Internet DRAFT - draft-byrne-v6ops-64share
draft-byrne-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
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This Internet-Draft will expire on April 12, 2013.
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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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