A syntax for the RADIUS Connect-Info attribute used in Wi-Fi networks
draft-grayson-connectinfo-00
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Mark Grayson , Joshua Redmore , Sri Gundavelli , Bruno Tomas , Michael Sym | ||
| Last updated | 2024-10-14 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-grayson-connectinfo-00
RADEXT Working Group M. Grayson
Internet-Draft Cisco Systems
Intended status: Informational J. Redmore
Expires: 18 April 2025 CableLabs
S. Gundavelli
Cisco Systems
B. Tomas
Wireless Broadband Alliance
M. Sym
Single Digits
15 October 2024
A syntax for the RADIUS Connect-Info attribute used in Wi-Fi networks
draft-grayson-connectinfo-00
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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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.
Grayson, et al. Expires 18 April 2025 [Page 1]
Internet-Draft WBA Connect-Info October 2024
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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Types of Connect-Info Metrics . . . . . . . . . . . . . . . . 4
3. ABNF syntax for Connect-Info . . . . . . . . . . . . . . . . 5
4. Example encoding in Access-Request . . . . . . . . . . . . . 9
5. Implementations . . . . . . . . . . . . . . . . . . . . . . . 9
6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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:
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.
+--------------------------------------------------------------+
| Attribute | Request | Accept | Reject | Challenge | Acct-Req |
+--------------------------------------------------------------+
| Connect- | 0-1 | 0 | 0 | 0 | 0+ |
| Info (77) | | | | | |
+--------------------------------------------------------------+
Grayson, et al. Expires 18 April 2025 [Page 2]
Internet-Draft WBA Connect-Info October 2024
Figure 1: RFC2869 defined occurrence rules for Connect-Info attribute
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.
Connect-Info = "CONNECT 11.00 Mbps 802.11b"
Figure 2: Example #1 Wi-Fi Connect-Info attribute
Other implementations have extended this baseline to signal
additional information to the RADIUS server, as illustrated in
Figure 3
Connect-Info = "CONNECT 54.00 Mbps / 802.11n / RSSI: 53 / Channel: 1"
Figure 3: Example #2 Wi-Fi Connect-Info attribute
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.
Grayson, et al. Expires 18 April 2025 [Page 3]
Internet-Draft WBA Connect-Info October 2024
1.2. Terminology
Access Network Provider (ANP):
A Wi-Fi operator that has configured its Wi-Fi equipment to
support inbound roaming of users.
Identity Provider (IDP):
An entity that authenticates end-user Wi-Fi devices onto ANP
networks.
Received Signal Strength Indicator (RSSI):
A measurement of the power level that is received by an antenna
from a wireless device.
Wireless Roaming Intermediary eXchange (WRIX):
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:
* the Wi-Fi 802.11 version,
* the Wi-Fi channel number, and
* 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:
* frame loss rate, and
* frame retry rate.
Still other use cases benefit from sharing characteristics pertaining
to the static configuration of the Wi-Fi network, including:
* the configured value of the minimum RSSI level for a device to
associate/authenticate to the access point.
Grayson, et al. Expires 18 April 2025 [Page 4]
Internet-Draft WBA Connect-Info October 2024
Finally, other quality characteristics include measured values of:
* received signal strength indicator (RSSI),
* airtime utilization, and
* noise floor.
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:
* whether a calculation represents an average or a median value,
* whether an average value represent a linear or exponential moving
average, and
* the configuration of the time duration over which a metric was
calculated.
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
;-----------------------------------------------------------------------
; Connect-Info RADIUS Attribute #77 Syntax
;-----------------------------------------------------------------------
connect-info-77 = "CONNECT" *SP connectAttribute
*( DELIMITER connectAttribute )
connectAttribute = (MAXSPEED " Mbps") / PHYRATE
; indication of maximum
; achievable data rate
connectAttribute =/ "802.11" WIFIGEN ; Wi-Fi 802.11 version
;-----------------------------------------------------------------------
; connectAttributes - NON-DEVICE/CLIENT RELATED.
Grayson, et al. Expires 18 April 2025 [Page 5]
Internet-Draft WBA Connect-Info October 2024
;
; These key-value pairs MAY be included in the Connect-Info attribute
; when the attribute is included in the Access-Request or
; Accounting-Request message.
;-----------------------------------------------------------------------
connectAttribute =/ "Channel:" *SP CHANNUM ; Wi-Fi channel number
connectAttribute =/ "Band:" *SP ("2.4"/"5"/"6")
; the Wi-Fi band - used to
; differentiate between
; re-use of channel
; numbers in 6 GHz
connectAttribute =/ "RSSI-min:" *SP SS ; the absolute value of
; configured minimum RSSI
; in dBm on the WLAN
; Access Point
connectAttribute =/ "Noise:" *SP SS ["(" CALC ")"]
; the absolute value of
; current noise floor
; in the operating band
; measured in dBm and
; optionally the
; algorithm used to
; calculate the value
connectAttribute =/ "ChanUtil:" *SP PCT ["(" CALC ")"]
; percentage of time AP
; considers channel busy
; due to 802.11 traffic,
; encoded as an integer %
; and optionally the
; algorithm used to
; calculate the value
;-----------------------------------------------------------------------
; connectAttributes - DEVICE/CLIENT RELATED
;
; The calculation of FrameLoss and FrameRetry attributes benefit from
; being based on a number of frames exchanged between device and access
; point. Their inclusion in the Connect-Info attribute MAY be limited to
; use cases where the attribute is included in the Accounting-Request
; message when the Acct-Status-Type has a value of Interim-Update or
; Stop.
;-----------------------------------------------------------------------
Grayson, et al. Expires 18 April 2025 [Page 6]
Internet-Draft WBA Connect-Info October 2024
connectAttribute =/ "RSSI:" *SP SS ["(" CALC ")"]
; the absolute value of
; Station RSSI in dBm and
; optionally the
; algorithm used to
; calculate the value
connectAttribute =/ "TxBitRate:" *SP RATE ; the latest TxRate used
; by the AP to send to
; the device
connectAttribute =/ "RxBitRate:" *SP RATE ; the latest RxRate used
; by the AP to receive
; from the device
connectAttribute =/ "FrameLoss:" *SP PCT ; the average 802.11 frame
; loss rate experienced,
; encoded as an integer %
connectAttribute =/ "FrameRetry:" *SP PCT ; the average 802.11 frame
; retry rate experienced,
; encoded as an integer %
;-----------------------------------------------------------------------
; Definitions
;-----------------------------------------------------------------------
MAXSPEED = (DIGIT / (NZDIGIT DIGIT) / (NZDIGIT DIGIT DIGIT) /
(NZDIGIT DIGIT DIGIT DIGIT) /
(NZDIGIT DIGIT DIGIT DIGIT DIGIT)) "." DIGIT DIGIT
; Maximum AP to Device speed in Mbps,
; (0.00 - 99999.99), calculated as:
; SC * MD * CR * SS / (SYM + GD)
; where:
; SC = Number of Data Sub-Carriers
; CR = Coding Rate, e.g., 0.5 (BPSK), 0.75 (256QAM)
; MD = Modulation rate (1-8),
; where 2^MD = num mod'n states
; SS = number of spatial streams
; SYM = symbol interval (micro-seconds)
; GD = guard interval (micro-seconds)
PHYRATE = "MaxRate" *SP "MCS" (DIGIT/(NZDIGIT DIGIT)) "-"
NZDIGIT "SS"
; where the digits after "MCS" corresponds to the
; Modulation and Coding Scheme and the digits
; preceding "SS" correspond to the number of
; spatial streams
Grayson, et al. Expires 18 April 2025 [Page 7]
Internet-Draft WBA Connect-Info October 2024
RATE = (DIGIT / (NZDIGIT DIGIT) / (NZDIGIT DIGIT DIGIT) /
(NZDIGIT DIGIT DIGIT DIGIT))
WIFIGEN = "b" / "g" / "a" / "n" / "ac" / "ax" / "be"
SS = DIGIT / (NZDIGIT DIGIT) / ("1" DIGIT DIGIT)
; Absolute value of Received Signal Strength when
; expressed in dBm
; e.g. 41 represents -41 dBm
CHANNUM = NZDIGIT / (NZDIGIT DIGIT) / ("1" DIGIT DIGIT) /
("2" U4DIGIT DIGIT)
; Encoding for Channel Numbers (1 - 249)
PCT = DIGIT / (NZDIGIT DIGIT) / "100"
; Percentage (0 - 100)
CALC = METRIC [ "-" ALG ]
METRIC = "AVG" / "MED"
; AVG indicates the metric is an average value
; MED indicates the metric is a median value
ALG = "LIN" DURATION
; LIN indicates the algorithm used is a linear
; average
ALG =/"EXP" WEIGHT
; EXP indicates the algorithm used is an exponential
; moving average
DURATION = ( DIGIT / (NZDIGIT DIGIT)/(NZDIGIT DIGIT DIGIT) ) "S"
; The duration in seconds over which an algorithm
; operates
WEIGHT = NZDIGIT
; where the exponential weighting is 2^WEIGHT
DELIMITER = SLASH / 1*SP
; existing vendor delimiters
SP = %x20
SLASH = *SP %x2F *SP
DIGIT = %x30-39 ; 0-9
NZDIGIT = %x31-39 ; 1-9
U4DIGIT = %x30-34 ; 0-4 (up to 4)
Grayson, et al. Expires 18 April 2025 [Page 8]
Internet-Draft WBA Connect-Info October 2024
Figure 4: ABNF definition for encoding of Connect-Info text field
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.
Connect-Info = "CONNECT 54.00 Mbps / 802.11n / Channel: 1 / RSSI: 53"
Connect-Info = "CONNECT 400.00 Mbps 802.11ac Channel:46 RSSI:50
RSSI-min:80"
Connect-Info = "CONNECT 400.00 Mbps 802.11ac Channel:46
RSSI:48(AVG-EXP8) RSSI-min:80 Noise:94"
Connect-Info = "CONNECT 400.00 Mbps 802.11ac Channel:46
RSSI:48(AVG-EXP8) RSSI-min:80 Noise:94(MED-LIN80S)
ChanUtil:25(AVG-LIN600S)"
Connect-Info = "CONNECT 400.00 Mbps 802.11ac
Channel:46 RSSI:56(AVG-EXP8) RSSI-min:80
Noise:90(MED-LIN80S) ChanUtil:35(AVG-LIN300S)
TxBitRate:150.0 RxBitRate:150.0"
Connect-Info = "CONNECT 400.00 Mbps 802.11ac Channel:46 Band:5
RSSI:56(AVG-EXP8) RSSI-min:80 Noise:90(MED-LIN80S)
ChanUtil:35(AVG-LIN300S) TxBitRate:150.0
RxBitRate:150.0 FrameLoss:3 FrameRetry:6"
Connect-Info = "CONNECT MaxRate MCS11-2SS / 802.11ax / Channel:37 /
Band:6 / RSSI:43(AVG-EXP8) / Noise:50 /
ChanUtil:2(AVG-LIN5S)"
Figure 5: Example encodings of Connect-Info attribute using ABNF
definition
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.
Grayson, et al. Expires 18 April 2025 [Page 9]
Internet-Draft WBA Connect-Info October 2024
6. Summary
To be completed.
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, March 1997,
<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,
May 2017, <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,
25 July 2024, <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, June 2000,
<https://www.rfc-editor.org/rfc/rfc2865>.
[RFC2869] Rigney, C., Willats, W., and P. Calhoun, "RADIUS
Extensions", RFC 2869, DOI 10.17487/RFC2869, June 2000,
<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, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
Grayson, et al. Expires 18 April 2025 [Page 10]
Internet-Draft WBA Connect-Info October 2024
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.
Authors' Addresses
Mark Grayson
Cisco Systems
10 New Square Park
Feltham
TW14 8HA
United Kingdom
Email: mgrayson@cisco.com
Joshua Redmore
CableLabs
858 Coal Creek Cr.
Louisville, 80027
United States of America
Email: j.redmore@cablelabs.com
Sri Gundavelli
Cisco Systems
170 West Tasman Drive
San Jose, 95134
United States of America
Email: sgundave@cisco.com
Bruno Tomas
Wireless Broadband Alliance
5000 Executive Parkway, Suite 302
San Ramon, 94583
United States of America
Email: bruno@wballiance.com
Michael Sym
Single Digits
4 Bedford Farms Drive, Suite 210
Bedford, 1608
United States of America
Email: msym@singledigits.com
Grayson, et al. Expires 18 April 2025 [Page 11]