Network Working Group B. Sarikaya Internet-Draft F. Xia Expires: September 11, 2008 Huawei USA March 10, 2008 Relay Based DHCPv6 Prefix Delegation for NEMO draft-sarikaya-mext-relay-dhcpv6pd-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 11, 2008. Sarikaya & Xia Expires September 11, 2008 [Page 1] Internet-Draft Prefix Delegation Support March 2008 Abstract This document defines DHCP Relay Agent based prefix delegation support for a mobile network. Mobile Router uses DHCPv6 prefix delegation to dynamically request its Mobile Network Prefixes from DHCP Server. DHCP Relay Agent located in MR enables MR to run the prefix delegation application with the same DHCP Server even after MR moves to a different local network. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Nemo Prefix Delegation Architecture . . . . . . . . . . . . . . 3 3.1. Message Encapsulation . . . . . . . . . . . . . . . . . . . 4 4. Nemo Prefix Delegation Protocol . . . . . . . . . . . . . . . . 5 5. Nemo Prefix Delegation Using AAA . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References . . . . . . . . . . . . . . . . . . . 7 9.2. Informative references . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Sarikaya & Xia Expires September 11, 2008 [Page 2] Internet-Draft Prefix Delegation Support March 2008 1. Introduction Nemo Basic Support Protocol requires that IPv6 prefixes called Home Network Prefix(es) delegated to a Mobile Router and advertized in the Mobile Network [RFC3963]. However the protocol does not provide any means of provisioning MNPs dynamically. Prefix delegation is widely discussed in IETF 16NG, MEXT, and NETLMM Working Groups. Corresponding solutions are also introduced. NEMO deals with synchronization of Mobile Network prefixes between a Mobile Router and a Home Agent, while the method is agnostic to the way that a Home Agent gets prefixes from back end servers. [RFC3633] defines Prefix Delegation options and procedures to provide a mechanism for automated delegation of IPv6 prefixes using the Dynamic Host Configuration Protocol (DHCP). A mechanism to manage prefixes dynamically by an AAA server can also be defined. [I-D.ietf-nemo-prefix-delegation] defines prefix request option for the binding update and prefix confirm for the binding acknowledgment messages of the Nemo Basic Support Protocol. Using these messages MR can request a prefix from HA with BU and HA can give prefixes to MR with BA. However, how HA gets prefixes is not defined. 2. Terminology This document uses the terminology defined in [RFC3315], [RFC3633] and [RFC4885]. 3. Nemo Prefix Delegation Architecture We assume that the prefixes are managed by an authority that owns the Home Network and subnets it into MNPs that it assigns to the MRs. An MNP can be preassigned to the associated MR (e.g. manually or automatically with a provisioning system). For dynamic prefix management there are two architectures. In HA- based architecture, HA is the requesting router and the DHCP Server is the delegating router. HA needs to be collocated with a DHCP Client to solicit/request prefixes from the DHCP Server. HA is configured with the address of the delegating router which is a backend DHCP Server. MR needs to request dynamically the prefixes from HA using BU/BA exchange defined in [I-D.ietf-nemo-prefix-delegation]. In MR-based architecture, MR is the requesting router and the Sarikaya & Xia Expires September 11, 2008 [Page 3] Internet-Draft Prefix Delegation Support March 2008 delegating router is a DHCP Server located in the home network. In this document, we elaborate on the signaling required for this architecture. [I-D.ietf-nemo-dhcpv6-pd] uses the MR-based architecture but it does not incorporate a DHCP Relay at the MR. [I-D.ietf-nemo-dhcpv6-pd] assumes a DHCP Client at the MR which requires an onlink DHCP Relay or Server [I-D.dupont-mext-dhcrelay]. However when MR moves it is not possible to satisfy this requirement. Figure 1 shows the MR-based architecture. +-----+ HA-MR +-----+ +--------+ -------------- | MR |-- tunnel --| HA |--------+ Edge | / \ +-----+ +-----+ | Router +-- | Backend | |Relay| |Relay| +--------+ \ / +-----+ +-----+ ------------- |DHCP |<--- | |Client| | +------+ +------+ -----DHCP Prefix Delegation------------>|DHCP | |Server| +------+ Figure 1: MR-based Architecture MR is co-located with DHCP Relay Agent. In order to run DHCP Prefix Delegation we also need a local DHCP Client at the MR. DHCP Client will initiate or respond to DHCP messages required for the MR to be the requesting router. DHCP Relay co-located with MR will relay the client's messages back and forth. DHCP Relay co-located at HA will be configured with the backend DHCP Server's address. The backend DHCP Server will be the delegating router. 3.1. Message Encapsulation DHCP Relay co-located at the MR encapsulates DHCP Client's messages in the form of DHCPv6 datagrams. These datagrams need to be sent over HA-MR tunnel when MR is not on the home link. This requires that each such message is piggybacked in a Binding Update message sent from MR to HA. IPv6 extension headers for each message sent by the DHCP Relay co- located at MR MUST contain the mobility header as described in Section 6.1 of [RFC3775]. MH type MUST be set to 5 for Binding Sarikaya & Xia Expires September 11, 2008 [Page 4] Internet-Draft Prefix Delegation Support March 2008 Update. The payload MUST contain the DHCP message being sent. DHCP Relay co-located at the HA encapsulates DHCP Prefix Delegation messages to be sent in the form of DHCPv6 datagrams. These datagrams need to be sent over HA-MR tunnel to the MR. This requires that each such message is piggybacked in a Binding Acknowledgement message sent from HA to MR. IPv6 extension header for each message sent by the DHCP Relay co- located at HA towards MR MUST contain the mobility header as described in Section 6.1 of [RFC3775]. MH type MUST be set to 6 for Binding Acknowledgement. The payload MUST contain the DHCP message being sent. 4. Nemo Prefix Delegation Protocol Figure 2 shows the process that a Mobile Router as the requesting router requests prefixes from a DHCP Server as the delegating router using DHCPv6 [RFC3315] and DHCPv6 Prefix delegation [RFC3633]. MR HA DHCP Server | | -->| |1. Trigger to DHCP Client |2 Relay-forward/Solicit|2. DHCP Relay-Forward/Solicit |---------------------> | |3 Relay-reply/Advertise|3. DHCP Relay-reply/ Advertise |<--------------------- | |4 Relay-forward/Request|4. DHCP Relay-Forward/Request (MNP) |---------------------> | |5 Relay-reply/Reply |5. DHCP Relay-reply/Reply (MNP) |<--------------------- | Figure 2: Prefix Delegation in NEMO 1. DHCP Client co-located with MR needs to be triggered to start requesting prefixes using DHCPv6 Prefix Delegation. The initial trigger should be when MR boots up. The subsequent triggers are timeout based. Each prefix received has a lifetime. When the lifetime of a prefix expires, a trigger SHOULD be received at the DHCP Client. 2. DHCP Client at the MR initiates DHCP Solicit procedure to request prefixes for the MN. HA creates and transmits a Solicit message as described in sections 17.1.1, "Creation of Solicit Messages" and 17.1.2, "Transmission of Solicit Messages" of RFC 3315. MR creates an IA_PD and assigns it an IAID. MR MUST include the Sarikaya & Xia Expires September 11, 2008 [Page 5] Internet-Draft Prefix Delegation Support March 2008 IA_PD option in the Solicit message. 3. The DHCP server sends an Advertise message to MR in the same way as described in section 17.2.2, "Creation and transmission of Advertise messages" of RFC 3315. 4. MR uses the same message exchanges as described in section 18, "DHCP Client-Initiated Configuration Exchange" of RFC 3315 to obtain or update prefixes from a DHCP server. MR and the DHCP server use the IA_PD Prefix option to exchange information about prefixes in much the same way as IA Address options are used for assigned addresses. 5. MR stores the prefix information it received in the Reply message. HA SHOULD add the route to the delegated prefix(es) and advertise the prefix(es) upstream. HA SHOULD use route aggregation, i.e. advertise the /48 prefix that is the extension of the delegated /64 prefixes. In Explicit Mode of NEMO Basic Protocol, MR includes the delegated prefix(es) to the prefix list in Prefix Information Option of Binding Update message. This message triggers HA to add a route for the prefixes included. 5. Nemo Prefix Delegation Using AAA Diameter prefix delegation application is currently to be defined. Once such an application is defined, Nemo prefix delegation using this Diameter application will be included in this section. 6. Security Considerations This document does not by itself introduce any security issues. 7. IANA Considerations None. 8. Acknowledgements TBD. 9. References Sarikaya & Xia Expires September 11, 2008 [Page 6] Internet-Draft Prefix Delegation Support March 2008 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, June 1999. [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963, January 2005. [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003. [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [I-D.ietf-nemo-prefix-delegation] Kniveton, T. and P. Thubert, "Mobile Network Prefix Delegation", draft-ietf-nemo-prefix-delegation-02 (work in progress), August 2007. [I-D.dupont-mext-dhcrelay] Dupont, F. and W. Haddad, "DHCPv6 Relay Agents and NEMO", draft-dupont-mext-dhcrelay-00 (work in progress), February 2008. [I-D.ietf-nemo-dhcpv6-pd] Droms, R. and P. Thubert, "DHCPv6 Prefix Delegation for NEMO", draft-ietf-nemo-dhcpv6-pd-03 (work in progress), December 2007. 9.2. Informative references [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC4885] Ernst, T. and H-Y. Lach, "Network Mobility Support Terminology", RFC 4885, July 2007. Sarikaya & Xia Expires September 11, 2008 [Page 7] Internet-Draft Prefix Delegation Support March 2008 Authors' Addresses Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075 Phone: +1 972-509-5599 Email: sarikaya@ieee.org Frank Xia Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075 Phone: +1 972-509-5599 Email: xiayangsong@huawei.com Sarikaya & Xia Expires September 11, 2008 [Page 8] Internet-Draft Prefix Delegation Support March 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Sarikaya & Xia Expires September 11, 2008 [Page 9]