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Versions: 00 01 02 03 draft-ietf-v6ops-64share

V6OPS Working Group                                             C. Byrne
Internet-Draft                                              T-Mobile USA
Intended Status: Informational                                  D. Drown
Expires: April 12, 2013                                  October 9, 2012


           Sharing /64 3GPP Mobile Interface Subnet to a LAN
                      draft-byrne-v6ops-64share-03


Abstract

   This document describes a known and implemented method of sharing a
   /64 IPv6 subnet from a User Equipment 3GPP radio interface to a
   tethered LAN.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   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 12, 2013.

Copyright and License Notice

   Copyright (c) 2012 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
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   described in the Simplified BSD License.




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Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. The Challenge of Providing IPv6 Addresses to a 3GPP Tethered
      LAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3. Method for Sharing the 3GPP Interface /64 to the Tethered LAN .  3
   4. Security Considerations . . . . . . . . . . . . . . . . . . . .  4
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  4
   6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . .  4
   7. Informative References  . . . . . . . . . . . . . . . . . . . .  4









































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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 [RFC3633] for
   delegating IPv6 addresses to a tethered LAN.  To facilitate the use
   of IPv6 in a tethered LAN prior to deployment of DHCPv6 in a 3GPP
   network, this document describes how the 3GPP User Equipment (UE)
   interface assigned /64 subnet may be shared from the 3GPP interface
   to a tethered LAN.  This is achieved by specifying the UE 3GPP
   interface as an IPv6 /128 subnet taken from the 3GPP interface's
   network assigned /64 subnet.  Then, assign the same address to the
   tethered LAN interface with the full /64 subnet.  The /64 tethered
   LAN subnet will then be advertised to the tethered LAN via Router
   Advertisements (RA) [RFC4861].

   The end result is that all UE interfaces have link-local IPv6
   addresses, the UE's 3GPP interface has a /128 address from the 3GPP
   network assigned /64, and the same address that is assigned to the
   3GPP interface is assigned to the tethered LAN interface with 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.


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

   As described in [RFC6459], 3GPP networks assign a /64 subnet to the
   UE with RA.  IPv6 prefix delegation is a 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 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 assign subnets to tethered LANs.  The
   method described in this document should only be applied when
   deploying DHCPv6 is not achievable in the 3GPP network.

3. Method for Sharing the 3GPP Interface /64 to the Tethered LAN

   As [RFC6459] describes, the 3GPP network assigned /64 is completely
   dedicated to the UE and the gateway does not consume any of the /64
   addresses.  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 the 3GPP network assigned /64 to assign
   itself a /128 subnet address to the 3GPP radio interface for
   consistent network reachability and the same address with a /64



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   subnet to the tethered LAN interface.  The tethered LAN interface may
   then advertise the /64 subnet to the LAN with RA.

   For example, if the 3GPP network assigns to the UE via RA the subnet
   2001:db8:ac10:f002::/64, the UE may choose the address for its 3GPP
   interface to be 2001:db8:ac10:f002:1234:4567::9/128.  When tethering
   a LAN, the UE may then assign that same address to its LAN interface
   with a /64 subnet, such as 2001:db8:ac10:f002:1234:4567::9/64.  The
   UE may then advertise the 2001:db8:ac10:f002::/64 subnet to the
   tethered LAN using RA.  Since the UE only consumes one address from
   the 3GPP network assigned /64 for both the 3GPP interface and the LAN
   interface, there is no address conflict potential.  On the LAN, the
   /64 subnet is announced via RA and the interface address is defended
   with Duplicate Address Detection (DAD) [RFC4862].  Since the 3GPP
   interface is a point-to-point link and the gateway does not consume
   an address from the network assigned /64, there is no chance of
   address conflict on the 3GPP interface for the /64.

   The UE should be compliant with the relevant requirements in [I-
   D.binet-v6ops-cellular-host-reqs-rfc3316update].

4. Security Considerations

   Security considerations identified in [I-D.binet-v6ops-cellular-host-
   reqs-rfc3316update] are to be taken into account.

5. IANA Considerations

   This document does not require any action from IANA.

6. Acknowledgments

   Many thanks for review and discussion from Masanobu Kawashima, Teemu
   Savolainen, Mikael Abrahamsson, Eric Vyncke, and Ales Vizdal.

7. Informative References

   [I-D.binet-v6ops-cellular-host-reqs-rfc3316update] Binet, D.,
              Boucadair, M., A. Vizdal, C. Byrne, "Internet Protocol
              Version 6 (IPv6) for Cellular Hosts", draft-binet-v6ops-
              cellular-host-reqs-rfc3316update-03 (work in progress),
              October 2012.

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

   [RFC4389]  Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery



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              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.

   [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

   Cameron Byrne
   T-Mobile USA
   Bellevue, Washington, USA

   EMail: Cameron.Byrne@T-Mobile.com

   Dan Drown
   Email: Dan@Drown.org



























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