renew the lease.  Thus recovery
   from problematic state of the DHCPv6 client will be much faster in
   such network configurations.

   For some of the Service Provider's configurations, DHCPv6 Relay adds
   access routes per subscriber (DHCPv6 client) and remove these routes
   on clearing the binding on receiving the REPLY for RELEASE or the
   RELEASE-REQUEST-REPLY.  Thus the Relay can restrict DHCPv6 client's
   network traffic based on the source or the destination address and
   thus restrict the harm and protects from two devices accessing the
   network with the same IPv6 address.

   This functionality SHOULD be a configurable behavior since there is
   no clear way to distinguish between DHCPv6 client unavailable and
   network unavailable.  Having configurable behavior equips
   administrator to enable this granular knob (send Relay Initiated
   Release on DHCPv6 client's unavailability) at Relay only if it is
   certain that such a situation will not occur or client will clear the



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   binding state and reestablish or the risk of such situation is being
   accounted.

2.  Requirements Language

   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 RFC 2119 [RFC2119].

3.  Protocol Details

3.1.  Message Definitions

   This document specifies 2 new DHCPv6 message types:

   o  RELEASE-REQUEST

   o  RELEASE-REQUEST-REPLY

   The RELEASE-REQUEST and RELEASE-REQUEST-REPLY messages use the
   Client/Server Message Formats described in Section 6 of [RFC3315],
   similar to the LEASEQUERY and LEASEQUERY-REPLY in [RFC5007].

3.1.1.  RELEASE-REQUEST

   This is the relay initiated release request message.

   The RELEASE-REQUEST message MAY be generated by the first DHCPv6
   network device ("DHCPv6 Relay 1" in Figure 1), on behalf of the
   DHCPv6 client.  The RELEASE-REQUEST message MUST contain one or more
   Client Data Options as described in Section 4.1.2.2 of [RFC5007],
   requesting release for one or more clients.

   The RELEASE-REQUEST message MUST contain the Server Identifier
   Option.  It MAY contain Interface-Id Option indicating common values
   for all the clients requesting the release.  This reduces the
   redundant data when there are multiple clients with common
   information.

   Each Client Data Option MUST include the Client Identifier Option
   OPTION_CLIENTID.  It MUST also include options containing the IAs -
   OPTION_IAADDR, OPTION_IAPREFIX, etc. - for the addresses or prefixes
   it is releasing.  If the Interface-Id option is different from the
   one included directly under RELEASE-REQUEST message then it MUST be
   included here.






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3.1.2.  RELEASE-REQUEST-REPLY

   This is the reply for the RELEASE-REQUEST message.

   The message RELEASE-REQUEST-REPLY will be generated by the DHCPv6
   Server to communicate the status of the request.  The server conveys
   the success or failure of the RELEASE-REQUEST by including Status
   Code Option at different levels:

   o  Status Code Option directly inside RELEASE-REQUEST: Indicates
      success or failure of the complete RELEASE-REQUEST message it
      received.

   o  Status Code Option inside Client Data Option: Indicates success or
      failure to release all the addresses or prefixes for a particular
      client.  Client Data Option MUST include the Client-Id Option.

   o  Status Code Option inside IA Option: Indicates success or failure
      to release a particular address or prefix for a particular client.
      Client Data Option MUST include the Client-Id Option and the IA
      option.

   The RELEASE-REQUEST-REPLY message MAY contain one or more Client Data
   Options, described in Section 4.1.2.2 of [RFC5007], responding to the
   request to release for each of the clients.

   The RELEASE-REQUEST-REPLY message SHOULD contain the Interface-Id
   option if it was included in RELEASE-REQUEST message.

3.2.  Message Validation

3.2.1.  RELEASE-REQUEST

   Clients MUST silently discard any received RELEASE-REQUEST messages.

   Relay MAY accept or discard any received RELEASE-REQUEST messages
   depending upon the configuration as explained in Section 4.1.2.

   Servers MUST discard any received RELEASE-REQUEST messages that meet
   any of the following conditions:

   o  The message does not include a Relay Id Option.

   o  The message does not include a Client Data Option.

   o  The Client Data Option does not include a Client Identifier
      Option.




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   o  The message does not include a Server Identifier option.

   o  The message includes a Server Identifier Option but the contents
      of the Server Identifier Option do not match the server's
      identifier.

3.2.2.  RELEASE-REQUEST-REPLY

   Clients MUST silently discard any received RELEASE-REQUEST-REPLY
   messages.

   Servers MUST silently discard any received RELEASE-REQUEST-REPLY
   messages.

   Relay MUST discard any received RELEASE-REQUEST-REPLY messages that
   meet any of the following conditions:

   o  The "transaction-id" field in the message does not match the value
      used in the RELEASE-REQUEST message.

   o  The message does not include a Status Code Option.

4.  Functionality

   The generation of a RELEASE-REQUEST message SHOULD be a configurable
   behavior at DHCPv6 network device.  Similarly, taking action to
   release the binding SHOULD also be a configurable behavior at the
   DHCPv6 server and intermediate DHCPv6 network devices.

4.1.  First DHCPv6 Network Device Behavior

   Devices MAY be configured to generate the newly defined RELEASE-
   REQUEST message.

   The first DHCPv6 network device ("DHCPv6 Relay 1" in Figure 1) can be
   configured such that when it detects the client is no longer
   available on the network or is replaced or the binding information
   needs to be deleted administratively, the device can generate the
   RELEASE-REQUEST message.

   In order to generate the RELEASE-REQUEST message this network device
   needs to store the information related to the client, e.g. the client
   identifier and the server identifier used while obtaining the client
   lease.







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4.1.1.  Generation and Transmission of RELEASE-REQUEST Message

   Set the "msg-type" field to RELEASE-REQUEST.

   Generate a transaction ID and insert it in the "transaction-id"
   field.

   MUST include Server-Id Option.

   MUST include Relay-Id option [RFC5460].

   MAY add Interface-Id option [RFC3315].

   MUST include one or more Client Data Options each one:

   o  MUST include Client Identifier and MUST be same as what was used
      when client obtained the lease.

   o  MAY include options containing the IAs (IA_NA, IA_TA, IA_PD) for
      the addresses or prefixes it is requesting to be released.
      Absence of this option indicates release of all the addresses and
      prefixes associated with this Client Identifier.

   o  MAY include Interface-Id option [RFC3315] if it is different from
      the one included outside of the Client Data Option

   Because RELEASE-REQUEST messages MAY be lost, the message SHOULD be
   retransmitted if no RELEASE-REQUEST-REPLY message is received.  The
   client transmits the message according to Section 14 of [RFC3315],
   using the following parameters:

   o  IRT REL_TIMEOUT

   o  MRT 0

   o  MRC REL_MAX_RC

   o  MRD 0

   If RELEASE-REQUEST-REPLY from a DHCPv6 server is lost, then the
   RELEASE-REQUEST will be retransmitted, and the server MAY respond
   with a RELEASE-REQUEST-REPLY indicating a status as NoBinding.
   Therefore, in this message exchange, the relay SHOULD NOT treat a
   RELEASE-REQUEST-REPLY message with a status of NoBinding as an error.







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4.1.2.  Receipt of RELEASE-REQUEST Message

   In order to protect against spoofed RELEASE-REQUEST messages
   attempting to disconnect the clients, the first DHCPv6 network device
   SHOULD drop any received RELEASE-REQUEST messages.  It MUST be a
   configurable behavior if these messages are from the trusted sources
   and needs to be forwarded to the server.

4.2.  Intermediate DHCPv6 Network Device Behavior

   The behavior of the intermediate DHCPv6 network device can be
   configurable to either accept or reject these messages.  On
   accepting, it can forward the messages as specified in Section 20.1
   and 20.2 of [RFC3315].

4.3.  DHCPv6 Server Behavior

   DHCPv6 server ("DHCPv6 Server" in Figure 1) SHOULD be configurable to
   either accept or reject the relay initiated release message RELEASE-
   REQUEST.  Upon receipt of a RELEASE-REQUEST message, the server MUST
   confirm the validity of the message.

   If server does not support the new message type then it MAY simply
   drop the packet.

   If the server is not configured to accept this relay initiated
   RELEASE-REQUEST message then it MAY simply drop the packet or send
   RELEASE-REQUEST-REPLY with status as NotConfigured.

   If the server decides not to accept the RELEASE-REQUEST from a
   particular relay, it MAY simply drop the packet or send RELEASE-
   REQUEST-REPLY with status as NotAllowed.

   The server SHOULD iterate through each of the Client Data Options and
   examine the Client-Id and the addresses in the IAs for validity.  If
   the addresses or prefixes in the IAs have been assigned by the
   server, the server deletes the binding of these addresses and
   prefixes and makes them available for assignment to other clients.
   Server keeps note of these addresses and prefixes in the IAs for
   generating the RELEASE-REQUEST-REPLY.

   After all of the clients have been processed, the server generates a
   RELEASE-REQUEST-REPLY message and includes a Status Code Option with
   value Success.  It also includes Server Identifier option.

   For each of the clients where there is a failure in releasing
   addresses or prefixes, server MUST include Client Data Option.  In
   the Client Data Option, it MUST include the Client Identifier option



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   from the RELEASE-REQUEST message.  It MUST also include Status Code
   Option for each of the failed IAs from the RELEASE-REQUEST message.
   For the clients or IAs for which the server has no binding
   information, correspondingly, the server MUST include a Status Code
   Option with the value NoBinding.  No other options are included in
   the IA option.

4.4.  Receipt of RELEASE-REQUEST-REPLY

   The first DHCPv6 network device ("DHCPv6 Relay 1" in Figure 1), upon
   receipt of a valid RELEASE-REQUEST-REPLY message, considers the
   completion of RELEASE-REQUEST event.  The action at this device is
   based on the status.  For all of the IAs or clients where the Status
   Code is not Success or NoBinding, addresses and prefixes remain
   unchanged until the lease expires.  For all other clients and IAs,
   bindings MUST be cleared.

5.  Security Considerations

   The RELEASE-REQUEST message provides a mechanism for releasing the
   client binding, it can be the cause of security threat.  The DHCPv6
   server SHOULD have some mechanism for determining that the relay
   agent is a trusted entity.  DHCPv6 servers and relay agents MAY
   implement relay message authentication as described in Section 21.1
   of [RFC3315].  DHCPv6 servers MAY also implement a control policy
   based on the content of a received Relay Identifier Option [RFC5460].
   Administrators MAY configure one of these security mechanisms.

   In an environment where the network connecting the relay agent to the
   DHCPv6 server is physically secure and does not contain devices not
   controlled by the server administrator, it MAY be sufficient to trust
   the Relay Agent Identifier provided by the relay agent.  In networks
   where the security of the machines with access to the data path is
   not under the control of the server administrator, IPsec [RFC4301] is
   necessary to prevent spoofing of messages.

   DHCPv6 servers MUST silently discard RELEASE-REQUEST messages
   originating from unknown or untrusted relay agents or reject the
   RELEASE-REQUEST.  Section 4.3 specifies the error code to return when
   the server is configured to reject RELEASE-REQUEST messages.

6.  IANA Considerations

   We request IANA to assign following new message types from the
   registry of Message Types maintained in:
   http://www.iana.org/assignments/dhcpv6-parameters/

   o  RELEASE-REQUEST



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   o  RELEASE-REQUEST-REPLY

7.  Acknowledgements

   We would like to acknowledge Utae Kim (Smart GiGA Network Project,
   Korea Telekom), Dan Seibel (Sr.  Engineer, TELUS), Ian Farrer
   (Network Architect, Deutsche Telekom) and Chris Topazi (Access
   Engineering, Cox Communications) for their valuable contributions,
   suggestions and support for this document.

   We would like to thank Bernie Volz, Ted Lemon, Andrew Sullivan, Ole
   Troan and Shrivinas Joshi for their valuable comments and suggestions
   for improving the document.

   Many thanks to Tomek Mrugalski, Bernie Volz and Jaya Bhawtankar (Lead
   Engineer, Coriant) for their support.

   We would like to acknowledge Anand Vijayvergiya, Jeff Haas and Ross
   Callon for their guidance and tirelessly reviewing the document
   multiple times.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

8.2.  Informative References

   [RFC3315]  Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
              C., and M. Carney, "Dynamic Host Configuration Protocol
              for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
              2003, <http://www.rfc-editor.org/info/rfc3315>.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              DOI 10.17487/RFC3633, December 2003,
              <http://www.rfc-editor.org/info/rfc3633>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <http://www.rfc-editor.org/info/rfc4301>.






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Internet-Draft       DHCPv6 Relay Initiated Release         October 2015


   [RFC5007]  Brzozowski, J., Kinnear, K., Volz, B., and S. Zeng,
              "DHCPv6 Leasequery", RFC 5007, DOI 10.17487/RFC5007,
              September 2007, <http://www.rfc-editor.org/info/rfc5007>.

   [RFC5460]  Stapp, M., "DHCPv6 Bulk Leasequery", RFC 5460,
              DOI 10.17487/RFC5460, February 2009,
              <http://www.rfc-editor.org/info/rfc5460>.

Author's Address

   Sunil M. Gandhewar
   Juniper Networks, Inc.

   Email: sgandhewar@juniper.net





































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