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general RADEXT Working Group Internet-Draft RADIUS EPCS Emergency Priority This document describes RADIUS attributes for supporting authorization of Emergency Preparedness Communication Service (EPCS), enabling authorized users to benefit from preferential access to Wi-Fi network resources during congestion.

Introduction Priority Services (PS) communications in support of National Security/Emergency Preparedness (NS/EP) services are operational in various countries around the world. While these have traditionally only been supported over cellular networks , the recent addition of Emergency Preparedness Communications Service (EPCS) functionality into Wi-Fi 7 means that Wi-Fi now supports preferred or prioritized channel access (PCA) to authorized users that can be used for Multimedia Priority Services (MPS) communications over public/private Wi-Fi networks in emergency service (ES) scenarios. Whereas Wi-Fi 7 defines the interactions between the Wi-Fi Access Point (AP) and the Wi-Fi Station (STA) device for prioritized channel access, it does not provide an end-to-end architecture for enabling EPCS authorization capability on a per device basis. CISRCVIII WG4 recommendations for FCC provide opportunities for regulatory bodies, like the FCC, to assess and promote Wi-Fi's role in emergency services . Earlier deliverables from CISRCV WG8 have provided recommendations for the role of the network within the priority services platform and to enforce priority levels on traffic associated with priority users . There are number of factors critical to this enforcement function: The priority user must be authenticated and authorized to receive priority treatment. The network must be able to uniquely identify priority user traffic and associate the authorized level of priority to that traffic. The network must then have prioritization means to apply to the identified traffic. For cases where networks interconnect, traffic prioritization indicators must be securely passed to interconnected networks for downstream prioritization. This document specifies an extension to the Remote Authentication Dial-In User Service (RADIUS) protocol that enables a Wi-Fi Network Access Server (NAS) to indicate to a RADIUS server that it is EPCS capable, as well as enabling a RADIUS server to indicate to a NAS that an authenticated user is authorized to receive the EPCS service.

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.

Terminology Authorizing Entity: Refers to the Authority (e.g., Government entity) responsible for vetting and assigning priority privileges and user priority levels to an individual or organization. Priority Services: A feature designed to enable NS (National Security) or EP (Emergency Preparedness) subscribers to make priority calls or data session on a Service Providers network, particularly at times of congestion. Service user: Means an individual or organization to whom or which a priority access assignment has been made. Wireless service provider: Refers to a provider of a wireless communications service or Internet Protocol-based service, including commercial or private mobile service. The term includes agents of the licensed provider and resellers of wireless service.

Overview of EPCS Provisioning This section first provides background on how MPS service is currently provisioned and authorized. The section then describes how that can be adapted for EPCS to support Wi-Fi use cases. The service user engages with an authorizing entity to request the provision of Multimedia Priority Service for a device that has a subscription with a service provider. The service provider, such as a cellular operator, will receive an indication from the authorizing entity, by an out of band mechanism, that a subscriber has been authorized for priority services and will store such an indication as part of the subscription profile of the subscriber (e.g., in the Home Subscriber Server (HSS)). illustrates the scenario where the service provider is a cellular operator that is also operating as a Wi-Fi Identity Provider. In such cases, the operator can mirror the authorization information in their Wi-Fi Authentication, Authorization and Accounting (AAA) system.

| | | | | | | |2. Receive Priority | | | Authorization | | | 3. Mirror HSS | (unchanged) | | | Authorization |<===============>| | | in Wi-Fi AAA | | | | //========| | | | || | | | | \\=======>| | | | | | | | | | ]]>

EPCS Authorization RADIUS Exchange The top level RADIUS Authorization flow for an EPCS Service User is illustrated in . In step 1, the EPCS enabled Wi-Fi Access Network provider configures the EPCS Roaming Consortium on its Wi-Fi access network. In step 2, the Wi-Fi Priority Service User enables an EPCS Passpoint profile on their device. This enables normal Passpoint automatic network selection. In step 3, the Wi-Fi Priority Service User's device matches the EPCS Roaming Consortium in the Wi-Fi beacon, probe response or Access Network Query Protocol (ANQP) response with its Passpoint profile. In steps 4 and 5, the Wi-Fi device triggers an association with the Wi-Fi Access Point/Wireless LAN Controller (AP/WLC). The device includes the EPCS Passpoint Roaming Consortium Organizational Indicator (RCOI) in the Roaming Consortium Selection element and receives an association response. In steps 6 and 7, the AP/WLC performs the Extensible Authentication Protocol exchange over the LAN using EAPOL frames exchanged with the device, requesting the devices EAP identity and receives the corresponding identity associated with the EPCS Passpoint profile in the EAP response. In step 8, the AP/WLC extracts the EAP identity and includes this in a RADIUS Access-Request that is sent to the Identity Provider. In this example, the identity realm corresponds to a Cellular operator as defined in , e.g., wlan.mnc100.mcc313.3gppnetwork.org. The AP/WLC adds the Civic-Location attribute to the RADIUS Access-Request, indicating the country code of the regulatory regime in which it is operating, the HS2.0-Roaming-Consortium attribute indicating the EPCS Passpoint RCOI signaled by the device in step 4, and the EPCS-Capable-Indication attribute, as specified in . If the Wi-Fi AP/WLC is expecting to receive payment for handling the priority service traffic, the AP/WLC can include additional attributes related to charging, for example the offered WBA-Linear-Volume-Rate . In step 9. the EAP dialogue completes between the supplicant in the Wi-Fi device and the Cellular Operator's EAP server. In step 10, the authenticated device is matched against the priority subscription profile. The provider MAY use the country code signalled in step 6 and compare that with the regulatory regimes in which priority service is authorized. In step 11, assuming the user is authorized, the cellular operator replies with a RADIUS Access-Accept including the EAP-SUCCESS message and the EPCS-Subscription-Info attribute defined in . In step 12, the AP/WLC recovers the keying material from the Access-Accept packet and forwards the EAP-SUCCESS message to the device. In step 13 and 14, the AP/WLC enables EPCS priority access by sending the EPCS Priority Access Enable Request frame to the device. The device (i.e., STA) responds with an EPCS Priority Access Enable Response frame in step 14. (Note: These steps assume the AP/WLC is configured or triggered to automatically enable EPCS for the device.) In step 15, the device receives EPCS Priority Access.

| | |5. Association | | | Response | | |<==============| | |6. EAP-Identity/ | | Request | | |<==============| | |7. EAP-Identity/ | | Response | | |==============>|8. RADIUS Access-Request | | EAP Response Identity | | Civic-Location (Country Code) | | EPCS-Capable-Indication | | HS2.0-Roaming-Consortium | | (opt) WBA-Linear-Volume-Rate | |==================>| | | | | 9. EAP Dialogue | |<=================================>|10. Match user with | | | priority | | | subscription | | | authorization | | |======\ | | | || | | |<=====/ | |11. RADIUS Access-Accept | | EAP-Success | | | EPCS-Regulatory-Info | | EPCS-Subscription-Info | |<==================| |12. EAP-SUCCESS| | |<==============| | | | | |13. EPCS Priority Access Enable Request |<==============| | | | | |14. EPCS Priority Access Enable Response |==============>| | | | | +------------------------+ | |15. EPCS Priority Access| | +------------------------+ | | | | ]]>

RADIUS EPCS Attributes The current RADIUS protocol does not have the support for the flow described in the previous section and therefore, the following attributes are required to enable it.

EPCS-Capable-Indication Description The EPCS-Capable-Indication (TBA1) Attribute allows a RADIUS NAS to indicate to a RADIUS server that it is EPCS capable. One EPCS-Capable-Indication Attribute MAY be included in an Access-Request packet. A summary of the EPCS-Capable-Indication Attribute format is shown in . The fields are transmitted from left to right.

Type

• • TBA1

Length

• • 6 octet

Data Type

• • Integer

Value

• The field is 2 octets, containing a 16-bit unsigned integer that represents whether the NAS and the device support the EPCS capability and what capabilities the NAS has to handle the traffic to the authorized EPCS users. This document defines two such values used with the EPCS-Capable-Indication attribute:

• • • 0     EPCS Priority Access is supported by the NAS. Irrespective of the EPCS support by the device, the NAS can prioritize downlink traffic to authorized EPCS users .

• • • 1     EPCS Priority Access is supported by the NAS and the device. The NAS can prioritize uplink and downlink traffic for EPCS priority access to authorized EPCS users.

Note: How the NAS treats the traffic is vendor specific implementation and is outside the scope of this document.

EPCS-Regulatory-Info Description The EPCS-Regulatory-Info (TBA2) Attribute allows a RADIUS Server that is authorizing a user to receive priority channel access to indicate the regulatory regime under which the RADIUS Server operates. One EPCS-Regulatory-Info Attribute MAY be included in an Access-Accept packet. A summary of the EPCS-Regulatory-Info Attribute format is shown in . The fields are transmitted from left to right.

Type

• • TBA2

Length

• • 6 octet

Data Type

• • Country-Code

Value

• The field is 2 octets, containing the two-letter ISO 3166 country code in capital ASCII letters, e.g., DE or US.

EPCS-Subscription-Info Description The EPCS-Subscription-Info (TBA3) Attribute allows a RADIUS Server to indicate to a NAS that a user is authorized to receive priority service. One EPCS-Subscription-Info Attribute MAY be included in an Access-Accept packet and its presence indicates the authenticated user is authorized to receive priority service accordingly to the priority level associated with the user's subscription. . A summary of the EPCS-Subscription-Info Attribute format is shown in . The fields are transmitted from left to right.

Type

• • TBA3

Length

• • 6 octet

Data Type

• • Integer

Value

• The field is 2 octets, containing a 16-bit unsigned integer that represents whether the priority level associated with the user's subscription. The priority levels can be determined by the entity that provides the authorization information and/or based on service provider's policies.

Security Considerations To be completed.

IANA Considerations To be completed.

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 procedures for conveying access-network ownership and location information based on civic and geospatial location formats in Remote Authentication Dial-In User Service (RADIUS) and Diameter. The distribution of location information is a privacy-sensitive task. Dealing with mechanisms to preserve the user's privacy is important and is addressed in this document. [STANDARDS-TRACK]

Acknowledgements The authors would like to thank all the members of the Wireless Broadband Alliance's Mission Critical & Emergency Services (e911) project.