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WiMAX Capabilities Negotiation


The ASN-GW and home agent each send a WiMAX-Capability attribute listing the capabilities they want to use in the session. The HAAA server selects from those received capabilities and responds with a WiMAX-Capability attribute listing the capabilities it can support for the session. The HAAA capabilities configuration (policy) may differ for the ASN-GW and home agent.

WiMAX-Capability Attribute

WiMAX-Capability Attribute

The WiMAX-Capability attribute is a structured VSA that contains subattributes that specify different capabilities that can be used in the session. If a subattribute (capability) was sent in the Access-Request, and the HAAA (Steel-Belted Radius Carrier) can support the capability, then the subattribute is returned in the Access-Accept message. If a subattribute (capability) is not sent in the Access-Request, it is not returned in the Access-Accept. Absence of a subattribute in the Access-Request, indicates the device (ASN-GW or home agent) does not support the capability.

WiMAX-Capability Structured Attribute

WiMAX-Capability Structured Attribute

The WiMAX-Capability structured attribute may contain the following subattributes, each representing a specific WiMAX capability:

  • WiMAX-Release attribute

  • Accounting-Capabilities attribute

  • Hotlining-Capabilities attribute

  • Idle-Mode-Notification-Capabilities attribute

WiMAX-Release Attribute

The WiMAX-Release subattribute indicates the release of the WiMAX Forum Networking Group (NWG) specification supported by the device. Steel-Belted Radius Carrier supports releases 1.0, 1.1, 1.1.1, 1.1.2, and 1.2. The WiMAX-Release subattribute is sent in the Access-Request by both the ASN-GW and home agent. If Steel-Belted Radius Carrier supports the requested release number, it returns that same release number with the Access-Accept. If Steel-Belted Radius Carrier does not support the requested release number it rejects the request.

WiMAX-Accounting-Capabilities Attribute

The WiMAX-Accounting-Capabilities subattribute specifies the type of accounting to be used for the session. It must be sent in the Access-Request by both ASN-GW and home agent, and it must be returned to both the ASN-GW and home agent by the HAAA server in the Access-Accept.

Steel-Belted Radius Carrier supports flow-based and IP-session-based accounting. A value of None is allowed only at the home agent. If the ASN-GW indicates a value of None, the request is rejected.

For more details about accounting, see WiMAX Post-Paid (Offline) Accounting.

Hotlining-Capabilities Attribute

Hotlining is the practice of diverting a subscriber from their desired destination to a destination controlled by the service provider, in order to rectify specific circumstances related to the subscriber account. Hotlining is typically used to reconcile issues such as prepayment of services, delinquent account issues, account updates, and administrative functions (for example IP address renewal). The subscriber is typically redirected to a webpage to reconcile the issue. After the issue is resolved, they are redirected to their desired destination.

There are two types of hotlining:

  • New session hotlining

  • Active session hotlining

New session hotlining is the process of returning hotlining parameters attached to the Access-Accept. The hotlining parameters are returned in the Access-Accept message based on the value of the Hotlining-Capabilities subattribute in the WiMAX-Capability attribute. The hotlining parameters are returned as WiMAX hotlining attributes. The values of these attributes can be stored in either an SQL or LDAP database, and are retrieved using the SQL or LDAP authentication files (sqlauth.aut or ldapauth.aut).

Active session hotlining is the process of returning hotlining parameters through Change of Authorization (CoA) messages. For more information about SBR Carrier’s support for CoA messages, see Managing and Controlling Sessions.

For more information about configuring new session hotlining, see Example Configuration for New Session Hotlining.

Idle-Mode-Notification-Capabilities Attribute

Idle mode notification can be negotiated at the time of network access. During network access, if the ASN-GW sends the WiMAX-Capabilities attribute using the Idle-Mode-Notification-Capability sub-attribute, it indicates the ASN-GW supports idle mode notification. Absence in the Access-Request means that idle mode notification is not supported by the ASN-GW.

The HAAA server indicates it requires idle mode notification by returning this subattribute to the ASN-GW in the Access-Accept. Absence of this subattribute in the WiMAX-Capabilities attribute in the Access-Accept indicates the HAAA server does not require idle mode notification.

The Idle-Mode-Notification-Capabilities subattribute is never sent to the home agent.

Idle mode notification is negotiated at network access and occurs when the mobile station (for example, cell phone) enters or exits the idle mode. The accounting server at the CSN (connectivity service network) is notified about the idle mode transition through accounting messages.

Enabling WiMAX Capabilities Negotiation

Enabling WiMAX Capabilities Negotiation

WiMAX capabilities negotiation may be performed by adding capabilities subattributes to the user or profile return list and enabling the Echo option for each capability you want Steel-Belted Radius Carrier to support. When using the SQL or LDAP authentication plug-ins (for EAP-AKA), this is done by defining the attributes in the return list of a profile.

If you want Steel-Belted Radius Carrier to support all requested WiMAX capabilities defined in an Access-Request message, enable the Echo option on the parent WiMAX-Capability attribute. If you want to selectively choose what capabilities Steel-Belted Radius Carrier supports, enable the Echo at the subattribute level only.

For example, if you do not want to support idle mode notification, do not enable Echo for the Idle-Mode-Notification-Capability subattribute.