Network Working Group J. Korhonen Internet-Draft U. Nilsson Intended status: Standards Track TeliaSonera Expires: March 8, 2009 September 4, 2008 Service Selection for Mobile IPv4 draft-korhonen-mip4-service-04.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 March 8, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract In some Mobile IPv4 deployments identifying the mobile node or the mobility service subscriber is not enough to distinguish between multiple services possibly provisioned to the said mobile node and its mobility service subscription. A capability to specify different services in addition to the mobile node identity can be leveraged to provide flexibility for mobility service providers to provide multiple services within a single mobility service subscription. This document describes a Service Selection Extension for Mobile IPv4 Korhonen & Nilsson Expires March 8, 2009 [Page 1] Internet-Draft Service Selection for MIPv4 September 2008 that is intended to assist home agents to make specific service selections for the mobility service subscription during the registration procedure. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Service Selection Extension . . . . . . . . . . . . . . . . . 4 4. Processing Considerations . . . . . . . . . . . . . . . . . . 5 4.1. Mobile Node Considerations . . . . . . . . . . . . . . . . 5 4.2. Home Agent Considerations . . . . . . . . . . . . . . . . 6 4.3. Foreign Agent Considerations . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Korhonen & Nilsson Expires March 8, 2009 [Page 2] Internet-Draft Service Selection for MIPv4 September 2008 1. Introduction Mobile IPv4 [1] can identify mobile nodes in various ways, including home addresses [1] and Network Access Identifiers (NAI) [5][6]. In some Mobile IPv4 deployments identifying the mobile node or the mobility service subscriber via a Proxy Mobile IPv4 client [7] (hereafter the mobile node and the Proxy Mobile IPv4 client are used interchangeably) is not enough to distinguish between multiple services possibly provisioned to the said mobile node and its mobility service subscription. The capability to specify different services in addition to the mobile node identity can be leveraged to provide flexibility for mobility service providers to provide multiple services within the same mobility service subscription. For example: o Provide an enterprise data access for which the mobility service provider hosts connectivity and mobility services on behalf of the enterprise. o Provide access to service domains that are otherwise not accessible from public networks because of some mobility service provider's business reasons. o Provide simultaneous access to different service domains that are separated based on policies of the mobility service provider. o Enable easier policy assignment for mobility service providers based on the subscribed services. o In absence of a specifically indicated service the home agent MUST act as if the default service, plain Internet access had been requested. There is no absolute requirement that this default service be allowed to all subscribers, but it is highly RECOMMENDED in order to avoid having normal subscribers employ operator-specific configuration values in order to get basic service. This document describes a Service Selection Extension for Mobile IPv4 that is intended to assist home agents to make specific service selections for the mobility service subscription during the registration procedure. The service selection may affect home agent routing decisions, Home Address assignment policies, firewall settings, and security policies. The Service Selection extension SHOULD be used in every Registration Request that makes a new registration to the home agent. The Service Selection extension from the Registration Request MAY be echoed back in the Registration Reply. Korhonen & Nilsson Expires March 8, 2009 [Page 3] Internet-Draft Service Selection for MIPv4 September 2008 Some of the potential use-cases were listed earlier in this section. The general aim is better manageability of services and service provisioning from both operators and service providers point of view. However, it should be understood that there are potential deployment possibilities where selecting a certain service may restricts simultaneous access to other services from an user point of view. For example, services may be located in different administrative domains or external customer networks that practice excessive filtering of inbound and outbound traffic. 2. Requirements 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 [2]. 3. Service Selection Extension At most one Service Selection extension MAY be included in any Mobile IPv4 Registration Request message. It SHOULD be included at least in the Registration Request message that is sent for the initial binding registration when the mobile node and the home agent do not have an existing binding. The Service Selection extension MUST be placed in the Registration Request message as follows: o When present the extension MUST appear after the MN-NAI extension, if the MN-NAI is also present in the message o If the extension was added by the mobile node to a Registration Request it MUST appear prior any authentication-enabling extensions [1][8] o In the event the foreign agent adds the Service Selection extension to a Registration Request, the extension MUST appear prior to any Foreign-Home authentication-enabling extensions [1] The Home Agent MAY echo the received Service Selection extension option back in a Mobile IPv4 Registration Reply message. The echoed Service Selection extension MUST be an unchanged copy of the Service Selection extension received in the corresponding Registration Request message. The Service Selection extension MUST be placed in the Registration Reply message as follows: o If the extension was originally added by the mobile node to a Registration Request it MUST appear in the Registration Reply prior any authentication-enabling extensions [1][8] Korhonen & Nilsson Expires March 8, 2009 [Page 4] Internet-Draft Service Selection for MIPv4 September 2008 o If the foreign agent added the Service Selection extension to a Registration Request, the extension MUST appear in the Registration Reply prior to any Foreign-Home authentication- enabling extensions [1] The Service Selection extension has the following format: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = TBD | Length | Identifier... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Service Selection Extension o Type: 8-bit identifier set to TBD (to be defined by IANA) of the type of this skippable extension. o Length: 8-bit unsigned integer, representing the length of the Service Selection Extension in octets, excluding the Type and Length fields. A value of zero (0) is not allowed. o Identifier: A variable-length encoded service identifier string used to identify the requested service. The identifier string length is between 1 and 255 octets. This specification allows international identifier strings that are based on the use of Unicode characters, encoded as UTF-8 [3], and formatted using Normalization Form KC (NFKC) as specified in [4]. 'ims', 'voip' and 'voip.companyxyz.example.com' are valid examples of Service Selection extension Identifiers. At minimum the Identifier MUST be unique among the home agents the mobile node is authorized to register to. 4. Processing Considerations 4.1. Mobile Node Considerations A mobile node or its proxy representative MAY include the Service Selection extension into any Registration Request message. The Service Selection extension can be used with any mobile node identification method. The extension is used to identify the service to be associated with the mobility session and SHOULD only be included into the initial Registration Request message sent to a home agent. If the mobile node wishes to change the selected service, it is RECOMMENDED that the mobile node de-register the existing binding Korhonen & Nilsson Expires March 8, 2009 [Page 5] Internet-Draft Service Selection for MIPv4 September 2008 with the home agent before proceeding with a binding registration for a different service. The provisioning of the service identifiers to the mobile node or its proxy representative is out of scope of this specification. If the mobile node receives a Registration Reply message with a Code set to SERVICE_AUTHORIZATION_FAILED and the mobile node has an existing binding with the Home Address used in the failed Registration Request message, the mobile node MUST delete the existing binding. If there is no existing binding the mobile node proceeds as with any failed initial registration. 4.2. Home Agent Considerations Upon receiving the Service Selection extension the home agent authenticates and authorizes the mobile node. If the home agent supports the Service Selection it MUST also verify that the mobile node is authorized to the service identified by the Service Selection extension. The services the mobile node is authorized to SHOULD be part of the general mobile node subscription data. If the mobile node is not authorized to the service the home agent MUST deny the registration and send a Registration Reply with a Code SERVICE_AUTHORIZATION_FAILED (error code TBD). The Service Selection extension is used to assist the mobile node authorization phase and identifies a specific service that is to be authorized. The Service Selection extension MAY also affect the Home Address allocation when for example used with the MN-NAI extension. For example, for the same NAI there MAY be different Home Addresses depending on the identified service. Furthermore, the Service Selection extension MAY also affect the routing of the outbound IP packets in the home agent depending on the selected service. The home agent MAY also apply different policy or quality of service treatment to traffic flows based on the selected service. If the newly arrived Registration Request message with a Service Selection extension indicates a change in the selected service, then the home agent MUST re-authorize the mobile node. Depending on the home agent policies, the services policies, Home Address allocation policies and the subscription policies the home agent may or may not be able to authorize the mobile node to the new service. For example the existing service and the new service could require different Home Addresses. If the authorization fails then the home agent MUST deny the registration, delete any binding with the existing Home Address and send a Registration Reply with a Code set to SERVICE_AUTHORIZATION_FAILED (error code TBD). Depending on the local home agent policy, the home agent MAY echo Korhonen & Nilsson Expires March 8, 2009 [Page 6] Internet-Draft Service Selection for MIPv4 September 2008 back the Service Selection extension in the corresponding Registration Reply message towards the mobile node or the foreign agent. The home agent MUST NOT change the content of the echoed Service Selection extension. 4.3. Foreign Agent Considerations A foreign agent MUST skip the Service Selection extension if the Registration Request already contains the Service Selection extension. If the Registration Request does not contain the Service Selection extension the foreign agent MAY add the Service Selection extension to the Registration Request message. How the foreign agent learns the service the mobile nodes needs to authorize to is outside of scope of this document. In the case a foreign agent added the Service Selection extension to the Registration Request on behalf of the mobile node, it MUST verify whether the corresponding Registration Reply message from a home agent also contains an echoed Service Selection extension. If the received Registration Reply message contains the echoed Service Selection extension, the foreign agent MUST NOT include the extension to the Registration Reply message that gets forwarded to the mobile node. 5. Security Considerations The protection for the Service Selection extension depends on the service that is being identified and eventually selected. If the service selection information should not be revealed on the wire it should be protected in a manner similar to Registration Requests and Registration Replies. The Service Selection extension is protected by the same authentication enabling extension as the rest of the Registration Request message. The home agent MUST verify that the mobile node is authorized to the service included in the Service Selection extension. The Service Selection extension authorization is part of the normal mobile node registration and authentication procedure. Both registration authentication and service authorization MUST succeed before the mobile node is allowed to register to the home agent. 6. IANA Considerations A new Mobile IPv4 skippable Extension type is required for the following new Extension described in Section 3. The Extension type must be from the 'skippable Extension' range (128-255): Korhonen & Nilsson Expires March 8, 2009 [Page 7] Internet-Draft Service Selection for MIPv4 September 2008 Service Selection Extension is set to TBD A new Mobile IPv4 registration denied by home agent error code is required. The error code must be allocated from the 'Error Codes from the Home Agent' range (128-192): SERVICE_AUTHORIZATION_FAILED is set to TBD 7. Acknowledgements The authors would like to thank Henrik Levkowetz and Kent Leung for their comments. 8. References 8.1. Normative References [1] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August 2002. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [3] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003. [4] Davis, M. and M. Durst, "Unicode Standard Annex #15; Unicode Normalization Forms", Unicode 5.0.0, October 2006. 8.2. Informative References [5] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Network Access Identifier", RFC 4282, December 2005. [6] Calhoun, P. and C. Perkins, "Mobile IP Network Access Identifier Extension for IPv4", RFC 2794, March 2000. [7] Leung, K., "WiMAX Forum/3GPP2 Proxy Mobile IPv4", draft-leung-mip4-proxy-mode-09 (work in progress), August 2008. [8] Perkins, C., Calhoun, P., and J. Bharatia, "Mobile IPv4 Challenge/Response Extensions (Revised)", RFC 4721, January 2007. Korhonen & Nilsson Expires March 8, 2009 [Page 8] Internet-Draft Service Selection for MIPv4 September 2008 Authors' Addresses Jouni Korhonen TeliaSonera Corporation. P.O.Box 970 FIN-00051 Sonera FINLAND Email: jouni.korhonen@teliasonera.com Ulf Nilsson TeliaSonera Corporation. Marbackagatan 11 S-123 86 Farsta SWEDEN Email: ulf.s.nilsson@teliasonera.com Korhonen & Nilsson Expires March 8, 2009 [Page 9] Internet-Draft Service Selection for MIPv4 September 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. 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