doc.: ieee 802.11-07/2889r0 submission november 2007 vijay patel, andrew corporationslide 1 lis-ale...
TRANSCRIPT
November 2007
Vijay Patel, Andrew Corporation
Slide 1
doc.: IEEE 802.11-07/2889r0
Submission
LIS-ALE Architecture, and FLAPDate: 2007-11-12
Name Affiliations Address Phone email Vijay Patel Andrew
Corporation 19700 Janelia Farm Blvd, Ashburn, VA 20147
+1 (703) 726-5693
Authors:
November 2007
Vijay Patel, Andrew Corporation
Slide 2
doc.: IEEE 802.11-07/2889r0
Submission
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 end-device.
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.
November 2007
Vijay Patel, Andrew Corporation
Slide 3
doc.: IEEE 802.11-07/2889r0
Submission
Internet location services model – Location Information Server (LIS)
Internet
Service
AccessDomain
InternetDomain
ServiceDomain
12
Location by value1. Device obtains location from
the location server in the access network
2. Device conveys location* to the service in the applicable application protocol.
Location by reference1. 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
Internet
Service
AccessDomain
InternetDomain
ServiceDomain
12
3LIS
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)
* Location values are encoded as a PIDF-LO per RFC4119
November 2007
Vijay Patel, Andrew Corporation
Slide 4
doc.: IEEE 802.11-07/2889r0
Submission
Internet location services model – OBO Requests
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.
Internet Service
AccessDomain
InternetDomain
ServiceDomain
12
3LIS
Trusted Service
Application*protocol
Target device
HELD
HELD
November 2007
Vijay Patel, Andrew Corporation
Slide 5
doc.: IEEE 802.11-07/2889r0
Submission
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.
November 2007
Vijay Patel, Andrew Corporation
Slide 6
doc.: IEEE 802.11-07/2889r0
Submission
Flexible LIS-ALE Protocol (FLAP) - ScopeExternal applications
Access Network LIS
User Device
FLAP
Location dereference request path
Networkmeasurement
requests
Devicemeasurement
requests
Networkmeasurements
Other measurements
Externalmeasurement sources
(e.g. GPS, RFID beacons)
Other measurements
Internet
Externalmeasurement sources
(e.g. GPS, LMUs)
ALEALE
ALEALE
Scope of FLAP
November 2007
Vijay Patel, Andrew Corporation
Slide 7
doc.: IEEE 802.11-07/2889r0
Submission
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
November 2007
Vijay Patel, Andrew Corporation
Slide 8
doc.: IEEE 802.11-07/2889r0
Submission
LIS-ALE Architecture
ALEALE ALE
ALE messages
HELD
LIS
HELD HELD
November 2007
Vijay Patel, Andrew Corporation
Slide 9
doc.: IEEE 802.11-07/2889r0
Submission
Location Determination: LIS-ALE Ntwk Model
November 2007
Vijay Patel, Andrew Corporation
Slide 10
doc.: IEEE 802.11-07/2889r0
Submission
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 meta-
objects 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• E.g. A layer 2 Ethernet switch extension defines a terminal by MAC address. Access parameters include
switch identity, connected port, and vlan ID.
– Vendor extensions permit new terminal and access parameters to be defined.• 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.
November 2007
Vijay Patel, Andrew Corporation
Slide 11
doc.: IEEE 802.11-07/2889r0
Submission
FLAP – Hierarchical definitionsTechnology specific ALE capabilities
FLAPFLAPBase XML SchemaBase XML Schema
Ethernet Ethernet switchswitch
WiFi WiFi AccessPointAccessPoint
WiMAXWiMAXBase StationBase Station
DSL DSL AggregatorAggregator
CableCableHead EndHead End
Vendor Vendor ExtensionsExtensions
Vendor Vendor ExtensionsExtensions
Vendor Vendor ExtensionsExtensions
Vendor Vendor ExtensionsExtensions
Vendor Vendor ExtensionsExtensions
Etc.
November 2007
Vijay Patel, Andrew Corporation
Slide 12
doc.: IEEE 802.11-07/2889r0
Submission
FLAP - XML Structure, Base definitionsType definitions
Header definitionTerminal definition
[vendor]ipaddress
Access definitionTimeExpiryTime
Messaging definitionsMessage component definitions
Transaction IDTechnologyVendor ID
Message definitionsAccessQueryAccessQueryResponseNotifySynchSynchResponse
Parameter definitionsError codesResult codes
Vendor…e.g. Alcatel_LiteSpanDSL_definitions
Extensions#include EthernetSwitchExtension#Include DHCPRelayExtension#Include DSLAggregatorExtension
Base definitions augmented by including vendor and technology specific extensions
Base definitions define semantic objects and messages
November 2007
Vijay Patel, Andrew Corporation
Slide 13
doc.: IEEE 802.11-07/2889r0
Submission
FLAP - messagingTo 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.
November 2007
Vijay Patel, Andrew Corporation
Slide 14
doc.: IEEE 802.11-07/2889r0
Submission
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>
November 2007
Vijay Patel, Andrew Corporation
Slide 15
doc.: IEEE 802.11-07/2889r0
Submission
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.
November 2007
Vijay Patel, Andrew Corporation
Slide 16
doc.: IEEE 802.11-07/2889r0
Submission
Example – WiMax Network Controller ALE
LIS
IP
WiMax extension schemaTerminal definition
MAC addressIP address
Access definition extensionBTS ID
Vendor X extension schemaVendor XProduct WAP-FamilyY-ModelZAccess definition extensions
Channel infoRoundTripTimeRxLevel
WiMax extension schemaTerminal definition
MAC addressIP address
Access definition extensionBTS ID
Vendor X extension schemaVendor XProduct WAP-FamilyY-ModelZAccess definition extensions
Channel infoRoundTripTimeRxLevel
ALE
NetworkController
FLAP
IP@ BTS ID f(Channel, RoundTripTime, RxLevel)Location
IP@ BTS ID Location
Generic LIS record
Vendor X proprietary support LIS recordlocation is determined by an algorithm which is a function of RF signal strength and timing measurements supported by the WiMax manufacturer
WiMax BTS
November 2007
Vijay Patel, Andrew Corporation
Slide 17
doc.: IEEE 802.11-07/2889r0
Submission
Example – A DSL Aggregator ALE
LIS
ALE
FLAP
Copper PVC IP
Device ATU-R DSLAM
ATM
DSLAggregator
ISP/Enterprise
DSL Aggregator extension schema
Terminal definition
IP address
Access definition extension
Aggregation device ID
ATM port ID
PVC ID
DSL Aggregator extension schema
Terminal definition
IP address
Access definition extension
Aggregation device ID
ATM port ID
PVC ID
IP@ Aggregation device ID
ATM Port PVC Location
November 2007
Vijay Patel, Andrew Corporation
Slide 18
doc.: IEEE 802.11-07/2889r0
Submission
Example – Ethernet Switch ALE
LIS
Ethernet
Switches
IP
Ethernet switch extension schemaTerminal definition
MAC address
IP address
Access definition extension
Switch ID
Switch address
Port ID
VLAN ID
Ethernet switch extension schemaTerminal definition
MAC address
IP address
Access definition extension
Switch ID
Switch address
Port ID
VLAN ID
ALE
ALE
ALE
Switch
FLAP
IP@ Switch ID Port ID Location
November 2007
Vijay Patel, Andrew Corporation
Slide 19
doc.: IEEE 802.11-07/2889r0
Submission
Example – 802.11x Access Point ALE
LIS
IP
802.11x AP extension schemaTerminal definition
MAC address
IP address
Access definition extension
WAP ID
Channel No
Vendor X extension schemaVendor X
Product WAP-FamilyY-ModelZ
Access definition extensions
RoundTripTime
RxLevel
802.11x AP extension schemaTerminal definition
MAC address
IP address
Access definition extension
WAP ID
Channel No
Vendor X extension schemaVendor X
Product WAP-FamilyY-ModelZ
Access definition extensions
RoundTripTime
RxLevel
ALEALE
Switch
FLAP
IP@ WAP ID f(Channel, RoundTripTime, RxLevel)Location
IP@ WAP ID Location
WAP
Generic LIS record
Vendor X proprietary support LIS recordlocation is determined by an algorithm which is a function of RF signal strength and timing measurements supported by the AP manufacturer
November 2007
Vijay Patel, Andrew Corporation
Slide 20
doc.: IEEE 802.11-07/2889r0
Submission
LIS-ALE Procedures
LIS
Device data
Update queries Access device
ALE
Device
Device
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.
1. LIS starts up2. LIS establishes FLAP sessions* with ALEs in area of coverage3. LIS optionally requests synchronization information from ALEs4. ALEs report measurements as device-related events occur5. LIS optionally informs ALEs if devices detected elsewhere6. LIS optionally polls ALEs for measurements as HELD requests occur
November 2007
Vijay Patel, Andrew Corporation
Slide 21
doc.: IEEE 802.11-07/2889r0
Submission
Incorporating device measurementsExternal applications
Access Network LIS
User Device
FLAP
Location dereference request path
Networkmeasurement
requests
Devicemeasurement
requests
Networkmeasurements
Other measurements
Externalmeasurement sources
(e.g. GPS, RFID beacons)
Other measurements
Internet
Externalmeasurement sources
(e.g. GPS, LMUs)
Device measured location parameters
As a generic constraint, a LIS cannot assume specific measurement capabilities or protocols supported by visiting devices. However, these capabilities should not be ignored.
As a generic constraint, a LIS cannot assume specific measurement capabilities or protocols supported by visiting devices. However, these capabilities should not be ignored.
November 2007
Vijay Patel, Andrew Corporation
Slide 22
doc.: IEEE 802.11-07/2889r0
Submission
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.
IPdevice
LIS
AccessNetwork
ALE FLAP
LocReqResp(LocCap(SubTechList(…))
GPSsatellites
LocReq( Type(locationURI), LocCap(TechList(…))
AppProtocol(LocationURI)
LocReq(signed)
1
3
4
2
HELD
Protocol specific message exchange Selected Location Technology protocol
5
5
Application
6
LocResp
November 2007
Vijay Patel, Andrew Corporation
Slide 23
doc.: IEEE 802.11-07/2889r0
Submission
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.