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
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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.
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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
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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
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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.
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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.
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[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.
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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
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RFC, FYI, BCP