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rfc:rfc5149

Network Working Group J. Korhonen Request for Comments: 5149 U. Nilsson Category: Informational TeliaSonera

                                                        V. Devarapalli
                                                                Azaire
                                                         February 2008
                 Service Selection for Mobile IPv6

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Abstract

 In some Mobile IPv6 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 on provisioning
 multiple services to one mobility service subscription.  This
 document describes a Service Selection Mobility Option for both
 conventional Mobile IPv6 and Proxy Mobile IPv6 that is intended to
 assist home agents to make a specific service selection for the
 mobility service subscription during the binding registration
 procedure.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
 2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . . . 3
 3.  Service Selection Mobility Option . . . . . . . . . . . . . . . 3
 4.  Processing Considerations . . . . . . . . . . . . . . . . . . . 4
   4.1.  Mobile Node Considerations  . . . . . . . . . . . . . . . . 4
   4.2.  Home Agent Considerations . . . . . . . . . . . . . . . . . 5
   4.3.  Correspondent Node Considerations . . . . . . . . . . . . . 5
 5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
 7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
 8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
   8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
   8.2.  Informative References  . . . . . . . . . . . . . . . . . . 7

Korhonen, et al. Informational [Page 1] RFC 5149 Service Selection for MIPv6 February 2008

1. Introduction

 Mobile IPv6 [2] can identify mobile nodes in various ways, including
 home addresses [2], Network Access Identifiers (NAIs) [6][7], and
 credentials suitable for the Internet Key Exchange Protocol version 2
 (IKEv2) [10].  In some Mobile IPv6 deployments, identifying the
 mobile node or the mobility service subscriber via a Proxy Mobile
 IPv6 client [5] (hereafter, the mobile node and the Proxy Mobile IPv6
 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 and quality of service assignment for
    mobility service providers based on the subscribed services.
 o  In the 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 Mobility Option for
 Mobile IPv6 that is intended to assist home agents to make specific
 service selections for the mobility service subscription during the
 binding registration procedure.  The service selection may affect
 home agent routing decisions, Home Address or Home Network Prefix
 assignment policies, firewall settings, and security policies.  The
 Service Selection option should be used in every Binding Update that
 makes a new registration to the home agent.

Korhonen, et al. Informational [Page 2] RFC 5149 Service Selection for MIPv6 February 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 the point of view of both operators and service
 providers.  However, it should be understood that there are potential
 deployment possibilities where selecting a certain service may
 restrict simultaneous access to other services from a user's 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 [1].

3. Service Selection Mobility Option

 At most one Service Selection Mobility Option MAY be included in any
 Binding Update message.  If the Binding Update message includes any
 authorization-related options (such as the Binding Authorization Data
 option [2]) or authentication related options (such as the Mobility
 Message Authentication option [8]), then the Service Selection option
 MUST appear before any mobility message authorization- or
 authentication-related options.
 The Service Selection option SHOULD NOT be sent to a correspondent
 node.  The mobile node cannot assume that the correspondent node has
 any knowledge about a specific service selection made between the
 mobile node and the home agent.
 The Service Selection option has no alignment requirement as such.
  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 = 20    |   Length      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Identifier...
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   Service Selection Mobility Option

Korhonen, et al. Informational [Page 3] RFC 5149 Service Selection for MIPv6 February 2008

 o  Type: 8-bit identifier set to 20 of the type of the skipable
    mobility option.
 o  Length: 8-bit unsigned integer, representing the length of the
    Service Selection Mobility Option in octets, excluding the Option
    Type and Option 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 option Identifiers.  At minimum, the
    Identifier MUST be unique among the home agents to which the
    mobile node is authorized to register.

4. Processing Considerations

4.1. Mobile Node Considerations

 A mobile node or a Proxy Mobile IPv6 client MAY include, at most, one
 Service Selection Mobility Option into a Binding Update message.  The
 option is used to identify the service to be associated with the
 binding registration and SHOULD only be included into the initial
 Binding Update 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 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 to the Proxy Mobile IPv6 client is out of the scope of this
 specification.
 The placement of the Service Selection option is as follows: when
 present, this option MUST appear after the Mobile Node-Network Access
 Identifier (MN-NAI) option, if the MN-NAI option is present, and
 before any authorization- and authentication-related options.  The
 Service Selection option can be used with any mobile node
 identification method such as a home address, an MN-NAI, and
 credentials suitable for IKEv2.
 If the mobile node receives a Binding Acknowledgement with a Status
 Code set to SERVICE_AUTHORIZATION_FAILED and the mobile node has an
 existing binding with the Home Address or the Home Network Prefix
 used in the failed Binding Update message, the mobile node MUST

Korhonen, et al. Informational [Page 4] RFC 5149 Service Selection for MIPv6 February 2008

 delete the existing binding.  If there is no existing binding, the
 mobile node proceeds as with any failed initial binding registration.

4.2. Home Agent Considerations

 Upon receiving a Binding Update message with a Service Selection
 option, 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 for the service it included in the
 Service Selection option.  The services the mobile node is authorized
 for SHOULD be part of the general mobile node subscription profile.
 If the mobile node is not authorized for the service, the home agent
 MUST deny the registration and send a Binding Acknowledgement with a
 Status Code set to SERVICE_AUTHORIZATION_FAILED (151).
 The Service Selection option is used to assist the authorization and
 identifies a specific service that is to be authorized.  The Service
 Selection option MAY also affect the Home Address or the Home Network
 Prefix allocation when, for example, used with the MN-NAI option.
 For example, for the same NAI there MAY be different Home Addresses
 or Home Network Prefixes depending on the identified service.
 Furthermore, the Service Selection option 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 Binding Update message with a Service Selection
 option 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 or Home Network Prefix
 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 Network Prefixes.  If the authorization fails,
 then the home agent MUST deny the registration, delete any binding
 with the existing Home Address or Home Network Prefix, and send a
 Binding Acknowledgement with a Status Code set to
 SERVICE_AUTHORIZATION_FAILED (151).

4.3. Correspondent Node Considerations

 Unless the correspondent node and the home agent share the same
 knowledge about mobility services, the Service Selection option is
 more or less useless information to the correspondent node.  The
 correspondent node SHOULD silently ignore the Service Selection
 option in this case.

Korhonen, et al. Informational [Page 5] RFC 5149 Service Selection for MIPv6 February 2008

 There are deployment cases where the home agent and a correspondent
 node, for example, belong to the same administrative domain.  In this
 case, it is possible that the correspondent node shares the same
 knowledge of the services as the home agent.  Therefore, the
 correspondent node is, for example, able to provide service-based
 traffic handling to mobile nodes.

5. Security Considerations

 The protection for the Service Selection Mobility Option depends on
 the service that is being identified and eventually selected.  If the
 service selection information should not be revealed on the wire,
 Binding Updates and Binding Acknowledgements should use Encapsulating
 Security Payload (ESP) [9] in transport mode with a non-null
 encryption transform to provide message confidentiality.

6. IANA Considerations

 A new Mobile IPv6 Mobility Option type has been assigned for the
 following new mobility option described in Section 3:
     Service Selection Mobility Option       is set to 20
 A new Mobile IPv6 registration denied by home agent Status Code has
 been assigned.  The Status Code was allocated from the range 128-255:
     SERVICE_AUTHORIZATION_FAILED            is set to 151

7. Acknowledgements

 Jouni Korhonen would like to thank the TEKES MERCoNe project for
 providing funding to work on this document.  The authors would like
 to thank Jari Arkko for his thorough review.

8. References

8.1. Normative References

 [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.
 [2]   Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
       IPv6", RFC 3775, June 2004.
 [3]   Yergeau, F., "UTF-8, a transformation format of ISO 10646",
       STD 63, RFC 3629, November 2003.

Korhonen, et al. Informational [Page 6] RFC 5149 Service Selection for MIPv6 February 2008

 [4]   Davis, M. and M. Duerst, "Unicode Standard Annex #15; Unicode
       Normalization Forms", Unicode 5.0.0, October 2006.

8.2. Informative References

 [5]   Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., and
       B. Patil, "Proxy Mobile IPv6", Work in Progress, December 2007.
 [6]   Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Network
       Access Identifier", RFC 4282, December 2005.
 [7]   Patel, A., Leung, K., Khalil, M., Akhtar, H., and K. Chowdhury,
       "Mobile Node Identifier Option for Mobile IPv6 (MIPv6)",
       RFC 4283, November 2005.
 [8]   Patel, A., Leung, K., Khalil, M., Akhtar, H., and K. Chowdhury,
       "Authentication Protocol for Mobile IPv6", RFC 4285,
       January 2006.
 [9]   Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303,
       December 2005.
 [10]  Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
       IKEv2 and the Revised IPsec Architecture", RFC 4877,
       April 2007.

Korhonen, et al. Informational [Page 7] RFC 5149 Service Selection for MIPv6 February 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
 Vijay Devarapalli
 Azaire Networks
 4800 Great America Pkwy
 Santa Clara, CA 95054
 USA
 EMail: vijay.devarapalli@azairenet.com

Korhonen, et al. Informational [Page 8] RFC 5149 Service Selection for MIPv6 February 2008

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 contained in BCP 78, and except as set forth therein, the authors
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Korhonen, et al. Informational [Page 9]

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