V6OPS Working Group                                             C. Byrne
Internet-Draft                                              T-Mobile USA
Intended Status: Informational                                  D. Drown
Expires: June 17, August 2, 2013                                 December 14, 2012

           Sharing                                 January 29, 2013

  Extending an IPv6 /64 Prefix from a 3GPP Mobile Interface Subnet to a LAN
                      draft-ietf-v6ops-64share-00
                      draft-ietf-v6ops-64share-01

Abstract

   This document describes a known and implemented method of sharing a
   /64 three methods for extending an IPv6 /64
   prefix from a User Equipment 3GPP radio interface to a
   tethered LAN.

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   This Internet-Draft will expire on June 17, August 2, 2013.

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   Copyright (c) 2012 2013 IETF Trust and the persons identified as the
   document authors. All rights reserved.

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V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012   draft-ietf-v6ops-64share-01       January 29, 2013

Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. The Challenge of Providing IPv6 Addresses to a 3GPP Tethered LAN via a 3GPP
      UE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3. Method Methods for Sharing Extending the 3GPP Interface /64 IPv6 Prefix to the Tethered a
      LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     3.0 General Behavior for All Scenarios . . . . . . . . . . . . .  3
     3.1 Scenario 1: No Global Address on the UE  . . . . . . . . . .  4
     3.2 Scenario 2: Global Address Only Assigned to LAN  . . . . . .  5
     3.3 Scenario 3: A Single Global Address Assigned to 3GPP Radio
         and LAN Interface  . . . . . . . . . . . . . . . . . . . . .  6
   4. Security Considerations . . . . . . . . . . . . . . . . . . . .  5  7
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5  7
   6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . .  5  7
   7. Informative References  . . . . . . . . . . . . . . . . . . . .  5  7

V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012   draft-ietf-v6ops-64share-01       January 29, 2013

1. Introduction

   3GPP mobile cellular networks such as GSM, UMTS, and LTE have
   architectural support for IPv6 [RFC6459], but only 3GPP Release-10
   and onwards of the 3GPP specification supports DHCPv6 Prefix
   Delegation [RFC3633] for delegating IPv6 addresses prefixes to a tethered LAN.  To
   facilitate the use of IPv6 in a tethered LAN prior to deployment of DHCPv6
   Prefix Delegation in a 3GPP
   network networks and in User Equipment (UE), this
   document describes how the 3GPP UE interface assigned global /64 subnet
   prefix may be shared extended from the 3GPP radio interface to a tethered LAN.  This
   is achieved by specifying receiving the UE
   3GPP interface as an Router Advertisement (RA) [RFC4861]
   announced globally unique /64 IPv6 /128 subnet taken prefix from the 3GPP interface's
   network assigned /64 subnet.  Then, assign radio
   interface and then advertise the same address IPv6 prefix to the
   tethered LAN interface with the full /64 subnet.  The /64 tethered
   LAN subnet will then be advertised RA.

   This document describes three methods for achieving IPv6 prefix
   extension from a 3GPP radio interface to the tethered a LAN via Router
   Advertisements (RA) [RFC4861]. including: 1) The end result is that all 3GPP
   UE interfaces does not have a global scope IPv6 address on any interface, only
   link-local IPv6
   addresses, addresses are present on the UE's UE 2) The 3GPP interface UE only
   has a /128 global scope address from on the LAN interface 3) The 3GPP
   network assigned /64, and UE
   maintains the same consistent 128 bit global scope IPv6 anycast
   address that is assigned to [RFC4291] on the 3GPP radio interface is assigned to and the tethered LAN interface.
   The LAN interface with is configured as a /64
   subnet and advertised to the LAN via RA.  This approach only impacts
   the UE configuration and does not require any changes to the 3GPP
   network. radio interface
   is configured as a /128.

   Section 3 describes the characteristics of each of the three
   approaches.

2. The Challenge of Providing IPv6 Addresses to a 3GPP Tethered LAN via a 3GPP UE

   As described in [RFC6459], 3GPP networks assign a /64 subnet global scope
   prefix to each UE with using RA.  IPv6 prefix delegation  DHCPv6 Prefix Delegation is an optional
   part of 3GPP Release-10 and is not covered by any earlier releases.
   Neighbor Discovery Proxy (ND Proxy) [RFC4389] functionality has been
   suggested as an option for sharing extending the assigned /64 from the 3GPP
   interface to the LAN, but ND Proxy is an experimental protocol and
   has some limitations with loop-avoidance.

   DHCPv6 is the best way to delegate a prefix to a tethered LAN.  The
   method methods
   described in this document should only be applied when deploying
   DHCPv6 Prefix Delegation is not achievable in the 3GPP network and
   the UE.

3. Method Methods for Sharing Extending the 3GPP Interface /64 IPv6 Prefix to the Tethered a LAN

3.0 General Behavior for All Scenarios

   As [RFC6459] describes, the 3GPP network assigned /64 is completely
   dedicated to the UE and the gateway does not consume any of the /64

V6OPS Working Group   draft-ietf-v6ops-64share-01       January 29, 2013

   addresses.  The gateway routes the entire /64 to the UE and does not
   perform ND or Network Unreachability Detection (NUD) [RFC4861].
   Communication between the UE and the gateway is only done using link-
   local addresses and the link is point-to-point.  This allows for the
   UE to use reliably manipulate the 3GPP network assigned /64 to assign itself a /128

V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012

   address to from the 3GPP radio interface for consistent network connection
   formation and the same address with a /64 to
   without negatively impacting the tethered LAN point-to-point 3GPP radio link
   interface.  The tethered LAN interface may then advertise the /64 to
   the LAN with RA.  The LAN interface RA configuration must be tightly
   coupled with the 3GPP interface state.  If the 3GPP interface goes
   down or changes address, that state should be reflected in the LAN
   IPv6 configuration.  Just as in a standard IPv6 router, the packet
   TTL will be decremented when passing packets between interfaces. interfaces
   across the UE.

3.1 Scenario 1: No Global Address on the UE

   In this case, the UE receives the /64 from the 3GPP network via RA
   and simply configures Neighbor Discovery Protocol (NDP) [RFC4861] on
   the LAN interface to announce the /64 via RA.  The procedure may also be described 3GPP UE does not
   assign itself any global IPv6 addresses.  The UE cannot originate or
   terminate any global scope packets in terms of this case since it does not
   have a global scope IPv6 address to source or receive packets. The
   LAN attached devices have complete access to the /64, but the 3GPP UE
   only has link-local addresses.

   This method is appropriate for a use-case where the UE is effectively
   an IPv6 router that does not require any global connectivity.  No
   global connectivity will prevent proper Path MTU Discovery [RFC1981]

   Below is the following usage
   example: general procedure for this scenario:

   1.  The user activates tethering on the wireless router functionality for a LAN of on the UE.

   2.  The UE checks to make sure the 3GPP interfaces interface is active and has
       an IPv6 address.  If the interface does not have an IPv6 address,
       an attempt will be made to acquire one, or else the procedure
       will terminate.

   3.  In this example, the UE finds the 3GPP interface has the IPv6
       address 2001:db8:ac10:f002:1234:4567:0:9/128 2001:db8:ac10:f002:1234:4567:0:9/64 assigned and active.

   4.  The UE copies the address 2001:db8:ac10:f002:1234:4567:0:9 with a
       64 bit mask prefix 2001:db8:ac10:f002::/64 from the 3GPP interfaces
       interface to the wireless LAN
       interfaces interface, removes the global IPv6 address
       configuration from the 3GPP radio interface, and begins
       announcing the global prefix 2001:db8:ac10:f002::/64 via RA to
       the wireless LAN.

   5.  The gateway in the 3GPP network routes all packets for
       2001:db8:ac10:f002::/64 to interface and LAN interface only maintain
       link-local addresses while the UE using uses RA to announce the link-local address as /64 to
       the next hop.  The gateway does not perform Neighbor Discover or
       Network Unreachability LAN.

V6OPS Working Group   draft-ietf-v6ops-64share-01       January 29, 2013

   5.  Since the UE and gateway do not assign any of the addresses from
       the /64, there is no chance of an address conflict on the 3GPP
       radio interface.  On the LAN interface, there is no chance of an
       address conflict since the hosts on the LAN will use Duplicate
       Address Detection (DAD) [RFC4862].

3.2 Scenario 2: Global Address Only Assigned to LAN

   For this case, the UE receives the RA from the 3GPP network but does
   not use a global address on the 3GPP wireless link segment
       towards interface.  The 3GPP RA /64
   prefix information is used to configure NDP on the LAN and assigns
   itself an address on the LAN link.  The LAN interface use RA to
   announces the prefix to the LAN.  The UE LAN interface defends its
   LAN IPv6 address with DAD.

   This method allows the UE to originate and terminate IPv6
   communications as a host while acting as an IPv6 router.  The
   movement of the IPv6 prefix from the 3GPP radio interface to the LAN
   interface may result in long-lived data connections being terminated
   during the transition from a host-only mode to router-and-host mode.
   This method is appropriate if the UE or software on the UE cannot
   support multiple interfaces with the same anycast IPv6 address and
   the UE requires global connectivity while acting as a router.

   Below is the general procedure for this scenario:

   1.  The user activates router functionality for a LAN on the UE.

   2.  The UE checks to make sure the 3GPP interfaces is active and has
       an IPv6 address.  If the interface does not have an IPv6 address,
       an attempt will be made to acquire one, or else the procedure
       will terminate.

   3.  In this example, the UE finds the 3GPP interface has the IPv6
       address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active.

   4.  The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as a
       /64 from the 3GPP interfaces to the LAN interface and begins
       announcing the prefix 2001:db8:ac10:f002::/64 via RA to the LAN.
       For this example, the LAN has 2001:db8:ac10:f002:1234:4567:0:9/64
       and the 3GPP radio only has a link-local address.

   5.  The UE directly processes all packets destine to itself at
       2001:db8:ac10:f002:1234:4567:0:9.

   6.  The UE, acting as a router running NDP on the LAN, will route

V6OPS Working Group   draft-ietf-v6ops-64share-01       January 29, 2013

       packet to and from the LAN.  IPv6 packets passing between
       interfaces will have the TTL decremented.

   7.  On the LAN interface, there is no chance of address conflict
       since the address is defended using DAD.  The 3GPP radio
       interface only has link-local addresses.

3.3 Scenario 3: A Single Global Address Assigned to 3GPP Radio and LAN
   Interface

   In this method, the UE assigns itself one address from the 3GPP
   network RA announced /64.  This one address is configured as anycast
   [RFC4291] on both the 3GPP radio interface as a /128 and on the LAN
   interface as a /64.  This allows the UE to maintain long lived data
   connections since the 3GPP radio interface address does not change
   when the router function is activated.  This method may cause
   complications for certain software that may not support multiple
   interfaces with the same anycast IPv6 address.  This method also
   creates complications for ensuring uniqueness for Privacy Extensions
   [RFC4941].  Privacy Extensions should be disabled on the 3GPP radio
   interface while this method is enabled.

   Below is the general procedure for this scenario:

   1.  The user activates router functionality for a LAN on the UE.

   6.

   2.  The UE directly processes all packets destine checks to itself at
       2001:db8:ac10:f002:1234:4567:0:9.

   7.  The UE, acting as a router running NDP on make sure the LAN, will route
       packet to 3GPP interfaces is active and from has
       an IPv6 address.  If the LAN. interface does not have an IPv6 packets passing between
       interfaces address,
       an attempt will have be made to acquire one, or else the TTL decremented.

   8.  If procedure
       will terminate.

   3.  In this example, the UE finds the 3GPP interface state changes, has the LAN will immediately
       update IPv6
       address 2001:db8:ac10:f002:1234:4567:0:9 assigned and active.

   4.  The UE moves the address 2001:db8:ac10:f002:1234:4567:0:9 as an
       anycast /64 from the 3GPP interface to reflect the change LAN interface and ensure that
       begins announcing the LAN IPv6 prefix
       remains a valid extension of 2001:db8:ac10:f002::/64 via RA to
       the LAN.  The 3GPP network.

   9.  Since interface maintains the same IPv6 anycast
       address 2001:db8:ac10:f002:1234:4567:0:9/128 is the
       only instance of with a /128.  For this example, the assigned /64 on LAN has
       2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP interface, there is
       no chance of an address conflict on that interface. radio interface
       has 2001:db8:ac10:f002:1234:4567:0:9/128.

   5.  The UE directly processes all packets destine to itself at
       2001:db8:ac10:f002:1234:4567:0:9.

   6.  On the LAN interface, there is no chance of address conflict
       since the

V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012 address is defended using Duplicate Address Detection (DAD). DAD.  The UE should be compliant with 3GPP radio

V6OPS Working Group   draft-ietf-v6ops-64share-01       January 29, 2013

       interface only has a /128 and no other systems on the relevant requirements in [I-
       D.draft-binet-v6ops-cellular-host-requirement]. 3GPP radio
       point-to-point link may use the global /64.

4. Security Considerations

   Security considerations identified in [I-D.draft-binet-v6ops-
   cellular-host-requirement] [I-D.draft-ietf-v6ops-
   rfc3316bis] are to be taken into account.  Since Scenario 3 does not
   allow for Privacy Extension to run the 3GPP interface, UEs that
   require this functionality must find an alternative method.

5. IANA Considerations

   This document does not require any action from IANA.

6. Acknowledgments

   Many thanks for review and discussion from Mark Smith, Dmitry Anipko,
   Masanobu Kawashima, Teemu Savolainen, Mikael Abrahamsson, Eric
   Vyncke, Alexandru Petrescu, Jouni Korhonen, Julien Laganier, and Ales
   Vizdal.

7. Informative References

   [I-D.draft-binet-v6ops-cellular-host-requirement] Binet, D.,
              Boucadair, M., A. Vizdal, C. Byrne, G. Chen, "Internet
              Protocol Version 6 (IPv6)

   [I-D.ietf-v6ops-rfc3316bis] Korhonen, J., Arkko, J., Savolainen, T.,
              and S. Krishnan, "IPv6 for 3GPP Cellular Hosts", draft-
              draft-binet-v6ops-cellular-host-requirement
              ietf-v6ops-rfc3316bis (work in progress), October November 2012.

   [RFC1981]  McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
              for IP version 6", RFC 1981, August 1996.

   [RFC3633]  Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
              Host Configuration Protocol (DHCP) version 6", RFC 3633,
              December 2003.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4389]  Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery
              Proxies (ND Proxy)", RFC 4389, April 2006.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              September 2007.

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

V6OPS Working Group   draft-ietf-v6ops-64share-01       January 29, 2013

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

   [RFC6459]  Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
              T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, January 2012.

   Authors' Addresses

V6OPS Working Group   draft-ietf-v6ops-64share-00      December 14, 2012

   Cameron Byrne
   T-Mobile USA
   Bellevue, Washington, USA

   EMail: Cameron.Byrne@T-Mobile.com

   Dan Drown
   Email: Dan@Drown.org