Transcript Introduction to 802.11u

July 2007
doc.: IEEE 802.11-07/2078r0
802.11u and Emergency Services
Date: 2007-07-19
Authors:
Name
Company
Address
Phone
email
Matthew Gast
Trapeze Networks
5753 W. Las Positas Blvd,
Pleasanton, CA 94588 USA
+1 925 474 2273
[email protected]
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Submission
Slide 1
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
Abstract
Introduction to 802.11u for the IEEE 802 emergency
services ad hoc in San Francisco, CA in July 2007.
Note: This presentation is based on 802.11u-D1.0 and
subject to change by future standards activity.
Submission
Slide 2
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
Major Features of 802.11u
• External network (“SSPN”) interface for extended
authorization
• New QoS features
• Generic Advertising Service (GAS)
• Emergency services recommendations (informative)
– Use case #1: open network
– Use case #2: public credentials
Submission
Slide 3
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
External Network (SSPN) Interface
• SSPN = Subscription Service Provider Network
– SSP holds user credentials
– May build or partner with 802.11 access networks
• The SSPN may direct the STA-AN, for example by:
– Requiring that a certain encryption type is used (e.g. CCMP only)
– Setting allowed access rates for different types of traffic (e.g. 80
kbps voice, no video, and up to 500 kbps best effort)
– Specifying a minimum delay bound on transmitted frames
• Admission Control
– TSPEC processing is subject to authorized data rates as specified
by SSPN
Submission
Slide 4
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
QoS Signaling in 802.11u
• Expedited Bandwidth Request
– 802.11 has only four categories (voice, video, best effort, and background)
– Many STAs may request high-priority voice service
– EBR allows a STA to describe the reason that it is requesting service and
the network can act accordingly
– Example: emergency calls and first-responder traffic can pre-empt
“normal” voice traffic
• QoS Map
– 802.11 QoS settings only affect last-hop access; QoS Map allows APs and
STAs to extend higher-layer QoS settings
– Ensures correct QoS treatment of frames even if destination networks use
DSCP differently
Submission
Slide 5
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
Generic Advertising Services (GAS)
• Interface to external information sources
– Example: Carrier of 802.21 data
– Extensible for types beyond 802.21
• “Native” query mode
– Assists STA with information stored in the 802.11 access network
– Example: enhances scan for multi-SSID use, so that a secondary
SSID can be used for emergency services
• Operational details (in brief)
– Multicast/unicast operation
– Query size limits: administrators can configure response limit size
– Emergency Services native query: type of authentication
Submission
Slide 6
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
Emergency Services Use Case #1:
Dedicated SSID
• Uses “emergency
services only” (ESO) bit
to signal that the SSID
can support emergency
services without any
802.11-level security
• Network must enforce
appropriate security (out
of scope for 802.11)
– Network is “locked
down” to emergency
calls only
– e.g. dedicated VLAN, IP
firewall
Submission
STA
AP
(11u-capable)
(11u-capable)
Beacon (w/ESO bit)
GAS Native Query (SSID list + ES info)
Note: SSID list is optional; used in multi-SSID
deployments
GAS Native Query Response
Association Request
Association Response
ADDTS Request (w/Expedited BW Req.)
ADDTS Response
Initiate higher-layer call (e.g. SIP)
Restricted Network
e.g. dedicated VLAN, IP filtering, etc.
Slide 7
Matthew Gast, Trapeze Networks
July 2007
doc.: IEEE 802.11-07/2078r0
Emergency Services Use Case #2: Public
Credentials
• ESO calls have no
cryptographic protection
(tampering, injection,
forgery)
• To provide cryptography,
802.11i security must be used
AP
(11u-capable)
GAS Native Query (emergency public credentials)
GAS Native Query Response (credentials)
Association Request
Association Response
– Pre-shared key for all
emergency networks is not
feasible
– 802.11u provides a way for a
network to set up an
“emergency public credential”
to use EAP methods
EAPOL/EAP-Identity-Request
EAPOL/EAP-Identity-Response (credentials)
EAP method authentication
4-Way Handshake
ADDTS Request (w/Expedited BW Request)
• EAP method needs
clarification
Submission
STA
(11u-capable)
ADDTS Response
Initiate higher-layer call (e.g. SIP)
Slide 8
Matthew Gast, Trapeze Networks