What problem does a Passpoint architecture solve?
One word answer is WiFi Roaming.
Cellular networks, when they cant find their home network, automatically identify and register with national and international roaming partners without need for user intervention. Before passpoint, WiFi networks lacked this feature because there was no widely adopted protocol to do this. Below are the cumbersomness in the pre-passpoint era of WiFi architecutre.
Today's Wifi Access points have only one publicly accessible label, the SSID. Hence this SSID is used to indicate different network types. Most SSIDs reflect the organization operating the Access point for e.g. "myhomewifi" while others indicate the service provider for e.g. "Docomowifi". IF someone needs to say that this the organization is having the wifi from a service provider, it would need to advertise two ssids. While it is possible to advertise multiple ssids, it is quite inefficient airtime and cannot be extended so far.
With the passpoint, the information about the service and service providers that are reachable via a hotspot are separated from SSID. A new protocol allows mobile device to discover a comprehensive profile of the hotspot before it associates so that it can quickly identify and prioritize hotspots suitable for its needs. with passpoint, a mobile device can silently find the appropriate network and associate with it and get authenticated silently while the device is in user's pocket itself.
The passpoint does the below for enhancing the hotspot experience.
- New info in the beacon and probe responses
- A new GAS/ANQP protocol to allow pre-association queries of a hotspots's capabiltiies
- New information fields that allow a mobile device to know which service providers are accessible via the hotspot
- New info fileds that allow mobile device to know which operator and the venue and configuration of the hotspot
- Security features to further enhance the security against attacks.
GAS & ANQP
ANQP (Accees network query protocol) is the protocol delivered inside the framework of GAS (Generic Advertisement Service). This protocol is used for querying the capability of a hotspot. The existing protocols are beacon and probe and they are quite inefficient for the automatic association and capability discovery and hence the ANQP was introduced.
The GAS/ANQP support of a hotspot can be detected by a mobile device using the beacon/probe response info field that has been newly added.
Below are the major new fields added to the Beacon/Probe response:
- Access network type, identifying whether the network is public/private/guest access etc
- Internet bit, indicating whether the hotspot can have internet access
- Advertisement bit whether the hotspot supports GAS/ANQP
- Roaming consortium element. list upto 3 names of reachable service providers.
- Venue information of the hotspot
- Homogeneous ESSID, a value identifying hotspots in a continuous zone
- P2P cross connectivity capability
- BSS load value, a value indicating the current load of the hotspot.
In most cases, device will identify the hotspot in the area using probe requests and more complex picture of the hotspot is queried using GAS/ANQP
In the initial release of passpoint, the following are the informational elements in the ANQP query
- venue name information
- Network authentication type info
- Roaming Consortium list
- IP address Type availalbility info
- NAI realm list
- 3GPP cellular network info
- Domain name list
- Hotspot operator friendly name
- Operating Class
- Hotspot WAN metrics
- Hotspot connection capability
- NAI home realm
References:
http://www.arubanetworks.com/pdf/technology/whitepapers/WP_Passpoint_Wi-Fi.pdf
One word answer is WiFi Roaming.
Cellular networks, when they cant find their home network, automatically identify and register with national and international roaming partners without need for user intervention. Before passpoint, WiFi networks lacked this feature because there was no widely adopted protocol to do this. Below are the cumbersomness in the pre-passpoint era of WiFi architecutre.
Today's Wifi Access points have only one publicly accessible label, the SSID. Hence this SSID is used to indicate different network types. Most SSIDs reflect the organization operating the Access point for e.g. "myhomewifi" while others indicate the service provider for e.g. "Docomowifi". IF someone needs to say that this the organization is having the wifi from a service provider, it would need to advertise two ssids. While it is possible to advertise multiple ssids, it is quite inefficient airtime and cannot be extended so far.
With the passpoint, the information about the service and service providers that are reachable via a hotspot are separated from SSID. A new protocol allows mobile device to discover a comprehensive profile of the hotspot before it associates so that it can quickly identify and prioritize hotspots suitable for its needs. with passpoint, a mobile device can silently find the appropriate network and associate with it and get authenticated silently while the device is in user's pocket itself.
The passpoint does the below for enhancing the hotspot experience.
- New info in the beacon and probe responses
- A new GAS/ANQP protocol to allow pre-association queries of a hotspots's capabiltiies
- New information fields that allow a mobile device to know which service providers are accessible via the hotspot
- New info fileds that allow mobile device to know which operator and the venue and configuration of the hotspot
- Security features to further enhance the security against attacks.
GAS & ANQP
ANQP (Accees network query protocol) is the protocol delivered inside the framework of GAS (Generic Advertisement Service). This protocol is used for querying the capability of a hotspot. The existing protocols are beacon and probe and they are quite inefficient for the automatic association and capability discovery and hence the ANQP was introduced.
The GAS/ANQP support of a hotspot can be detected by a mobile device using the beacon/probe response info field that has been newly added.
Below are the major new fields added to the Beacon/Probe response:
- Access network type, identifying whether the network is public/private/guest access etc
- Internet bit, indicating whether the hotspot can have internet access
- Advertisement bit whether the hotspot supports GAS/ANQP
- Roaming consortium element. list upto 3 names of reachable service providers.
- Venue information of the hotspot
- Homogeneous ESSID, a value identifying hotspots in a continuous zone
- P2P cross connectivity capability
- BSS load value, a value indicating the current load of the hotspot.
In most cases, device will identify the hotspot in the area using probe requests and more complex picture of the hotspot is queried using GAS/ANQP
In the initial release of passpoint, the following are the informational elements in the ANQP query
- venue name information
- Network authentication type info
- Roaming Consortium list
- IP address Type availalbility info
- NAI realm list
- 3GPP cellular network info
- Domain name list
- Hotspot operator friendly name
- Operating Class
- Hotspot WAN metrics
- Hotspot connection capability
- NAI home realm
References:
http://www.arubanetworks.com/pdf/technology/whitepapers/WP_Passpoint_Wi-Fi.pdf
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