V6OPS Working Group C. Byrne Internet-Draft T-Mobile USA Intended Status: Informational D. Drown Expires: August 2, 2013 January 29, 2013 Extending an IPv6 /64 Prefix from a 3GPP Mobile Interface to a LAN draft-ietf-v6ops-64share-01 Abstract This document describes three methods for extending an IPv6 /64 prefix from a User Equipment 3GPP radio interface to a 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 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 August 2, 2013. Copyright and License Notice Copyright (c) 2013 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. Byrne Expires August 2, 2013 [Page 1] V6OPS Working Group draft-ietf-v6ops-64share-01 January 29, 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. The Challenge of Providing IPv6 Addresses to a LAN via a 3GPP UE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Methods for Extending the 3GPP Interface /64 IPv6 Prefix to 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 . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Informative References . . . . . . . . . . . . . . . . . . . . 7 Byrne Expires August 2, 2013 [Page 2] V6OPS Working Group 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 prefixes to a LAN. To facilitate the use of IPv6 in a LAN prior to deployment of DHCPv6 Prefix Delegation in 3GPP networks and in User Equipment (UE), this document describes how the 3GPP UE interface assigned global /64 prefix may be extended from the 3GPP radio interface to a LAN. This is achieved by receiving the Router Advertisement (RA) [RFC4861] announced globally unique /64 IPv6 prefix from the 3GPP radio interface and then advertise the same IPv6 prefix to the LAN with RA. This document describes three methods for achieving IPv6 prefix extension from a 3GPP radio interface to a LAN including: 1) The 3GPP UE does not have a global scope IPv6 address on any interface, only link-local IPv6 addresses are present on the UE 2) The 3GPP UE only has a global scope address on the LAN interface 3) The 3GPP UE maintains the same consistent 128 bit global scope IPv6 anycast address [RFC4291] on the 3GPP radio interface and the LAN interface. The LAN interface is configured as a /64 and the 3GPP 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 LAN via a 3GPP UE As described in [RFC6459], 3GPP networks assign a /64 global scope prefix to each UE using RA. 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 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 LAN. The 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. Methods for Extending the 3GPP Interface /64 IPv6 Prefix to 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 Byrne Expires August 2, 2013 [Page 3] 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 reliably manipulate the /64 from the 3GPP radio interface without negatively impacting the point-to-point 3GPP radio link interface. 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 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 3GPP UE does not assign itself any global IPv6 addresses. The UE cannot originate or terminate any global scope packets in 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 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 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:f002:1234:4567:0:9/64 assigned and active. 4. The UE copies the prefix 2001:db8:ac10:f002::/64 from the 3GPP interface to the LAN 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 LAN. The 3GPP interface and LAN interface only maintain link-local addresses while the UE uses RA to announce the /64 to the LAN. Byrne Expires August 2, 2013 [Page 4] 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 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 Byrne Expires August 2, 2013 [Page 5] 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. 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 an anycast /64 from the 3GPP interface to the LAN interface and begins announcing the prefix 2001:db8:ac10:f002::/64 via RA to the LAN. The 3GPP interface maintains the same IPv6 anycast address with a /128. For this example, the LAN has 2001:db8:ac10:f002:1234:4567:0:9/64 and the 3GPP 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 address is defended using DAD. The 3GPP radio Byrne Expires August 2, 2013 [Page 6] V6OPS Working Group draft-ietf-v6ops-64share-01 January 29, 2013 interface only has a /128 and no other systems on the 3GPP radio point-to-point link may use the global /64. 4. Security Considerations Security considerations identified in [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.ietf-v6ops-rfc3316bis] Korhonen, J., Arkko, J., Savolainen, T., and S. Krishnan, "IPv6 for 3GPP Cellular Hosts", draft- ietf-v6ops-rfc3316bis (work in progress), 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. Byrne Expires August 2, 2013 [Page 7] 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 Cameron Byrne T-Mobile USA Bellevue, Washington, USA EMail: Cameron.Byrne@T-Mobile.com Dan Drown Email: Dan@Drown.org Byrne Expires August 2, 2013 [Page 8]