Internet DRAFT - draft-cao-dhc-anqp-option
draft-cao-dhc-anqp-option
Internet Engineering Task Force Z. Cao
Internet-Draft T. Sun
Intended status: Informational China Mobile
Expires: April 25, 2013 S. McCann
Research in Motion
October 22, 2012
DHCPv4 and DHCPv6 Options for Access Network Query Protocol Servers
draft-cao-dhc-anqp-option-01
Abstract
This document defines a DHCPv4 option and DHCPv6 option of the Access
Network Query Protocol (ANQP) server address. These options are used
to configure the ANQP server addresses on the Access Point of WLAN
system.
Status of this Memo
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This Internet-Draft will expire on April 25, 2013.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. DHCPv4 Option of ANQP Server Address . . . . . . . . . . . . . 4
4. DHCPv6 Option of ANQP Server Address . . . . . . . . . . . . . 5
5. Advertisement Server Type . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Access Network Query Protocol (ANQP) was defined by IEEE 802.11u Task
Group [IEEE-ELEVENU]and is now integrated into the 802.11-2012
specification suite. And ANQP has been further extended by the
Hotspot 2.0 Technical Group of Wi-Fi Alliance (WFA), and it has been
included in the representative certification program called
"Passpoint" [PASSPOINT].
ANQP is an example of the query protocol for access network
information retrieval, and it is transported by the IEEE 802.11
defined Generic Advertisement Service (GAS) Public Action frames.
GAS enables a WLAN client (e.g., a STA) to exchange messages with an
advertisement server (e.g., an ANQP server) in the pre-association
state, i.e., prior to association. With the information retrieved
via this server, the WLAN client connection manager can make informed
selection among multiple access networks. One example of using ANQP
is that the WLAN client in a roaming environment can select the
correct visited access network that has roaming relationship with its
home service provider without user intervention.
In a scalable deployment environment, the ANQP server will not be
placed on the Access Point (AP), rather it should be placed on a
centralized device that serves different APs. The AP will forward
the ANQP message on the IP network between AP and ANQP Server. Then
the problem of configuring the ANQP server address on the AP arises.
This document defines a DHCPv4 option and DHCPv6 option of the ANQP
server addresses. As introduced above, these options are used to
configure the ANQP server addresses on the APs. This document also
defines the "Advertisement Protocol Type" field in the DHCPv4/v6
options which can be extended to configure other types of
advertisement protocols servers.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology
ANQP: Access Network Query Protocol. ANQP is an example of a query
protocol for access network information retrieval transported by
Generic Advertisement Service (GAS) Public Action frames defined in
IEEE 802.11. ANQP message exchanges happen before network
association. ANQP is defined in the IEEE 802.11 specification and
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has been further extended by the Wi-Fi Alliance.
ANQP Server: ANQP Server is the network entity that terminates and
responds to ANQP enquiries. In a scalable deployment, the ANQP
Server is placed in centralized device and administrated by the Wi-Fi
server provider.
IEEE 802.11u: IEEE 802.11u-2011 is an amendment to the IEEE 802.11-
2007 standard that added features that improve interworking with
external networks. It is now incorporated within IEEE 802.11-2012.
A key amendment to IEEE 802.11-2012 is the capability of WLAN client
network discovery and selection.
Passpoint: Wi-Fi Alliance Certified Program Name. The technical
specification of Passpoint is based on the output of the WFA Hotspot
2.0 (HS2.0) Technical Task Group. HS2.0 defines further vendor
specific ANQP options and has developed a test plan for Passpoint
certification.
RLQP: Registered Location Query Protocol. This is an additional
advertisement protocol defined by IEEE 802.11af [RLQP] (TV White
Spaces), which assists with location information, but operates as a
separate RLQP Server. The RLQP Server and ANQP Server may be co-
located.
3. DHCPv4 Option of ANQP Server Address
This section describes the ANQP Server Address Option for DHCPv4.
The option layout is depicted below Figure 1:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Code | Length_1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length_2 | IPv4 Address (0-15) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (16-31) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: ANQP Server Address Option for DHCPv4
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Option Code: OPTION-IPv4_Address-Adv-Server
Length_1 Length (in bytes) of the option excluding the 'Option Code'
and the 'Length_1' fields;
Type (Advertisement Server Type): Indicates the type of the
advertisement server. There are different advertisement servers
defined in 802.11, including ANQP and RLQP. The values of those
server types are discussed in Section 5.
Length_2: Length (in bytes) of the IPv4 addresses of the
advertisement server; its value equals four times of the number of
IPv4 addresses (4*N);
IP Address: IPv4 address(es) of ANQP server(s)
Note: Length_2 is necessary because there are multiple types of
advertisement servers and each has different number of IPv4 addresses
configured.
4. DHCPv6 Option of ANQP Server Address
This section describes the ANQP Server Address Option for DHCPv6.
The option layout is depicted below Figure 2:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Code | Length_1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length_2 | IPv6 Address (0-15) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Address(16-127) |
| _______________________________|
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: ANQP Server Address Option for DHCPv6
Option Code: OPTION-IPv6_Address-Adv-Server
Length_1: Length (in bytes) of the option excluding the 'Option
Code' and the 'Length_1' fields;
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Type (Advertisement Server Type): Indicates the type of the
advertisement server. There are different advertisement servers
defined in 802.11, including ANQP and RLQP. The values of those
server types are discussed in Section 5.
Length_2: Length (in bytes) of the IPv6 addresses of the
advertisement server; its value equals 16 times of the number of
IPv6 addresses (16*N);
IP address: IPv6 address(es) of ANQP server(s)
Note: Length_2 is necessary because there are multiple types of
advertisement servers and each has different number of IPv6 addresses
configured.
5. Advertisement Server Type
There are different types of advertisement servers defined in 802.11,
including ANQP Server and RLQP Server. IEEE may define other
advertisement servers in future. To make options defined in this
document scalable to further extensions, and also avoid the need of
an individual option code for each of such advertisement servers,
this document defines the Avertisement Server Type field in both the
DHCPv4 and DHCPv6 options.
The Advertisement Server Type value of ANQP is suggested in this
document as below.
+-----------+---------------+
| Type | Value |
+-----------+---------------+
| Reserved | 0 |
+-----------+---------------+
| ANQP | 1 |
+-----------+---------------+
| Reserved | 2-255 |
+-----------+---------------+
In addition to ANQP, other advertisement protocols have been defined
within IEEE 802.11 (e.g. RLQP). These operate in a similar manner
to ANQP, but allow information exchange with different servers than
that of the ANQP Server. The Advertisement Server Type value of
other protocols including RLQP will be extended by future work.
6. IANA Considerations
This document has the following requests to the IANA.
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Option Code for OPTION-IPv4_Address-Adv-Server in DHCPv4, as defined
in Section. 3 of this document.
Option Code for OPTION-IPv6_Address-Adv-Server in DHCPv6, as defined
in Section. 4 of this document.
Advertisement Server Type for ANQP, as defined in Section. 5 or this
document.
7. Security Considerations
If adversaries are able forge rogue ANQP Server options, the ANQP
messages will be directed to wrong servers and bogus information
about the queried access network would be injected. The DHCP
authentication option described in [RFC3315] and [RFC3118] MAY be
used to mitigate the above attacks. Lower layer security such as L2
traffic filtering and firewall SHOULD be configured prevent such
attacks.
8. References
8.1. Normative References
[IEEE-ELEVENU]
IEEE, "IEEE 802.11u Specification", 2011, <http://
standards.ieee.org/findstds/standard/802.11-2012.html>.
[PASSPOINT]
Wi-Fi Alliance, "Wi-Fi CERTIFIED Passpoint", 2012, <http:/
/www.wi-fi.org/discover-and-learn/
wi-fi-certified-passpoint>.
[RLQP] "Wireless LAN in the TV White Space", 2012,
<http://www.ieee802.org/11/Reports/tgaf_update.htm>.
8.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3118] Droms, R. and W. Arbaugh, "Authentication for DHCP
Messages", RFC 3118, June 2001.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
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Authors' Addresses
Zhen Cao
China Mobile
Xuanwumenxi Ave. No. 32
Beijing, 100871
China
Phone: +86-10-52686688
Email: zehn.cao@gmail.com, caozhen@chinamobile.com
Tao Sun
China Mobile
Xuanwumenxi Ave. No. 32
Beijing, 100871
China
Phone: +86-10-52686688
Email: suntao@chinamobile.com
Stephen McCann
Research in Motion
200 Bath Road
Slough, SL1 3XE,
United Kingdom
Phone: +44 1754 66700
Fax:
Email: smccann@rim.com
URI:
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