Transcript - IEEE Mentor

November 2007
doc.: IEEE 802.11-07/2889r0
LIS-ALE Architecture, and FLAP
Date: 2007-11-12
Authors:
Name
Affiliations
Address
Phone
email
Vijay Patel
Andrew
Corporation
19700 Janelia Farm
Blvd, Ashburn, VA
20147
+1 (703) 7265693
[email protected]
Submission
Slide 1
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Abstract
Emergency Services Interconnection Forum (ESIF), a division of ATIS,
is working on FLAP. The purpose of FLAP (Flexible LIS-ALE
Protocol) is to facilitate transfer of values of location measurement
parameters from the network to the LIS (Location Information
Server) enabling the latter to compute the location of an IP enddevice.
LIS interacts with ALE (Access Location Entity) residing in the access
network to retrieve location measurements.
ESIF/NGES plans to send a liaison shortly to many SDOs (including
IEEE802, 3GPP, IETF, and ITU-T) to seek input from the industry
on this work for developing a standardized location parameter
conveyance framework (requirements, architecture, and protocols)
following the ANSI guidelines.
Submission
Slide 2
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Internet location services model – Location
Information Server (LIS)
Internet
1
2
Access
Domain
Internet
Domain
LIS
Internet
1
Access
Domain
Service
Service
Domain
3
2
Internet
Domain
Service
Service
Domain
Location by value
1. Device obtains location from
the location server in the
access network
2. Device conveys location* to
the service in the applicable
application protocol.
* Location values are encoded as a
PIDF-LO per RFC4119
Location by reference
1. Device obtains reference from
the location server in the
access network
2. Device conveys reference to
the service in the applicable
application protocol.
3. Service queries location server
directly for location value one
or more times
The protocol used for 1 & 3 is HELD (HTTP Enabled Location Delivery). Step 2, location conveyance, is
application protocol dependent (e.g. SIP supports location conveyance)
Submission
Slide 3
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Internet location services model – OBO
Requests
Application*
protocol
Trusted
Service
2
1
Internet
HELD
LIS
Target device
Access
Domain
HELD
3
Internet
Domain
Service
Service
Domain
On-Behalf-Of (OBO)
1. Trusted third party application
(service) queries for location of
the device. A client identity which
is understood by the LIS is used
as a query parameter (e.g. IP
address)
2. If applicable, third party provides
location information to external
service entities.
3. If location was requested and
provided by-reference, the
external entity queries back to
the LIS for location value
updates.
* OBO requests are typically applicable where the target device and/or application protocol do not have native support for the
communication of location information. For example a large enterprise with legacy deployment of standard form factor VoIP
phones using H.323 may need to provide location-based routing for emergency and other calls from geographically diverse sites.
The IP PABX in this case may perform OBO queries to the LIS using the IP address of the phone(s) as the query parameter. The
PABX may use SIP conveyance externally if the location needs to sent to an external service entity. OBO implies two important
characteristics of the service making the query. The service needs to be trusted by the LIS such that it is authorized, by whatever
mechanism is suitable to the situation, to query for the location of devices in the LIS’ network. Where there are multiple possible
LIS that the service could query, it needs to be able to ensure that it is associating the device with the correct LIS to provide the
location.
Submission
Slide 4
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
How does a LIS “know” Location
• The Internet location services model describes how LIS
clients request and receive location information from
the LIS
• It does not describe how a LIS determines the location
associated with the device
• The value of parameters derived from the
communication network used by the device can be used
by the LIS to determine location
• In order to make use of these parameters, it is necessary
for their values to be transferred from the
communication network elements to the LIS
• This is the purpose of FLAP.
Submission
Slide 5
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Flexible LIS-ALE Protocol (FLAP) - Scope
External applications
Scope of FLAP
Internet
Location dereference
request path
Access Network
Network
measurements
ALE
ALE
FLAP
LIS
Network
measurement
requests
Device
measurement
requests
User Device
Other
measurements
ALE
ALE
External
measurement sources
(e.g. GPS, LMUs)
Other
measurements
Submission
Slide 6
External
measurement sources
(e.g. GPS, RFID beacons)
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Location Measurement
•
•
•
•
Location measurement involves determining the value of a number of
parameters associated with the network connection in use by the IP device.
Since devices will typically connect to a network using some form of link, the
parameters will often be layer 2 information directly associated with the
physical link in use by the device – though not always
– e.g. Typical layer 2 pieces of information are the Ethernet switch port the
device is connected to or the identity of a wireless access point the device is
using.
– e.g. The permanent virtual circuit (PVC) identifier on the ATM aggregation of
a DSL network may be measured even though it is physically separate from
the copper pair or DSLAM connections of the physical link.
Parameters taken from access networks need to be uniquely associated with
the IP device in question and this association will often, if not always, be able
to be done against the IP address of the device or terminating equipment.
A common framework for access networks to transfer parameter values from
the network equipment to the LIS is desirable.
– The XML based flexible LIS-ALE protocol (FLAP) is proposed for this
purpose
Submission
Slide 7
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
LIS-ALE Architecture
HELD
HELD
LIS
ALE
Submission
ALE
Slide 8
ALE messages
HELD
ALE
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Location Determination: LIS-ALE Ntwk Model
Submission
Slide 9
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
FLAP - message structure and content
•
•
The LIS is responsible for establishing connections to each of the ALE instances in
its service area.
FLAP messaging is XML based
–
–
–
–
•
XML objects are sent as part of a continuous stream on a reliable secure link – recommended to
be TLS.
The XML schema defines the messages supported by the FLAP protocol and includes the metaobjects of terminal and access.
The base definition of terminal includes the IP address of the terminal. This will generally apply
to IP devices that measurements are being provided for.
FLAP also supports sending measurements for access parameters not immediately associated
with an IP device, particularly where the LIS may subsequently be able to make the association.
In this case, the ALE may exclude the IP address.
The base XML schema supports technology and vendor extensions
–
Standard technology schema extensions define the detail of what defines a terminal in a given
technology as well as the standard subset of access parameters that apply to that technology
•
–
Vendor extensions permit new terminal and access parameters to be defined.
•
•
Submission
E.g. A layer 2 Ethernet switch extension defines a terminal by MAC address. Access parameters include
switch identity, connected port, and vlan ID.
This permits a vendor to provide additional measurement information which may contribute to improved
location measurement performance.
A LIS may recognize, and utilize, vendor extensions or it may ignore them.
Slide 10
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
FLAP – Hierarchical definitions
Technology specific ALE capabilities
FLAP
Base XML Schema
Etc.
Ethernet
switch
Vendor
Extensions
Submission
WiFi
AccessPoint
WiMAX
Base Station
Vendor
Extensions
Vendor
Extensions
Slide 11
DSL
Aggregator
Vendor
Extensions
Cable
Head End
Vendor
Extensions
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
FLAP - XML Structure, Base definitions
Type definitions
Header definition
Terminal definition
[vendor]
ipaddress
Access definition
Time
ExpiryTime
Messaging definitions
Message component definitions
Transaction ID
Technology
Vendor ID
Base definitions define semantic objects and
messages
Message definitions
AccessQuery
AccessQueryResponse
Notify
Synch
SynchResponse
Parameter definitions
Error codes
Result codes
Vendor
…e.g. Alcatel_LiteSpanDSL_definitions
Extensions
#include EthernetSwitchExtension
#Include DHCPRelayExtension
#Include DSLAggregatorExtension
Submission
Base definitions augmented by including
vendor and technology specific
extensions
Slide 12
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
FLAP - messaging
To avoid unnecessary polling in the network, FLAP also supports the ability of the ALE
to provide asynchronous indications of client location measurement changes. This is
done via a “Notification” message from the ALE to the LIS.
Notification may also occur downstream from the LIS to the ALE, where the LIS has
learnt of a change in client connectivity, in order that the ALE may also refresh its state
information in a timely manner.
Submission
Slide 13
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Example FLAP message
The following message uses the Ethernet extension with additional vendor extension
parameters to do a notification message:
<ntfy xsi:type=”enet:ntfy”
xmlns:vnd1=”http://www.example.com/flap/terminal/hw”
xmlns:vnd2=”http://www.example.com/flap/access/skew”>
<enet:terminal
<ip>192.168.0.1</ip>
<enet:hwaddr>12:34:56:78:90:ab</enet:hwaddr>
<vnd1:hw revision="1.2"/>
</enet:terminal>
<enet:access time="2005-04-14T10:51:23.000+10:00">
<enet:switch><ip>192.168.0.1</ip></enet:switch>
<enet:port>4</enet:port>
<vnd2:skew>0.5127</vnd2:skew>
</enet:access>
</ntfy>
Submission
Slide 14
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
FLAP - messaging (contd)
A LIS will typically be configured with information about the access networks that it
provides location services for. This will include the definitive list of ALE instances that it
can obtain location measurements from.
The LIS may poll the serving ALE set with a “Query Access” message. Each ALE will
provide a response for each connected device and the measurement set applicable to it.
The LIS may request a refresh of information from the ALE set using a
“Resynchronization” message in the event of, for example, coming back on line after an
outage. Each ALE will provide a response covering the state of all currently connected
devices or, alternatively, a response covering all changes since a given specific time.
Submission
Slide 15
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Example – WiMax Network Controller ALE
Network
Controller
IP
ALE
FLAP
WiMax extension schema
Terminal definition
MAC address
IP address
Access definition extension
BTS ID
Vendor X extension schema
Vendor X
Product WAP-FamilyY-ModelZ
Access definition extensions
Channel info
RoundTripTime
RxLevel
Submission
WiMax BTS
LIS
Generic LIS record
IP@
BTS ID
IP@
BTS ID
Location
f(Channel, RoundTripTime, RxLevel)
Location
Vendor X proprietary support LIS record
location is determined by an algorithm which
is a function of RF signal strength and timing
measurements supported by the WiMax
manufacturer
Slide 16
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Example – A DSL Aggregator ALE
Copper
PVC
IP
DSL
Aggregator
ALE
ISP/
Enterprise
FLAP
ATM
Device
ATU-R
DSLAM
DSL Aggregator extension schema
Terminal definition
IP address
Access definition extension
Aggregation device ID
ATM port ID
PVC ID
Submission
LIS
IP@
Aggregation device
ID
Slide 17
ATM Port
PVC
Location
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Example – Ethernet Switch ALE
Switch
IP
ALE
ALE
FLAP
Ethernet
ALE
Switches
Ethernet switch extension schema
Terminal definition
MAC address
IP address
Access definition extension
Switch ID
Switch address
Port ID
VLAN ID
Submission
LIS
IP@
Slide 18
Switch ID
Port ID
Location
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Example – 802.11x Access Point ALE
Switch
WAP
IP
ALE
ALE
802.11x AP extension schema
Terminal definition
MAC address
IP address
Access definition extension
WAP ID
Channel No
FLAP
LIS
Generic LIS record
IP@
WAP ID
IP@
WAP ID
Location
Vendor X extension schema
Vendor X
Product WAP-FamilyY-ModelZ
Access definition extensions
RoundTripTime
RxLevel
Submission
f(Channel, RoundTripTime, RxLevel)
Location
Vendor X proprietary support LIS record
location is determined by an algorithm which
is a function of RF signal strength and timing
measurements supported by the AP
manufacturer
Slide 19
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
LIS-ALE Procedures
Device data
LIS
Update queries
ALE
Access device
1. LIS starts up
2. LIS establishes FLAP sessions* with ALEs in area of coverage
Device
3. LIS optionally requests synchronization information from ALEs
4. ALEs report measurements as device-related events occur
Device
5. LIS optionally informs ALEs if devices detected elsewhere
6. LIS optionally polls ALEs for measurements as HELD requests occur
Device
Device
• FLAP supports the transmission, including periodic updates, of location measurement
information to the LIS as it applies to connected devices.
• FLAP messaging is based on streamed XML and a secure and reliable transport is
required. * BEEP with TLS is the recommended transport and session protocol.
Submission
Slide 20
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Incorporating device measurements
As a generic constraint, a LIS cannot
assume specific measurement
capabilities or protocols supported
by visiting devices. However, these
capabilities should not be ignored.
External applications
Internet
Location dereference
request path
Access Network
Network
measurements
FLAP
LIS
Network
measurement
requests
Device
measurement
requests
Other
measurements
User Device
External
measurement sources
(e.g. GPS, LMUs)
Device measured
location parameters
Submission
Other
measurements
Slide 21
External
measurement sources
(e.g. GPS, RFID beacons)
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Device based measurements
• In addition to the device being able to make measurements and perform location determination independently, it may be
able to:
- Provide the raw measurements to the LIS and leave the location determination process up to the LIS - e.g. the
device takes wireless RF measurements but the LIS applies these measurements to base station data to calculate location
- Perform the location determination itself but need the assistance of the LIS as part of taking the necessary
measurements - e.g. the device can perform GPS but needs GPS assistance data. The LIS calculates approximate
location and delivers assistance data.
• The specific protocols used to perform such co-operative location determination can be outside the scope of HELD
- E.g. SUPL for AGPS operations or SNMP for LLDP related measurement transfer.
• HELD supports the exchange of a “client capability” parameter set between the device and the LIS
- The device volunteers its capabilities and the LIS responds with an indication of which may be supported
- Extension types are used in the HELD protocol to identify the specifics of these protocols.
AppProtocol(LocationURI)
GPS
satellites
3
Access
Network
4
Application
LocReq(signed)
1
LocReqResp(LocCap(SubTechList(…))
ALE
Submission
6
HELD
LocReq( Type(locationURI), LocCap(TechList(…))
Selected Location Technology protocol
Protocol specific message exchange
FLAP
Slide 22
2
5
5
LIS
LocResp
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
Summary
• FLAP:
– Does not convey location
– Facilitates location parameter conveyance to LIS, from ALE
– Being worked in ESIF (a division of ATIS).
• HELD:
– Location dereferencing/conveyance protocol
– A standards track specification from IETF/Geopriv
• ESIF/NGES plan to shortly send a liaison to IEEE
requesting input on this development effort to create
location parameter conveyance framework, in support
of next generation emergency services.
Submission
Slide 23
Vijay Patel, Andrew Corporation
November 2007
doc.: IEEE 802.11-07/2889r0
References
• Technical Report: Location Acquisition and Location
Parameter Conveyance for Internet Access Networks in
Support of Emergency Services (Draft); Doc#: ATISxxxxxx; Source - ESIF
Submission
Slide 24
Vijay Patel, Andrew Corporation