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general RADEXT Working Group Internet-Draft Connect-Info RADIUS This document defines a set of RADIUS Vendor-Specific Attributes (VSAs) designed to encode network quality metrics that are not uniquely associated with an IEEE 802.11 (Wi-Fi) connection. These attributes enable access network quality information to be communicated between RADIUS clients and servers.

Introduction The RADIUS Connect-Info attribute is defined in to enable a Network Access Server (NAS) to indicate to a RADIUS server "the nature of the user's connection". defines a syntax for the Connect-Info attribute, enabling RADIUS clients to provide RADIUS servers information pertaining to a user's connection with an IEEE 802.11 wireless network. Reception of the Connect-Info attribute by a RADIUS server is intended to be used to assist the operator of the RADIUS server in making authorization decisions. There are use cases that benefit from sharing generic quality metric information not uniquely associated with an IEEE 802.11 Wi-Fi connection. Similar to the RADIUS Connect-Info attribute, this information is intended to assist the RADIUS server operator in making authorization decisions. This document defines a set of RADIUS Vendor Specific Attributes (VSAs) for encoding the non-802.11-connection metrics. The technique by which a server uses the information encoded in these attributes to assist in making authorization decisions is not defined in this document.

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 when, and only when, they appear in all capitals, as shown here.

Wi-Fi Quality Metrics The following metrics are defined as being not uniquely associated with the specifics of an 802.11 connection: WAN Round Trip Time (WAN-RTT) Airtime (Channel) Utilization Noise Level The number of active Wi-Fi stations Minimum RSSI (AP configuration parameter) A supported Wi-Fi Global Operating Class These attributes encode values that do not describe the properties of a specific association between a client and a Wi-Fi access point, but rather general access network characteristics. Wi-Fi access points supporting these attributes SHOULD use measurements associated with multiple Wi-Fi devices, potentially across multiple WLANs, when calculating these metrics as described in the individual attributes. These attributes MAY be sent in both Access-Request and Accounting-Request messages, as shown in .

Quality-Metric Attribute Definitions Each Quality-Metric is encoded as a separate VSA as defined in section 5.26 of using the Vendor-ID 14122 for the Wireless Broadband Alliance, Inc. The metrics are encoded using complex-data types, as described in section 3.2.3 of . While section 3.2.4 of generally discourages the use of complex data types when viable alternatives exist, this document adopts them to maintain logical cohesion between the reported metric, the calculation algorithm, and the associated algorithm parameters. This approach avoids the proliferation of fragmented, atomic VSAs that would otherwise be required to represent these metrics. By encapsulating related fields within a single VSA, this design reduces complexity in non-RADIUS systems and avoids the operational awkwardness of requiring multiple, loosely-coupled attributes to convey a single, unified measurement. This usage is consistent with the provision in section 2.1 of that states that complex data types may be employed where they reduce complexity or where basic data types would necessitate cumbersome grouping mechanisms.

WAN Round Trip Time The WAN Round Trip Time (RTT) can be measured by the Wi-Fi infrastructure using a well-known anycast IP address, e.g., linked to a DNS service, that automatically routes to the closest destination. In all cases of signalling WAN-RTT, the NAS SHOULD use multiple measurements when calculating the reported value according to the Algorithm and Algorithm-Parameter. Where the Wi-Fi access points supports multiple WLANs that operate using different policy based routing decisions, the WAN-RTT metric SHOULD only correspond to the WLAN associated with the RADIUS session.

WBA-WAN-RTT Attribute

Algorithm: An unsigned 16 bit value encoding the algorithm used to calculate the WAN-RTT parameter:

• 1 - Maximum round-trip time 2 - Minimum round-trip time 3 - Median round-trip time 4 - Linear-Average round-trip time 5 - Exponential-Average round-trip time

Algorithm-Parameter:

• An unsigned 16 bit value. When algorithm is 1, 2, 3, or 4, the value represents the time window duration in seconds. When algorithm is 5, the high byte (bits 8-15) represents the Sample Period in milliseconds, and the low byte (bits 0-7) represents the weight of the exponential moving average, where the exponential weight is 2^n (n being the value of the low byte).

WAN-RTT:

• An unsigned 32 bit value representing the calculated Wide Area Network Round Trip Time in milliseconds.

Channel Utilization Used to signal the percentage of time an access point considers the channel busy due to IEEE 802.11 traffic. In all cases of signalling Channel-Utilization, the NAS SHOULD use multiple measurements when calculating the reported value according to the Algorithm and Algorithm-Parameter. Where the Wi-Fi access point supports multiple WLANs that operate using different bands and/or radios, the reported Channel-Utilization MUST only correspond to the channel utilization associated with the signaled band/radio.

WBA-Chan-Util Attribute

Algorithm: An unsigned 16 bit value encoding the algorithm used to calculate the Channel-Utilization parameter:

• 1 - Maximum Channel Utilization 2 - Minimum Channel Utilization 3 - Median Channel Utilization 4 - Linear-Average Channel Utilization 5 - Exponential-Average Channel Utilization

Algorithm-Parameter:

• An unsigned 16 bit value. When algorithm is 1, 2, 3, or 4, the value represents the time window duration in seconds. When algorithm is 5, the high byte (bits 8-15) represents the Sample Period in milliseconds, and the low byte (bits 0-7) represents the weight of the exponential moving average, where the exponential weight is 2^n (n being the value of the low byte).

Band: An 8-bit unsigned integer representing the Wi-Fi band:

• 1 - 2.4 GHz Band 2 - 5 GHz Band 3 - 6 GHz Band

Radio:

• An 8-bit unsigned integer representing a radio instance that allows a report to distinguish between an access point with multiple radios operating using common band.

Channel-Utilization:

• A 16-bit unsigned integer representing the calculated channel utilization percentage (0-100).

Noise Used to signal the noise level in dBm as reported by the radio survey data from the access point. In all cases of signalling Noise, the NAS SHOULD use multiple measurements when calculating the reported value according to the Algorithm and Algorithm-Parameter. Where the Wi-Fi access point supports multiple WLANs that operate using different bands and/or radios, the reported noise MUST only correspond to the noise level associated with the signaled band/radio.

WBA-Noise Attribute

Algorithm: An unsigned 16 bit value encoding the algorithm used to calculate the Noise parameter:

• 1 - Maximum Noise 2 - Minimum Noise 3 - Median Noise 4 - Linear-Average Noise 5 - Exponential-Average Noise

Algorithm-Parameter:

• An unsigned 16 bit value. When algorithm is 1, 2, 3, or 4, the value represents the time window duration in seconds. When algorithm is 5, the high byte (bits 8-15) represents the Sample Period in milliseconds, and the low byte (bits 0-7) represents the weight of the exponential moving average, where the exponential weight is 2^n (n being the value of the low byte).

Band: An 8-bit unsigned integer representing the Wi-Fi band:

• 1 - 2.4 GHz Band 2 - 5 GHz Band 3 - 6 GHz Band

Radio:

• An 8-bit unsigned integer representing a radio instance that allows a report to distinguish between an access point with multiple radios operating on using common band.

Noise:

• A 16-bit signed integer, representing the calculated noise value in dBm.

Station Count Used to report the number of Wi-Fi Stations associated with a WLAN Radio. In all cases of Station-Count, the NAS SHOULD use multiple measurements when calculating the reported value according to the Algorithm and Algorithm-Parameter.

WBA-STA-Count Attribute

Algorithm: An unsigned 16 bit value encoding the algorithm used to calculate the Station-Count parameter:

• 1 - Maximum Station Count 2 - Minimum Station Count 3 - Median Station Count 4 - Linear-Average Station Count

Algorithm-Parameter:

• An unsigned 16 bit value representing the time window duration in seconds.

Band: An 8-bit unsigned integer representing the Wi-Fi band:

• 1 - 2.4 GHz Band 2 - 5 GHz Band 3 - 6 GHz Band

Radio:

• An 8-bit unsigned integer representing a radio instance that allows a report to distinguish between an access point with multiple radios operating on using common band.

Station-Count:

• A 16-bit unsigned integer representing the calculated station count.

Minimum RSSI An Wi-Fi access point configuration parameter representing the minimum RSSI level for a device to associate/authenticate to the access point.

WBA-Min-RSSI Attribute

Band: An 8-bit unsigned integer representing the Wi-Fi band:

• 0 - Identical for all bands 1 - 2.4 GHz Band 2 - 5 GHz Band 3 - 6 GHz Band

Radio:

• An 8-bit unsigned integer representing a radio instance that allows a report to distinguish between an access point with multiple radios operating on using common band.

Min-RSSI:

• A 16-bit signed integer representing the configured value of RSSI-min in dBm.

WBA-Wi-Fi-Global-OC Used to signal a Global Operating Class which in turn encodes band and channel bandwidth information.

WBA-Wi-Fi-Global-OC Attribute

Supported-OC:

• An 8 bit unsigned integer representing a supported operating class broadcast by the AP, as defined in Annex E.

Encoding All multi-byte integer fields defined in this document are encoded in network byte order (Big-Endian). Where the NAS is using the RADIUS Connect-Info attribute to report information pertaining to a user's connection with an IEEE 802.11 wireless network, a NAS supporting a particular sub-type that includes the definition of Band/Radio sub-attribute, SHOULD report the sub-type value associated with the Band(s) and/or Radio(s) associated with the user's connection. The NAS MAY optionally report sub-type values associated with other Band(s) and/or Radio(s) not associated with the user's connection.

Security Considerations This document describes a set of vendor specific attributes that enables a RADIUS client to provide a RADIUS server quality metric information pertaining to the operation of an IEEE 802.11 wireless network. The terms agreed between the operator of the RADIUS client and the operator of the RADIUS server SHOULD include restrictions on the use of such non-personal information by the operator of the RADIUS server, for example limiting the use of such information to making RADIUS server authorization decisions and prohibiting a RADIUS server from disclosing information signalled to any third-party.

IANA Considerations This document has no IANA Actions.

In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document describes a protocol for carrying authentication, authorization, and configuration information between a Network Access Server which desires to authenticate its links and a shared Authentication Server. [STANDARDS-TRACK] This document describes additional attributes for carrying authentication, authorization and accounting information between a Network Access Server (NAS) and a shared Accounting Server using the Remote Authentication Dial In User Service (RADIUS) protocol described in RFC 2865 and RFC 2866. This memo provides information for the Internet community. This document provides guidelines for the design of attributes used by the Remote Authentication Dial In User Service (RADIUS) protocol. It is expected that these guidelines will prove useful to authors and reviewers of future RADIUS attribute specifications, within the IETF as well as other Standards Development Organizations (SDOs). This memo documents an Internet Best Current Practice. Cisco Systems CableLabs This document describes a syntax for the Connect-Info attribute used with the RADIUS protocol, enabling RADIUS clients to provide RADIUS servers information pertaining to a user's connection with an IEEE 802.11 wireless network.

Acknowledgements The definition of network quality metrics has been inspired by WBA's deliverable on Access Network Metrics . The authors would like to thank all the members of the WBA's Access Network Metrics project team who have helped review and refine this document.

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