v6ops                                                      J. Brzozowski
Internet-Draft                                             Comcast Cable
Intended status: Best Current Practice                   G. Van De Velde
Expires: April 21, 2016                                   Alcatel-Lucent
                                                        October 19, 2015

                      Unique IPv6 Prefix Per Host


   In some IPv6 environments the need has arisen for hosts to be able to
   utilise a unique IPv6 prefix even though the link or media may be
   shared.  Typically hosts (subscribers) on a shared network, like Wi-
   Fi or Ethernet, will acquire unique IPv6 addresses from a common IPv6
   prefix that is allocated or assigned for use on a specific link.
   Benefits of a unique IPv6 prefix compared to a unique IPv6 address
   from the service provider are going from enhanced subscriber
   management to improved isolation between subscribers.

   In most deployments today IPv6 address assignment from a single IPv6
   prefix on a shared network is done by either using IPv6 stateless
   address auto-configuration (SLAAC) and/or stateful DHCPv6.  While
   this is still viable and operates as designed there are some large
   scale environments where this concept introduces significant
   performance challenges and implications, specifically related to IPv6
   router and neighbor discovery.  This document outlines an approach
   utilising existing IPv6 protocols to allow hosts to be assigned a
   unique IPv6 prefix (instead of a unique IPv6 address from a shared
   IPv6 prefix).

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 21, 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Motivation and Scope of Applicability . . . . . . . . . . . .   3
   3.  Design Princinples  . . . . . . . . . . . . . . . . . . . . .   4
   4.  Behaviour . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Community Wi-Fi Network Topology Description  . . . . . .   4
     4.2.  Wi-Fi Subscriber Onboarding Procedures  . . . . . . . . .   6
     4.3.  UE IPv6 Addressing and Configuration  . . . . . . . . . .  10
       4.3.1.  IPv6 Addressing . . . . . . . . . . . . . . . . . . .  10
       4.3.2.  IPv6 Configuration  . . . . . . . . . . . . . . . . .  11
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .  11
   6.  Future work . . . . . . . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     10.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The concepts in this document were originally developed as part of a
   large scale, production deployment of IPv6 support for a community
   Wi-Fi service.  In this document IPv6 support does not preclude
   support for IPv4, however, the primary objectives for this work was
   to make it so that user equipment (UE) were capable of an IPv6 only
   experience from a network operators perspective.  Details of IPv4
   support are out of scope for this document.  This document will also,
   in general, outline the requirements that must be satified by UE to
   allow for an IPv6 only experience.

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   In most deployments today User Equipment (UE) IPv6 address assignment
   is commonly done using either IPv6 SLAAC RFC4862 [RFC4862] and/or
   DHCP IA_NA RFC3315 [RFC3315].  However, at current time there is a
   non-trivial UE/subscriber base not supporting DHCPv6 IA_NA, making
   IPv6 SLAAC based subscriber and address management for community Wi-
   Fi services the technology of choice as it does not exclude any known
   IPv6 implementation.  This document will detail the mechanics
   involved for IPv6 SLAAC based address and subscriber management
   coupled with stateless DHCPv6, where beneficial.

   A community Wi-Fi service is an environment to allow subscribers
   (hosts) to connect to a shared network providing Internet and/or
   closed network services.  Often Service providers use community Wi-Fi
   networks to provide enhanced subscriber connectivity experiences.
   Additionally retail owners frequently provide community Wi-Fi
   services to improve their customers retail experience.

   Upon further exploration the approach documented here has
   applicability in other environments including corporate, enterprise,
   or university settings where IPv6 support is desired over a shared
   media.  Where applicable details related to the same will be

2.  Motivation and Scope of Applicability

   The motivation for this work falls into the following categories:

   o  Deploy support for IPv6 that will allow for an IPv6 only
      experience, even if IPv4 support is present

   o  Ensure support for IPv6 is efficient and does not impact the
      performance of the underlying network and in turn the customer

   o  Allow for the greatest flexibility across host implementation to
      allow for the widest range of addressing and configuration
      mechanisms to be employed.  The goal here is the ensure that the
      widest population of UE implementations can leverage the
      availability of IPv6.

   o  Lay the technological foundation for future work related to the
      use of IPv6 over shared media like Wi-Fi

   While this work was originally conceived in the context of large
   scale Wi-Fi networks, the scope of applicability is much broader.
   The techniques and concepts or subsets of the same may also be
   applicable in residential or SOHO networking environments.

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3.  Design Princinples

   The Wireless LAN Gateway (WLAN-GW) discussed in this document is the
   L3-Edge router responsible for the communication with the Wi-Fi
   subscribers (hosts) and to aggregate the traffic from the Wi-Fi
   subscribers and the Wireless LAN network towards the community Wi-Fi

   The goal of a WLAN-GW is to provide sufficient data-plane throughput
   capacity to aggregate all Wi-Fi subscriber traffic, while at the same
   time it is functioning as control-plane anchor point to make sure
   that each subscriber is receiving the expected subscriber policy and
   service levels (throughput, QoS, security, parental-control,
   subscriber mobility management, etc.).

   The work detailed in this document intends to provide details
   regarding the WLAN-GW Wi-Fi subscriber/host addressing methodology.
   Evolved WLAN-GW capabilities regarding fixed/mobile convergence,
   traffic steering, etc. are not the main focus and are outside the
   scope of this document.

4.  Behaviour

   This section outlines the essential components of the described
   system and interaction amongst the same.

4.1.  Community Wi-Fi Network Topology Description

   The topology and design referenced in this document is a generalized
   description of functional components currently deployed in a large
   scale subscriber oriented network.

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                                         | AAA |
                                    | CP |
                +----+              +---------+
    UE--802.11--| AP |---Soft_GRE---| WLAN-GW |----Internet/WAN access
                +----+              +---------+
                              | HTTP Captive Portal |

                                 Figure 1

   o  UE: User Equipment.

   o  802.11: Wireless Network

   o  AP: Access Point.

   o  Soft-GRE: Stateless GRE tunnel

   o  WLAN-GW: Wireless LAN Gateway

   o  CP: Control Plane component of the WLAN-GW

   o  AAA: Accounting, Authorisation and Authentication

   o  HTTP Captive Portal: Captive portal used to redirect traffic
      towards during subscriber onboarding process

   While there are many ways for UE to associate to a Wi-Fi network
   (e.g.  EAP-SIM, EAP-AKA, WPA2-PSK, etc.), community Wi-Fi
   predominantly leverages an HTTP Captive Portal.  The key function for
   the Captive Portal is to identify the UE/subscriber and create on the
   WLAN-GW the corresponding UE/subscriber context for policy and

   The Soft-GRE session is a stateless GRE tunnel between AP and the
   WLAN-GW.  The AP is configured with the IP address or FQDN of the
   tunnel concentrator or aggregation point and initiates the GRE

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   tunnel, over IPv6 preferrably, by encapsulating packets towards the
   WLAN-GW.  The WLAN-GW is configured as a GRE tunnel head-end server
   and accepts these GRE packets, while at the same time creating
   correct tunnel context to identify the AP.  Soft-GRE is a very well
   established pragmatic technology.  The use of GRE over IPv4 only
   furthers an operators dependence on IPv4 and should be deprecated by
   using GRE over IPv6 only.

   The AP has, as seen in the illustration, an interface attached to the
   Wi-Fi network and will bridge traffic received on this Wi-Fi
   interface over the Soft-GRE tunnel to the WLAN-GW.  This will include
   traffic from newly attached UE/subscribers which have not been
   identified or authorized on the Wi-Fi network.  At the same time the
   AP implements split-horizon for BUM (broadcast, unknown and
   multicast) traffic, making sure that there is no undesired leakage of
   traffic between UE/subscribers attached to the Wi-Fi network.

   The Control Plane (CP) of the WLAN-GW is a key component used during
   onboarding of UE/subscribers to identify the UE/subscriber and to
   exchange IP address related details.  For that purpose it can make
   usage of DHCP, ARP, DHCPv6, ICMPv6 (RS/RA/NS/NA), Radius, Diameter,

4.2.  Wi-Fi Subscriber Onboarding Procedures

   This section provides detail about Best Practice operational steps to
   onboard a UE/subscriber and the key architectural technology used to
   create the WLAN-GW UE/subscriber policy and IP addressing context.

   The flow chart pictured below is providing a sequential overview of
   the operational steps performed to onboard a UE onto a community Wi-
   Fi network.

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   UE               WLAN-GW              AAA         Captive-Portal DNS
   |                   |                  |                |         |
   |                   |                  |                |         |
   |--------RS-------->|                  |                |         |
   |                   |---Access-Req---->|                |         |
   |                   |<--Access-Acc-----|                |         |
   |                   |(=Radius UE info) |                |         |
   |<-------RA---------|                  |                |         |
   |(/64; M,L=0; O,A=1)|                  |                |         |
   |                   |                  |                |         |
   |------NS(DAD)----->|                  |                |         |
   |                   |                  |                |         |
   |-DHCPv6(info Req)->|                  |                |         |
   | (Ask DNS IP addr.)|                  |                |         |
   |                   |                  |                |         |
   |<---DHCPv6 Reply---|                  |                |         |
   |                   |                  |                |         |
   |                   |                  |                |         |
   |------HTTP GET---->|                  |                |         |
   |<--HTTP Redirect---|                  |                |         |
   |                   |                  |                |         |
   |                   |                  |                |         |
   |<------------------------HTTP Login------------------->|         |
   |                   |                  |                |         |
   |                   |                  |<-UE Identified-|         |
   |                   |<--Radius CoA-----|                |         |
   |                   |(remove HTTP Red.)|                |         |
   |                   |                  |                |         |
   |<--------UE/Subscriber connected to Internet/WAN------------------->
   |                   |                  |                |         |
   |                   |                  |                |         |

                                 Figure 2

   Note that the Wireless Access Point (AP) is not pictured in the flow
   chart above.  This is because the AP is from architectural
   perspective functioning as a L2 bridge between the UE and WLAN-GW.
   For Wi-Fi community service the AP is configured to setup a Soft-GRE
   tunnel towards the WLAN-GW and to bridge relevant Wi-Fi traffic upon
   the Soft-GRE tunnel.  The AP is also configured for split-horizon
   towards the Wi-Fi interface for subscriber isolation and security
   purpose.  The AP will for the remainder of this document be silently
   inserted between UE and WLAN-GW to bridge traffic between the WLAN-GW
   and AP and vice versa

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   When a new UE connects to the community Wi-Fi it connects to the Wi-
   Fi network by attaching to the relevant 'open' SSID advertised for
   use as part of the community Wi-Fi offering.  Once the UE/subscriber
   is attached to the Wi-Fi SSID it will initiate IP configuration.  The
   focus of this document is to share IPv6 address assignment Best
   Practices, and hence will focus around those topics, eventhough there
   are many more aspects to deploy a quality community Wi-Fi service
   offering successfully.

   Once the UE is connected to the Wi-Fi shared network, it will from an
   IPv6 perspective attempt to learn the default IPv6 gateway, the IPv6
   prefix information, the DNS information, and the remaining
   information required to establish globally routable IPv6
   connectivity.  For that purpose the the UE/subscriber sends a RS
   (Router Solicitation) message.  This RS is forwarded by the AP-bridge
   over the Soft-GRE interface, however due to the split-horizon
   configuration for BUM traffic it is not relayed to any other UE/
   Subscribers attached to the Wi-Fi network.

   The WLAN-GW received this UE/subscriber RS message, and because it is
   the first time this UE/subscriber attaches to the Wi-Fi the UE/
   subscriber is by default not authorized.  The WLAN-GW will now try to
   discover additional information about the subscriber information by
   querying the AAA server.  This is done by sending a Radius Access-

   The Radius server receives this Access-Request, and performs a lookup
   in its policy database.  If radius server discovers that the UE/
   subscriber is a fresh device trying to gain access onto the Wi-Fi
   network it will identify some parameters (e.g.  IPv6 /64 prefix) to
   send back to the WLAN-GW together with a message to install a HTTP-
   redirect to a Captive Portal for further UE/subscriber
   identification.  This will be sent from the AAA server to the WLAN-GW
   in a Radius Access-Ackowledge message.

   The WLAN-GW will use the received Radius information to compose the
   response to the UE/subscriber originated RS message.  The WLAN-GW
   will answer using a unicast RA (Router Advertisement) to the UE/
   subscriber.  This RA contains a few important parameters for the EU/
   subscriber to consume: (1) a /64 prefix and (2) flags.  The /64
   prefix can be derived from a locally managed pool or aggregate IPv6
   block assigned to the WLAN-GW or from a pool signalled by the Radius
   server in a radius attribute.  The flags may indicate to the UE/
   subscriber to use SLAAC and/or DHCPv6 for address assignment, it may
   indicate if the autoconfigured address is on/off-link and if 'Other'
   information (e.g.  DNS server address) needs to be requested.

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   The IPv6 RA flags used for best common practice in IPv6 SLAAC based
   community Wi-Fi are:

   o  M-flag = 0 (UE/subscriber address is not managed through DHCPv6),
      this flag may be set to 1 in the future if/when DHCPv6 prefix
      delegation support over Wi-Fi is desired)

   o  O-flag = 1 (DHCPv6 is used to request configuration information
      i.e. DNS, NTP information, not for IPv6 addressing)

   o  A-flag = 1 (The UE/subscriber can configure itself using SLAAC)

   o  L-flag = 0 (The UE/subscriber is off-link, which means that the
      UE/subscriber will send packets ALWAYS to his default gateway,
      even if the destination is within the range of the /64 prefix)

   The use of a unique IPv6 prefix per UE adds an additional level of
   protection and efficiency as it relates to how IPv6 Neighbor
   Discovery and Router Discovery processing.  Since the UE has a unique
   IPv6 prefix all traffic by default will be directed to the WLAN-GW.
   Further, the flag combinations documented above maximize the IPv6
   configurations that are available by hosts including the use of
   privacy IPv6 addressing.

   The architected result of designing the RA as documented above is
   that each UE/subscriber gets its own unique /64 IPv6 prefix for which
   it can use SLAAC or any other method to select its /128 unique
   address.  In addition it will use stateless DHCPv6 to get the IPv6
   address of the DNS server, however it SHOULD NOT use stateful DHCPv6
   to receive a service provider managed IPv6 address.  If the UE/
   subscriber desires to send anything external including other UE/
   subscriber devices (assuming device to device communications is
   enabled and supported), then due to the L-bit set it SHOULD send this
   traffic to the WLAN-GW.

   Now that the UE/subscriber received the RA and the associated flags,
   it will assign itself a 128 bit IPv6 address using SLAAC.  Since the
   address is composed by the UE/subscriber device itself it will need
   to verify that the address is unique on the shared network.  The UE/
   subscriber will for that purpose perform Duplicate Address Detection
   algorithm.  This will occur for each address the UE attempts to
   utilize on the Wi-Fi network.

   At this stage the UE/subscriber has acquired a valid IPv6 address,
   however it may not have received one or more DNS server IPv6 address.
   The UE/subscriber can use stateless DHCPv6 exchange to identify a
   valid DNS server address(es).  An alternative solution, albeit less
   supported by IPv6 hosts is to signal DNS server addresses is by

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   utilising RA extensions described in RNDSS RFC6106 [RFC6106] in which
   the router uses Router Advertisement options to advertise a list of
   DNS recursive server addresses and a DNS Search List to IPv6 UE/
   subscribers.  The use of RNDSS and stateless DHCPv6 for the
   configuration of hosts are not mutually exclusive.  Both methods can
   and should be enabled simultaneously allowing for the widest range of
   hosts or UEs to learn and use DNS over IPv6.  DNS server IPv6
   address(es) sent via DHCPv6 and RDNSS must be identical.

   At this moment the UE/subscriber has all information to be connected
   to the Internet, nevertheless the community Wi-Fi service provider
   has no idea about the identity or credentials of the UE/subscriber.
   For that purpose the Service provider has installed on the WLAN-GW a
   HTTP redirect for this particular UE/subscriber towards HTTP captive
   portal.  First the subscriber utilises DNS to correlate the domain
   name with an IP address, next the HTTP GET is intercepted and an HTTP
   Redirect is issued to Redirect the HTTP session towards the Captive
   portal.  The ultimate goal of this process is for the service
   provider to identify the UE/subscriber.  From the moment the UE/
   subscriber identified itself on the captive portal (login-ID/PW, PIN
   Challenge, etc.) then the captive portal informs the WLAN-GW about
   the correct policies (QoS, policing, etc.) and to remove the HTTP-

   From now onwards the WLAN-GW has identified the UE/subscriber and
   installed all the subscriber context for identification, billing,
   traffic conditioning.  The UE/subscriber can access the Internet/WAN
   within his agreed commuity Wi-Fi parameters.

4.3.  UE IPv6 Addressing and Configuration

   An over arching objective for any IPv6 deployment where subscriber
   endpoints or UEs are concerned must include an IPv6 only experience.
   Specifically, similar to residential broadband networks, Wi-Fi
   networks that support IPv6 must ensure there are no dependencies on
   IPv4.  Due to fragmented support for various IPv6 address and
   configuration mechanisms network operators must effectively enable
   and support every combination of IPv6 address and configuration
   technique.  Coordinating the configuraiton and values for the same is
   important to ensure proper UE behavior.

4.3.1.  IPv6 Addressing

   Stateless IPv6 address autoconfiguration is expected to be the
   primary mechanism for UEs to leverage when establing globally
   routable IPv6 connectivity.  Stateful DHCPv6 is currently not
   utilized in this model for host addressing since stateful DHCPv6 is
   not universally supported for address acquisition.  Stateful DHCPv6

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   may be considering in the future as part of enabling support for IPv6
   prefix delegation [RFC3633].

4.3.2.  IPv6 Configuration

   In order to make an IPv6 only experience possible Wi-Fi network
   operators must ensure that UEs are able to reach all critical network
   services over IPv6.  Today, many host operating systems still prefer
   querying DNS over IPv4.  Additionally, widely deployed hosts do not
   truly leverage a single common approach for IPv6 configuration.  As
   such the following should be expected to be available to support a
   proper IPv6 only configuration:

   o  RDNSS [RFC6106] is enabled by default and is expected to contain
      one or more globally routable IPv6 addresses

   o  Stateless DHCPv6 [RFC3315] is enabled by default and will
      minimally transmit one or more DNS server IPv6 addresses.  To
      ensure the desired behavior is triggered IPv6 router
      advertisements transmitted by the WLAN-GW will set the M flag to 0
      and the O flag to 1.

5.  Operational Considerations

   An operational consideration when using IPv6 address assignment using
   IPv6 SLAAC is that after the onboarding procedure the UE/subscriber
   will have a prefix with certain preferred and valid lifetimes.  The
   WLAN-GW extends these lifetimes by sending an unsolicited RA, the
   applicable MaxRtrAdvInterval on the WLAN-GW MUST therefore be lower
   than the preferred lifetime.  As a consequence of this process is
   that the WLAN-GW never knows when a UE/subscriber stops using
   addresses from a prefix and additional procedures are required to
   help the WLAN-GW to gain this information.  When using stateful
   DHCPv6 IA_NA for IPv6 UE/subscriber address assignment this
   uncertainty on the WLAN-GW is not of impact due to the stateful
   nature of DHCPv6 IA_NA address assignment.

   Following is reference table of the key IPv6 router discovery and
   neighbor discovery timers:

   o  IPv6 Router Advertisement Interval = 300s

   o  IPv6 Router LifeTime = 3600s

   o  Reachable time = 30s

   o  IPv6 Valid Lifetime = 3600s

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   o  IPv6 Preferred Lifetime = 1800s

   o  Retransmit timer = 0s

   The stateless nature of the UE/subscriber IPv6 SLAAC connectivity
   model provides value to make sure that the UE/subscriber context is
   timely removed from the WLAN-GW to avoid ongoing resource depletion.
   A possible solution is to use a subscriber inactivity timer which
   after tracking a pre-defined (currently unspecified) # of minutes
   deletes the subscriber context on the WLAN-GW.

   When using SLAAC the UE/subscriber the IP address assignment happens
   without a WLAN-GW controlled state machine, and as result there is no
   state-information on the WLAN-GW about actual IPv6 address usage.  To
   accomodate this the WLAN-GW can periodically perform a Subscriber
   Host Connectivity Verification (i.e. periodically ping each IPv6 UE/
   subscriber from the WLAN-GW) to make sure that the subscriber table
   on the WLAN-GW is correct and that the inactive UE/subscribers are

   When employing stateless IPv6 address assignment a number of widely
   deployed operating systems will attempt to utilize RFC 4941 RFC4941
   [RFC4941] temporary 'private' addresses.  This can lead to the
   consequence that a UE has multiple /128 addresses from the same IPv6
   prefix.  The WLAN-GW MUST be able to handle the presence and use of
   multiple globally routable IPv6 addresses.

   When geo-localisation is of importance the WLAN-GW needs to have
   information about the Access Point to which the UE/subscriber is
   connected.  In an environment using DHCPv6 IA_NA for IPv6 address
   assignment this is achieved by having the AP insert an interface-id
   RFC3315 [RFC3315] in the UE/subscriber DHCPv6 Solicit message.  The
   interface-id format expected is [ap-mac;ssid;[o-s]], e.g.
   [00:11:22:33:44:55;example;o] (o stands for open, s for secure).
   This way the service provider can learn both the AP-MAC (identifies
   location) and the SSID (identifies service).  When a service provider
   uses SLAAC IPv6 address assignment it becomes harder for the service
   provider to rely on this type of information and alternate solutions
   have to be used to acquire the MAC address of the Access Point to
   which the UE/subscriber is connected.  A solution could be for the
   WLAN-GW to support NSoGRE to harvest the Access-Point MAC address to
   which the UE/subscriber is connected.

   For security purposes it will be important for the service provider
   to have the capability on the WLAN-GW to have supported mechanics for
   LI (Lawfull Intercept) and the installation of IPv6 filters per

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   For accounting purposes the WLAN-GW must be able to send usage
   statistics per UE/subscriber using Radius attributes.

6.  Future work

   o  Support for IPv6 prefix delegation over Wi-Fi

7.  IANA Considerations

   No IANA considerations are defined at this time.

8.  Security Considerations

   No Additional Security Considerations are made in this document.

9.  Acknowledgements

   The authors would like to thank the following, in alphabetical order,
   for their contributions:

   Lorenzo Colitti, Killian Desmedt, Brad Hilgenfeld, Wim Henderickx,
   Erik Kline, Thomas Lynn, Phil Sanderson, Colleen Szymanik, Sanjay

10.  References

10.1.  Normative 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>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862, DOI 10.17487/
              RFC4862, September 2007,

   [RFC4941]  Narten, T., Draves, R., and S. Krishnan, "Privacy
              Extensions for Stateless Address Autoconfiguration in
              IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,

   [RFC6106]  Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
              "IPv6 Router Advertisement Options for DNS Configuration",
              RFC 6106, DOI 10.17487/RFC6106, November 2010,

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Internet-Draft         Unique IPv6 Prefix Per Host          October 2015

   [RFC6180]  Arkko, J. and F. Baker, "Guidelines for Using IPv6
              Transition Mechanisms during IPv6 Deployment", RFC 6180,
              DOI 10.17487/RFC6180, May 2011,

10.2.  Informative References

              Carpenter, B., Jiang, S., and V. Kuarsingh, "Framework for
              IP Version Transition Scenarios", draft-ietf-v6ops-
              v4v6tran-framework-02 (work in progress), July 2011.

   [RFC6343]  Carpenter, B., "Advisory Guidelines for 6to4 Deployment",
              RFC 6343, DOI 10.17487/RFC6343, August 2011,

Authors' Addresses

   John Jason Brzozowski
   Comcast Cable
   1701 John F. Kennedy Blvd.
   Philadelphia, PA

   Email: john_brzozowski@cable.comcast.com

   Gunter Van De Velde

   Email: gunter.van_de_velde@alcatel-lucent.com

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