Network Working Group T. Melia Internet-Draft Y. El Mghazli Intended status: Experimental Alcatel-Lucent Expires: August 24, 2009 February 20, 2009 DHCP option to transport Protocol Configuration Options draft-melia-dhc-pco-00 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 August 24, 2009. Copyright Notice Copyright (c) 2009 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. Abstract This document specifies how to convey Protocol Configuration Options (PCO) [24008] from/to the access network to/from the Mobile Node Melia & El Mghazli Expires August 24, 2009 [Page 1] Internet-Draft PCO over DHCP February 2009 (MN). There are scenarios defined in 3GPP (TS 23.402) and WiMax forum NWG where the mobile node accessing the non-3GPP trusted system needs to convey such information to the Mobility Access Gateway (MAG) functionality implemented in the serving gateway (S-GW). The MAG requires the PCO field to send such information to the Local Mobility Agent (LMA) (implemented in the PDN gateway, P-GW) in a Proxy Binding Update (PBU) message. PCO options are exchanged between the MN and the LMA to transport information such as P-CSCF address, DNS server address. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. DHCPv4 option for PCO . . . . . . . . . . . . . . . . . . . . . 3 3. DHCPv6 option for PCO . . . . . . . . . . . . . . . . . . . . . 4 4. Option usage . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Usage of DHCPv4 Options for PCO transport . . . . . . . . . 5 4.1.1. Mobile Node behavior . . . . . . . . . . . . . . . . . 5 4.1.2. DHCP server behavior . . . . . . . . . . . . . . . . . 5 4.2. Usage of DHCPv6 Options for PCO transport . . . . . . . . . 5 4.2.1. Mobile node behavior . . . . . . . . . . . . . . . . . 5 4.2.2. DHCP server behavior . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Melia & El Mghazli Expires August 24, 2009 [Page 2] Internet-Draft PCO over DHCP February 2009 1. Introduction The 3GPP standardization body is currently defining the Evolved Packet Core (EPC) architecture. The system integrates several access technologies classified as 3GPP access, non-3GPP trusted access system (e.g. WiMax) or non-3GPP non trusted access system (e.g. WIFI). Among others, two components of the EPC are relevant for this document, namely the S-GW and the P-GW implementing the MAG and the LMA function respectively. When the MN performs a network attachment it sends several info to allow the MAG functionality to send a Proxy Binding Update to the LMA for connectivity setup and IP address configuration. The PBU optionally contains, as specified in 3GPP 29275, the Protocol Configuration Options. The LMA receiving the PBU message replies with a PBA message containing the requested information. If the interface between the MAG and LMA for non-3GPP trusted access (S2a) is implemented via Proxy Mobile IPv6 then the MN exchanges DHCPv4, DHCPv6 or Neighbor Discovery messages with the S-GW to trigger the MAG functionality to send PBU messages. This document specifies how to encode PCO options into DHCPv4 and DHCPv6 messages when the host accesses the EPC through a non-3GPP access system i.e. WiMax interface. 2. DHCPv4 option for PCO This option enables the host using an IPv4 stack to convey PCO data to the access network. The host includes this option in the DHCP Request message sent to the access gateway/NAS (Network Access Server) which acts as the DHCP server or relay. Melia & El Mghazli Expires August 24, 2009 [Page 3] Internet-Draft PCO over DHCP February 2009 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Code | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DATA..... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Option Code OPTION-IPv4-PCO (To Be Assigned) - 1 byte. Length An 8-bit field indicating the length of the option excluding the 'Option Code' and the 'Length' fields. DATA PCO data that is carried in this message. Figure 1 3. DHCPv6 option for PCO This option enables the host using an IPv6 stack to convey PCO data to the access network. The host includes this option in the DHCP Request message sent to the access gateway/NAS (Network Access Server) which acts as the DHCP server or relay. 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Option Code | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DATA....... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Option Code OPTION-IPv6-PCO (To Be Assigned) - 1 byte. Length An 8-bit field indicating the length of the option excluding the 'Option Code' and the 'Length' fields. DATA PCO data that is carried in this message. Melia & El Mghazli Expires August 24, 2009 [Page 4] Internet-Draft PCO over DHCP February 2009 4. Option usage 4.1. Usage of DHCPv4 Options for PCO transport The requesting and sending of the proposed DHCP options follow the rules specified for DHCP options in [RFC2131]. 4.1.1. Mobile Node behavior The mobile node may include PCO data in the DHCPREQUEST message. The MN may receive unsolicited PCO data in the DHCPACK message. 4.1.2. DHCP server behavior When the DHCP server receives the DHCPREQUEST message with a PCO Option the DHCP server MUST always construct the response according to the requested option. The DHCP might optionally decide to send PCO data to the mobile node in the DHCPACK message. 4.2. Usage of DHCPv6 Options for PCO transport The requesting and sending of the proposed DHCP options follow the rules specified for DHCP options in [RFC3315]. 4.2.1. Mobile node behavior The mobile node may include PCO data in the REQUEST message. The MN may receive unsolicited PCO data in the REPLY message. 4.2.2. DHCP server behavior When the DHCP server receives the REQUEST message with a PCO Option the DHCP server MUST always construct the response according to the requested option. The DHCP might optionally decide to send unsolicited PCO data to the mobile node in the REPLY message. 5. IANA Considerations This document defines one new DHCPv4 option: PCO Option for DHCPv4 (OPTION-IPv4-PCO) To Be Assigned This document defines one new DHCPv6 option: Melia & El Mghazli Expires August 24, 2009 [Page 5] Internet-Draft PCO over DHCP February 2009 PCO Option for DHCPv6 (OPTION-IPv6-PCO) To Be Assigned 6. Security Considerations The security considerations in [RFC2131] apply. If an adversary manages to modify the response from a DHCP server or insert its own response, an MN could be led to obtain rogue PCO information. It is recommended to use either DHCP authentication option described in [RFC3118] where available, or rely upon link layer security. This will also protect the denial of service attacks to DHCP servers. [RFC3118] provides mechanisms for both entity authentication and message authentication. 7. Acknowledgements 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages", RFC 3118, June 2001. [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. [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. 8.2. Informative References [24008] "3GPP 24.008 -- Mobile radio interface Layer 3 specification; Core network protocols; Stage 3", December 2008, <3GPP 24008>. Melia & El Mghazli Expires August 24, 2009 [Page 6] Internet-Draft PCO over DHCP February 2009 Authors' Addresses Telemaco Melia Alcatel-Lucent Route de Villejust Nozay 91620 France Email: telemaco.melia@alcatel-lucent.com Yacine El Mghazli Alcatel-Lucent Route de Villejust Nozay 91620 France Email: yacine.el_mghazli@alcatel-lucent.com Melia & El Mghazli Expires August 24, 2009 [Page 7]