PMIPv6 ANI option: Access Network Identifier (ANI) Option for Proxy Mobile IPv6
Telling the mobility anchor which access network a mobile device is on, so the operator can treat it differently.
Gundavelli, S., Ed., Korhonen, J., Ed., Grayson, M., Leung, K., and R. Pazhyannur, "Access Network Identifier (ANI) Option for Proxy Mobile IPv6", RFC 6757, DOI 10.17487/RFC6757, October 2012, <https://www.rfc-editor.org/info/rfc6757>.
@misc{rfc6757,
series = {Request for Comments},
number = 6757,
howpublished = {RFC 6757},
publisher = {RFC Editor},
doi = {10.17487/RFC6757},
url = {https://www.rfc-editor.org/info/rfc6757},
author = {S. Gundavelli and J. Korhonen and M. Grayson and K. Leung and R. Pazhyannur},
title = {{Access Network Identifier (ANI) Option for Proxy Mobile IPv6}},
pagetotal = 19,
year = 2012,
month = oct,
} RFC text
Contents
Internet Engineering Task Force (IETF) S. Gundavelli, Ed.
Request for Comments: 6757 Cisco
Category: Standards Track J. Korhonen, Ed.
ISSN: 2070-1721 Nokia Siemens Networks
M. Grayson
K. Leung
R. Pazhyannur
Cisco
October 2012
Access Network Identifier (ANI) Option for Proxy Mobile IPv6
Abstract
The local mobility anchor in a Proxy Mobile IPv6 (PMIPv6) domain is
able to provide access-network- and access-operator-specific handling
or policing of the mobile node traffic using information about the
access network to which the mobile node is attached. This
specification defines a mechanism and a related mobility option for
carrying the access network identifier and the access operator
identification information from the mobile access gateway to the
local mobility anchor over Proxy Mobile IPv6.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6757.
Copyright Notice
Copyright (c) 2012 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. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................3
2. Conventions and Terminology .....................................5
2.1. Conventions ................................................5
2.2. Terminology ................................................5
3. Access Network Identifier Option ................................5
3.1. Format of the Access Network Identifier Sub-Option .........6
3.1.1. Network-Identifier Sub-Option .......................7
3.1.2. Geo-Location Sub-Option .............................8
3.1.3. Operator-Identifier Sub-Option ......................9
4. Protocol Considerations ........................................10
4.1. Mobile Access Gateway Considerations ......................10
4.2. Local Mobility Anchor Considerations ......................13
5. IANA Considerations ............................................14
6. Protocol Configuration Variables ...............................15
7. Security Considerations ........................................16
8. Acknowledgements ...............................................17
9. References .....................................................17
9.1. Normative References ......................................17
9.2. Informative References ....................................18
1. Introduction
Proxy Mobile IPv6 [RFC5213] can be used for supporting network-based
mobility management in various types of network deployments. Network
architectures such as service provider Wi-Fi access aggregation or
Wireless Local Area Network (WLAN) integrated with mobile packet core
are examples where Proxy Mobile IPv6 is a component of the overall
architecture. Some of these architectures require the ability of the
local mobility anchor (LMA) [RFC5213] to provide differentiated
services and policing of traffic to the mobile nodes based on the
access network to which they are attached. Policy systems in
mobility architectures such as the Policy and Charging Control (PCC)
Framework [TS23203] and the Access Network Discovery and Selection
Function (ANDSF) [TS23402] in Third Generation Partnership Project
(3GPP) systems allow configuration of policy rules with conditions
based on the access network information. For example, the service
treatment for the mobile node's traffic may be different when it is
attached to an access network owned by the home operator than when
owned by a roaming partner. The service treatment can also be
different based on the configured Service Set Identifiers (SSIDs) in
the case of access networks based on IEEE 802.11. Other examples of
location services include the operator's ability to display a
location-specific web page or apply tariff based on the location.
The Proxy Mobile IPv6 specification [RFC5213] requires the Access
Technology Type (ATT) option to be carried from the mobile access
gateway (MAG) to the local mobility anchor. This is a mandatory
option. However, the Access Technology Type alone is not necessarily
sufficient for a suitable policy to be applied at the local mobility
anchor. Therefore, there is a need for additional access-network-
related information to be available at the local mobility anchor.
Learning the identity of the access network operator may not be
possible for a local mobility anchor without the support of an
additional policy framework that is able to provide required
information out of band to the local mobility anchor. Such a policy
framework may not be required for all Proxy Mobile IPv6 deployments;
hence, an alternative approach for optionally carrying such
information is required to ensure that additional information related
to the access network is available.
This document defines a new mobility option, the Access Network
Identifier (ANI) option, and its sub-options for Proxy Mobile IPv6,
which can be used by the mobile access gateway to signal the access
network information to the local mobility anchor. The specific
details on how the local mobility anchor uses the information
contained in the Access Network Identifier option are out of scope
for this document. This information is intended for use between
infrastructure nodes providing mobile management service and is not
exposed to outside entities, which ensures the location of the
network to which the mobile node is attached, or any other access-
network-specific information, is not revealed to other mobile nodes
within the PMIPv6 domain or to other nodes outside the PMIPv6 domain.
However, the location and access information MAY be exposed to
specific parties outside the PMIPv6 domain based on an agreement
approved by the subscriber; otherwise, this information MUST NOT be
exposed in the absence of such agreements. If the location
information is to be exposed outside the PMIPv6 domain, then that
MUST be done using a Presence Information Data Format Location Object
(PIDF-LO) [RFC5139] carrying the usage rules to which the subscriber
has agreed. This mobility option is optional and is not mandatory
for the Proxy Mobile IPv6 protocol. However, the Access Technology
Type option continues to be a mandatory option and always needs to be
carried in the Proxy Mobile IPv6 signaling messages.
SSID: IETF-1
Geo-Location: 37o49'11"N 122o28'43"W
Operator-Identifier: provider1.example.com
+--+
|AP|-------. {Access-Specific Policies)
+--+ | _-----_ |
+-----+ _( )_ +-----+
| MAG |-=====( PMIPv6 )======-| LMA |-
+-----+ (_ Tunnel_) +-----+
+--+ | '-----'
|AP|-------'
+--+
SSID: IETF-2
Geo-Location: 59o19'40.21"N 18o 3'18.36"E
Operator-Identifier: provider2.example.com
Figure 1: Access Networks Attached to MAG
Figure 1 illustrates an example Proxy Mobile IPv6 deployment where
the mobile access gateway delivers the information elements related
to the access network to the local mobility anchor over Proxy Mobile
IPv6 signaling messages. In this example, the additional information
could comprise the SSID of the used IEEE 802.11 network, the geo-
location of the network to which the mobile node is attached, and the
identities of the operators running the IEEE 802.11 access network
infrastructure.
2. Conventions and Terminology
2.1. Conventions
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].
2.2. Terminology
All the mobility-related terms used in this document are to be
interpreted as defined in the Proxy Mobile IPv6 specifications
[RFC5213] and [RFC5844]. Additionally, this document uses the
following abbreviations:
Service Set Identifier
Service Set Identifier (SSID) identifies the name of the IEEE
802.11 network. SSID differentiates one network from the other.
Operator-Identifier
The Operator-Identifier is the Structure of Management Information
(SMI) Network Management Private Enterprise Code of the IANA-
maintained "Private Enterprise Numbers" registry [SMI]. It
identifies the operator running the network attached to a specific
interface of the mobile access gateway.
3. Access Network Identifier Option
The Access Network Identifier option is a mobility header option used
to exchange information related to the access network between a local
mobility anchor and a mobile access gateway. The option can be
included in both Proxy Binding Update (PBU) and Proxy Binding
Acknowledgement (PBA) messages, and there MUST NOT be more than a
single instance of this mobility option in a mobility message. The
Access Network Identifier mobility option MUST contain one or more
Access Network Identifier sub-options. The Access Network Identifier
sub-option is described in Section 3.1.
The alignment requirement for this option is 4n [RFC2460].
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ANI Sub-option(s) ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Access Network Identifier Option
Type: MUST be set to the value of 52, indicating that it is a
Network-Identifier option.
Length: 8-bit unsigned integer indicating the length in octets of
the option, excluding the Type and Length fields.
3.1. Format of the Access Network Identifier Sub-Option
The Access Network Identifier sub-options are used for carrying
information elements related to the access network to which the
mobile node is attached. These sub-options can be included in the
Access Network Identifier option defined in Section 3. The format of
this sub-option is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANI Type | ANI Length | Option Data ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Access Network Identifier Sub-Option
ANI Type: 8-bit unsigned integer indicating the type of the Access
Network Identifier sub-option. This specification defines the
following types:
0 - Reserved
1 - Network-Identifier sub-option
2 - Geo-Location sub-option
3 - Operator-Identifier sub-option
ANI Length: 8-bit unsigned integer indicating the number of octets
needed to encode the Option Data, excluding the ANI Type and ANI
Length fields of the sub-option.
3.1.1. Network-Identifier Sub-Option
The Network-Identifier is a mobility sub-option carried in the Access
Network Identifier option defined in Section 3. This sub-option
carries the name of the access network (e.g., an SSID in the case of
an IEEE 802.11 Access Network or a Public Land-based Mobile Network
(PLMN) Identifier [TS23003] in the case of 3GPP access) to which the
mobile node is attached. There MUST be no more than a single
instance of this specific sub-option in any Access Network Identifier
option. The format of this option is defined below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANI Type=1 | ANI Length |E| Reserved | Net-Name Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Network Name (e.g., SSID or PLMNID) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AP-Name Len | Access-Point Name ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Network-Identifier Sub-Option
ANI Type: MUST be set to the value of (1), indicating that it is a
Network-Identifier sub-option
ANI Length: Total length of this sub-option in octets, excluding the
ANI Type and ANI Length fields. The value can be in the range of
5 to 32 octets.
E: 1-bit flag indicating whether the Network Name is encoded in
UTF-8. If this flag is set to one (1), then the Network Name is
encoded using UTF-8 [RFC3629]. If the flag is set to zero (0),
this indicates that the encoding is undefined and is determined by
out-of-band mechanisms. Implementations SHOULD use UTF-8
encoding.
Reserved: MUST be set to zero when sending and ignored when
received.
Net-Name Length: 8-bit field for representing the length of the
Network Name in octets. This field MUST NOT be set to zero.
Network Name: The name of the access network to which the mobile
node is attached. The type of the Network Name is dependent on
the access technology to which the mobile node is attached. If it
is 802.11 access, the Network Name MUST be the SSID of the
network. If the access network is 3GPP access, the Network Name
is the PLMN Identifier of the network. If the access network is
3GPP2 access, the Network Name is the Access Network Identifier
[ANI].
When encoding the PLMN Identifier, both the Mobile Network Code
(MNC) [TS23003] and Mobile Country Code (MCC) [TS23003] MUST be 3
digits. If the MNC in use only has 2 digits, then it MUST be
preceded with a '0'. Encoding MUST be UTF-8.
AP-Name Len: 8-bit field for representing the length of the Access-
Point Name in octets. If the Access-Point Name is not included,
then this length MUST be set to a value of zero.
Access-Point Name: The name of the access point (physical device
name) to which the mobile node is attached. This is the
identifier that uniquely identifies the access point. While
Network Name (e.g., SSID) identifies the operator's access
network, Access-Point Name identifies a specific network device in
the network to which the mobile node is attached. In some
deployments, the Access-Point Name can be set to the Media Access
Control (MAC) address of the device or some unique identifier that
can be used by the policy systems in the operator network to
unambiguously identify the device. The string is carried in UTF-8
representation.
3.1.2. Geo-Location Sub-Option
The Geo-Location is a mobility sub-option carried in the Access
Network Identifier option defined in Section 3. This sub-option
carries the geo-location of the network to which the mobile node is
attached, as known to the mobile access gateway. There MUST be no
more than a single instance of this specific sub-option in any Access
Network Identifier option. The format of this option is defined
below and encodes the coordinates of an ellipsoid point. The format
is based on the coordinate reference system specified in the World
Geodetic System 1984 [WGS84].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANI Type=2 | ANI Length=6 | Latitude Degrees
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Longitude Degrees |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Geo-Location ANI Sub-Option
ANI Type: MUST be set to the value of (2), indicating that it is the
Geo-Location sub-option
ANI Length: Total length of this sub-option in octets, excluding the
ANI Type and ANI Length fields. It MUST be set to a value of (6).
Latitude Degrees: A 24-bit latitude degree value encoded as a two's
complement, fixed point number with 9 whole bits. Positive
degrees correspond to the Northern Hemisphere and negative degrees
correspond to the Southern Hemisphere. The value ranges from -90
to +90 degrees.
Longitude Degrees: A 24-bit longitude degree value encoded as a
two's complement, fixed point number with 9 whole bits. The value
ranges from -180 to +180 degrees.
3.1.3. Operator-Identifier Sub-Option
The Operator-Identifier is a mobility sub-option carried in the
Access Network Identifier option defined in Section 3. This sub-
option carries the Operator-Identifier of the access network to which
the mobile node is attached. There MUST be no more than a single
instance of this specific sub-option in any Access Network Identifier
option. The format of this option is defined below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ANI Type=3 | ANI Length | Op-ID Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Operator-Identifier ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Operator-Identifier Sub-Option
ANI Type: It MUST be set to the value of (3), indicating that it is
the Operator-Identifier sub-option
ANI Length: Total length of this sub-option in octets, excluding the
ANI Type and ANI Length fields.
Operator-Identifier (Op-ID) Type: 8-bit unsigned integer indicating
the type of the Operator-Identifier. Currently, the following
types are defined:
0 - Reserved.
1 - Operator-Identifier as a variable-length Private Enterprise
Number (PEN) [SMI] encoded in a network-byte order. The
maximum PEN value depends on the ANI Length and is calculated
using the formula: maximum PEN = 2^((ANI_length-1)*8)-1. For
example, the ANI Length of 4 allows for encoding PENs from 0
to 2^24-1, i.e., from 0 to 16777215, and uses 3 octets of
Operator-Identifier space.
2 - Realm of the operator. Realm names are required to be unique
and are piggybacked on the administration of the DNS
namespace. Realms meet the syntactic requirements of the
"Preferred Name Syntax" defined in Section 2.3.1 of
[RFC1035]. They are encoded as US-ASCII. 3GPP specifications
also define realm names that can be used to convey PLMN
Identifiers [TS23003].
Operator-Identifier: Up to 253 octets of the Operator-Identifier.
The encoding of the identifier depends on the used Operator-
Identifier Type. For Operator-Identifiers defined in this
specification, the Operator-Identifier MUST NOT be empty.
4. Protocol Considerations
The following considerations apply to the local mobility anchor and
the mobile access gateway.
4.1. Mobile Access Gateway Considerations
o The conceptual Binding Update List entry data structure maintained
by the mobile access gateway, described in Section 6.1 of
[RFC5213], MUST be extended to store the access-network-related
information elements associated with the current session.
Specifically, the following parameters MUST be defined:
Network-Identifier
Operator-Identifier
Geo-Location
o If the mobile access gateway is configured to support the Access
Network Information option, it SHOULD include this option with the
specific sub-options in all Proxy Binding Update messages
(including Proxy Binding Updates for lifetime extension and for
deregistration) that it sends to the local mobility anchor. The
Access Network Information option MUST be constructed as specified
in Section 3. It SHOULD include the ANI sub-option(s) that the
mobile access gateway is configured to carry in the Proxy Mobile
IPv6 messages.
o The access network information elements, such as Network-
Identifier, Geo-Location, and Operator-Identifier, typically are
statically configured on the mobile access gateway on a per-
interface basis (for example, access point (AP-1) is attached
through interface-1, and the SSID is X, Geo-Location is Y). In
some deployments, this information can also be dynamically
obtained, such as through DHCP Option (82), which is the DHCP
Relay Agent Information option [RFC3046]. When the mobile node
sends a DHCP Request, the access points typically add the SSID
information to the Option 82 of the DHCP request, and when the
mobile access gateway receives this request, it can parse the
Option 82 of the DHCP request and obtain the SSID name. The
mobility access gateway can also obtain this information from the
DHCPv6 GeoLoc Option [RFC6225]. The specific details on how the
mobile access gateway obtains these information elements are
access technology and deployment specific and are outside the
scope of this document. It is possible those information elements
are configured on the MAG on a per-interface basis or dynamically
obtained through some out-of-band means, such as based on the
Control and Provisioning of Wireless Access Points (CAPWAP)
protocol.
o If the protocol configuration variable
EnableANISubOptNetworkIdentifier (Section 6) is set to a value of
(1), the mobile access gateway SHOULD include the Network-
Identifier sub-option in the Access Network Identifier option
carried in the Proxy Binding Update. However, if the mobile
access gateway is unable to obtain the Network-Identifier, then it
MUST NOT include this sub-option. For including the Network-
Identifier sub-option, the mobile access gateway needs to be aware
of the Network Name of the access network (e.g., SSID in the case
of a WLAN access network) to which the mobile node is attached.
This sub-option also includes the Access-Point Name for carrying
the name of the access point to which the mobile node is attached.
The Access-Point Name is specially important for applying location
services, given that the Network Name (e.g., SSID) may not provide
the needed uniqueness for identifying a location. When included,
this sub-option MUST be constructed as described in Section 3.1.1
o If the protocol configuration variable EnableANISubOptGeoLocation
(Section 6) is set to a value of (1), the mobile access gateway
SHOULD include the Geo-Location sub-option in the Access Network
Identifier option carried in the Proxy Binding Update. However,
if the mobile access gateway is unable to obtain the Geo-location,
then it MUST NOT include this sub-option. For including the Geo-
Location sub-option, the mobile access gateway needs to be aware
of the GPS coordinates of the network to which the mobile node is
attached. When included, this sub-option MUST be constructed as
described in Section 3.1.2.
o If the protocol configuration variable
EnableANISubOptOperatorIdentifier (Section 6) is set to a value of
(1), the mobile access gateway SHOULD include the Operator-
Identifier sub-option in the Access Network Identifier option
carried in the Proxy Binding Update. For including the Operator-
Identifier sub-option, the mobile access gateway needs to be aware
of the operator identity of that access network. The access
network operator SHOULD obtain an identifier from the "Private
Enterprise Number" registry, in order for the mobile access
gateway to carry the Operator-Identifier. If a given access
network operator has not obtained an identifier from the "Private
Enterprise Number" registry or if the mobile access gateway is
unable to learn the operator identity for any other administrative
reasons, then it MUST NOT include this sub-option. When included,
this sub-option MUST be constructed as described in Section 3.1.3.
If the mobile access gateway had any of the Access Network
Information mobility options included the Proxy Binding Update sent
to a local mobility anchor, then the Proxy Binding Acknowledgement
received from the local mobility anchor SHOULD contain the Access
Network Information mobility option with the specific sub-options.
If the mobile access gateway receives a Proxy Binding Acknowledgement
with a successful Status Value but without an Access Network
Information mobility option, then the mobile access gateway SHOULD
log the event and, based on its local policy, MAY proceed to
terminate the mobility session. In this case, the mobile access
gateway knows the local mobility anchor does not understand the
Access Network Information mobility option and therefore MAY consider
it as a misconfiguration of the Proxy Mobile IPv6 domain.
4.2. Local Mobility Anchor Considerations
o The conceptual Binding Cache entry data structure maintained by
the local mobility anchor, described in Section 5.1 of [RFC5213],
MUST be extended to store the access-network-related information
elements associated with the current session. Specifically, the
following parameters MUST be defined:
Network-Identifier
Geo-Location
Operator-Identifier
o On receiving a Proxy Binding Update message [RFC5213] from a
mobile access gateway with the Access Network Information option,
the local mobility anchor must process the option and update the
corresponding fields in the Binding Cache entry. If the option is
not understood by that LMA implementation, it will skip the
option.
o If the local mobility anchor understands the Access Network
Identifier mobility option received in a Proxy Binding Update and
also supports the sub-option(s), then the local mobility anchor
MUST echo the Access Network Identifier mobility option with the
specific sub-option(s) that it accepted back to the mobile access
gateway in a Proxy Binding Acknowledgement. The Access Network
Identifier sub-options defined in this specification MUST NOT be
altered by the local mobility anchor.
o If the received Proxy Binding Update message does not include the
Access Network Information option, then the mobility session
associated with that Proxy Binding Update MUST be updated to
remove any access network information elements.
o The local mobility anchor MAY choose to use the Access Network
Information sub-options for applying any access-operator-specific
handling or policing of the mobile node traffic. The specific
details on how these sub-options are used is outside the scope of
this document.
5. IANA Considerations
Per this document, the following IANA actions have been completed.
o Action 1: This specification defines a new mobility header option,
the Access Network Identifier. This mobility option is described
in Section 3. The type value (52) for this option has been
assigned from the same numbering space as allocated for the other
mobility options, as defined in [RFC6275].
o Action 2: This specification defines a new mobility sub-option
format, the Access Network Information (ANI) sub-option. The
format of this mobility sub-option is described in Section 3.1.
This sub-option can be carried in the Access Network Information
option. The type value for this sub-option is managed by IANA,
under the registry "Access Network Information (ANI) Sub-Option
Type Values". This specification reserves the following type
values. Approval of new Access Network Information (ANI) sub-
option type values are to be made through IANA Expert Review.
+=========================================================+
| 0 | Reserved |
+=========================================================+
| 1 | Network-Identifier sub-option |
+=========================================================+
| 2 | Geo-Location sub-option |
+=========================================================+
| 3 | Operator-Identifier sub-option |
+=========================================================+
o Action 3: This specification defines a new mobility sub-option,
the Operator-Identifier sub-option. The format of this mobility
sub-option is described in Section 3.1.3. The Operator-Identifier
(Op-ID) Type field of this sub-option introduces a new number
space. This number space is managed by IANA, under the registry
"Operator-Identifier Type Registry". This specification reserves
the following type values. Approval of new Operator-Identifier
type values are to be made through IANA Expert Review.
+===============================================+
| 0 | Reserved |
+===+===========================================+
| 1 | Operator-Identifier as a variable-length |
| | Private Enterprise Number (PEN) |
+===+===========================================+
| 2 | Realm of the Operator |
+===+===========================================+
6. Protocol Configuration Variables
This specification defines the following configuration variables that
control the use of sub-options related to the Access Network
Information in Proxy Mobile IPv6 signaling messages. The mobility
entities, local mobility anchor, and mobile access gateway MUST allow
these variables to be configured by the system management. The
configured values for these protocol variables MUST survive server
reboots and service restarts.
EnableANISubOptNetworkIdentifier
This flag indicates the operational state of the Network-
Identifier sub-option support. This configuration variable is
available at both the mobile access gateway and the local mobility
anchor. The default value for this flag is set to (0), indicating
that support for the Network-Identifier sub-option is disabled.
When this flag on the mobile access gateway is set to a value of
(1), the mobile access gateway SHOULD include this sub-option in
the Proxy Binding Update messages that it sends to the local
mobility anchor; otherwise, it SHOULD NOT include the sub-option.
There can be situations where the mobile access gateway is unable
to obtain the Network-Identifier and may not be able to construct
this sub-option.
Similarly, when this flag on the local mobility anchor is set to a
value of (1), the local mobility anchor SHOULD enable support for
this sub-option; otherwise, it SHOULD ignore this sub-option.
EnableANISubOptGeoLocation
This flag indicates the operational state of the Geo-Location sub-
option support. This configuration variable is available at both
the mobile access gateway and the local mobility anchor. The
default value for this flag is set to (0), indicating that support
for the Geo-Location sub-option is disabled.
When this flag on the mobile access gateway is set to a value of
(1), the mobile access gateway SHOULD include this sub-option in
the Proxy Binding Update messages that it sends to the local
mobility anchor; otherwise, it SHOULD NOT include the sub-option.
There can be situations where the mobile access gateway is unable
to obtain the geo-location information and may not be able to
construct this sub-option.
Similarly, when this flag on the local mobility anchor is set to a
value of (1), the local mobility anchor SHOULD enable support for
this sub-option; otherwise, it SHOULD ignore this sub-option.
EnableANISubOptOperatorIdentifier
This flag indicates the operational state of the Operator-
Identifier sub-option support. This configuration variable is
available at both the mobile access gateway and the local mobility
anchor. The default value for this flag is set to (0), indicating
that support for the Operator-Identifier sub-option is disabled.
When this flag on the mobile access gateway is set to a value of
(1), the mobile access gateway SHOULD include this sub-option in
the Proxy Binding Update messages that it sends to the local
mobility anchor; otherwise, it SHOULD NOT include the sub-option.
There can be situations where the mobile access gateway is unable
to obtain the Operator-Identifier information and may not be able
to construct this sub-option.
Similarly, when this flag on the local mobility anchor is set to a
value of (1), the local mobility anchor SHOULD enable support for
this sub-option; otherwise, it SHOULD ignore this sub-option.
7. Security Considerations
The Access Network Information option defined in this specification
is for use in Proxy Binding Update and Proxy Binding Acknowledgement
messages. This option is carried like any other mobility header
option as specified in [RFC6275] and does not require any special
security considerations.
The Geo-Location sub-option carried in the Access Network Information
option exposes the geo-location of the network to which the mobile
node is attached. This information is considered to be very
sensitive, so care must be taken to secure the Proxy Mobile IPv6
signaling messages when carrying this sub-option. The base Proxy
Mobile IPv6 specification [RFC5213] specifies the use of IPsec for
securing the signaling messages, and those mechanisms can be enabled
for protecting this information. Operators can potentially apply
IPsec Encapsulating Security Payload (ESP) with confidentiality and
integrity protection for protecting the location information.
Access-network-specific information elements that the mobile access
gateway sends may have been dynamically learned over DHCP or using
other protocols. If proper security mechanisms are not in place, the
exchanged information may be potentially compromised with the mobile
access gateway sending incorrect access network parameters to the
local mobility anchor. This situation may potentially result in
incorrect service policy enforcement at the local mobility anchor and
impact to other services that depend on this access network
information. This threat can be mitigated by ensuring the
communication path between the mobile access gateway and the access
points is properly secured by the use of IPsec, Transport Layer
Security (TLS), or other security protocols.
8. Acknowledgements
The authors would like to thank Basavaraj Patil, Carlos Bernardos,
Gerardo Gieratta, Eric Voit, Hidetoshi Yokota, Ryuji Wakikawa,
Sangram Kishore, William Wan, Stefano Faccin, and Brian Haberman for
all the discussions related to this topic. The authors would also
like to acknowledge the IESG reviews from Benoit Claise, Stephen
Farrell, Pete Resnick, Robert Spark, Martin Thomson, and Ralph Droms.
9. References
9.1. Normative References
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC5139] Thomson, M. and J. Winterbottom, "Revised Civic Location
Format for Presence Information Data Format Location
Object (PIDF-LO)", RFC 5139, February 2008.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5844] Wakikawa, R. and S. Gundavelli, "IPv4 Support for Proxy
Mobile IPv6", RFC 5844, May 2010.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
9.2. Informative References
[ANI] 3GPP2 TSG-A, "Interoperability Specification (IOS) for
High Rate Packet Data (HRPD) Radio Access Network
Interfaces with Session Control in the Access Network",
A.S0008-A v3.0, October 2008.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC 3046, January 2001.
[RFC6225] Polk, J., Linsner, M., Thomson, M., and B. Aboba, "Dynamic
Host Configuration Protocol Options for Coordinate-Based
Location Configuration Information", RFC 6225, July 2011.
[SMI] IANA, "PRIVATE ENTERPRISE NUMBERS", SMI Network Management
Private Enterprise Codes,
<http://www.iana.org/assignments/enterprise-numbers>.
[TS23003] 3GPP, "Numbering, addressing and identification", 3GPP
TS 23.003 3.15.0, 2012.
[TS23203] 3GPP, "Policy and Charging Control Architecture", 3GPP
TS 23.203 10.7.0, 2012.
[TS23402] 3GPP, "Architecture enhancements for non-3GPP accesses",
3GPP TS 23.402 10.7.0, 2012.
[WGS84] NIMA, "World Geodetic System 1984", Third Edition,
NIMA TR8350.2, June 2004.
Authors' Addresses
Sri Gundavelli (editor)
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
EMail: sgundave@cisco.com
Jouni Korhonen (editor)
Nokia Siemens Networks
Linnoitustie 6
Espoo FIN-02600
Finland
EMail: jouni.nospam@gmail.com
Mark Grayson
Cisco
11 New Square Park
Bedfont Lakes, Feltham TW14 8HA
England
EMail: mgrayson@cisco.com
Kent Leung
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
EMail: kleung@cisco.com
Rajesh Pazhyannur
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
EMail: rpazhyan@cisco.com
ISO Plain Language
On this page
§1Introduction
Proxy Mobile IPv6 can be used for supporting network-based mobility management in various types of network deployment. Network architectures such as service provider Wi-Fi access aggregation, or a Wireless Local Area Network integrated with a mobile packet core, are examples where Proxy Mobile IPv6 is a component of the overall architecture.
Some of these architectures require the local mobility anchor to provide differentiated services and policing of traffic to the mobile nodes based on the access network to which they are attached. Policy systems in mobility architectures, such as the Policy and Charging Control Framework and the Access Network Discovery and Selection Function in 3GPP systems, allow the configuration of policy rules with conditions based on access network information. For example, the service treatment for the mobile node's traffic may be different when it is attached to an access network owned by the home operator than when it is owned by a roaming partner, and it can be different based on the configured service set identifiers in the case of access networks based on IEEE 802.11. Other examples of location services include the operator's ability to display a location-specific web page or apply a tariff based on the location.
The Proxy Mobile IPv6 specification requires the Access Technology Type option to be carried from the mobile access gateway to the local mobility anchor. That option is mandatory. However, the access technology type alone is not necessarily sufficient for a suitable policy to be applied at the local mobility anchor, so additional access-network-related information is needed there. Learning the identity of the access network operator may not be possible for a local mobility anchor without the support of an additional policy framework able to provide the information out of band, and such a framework may not be required for all Proxy Mobile IPv6 deployments, so an alternative approach for optionally carrying the information is required.
This document defines a new mobility option, the Access Network Identifier option, and its sub-options, which can be used by the mobile access gateway to signal access network information to the local mobility anchor. The specific details of how the local mobility anchor uses the information are out of scope. The information is intended for use between infrastructure nodes providing mobile management service and is not exposed to outside entities, which ensures that the location of the network to which the mobile node is attached, or any other access-network-specific information, is not revealed to other mobile nodes within the Proxy Mobile IPv6 domain or to nodes outside it. However, the location and access information may be exposed to specific parties outside the domain based on an agreement approved by the subscriber; otherwise it must not be exposed in the absence of such agreements. If the location information is to be exposed outside the domain, that must be done using a Presence Information Data Format Location Object carrying the usage rules to which the subscriber has agreed. The mobility option is optional and not mandatory for the Proxy Mobile IPv6 protocol, while the Access Technology Type option continues to be mandatory and always needs to be carried.
Knowing that a device is on a Wi-Fi network is not the same as knowing which Wi-Fi network. The anchor needs the second to apply the operator's rules, and the RFC defines a way to carry it.
§2.2Terminology
All the mobility-related terms used in this document are to be interpreted as defined in the Proxy Mobile IPv6 specifications. The document also uses two abbreviations of its own.
The Service Set Identifier identifies the name of the IEEE 802.11 network and differentiates one network from another. The Operator-Identifier is the Structure of Management Information Network Management Private Enterprise Code of the IANA-maintained Private Enterprise Numbers registry. It identifies the operator running the network attached to a specific interface of the mobile access gateway.
Two names are defined. The service set identifier is the name of the wireless network. The operator identifier is a number from a public registry that stands for the company running the network.
§3The Access Network Identifier Option
The Access Network Identifier option is a mobility header option used to exchange information related to the access network between a local mobility anchor and a mobile access gateway. The option can be included in both Proxy Binding Update and Proxy Binding Acknowledgement messages, and there must not be more than a single instance of this mobility option in a mobility message. The option must contain one or more Access Network Identifier sub-options.
The option has a Type field, which must be set to the value 52, and a Length field, an 8-bit unsigned integer giving the length in octets of the option excluding the Type and Length fields. The alignment requirement for this option is 4n.
The sub-option format has an ANI Type field, an 8-bit unsigned integer giving the type of the sub-option, and an ANI Length field, an 8-bit unsigned integer giving the number of octets needed to encode the option data, excluding the ANI Type and ANI Length fields. The types defined by this specification are 0 for reserved, 1 for the Network-Identifier sub-option, 2 for the Geo-Location sub-option, and 3 for the Operator-Identifier sub-option.
The option is a small header followed by one or more sub-options, each with a type number and a length. A message may carry only one copy of the option, but the option may carry several different sub-options.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
TYPE | Type | 1 byte | 52 | Must be 52, identifying the Access Network Identifier option. |
LENGTH | Length | 1 byte | Length in octets of the option, excluding the Type and Length fields. The sub-options follow. |
§3.1The Three Sub-Options
The Network-Identifier sub-option carries the name of the access network to which the mobile node is attached, such as an SSID in the case of an IEEE 802.11 access network or a PLMN identifier in the case of 3GPP access. There must be no more than a single instance of this sub-option in any Access Network Identifier option. Its ANI Type is 1, and its ANI Length, the total length excluding the ANI Type and ANI Length fields, can be in the range of 5 to 32 octets.
The sub-option also carries a 1-bit flag saying whether the network name is encoded in UTF-8, a reserved field that must be set to zero on sending and ignored on receipt, an 8-bit network name length that must not be set to zero, the network name itself, an 8-bit access point name length which must be zero if the access point name is not included, and the access point name. The type of the network name depends on the access technology: for 802.11 access it must be the SSID, for 3GPP access it is the PLMN identifier, and for 3GPP2 access it is the Access Network Identifier. When encoding the PLMN identifier, both the Mobile Network Code and the Mobile Country Code must be 3 digits, so a 2-digit network code must be preceded with a zero, and the encoding must be UTF-8. The access point name is the name of the physical access point to which the mobile node is attached. While the network name identifies the operator's access network, the access point name identifies a specific device in it, and in some deployments it can be set to the MAC address of the device or another unique identifier that the operator's policy systems can use to identify it unambiguously. It is carried in UTF-8.
The Geo-Location sub-option carries the geographic location of the network to which the mobile node is attached, as known to the mobile access gateway. Its ANI Type is 2 and its ANI Length must be 6. It encodes the coordinates of an ellipsoid point based on the coordinate reference system specified in the World Geodetic System 1984. The latitude is a 24-bit value encoded as a two's complement fixed point number with 9 whole bits, where positive degrees correspond to the Northern Hemisphere and negative degrees to the Southern Hemisphere, and the value ranges from -90 to +90 degrees. The longitude is a 24-bit value encoded in the same way, ranging from -180 to +180 degrees.
The Operator-Identifier sub-option carries the operator identifier of the access network. Its ANI Type is 3. An 8-bit Op-ID Type field gives the type of the identifier, with 0 reserved, 1 meaning a variable-length Private Enterprise Number encoded in network byte order, and 2 meaning the realm of the operator. The maximum PEN value depends on the ANI Length and is calculated as 2 to the power of (ANI_length minus 1) times 8, minus 1, so an ANI Length of 4 allows PENs from 0 to 2^24-1, that is from 0 to 16777215, using 3 octets of operator identifier space. A realm of the operator is required to be unique, is piggybacked on the administration of the DNS namespace, meets the syntactic requirements of the Preferred Name Syntax, and is encoded as US-ASCII; 3GPP specifications also define realm names that can be used to convey PLMN identifiers. The operator identifier is up to 253 octets, and must not be empty for the identifiers defined in this specification.
Three pieces of information, each optional. Which network and which access point the device is on. Where that network physically is, as a latitude and longitude. And a number or a DNS name for the company that runs it.
- 0Reserved
- 1Network-Identifier sub-option — The name of the access network and the access point.
- 2Geo-Location sub-option — The latitude and longitude of the network.
- 3Operator-Identifier sub-option — The identity of the operator running the network.
| Field | Name | Size | Value | Description |
|---|---|---|---|---|
ANI-TYPE | ANI Type | 1 byte | 2 | Must be 2, indicating the Geo-Location sub-option. |
ANI-LENGTH | ANI Length | 1 byte | 6 | Must be 6. |
LATITUDE | Latitude Degrees | 3 bytes | Two's complement fixed point with 9 whole bits, from -90 to +90 degrees. | |
LONGITUDE | Longitude Degrees | 3 bytes | Two's complement fixed point with 9 whole bits, from -180 to +180 degrees. |
- 0Reserved
- 1Private Enterprise Number — A variable-length PEN in network byte order. The largest value is 2^((ANI_length-1)*8)-1, so an ANI Length of 4 allows 0 to 16777215.
- 2Realm of the operator — A DNS realm name, encoded as US-ASCII.
§4Protocol Considerations
The conceptual Binding Update List entry data structure maintained by the mobile access gateway must be extended to store the access-network-related information elements associated with the current session, with parameters defined for the Network-Identifier, the Operator-Identifier and the Geo-Location. If the mobile access gateway is configured to support the option, it should include it with the specific sub-options in all Proxy Binding Update messages, including those for lifetime extension and for deregistration, that it sends to the local mobility anchor, and it should include the sub-options it is configured to carry.
The access network information elements are typically configured statically on the mobile access gateway on a per-interface basis, for example access point AP-1 attached through interface-1 with a given SSID and geo-location. In some deployments the information can also be obtained dynamically, such as through the DHCP Relay Agent Information option: when the mobile node sends a DHCP request, the access points typically add the SSID information to Option 82, and the mobile access gateway can parse it to obtain the SSID name. It can also be obtained from the DHCPv6 GeoLoc option. The details of how the gateway obtains the elements are access technology and deployment specific and outside the scope of the document.
Each sub-option has its own configuration flag. If the flag for a sub-option is set to 1, the gateway should include that sub-option in the Proxy Binding Update; if the gateway is unable to obtain the information it must not include the sub-option. The access network operator should obtain an identifier from the Private Enterprise Number registry in order for the gateway to carry the operator identifier, and if the operator has not obtained one, or the gateway cannot learn the identity for other administrative reasons, the gateway must not include the sub-option.
If the gateway had included the option in the Proxy Binding Update, the Proxy Binding Acknowledgement received from the local mobility anchor should contain the option with the specific sub-options. If the gateway receives an acknowledgement with a successful status value but without the option, it should log the event and, based on its local policy, may proceed to terminate the mobility session, because it then knows the anchor does not understand the option and may consider it a misconfiguration of the Proxy Mobile IPv6 domain.
On the anchor side, the conceptual Binding Cache entry must be extended with parameters for the Network-Identifier, the Geo-Location and the Operator-Identifier. On receiving a Proxy Binding Update with the option, the anchor must process it and update the corresponding fields in the Binding Cache entry; if the option is not understood, it will skip it. If the anchor understands the option and also supports the sub-options, it must echo the option back with the specific sub-options it accepted in the Proxy Binding Acknowledgement, and the sub-options defined in this specification must not be altered by the anchor. If the received Proxy Binding Update does not include the option, the mobility session must be updated to remove any access network information elements. The anchor may choose to use the sub-options for applying access-operator-specific handling or policing of the mobile node traffic, and the details of how are outside the scope of the document.
Both ends have a switch for each piece of information, off by default. The gateway turns them on to include the information, the anchor turns them on to accept it, and the anchor sends back exactly what it accepted so the gateway knows the other side understood.
| Task | Mobile access gateway | Local mobility anchor |
|---|---|---|
| Store the information | Extends the Binding Update List entry with the Network-Identifier, Operator-Identifier and Geo-Location | Extends the Binding Cache entry with the Network-Identifier, Geo-Location and Operator-Identifier |
| Send and answer | Should include the option in Proxy Binding Update messages when configured to | Must echo back the sub-options it accepted, unaltered |
| When the option is absent | Should log the event and may terminate the session | Must remove any access network information from the session |
§5IANA Considerations
Three IANA actions were completed. First, a new mobility header option, the Access Network Identifier, was defined, with the type value 52 assigned from the same numbering space as the other mobility options. Second, a new mobility sub-option format, the Access Network Information sub-option, was defined, with the type values managed by IANA under the registry for Access Network Information sub-option type values; the values 0 for reserved, 1 for the Network-Identifier sub-option, 2 for the Geo-Location sub-option and 3 for the Operator-Identifier sub-option are reserved by this specification, and approval of new values is through IANA Expert Review. Third, the Operator-Identifier sub-option introduces a new number space for the Op-ID Type field, managed under the Operator-Identifier Type Registry, with 0 reserved, 1 for an operator identifier as a variable-length Private Enterprise Number and 2 for the realm of the operator, again approved through IANA Expert Review.
IANA keeps two short lists: the kinds of sub-option the option can hold, and the kinds of operator identifier. Both are worked out by expert review rather than by general agreement.
§7Security Considerations
The Access Network Information option is for use in Proxy Binding Update and Proxy Binding Acknowledgement messages, is carried like any other mobility header option, and does not require any special security considerations.
The Geo-Location sub-option exposes the geographic location of the network to which the mobile node is attached. This information is considered to be very sensitive, so care must be taken to secure the Proxy Mobile IPv6 signaling messages when carrying this sub-option. The base Proxy Mobile IPv6 specification specifies the use of IPsec for securing the signaling messages, and those mechanisms can be enabled to protect this information. Operators can potentially apply IPsec Encapsulating Security Payload with confidentiality and integrity protection for the location information.
Access-network-specific information elements that the mobile access gateway sends may have been dynamically learned over DHCP or using other protocols. If proper security mechanisms are not in place, the exchanged information may be compromised, with the mobile access gateway sending incorrect access network parameters to the local mobility anchor. That may result in incorrect service policy enforcement at the anchor and impact other services that depend on the access network information. The threat can be mitigated by ensuring the communication path between the mobile access gateway and the access points is properly secured by the use of IPsec, Transport Layer Security, or other security protocols.
The option itself needs no special protection, but the location it can carry is private. Encrypt the signalling that carries it, and make sure the path the gateway learns the access network details over cannot be tampered with.
- The location is sensitiveThe Geo-Location sub-option reveals where the network is, so the signalling carrying it should be protected with IPsec.
- The information may be wrongIf the path the gateway learns the access details over is not secured, a bad value can lead to the wrong policy being applied.
- The option itself needs nothing specialIt is carried like any other mobility header option, so no additional security rules apply to it.