Internet-Draft | WBA Connect-Info | October 2024 |
Grayson, et al. | Expires 18 April 2025 | [Page] |
- Workgroup:
- RADEXT Working Group
- Internet-Draft:
- draft-grayson-connectinfo-00
- Published:
- Intended Status:
- Informational
- Expires:
A syntax for the RADIUS Connect-Info attribute used in Wi-Fi networks
Abstract
This document describes a syntax for the Connect-Info attribute used with the Remote Authentication Dial In User Service (RADIUS) protocol, enabling clients to provide servers information pertaining to the operation of an IEEE 802.11 wireless network.¶
Status of This Memo
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This Internet-Draft will expire on 18 April 2025.¶
Copyright Notice
Copyright (c) 2024 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 (https://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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
1. Introduction
The Connect-Info attribute is defined in [RFC2865] to enable a Network Access Server (NAS) to indicate to a RADIUS server "the nature of the user's connection". [RFC2869] includes the recommendation that:¶
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The connection speed SHOULD be included at the beginning of the first Connect-Info attribute in the packet. If the transmit and receive connection speeds differ, they may both be included in the first attribute with the transmit speed first (the speed the NAS modem transmits at), a slash (/), the receive speed, then optionally other information.¶
but where the definition of "speed" is not defined in [RFC2869].¶
The Connect-Info attribute can be sent in both Access-Request and Accounting-Request messages, as shown in Figure 1.¶
Many NAS implementations have implemented the Connect-Info attribute. Wi-Fi vendors supporting the Connect-Info attribute start the text field with "CONNECT" that is typically followed by a floating point value representing the maximum connection speed in Mbps. Implementations follow this with text information about the 802.11 version supported, as illustrated in Figure 2.¶
Other implementations have extended this baseline to signal additional information to the RADIUS server, as illustrated in Figure 3¶
The Wireless Broadband Alliance (WBA) defines the Wireless Roaming Intermediary eXchange (WRIX) framework, aimed at facilitating interconnectivity between Wi-Fi operators and the Wi-Fi roaming hub services, the Carrier Wi-Fi Services program that provides guidelines to improve customer experience on Carrier Wi-Fi networks, as well as the technical and legal frameworks that support the OpenRoaming federation of access and identity providers, enabling an automatic and secure Wi-Fi roaming experience globally [I-D.tomas-openroaming].¶
As part of its work program, the WBA has identified a number of use-cases that benefit from being able to share Wi-Fi access network quality metrics between a NAS and a server, including where the NAS is operated by an OpenRoaming Access Network Provider (ANP) and the server is operated by an OpenRoaming Identity Provider (IDP).¶
The rest of this document describes a syntax for the Connect-Info attribute that is simultaneously able to support existing vendor implementations, while being enhanced with additional optional information to support new use-cases and requirements.¶
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
1.2. Terminology
Access Network Provider (ANP):¶
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A Wi-Fi operator that has configured its Wi-Fi equipment to support inbound roaming of users.¶
Identity Provider (IDP):¶
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An entity that authenticates end-user Wi-Fi devices onto ANP networks.¶
Received Signal Strength Indicator (RSSI):¶
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A measurement of the power level that is received by an antenna from a wireless device.¶
Wireless Roaming Intermediary eXchange (WRIX):¶
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A framework, aimed at facilitating interconnectivity between operators and the Wi-Fi roaming hub services.¶
2. Types of Connect-Info Metrics
The access network characteristics that can be shared between NAS and AAA include those that can be used to derive a quality metric of the performance of a Wi-Fi network. These include characteristics associated with the IEEE 802.11 connection:¶
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the Wi-Fi 802.11 version,¶
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the Wi-Fi channel number, and¶
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the Wi-Fi transmit and receive bit rates.¶
Other use cases benefit from being able to share characteristics able to be calculated by the Wi-Fi access point's 802.11 driver, including:¶
Still other use cases benefit from sharing characteristics pertaining to the static configuration of the Wi-Fi network, including:¶
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the configured value of the minimum RSSI level for a device to associate/authenticate to the access point.¶
Finally, other quality characteristics include measured values of:¶
The identified use cases include those where the metrics shared using the Connect-Info attribute are compared between different Wi-Fi systems, that may be operated using equipment from different vendors. In such a scenario, the algorithm used to generate a quality metric on a first installation may be different from the algorithm used to generate the same quality metric in a second installation. In order to facilitate comparisons in such a situation, there are benefits in sharing additional information pertaining to how a quality metric is calculated. This additional information includes:¶
3. ABNF syntax for Connect-Info
The Augmented Backus-Naur form (ABNF) is a syntax for specifications defined in [RFC5234]. The proposed ABNF syntax for the text of the Connect-Info attribute is shown below. The ABNF syntax allows measured¶
4. Example encoding in Access-Request
The Connect-Info attribute value is limited to 253 bytes. Example encodings using the ABNF definition are illustrated in Figure 5, indicating that the metrics can be signaled while keeping the attribute size below 253 bytes. In these examples, less than 180 bytes are used to encode the access network metric information.¶
5. Implementations
A proof of concept has been built using modified hostapd code (https://w1.fi/) that is able to populate the connect-info attributes according to the syntax defined above.¶
7. IANA Considerations
To be completed.¶
8. References
8.1. Normative References
- [RFC2119]
- Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
- [RFC8174]
- Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.
8.2. Informative References
- [I-D.tomas-openroaming]
- Tomas, B., Grayson, M., Canpolat, N., Cockrell, B. A., and S. Gundavelli, "WBA OpenRoaming Wireless Federation", Work in Progress, Internet-Draft, draft-tomas-openroaming-03, , <https://datatracker.ietf.org/doc/html/draft-tomas-openroaming-03>.
- [RFC2865]
- Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, DOI 10.17487/RFC2865, , <https://www.rfc-editor.org/rfc/rfc2865>.
- [RFC2869]
- Rigney, C., Willats, W., and P. Calhoun, "RADIUS Extensions", RFC 2869, DOI 10.17487/RFC2869, , <https://www.rfc-editor.org/rfc/rfc2869>.
- [RFC5234]
- Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, , <https://www.rfc-editor.org/rfc/rfc5234>.
Acknowledgements
The authors would like to thank all the members of the WBA's Access Network Metrics project team who help review and refine the Connect-Info syntax.¶