Interworking is the occurrence of two or more things working together. For a better Wireless network experience information about the network must be exchanged between Access Points and Wireless client devices, the information that can be found basic Wireless beacons and probe requests in limited, for this reason the IEEE 802.11u™-2011 (Interworking with External Networks) standard was created, that specifies how devices should exchange information between each other. With the Interworking service network discovery and Access Point selection process can be enhanced. Wireless client devices can have more criteria upon which they can choose the network with which to associate with.
Hotspot 2.0 is a specification developed and owned by the Wi-Fi Alliance. It was designed to enable a more cellular-like experience when connecting to Wi-Fi networks. In the attempt to increase Wireless network security Hotspot 2.0 access points use mandatory WPA2 authentication. Hotspot 2.0 relies on Interworking as well as adds some of its own properties and procedures.
Information elements in beacon and probe response
Some information can be added to beacon and probe response packets with interworking element. Following parameters of Interworking element can be configured:
|asra (yes | no; Default: no)||Additional Steps Required for Access. Set to
|esr (yes | no; Default: no)||Emergency services reachable (ESR). Set to
|hessid (MAC address; Default: )||Homogenous extended service set identifier (HESSID). Devices that provide access to same external networks are in one homogenous extended service set. This service set can be identified by HESSID that is the same on all access points in this set. 6-byte value of HESSID is represented as MAC address. It should be globally unique, therefore it is advised to use one of the MAC address of access point in the service set.|
|internet (yes | no; Default: yes)||Whether the internet is available through this connection or not. This information is included in the interworking element.|
|network-type (emergency-only | personal-device | private | private-with-guest | public-chargeable | public-free | test | wildcard; Default: wildcard)||Information about network access type.
|uesa (yes | no; Default: no)||Unauthenticated emergency service accessible (UESA).
|venue (venue; Default: unspecified)||Specify the venue in which the access point is located. Choose the value from available ones. Some examples:
venue=business-bank venue=mercantile-shopping-mall venue=educational-university-or-college
Access network query protocol (ANQP). Not all necessary information is included in probe response and beacon frames. For client device to get more information before choosing access point to associate with ANQP is used. The access point can have stored information in multiple ANQP elements. Client device will use ANQP to query only for the information it is interested in. This reduces the time needed before association.
|3gpp (octet string in hex; Default: )||Cellular network advertisement information - country and network codes. This helps Hotspot 2.0 client in the selection of an access point to access 3GPP network. Please see 3GPP TS 24.302. (Annex H) for a format of this field. This value is sent ANQP response if queried.|
||This property is only effective when asra is set to
|connection-capabilities (number:number:closed|open|unknown; Default: )||This option allows to provide information about allowed IP protocols and ports. This information can be provided in ANQP response. The first number represents the IP protocol number, the second number represents a port number.
Setting such value access point informs station, that is connecting, that HTTP(6 - TCP, 80 - HTTP) is allowed and VoIP (17 - UDP; 5060 - VoIP) is not allowed.This property does not restrict or allow these protocols and ports, it only gives information to station device which is connecting to access point.
|domain-names (list of strings; Default: )||None or more fully qualified domain names (FQDN) that indicate the entity operating the hotspot. A station that is connecting to the access point can request this AQNP property and check if there is a suffix match with any of the domain names it has credentials to.|
|ipv4-availability (double-nated | not-available | port-restricted | port-restricted-double-nated | port-restricted-single-nated | public | single-nated | unknown; Default: not-available)||Information about what IPv4 address and access are available.
|ipv6-availability (available | not-available | unknown; Default: not-available)||Information about what IPv6 address and access are available.
|realms (string:eap-sim|eap-tls|not-specified; Default: )||Information about supported realms and the corresponding EAP method.
|realms-raw (octet string in hex; Default: )||Set NAI Realm ANQP-element manually.|
|roaming-ois (octet string in hex; Default: )||Organization identifier (OI) usually are 24-bit is unique identifiers like organizationally unique identifier (OUI) or company identifier (CID). In some cases, OI is longer for example OUI-36.
A subscription service provider (SSP) can be specified by its OI.
|venue-names (string:lang; Default: )||Venue name can be used to provide additional info on the venue. It can help the client to choose a proper access point.
Venue-names parameter consists of zero or more duples that contain Venue Name and Language Code:
venue-names=CoffeeShop:eng,TiendaDeCafe:esThe Language Code field value is a two or three-character 8 language code selected from ISO-639.
Hotspot 2.0 ANQP elements
Hotspot 2.0 specification introduced some additional ANQP elements. These elements use ANQP vendor specific element ID. Here are available properties to change these elements.
|hotspot20 (yes | no; Default: yes)||Indicate Hotspot 2.0 capability of the access point.|
|hotspot20-dgaf (yes | no; Default: yes)||Downstream Group-Addressed Forwarding (DGAF). Sets value of DGAF bit to indicate whether multicast and broadcast frames to clients are disabled or enabled.
|operational-classes (list of numbers; Default: )||Information about other available bands of the same ESS.|
|operator-names (string:lang; Default: )||Set operator name. Language must be specified for each operator name entry.
Operator-names parameter consists of zero or more duples that contain Operator Name and Language Code:
operator-names=BestOperator:eng,MejorOperador:esThe Language Code field value is a two or three-character 8 language code selected from ISO-639.
|wan-at-capacity (yes | no; Default: no)||Whether the access point or network is at its max capacity. If set to yes no additional mobile devices will be permitted to associate to the AP.|
|wan-downlink (number; Default: 0)||The downlink speed of WAN connection set in kbps. If downlink speed is not known, set to 0.|
|wan-downlink-load (number; Default: 0)||The downlink load of WAN connection measured over
|wan-measurement-duration (number; Default: 0)||Duration during which
|wan-status (down | reserved | test | up; Default: reserved)||Information about the status of access points WAN connection. The value
|wan-symmetric (yes | no; Default: no)||Weather WAN link is symmetric (upload and download speeds are the same) or not.|
|wan-uplink (number; Default: 0)||The uplink speed of WAN connection set in kbps. If uplink speed is not known set to 0.|
|wan-uplink-load (number; Default: 0)||The uplink load of WAN connection measured over
|comment (string; Default: )||Short description of the profile|
|name (string; Default: )||Name of interworking profile.|