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The Next Generation 9-1-1 Proof-of-Concept System
Jong Yul Kim
Wonsang Song
Henning Schulzrinne
SIP 2009 (Paris, January 2009)
Talk Outline
• Background– why is emergency calling difficult for VoIP?– numbers, call routing, …
• High level proof-of-concept architecture
• Location configuration
• Call routing
• Lessons learned
3
Modes of emergency communications
emergency call
civic coordination
emergency alert(“inverse 911”)
dispatch
information“I-am-alive”
4
Background on 9-1-1
• Established in Feb. 1968– 1970s: selective call routing– late 1990s: 93% of population/96% of area covered by 9-1-1– 95% of 9-1-1 is Enhanced 9-1-1– US and Canada
• Roughly 200 mio. calls a year (6 calls/second)– 1/3 wireless
• 6146 PSAPs in 3135 counties– most are small (2-6 call takers)– 83.1% of population have some Phase II (April 2007)
• “12-15 million households will be using VoIP as either primary or secondary line by end of 2008” (NENA)
http://www.nena.org/
IEEE NY 5
Local Switch
Automatic Number Identification
Automatic Location Identification
Collaboration between local phone providers and local public safety agencies
6
What makes VoIP 112/911 hard?POTS PSTN-emulation VoIP end-to-end VoIP
(landline) phone number limited to limited area
landline phone number anywhere in US (cf. German 180)
no phone number or phone number anywhere around the world
regional carrier national or continent-wide carrier
enterprise “carrier” or anybody with a peer-to-peer device
voice provider = line provider (~ business relationship)
voice provider ≠ ISP voice provider ≠ ISP
national protocols and call routing
probably North America + EU
international protocols and routing
location = line location mostly residential or small business
stationary, nomadic, wireless
7
Emergency numbers
• Each country and region has their own– subject to change
• Want to enable– traveler to use familiar home
number– good samaritan to pick up cell
phone
• Some 3/4-digit numbers are used for non-emergency purposes (e.g., directory assistance) Emergency number
8
Service URN• Idea: Identifiers to denote emergency calls
– and other generic (communication) services• Described in IETF ECRIT RFC 5031• Emergency service identifiers:
sos General emergency services sos.animal-control Animal control sos.fire Fire service sos.gas Gas leaks and gas emergencies sos.marine Maritime search and rescue sos.mountain Mountain rescue sos.physician Physician referral service sos.poison Poison control center sos.police Police, law enforcement
“EMERGENCY HELP. Anytime, anywhere, any device.”™National Emergency Number Association (NENA)
Technical standardsIETF ECRIT Working GroupIETF GEOPRIV Working Group
The NG9-1-1 POC System
High level requirements
Use of multimediaData delivery and sharing
Recording and incident detailsCall taker user interface
Technical standards
System architectureBehavior of components
Format of location objects
IETF ECRIT Working GroupIETF GEOPRIV Working Group
NENA
The POC system is deployed in 5 real PSAPs and 3 labs across the USA.PSAP: Public Safety Answering Point (=Emergency call center)
Fort Wayne, IN
Rochester, NY
Bozeman, MT
King County, WA
St. Paul, MN
BAH Lab
Columbia Univ. Lab
TAMU Lab
Emergency Services Network (ESN)Network used by emergency caller to ask for help
Examples: PSTN, Cellular, Residential VoIP
Role1. Determine location of caller2. Route call to ESN
9-1-1
Access Network
Emergency Services Network (ESN)
Emergency Services Routing Proxy (ESRP) Call Distributor
SIP Back-to-back User Agent
PSAP A
PSAP SIP Proxy
.
.
.
Location-to-Service Translation (LoST)
Server
.
.
.
Call Takers
PSAP Z
PSAP SIP Proxy
.
.
.
Call TakersCall DistributorSIP Back-to-back
User Agent
Public Safety Answering Points (PSAP)
Conference Server
POC system is divided into two networks
SIP-based network of PSAPs managed by the emergency authorities
Why is location important?• Send help to the site of emergency• Route call to the correct destination
Cell Tower
LLDP-MED
GPS
DHCP
Manual Entry
Skyhook Wireless
How do I send my location?•Sent along with SIP INVITE •Formatted as PIDF-LO XML object
① ②
14
Location determination optionsMethod CDP or LLDP-
MEDDHCP HELD GPS manual entry
Layer L2 L3 L7 (HTTP) - user
advantages • simple to implement
• built into switch• direct port/room
mapping
• simple to implement
• network locality
• traverses NATs
• can be operated by L2 provider
• accurate• mobile
devices• no carrier
cooperation
• no infrastructure changes
• no carrier cooperation
problems may be hard to automate for large enterprises
mapping MAC address to location?
mapping IP address to switch port?
• indoor coverage
• acquisition time
• fails for mobile devices
• unreliable for nomadic
Use Ethernet LANs Enterprise LANs
Some ISPs
DSL, cable mobile devices fall back
LoST
• LoST = Location-to-Service Translation
• LoST lets you find a PSAP
• RFC 5222 from IETF ECRIT WG
Caller’s location
Service identifier
(urn:service:sos)
+Service provider
(PSAP URL)
Emergency Dial String
+
16
LoST: Location-to-URL Mapping
clusterserves VSP2
NYUS
NJUS
Bergen CountyNJ US
123 Broad AveLeoniaBergen CountyNJ US
cluster serving VSP1replicateroot information
searchreferral
rootnodes
LeoniaNJ US
VSP1
LoST
17
LoST Architecture
T1
(.us)
T2
(.de) T3
(.dk)
G
G
GG
G broadcast (gossip)T1: .us
T2: .de
resolver
seeker313 Westview
Leonia, NJ US
Leonia, NJ sip:[email protected]
tree guide
18
LoST: Query example
• Uses HTTP or HTTPS
<findService xmlns="urn:…:lost1”recursive="true" serviceBoundary="value">
<location profile="basic-civic"> <civicAddress> <country>Germany</country> <A1>Bavaria</A1> <A3>Munich</A3> <A6>Neu Perlach</A6> <HNO>96</HNO> </civicAddress> </location> <service>urn:service:sos.police</service></findService>
19
LoST “Find Service” response/warning example
<findServiceResponse xmlns="urn:ietf:params:xml:ns:lost1"> <mapping expires=“1990-12-31T23:59:60Z” lastUpdated=“2006-11-01T01:00:00Z”> <displayName xml:lang="de">München Polizei-Abteilung</displayName> <service>urn:service:sos.police</service> <serviceBoundary profile=”civic”> <civicAddress xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"> <country>Germany</country> <A1>Bavaria</A1><A3>Munich</A3><PC>81675</PC> </civicAddress> </serviceBoundary> <uri>sip:[email protected]</uri> <serviceNumber>110</serviceNumber> </mapping> <path> <via source=“lost:esgw.uber-110.de.example”/> <via source=“lost:polizei.munchen.de.example”> </path></findServiceResponse>
Emergency Services Network (ESN)
Emergency Services Routing Proxy (ESRP) Call Distributor
SIP Back-to-back User Agent
PSAP A
PSAP SIP Proxy
.
.
.
Location-to-Service Translation (LoST)
Server
.
.
.
Call Takers
PSAP Z
PSAP SIP Proxy
.
.
.
Call TakersCall DistributorSIP Back-to-back
User Agent
Public Safety Answering Points (PSAP)
Conference Server
RTP
LoST
Cellular
Access Network
SIP
9-9-1-19-1-9-1-1
Emergency Services Network (ESN)
Emergency Services Routing Proxy (ESRP) Call Distributor
SIP Back-to-back User Agent
PSAP A
PSAP SIP Proxy
.
.
.
Location-to-Service Translation (LoST)
Server
.
.
.
Call Takers
PSAP Z
PSAP SIP Proxy
.
.
.
Call TakersCall DistributorSIP Back-to-back
User Agent
Public Safety Answering Points (PSAP)
Conference Server
LoST
SMS
Access Network
SIP
9-9-1-19-1-9-1-1
“Bank robbery!”
S
Emergency Services Network (ESN)
Emergency Services Routing Proxy (ESRP) Call Distributor
SIP Back-to-back User Agent
PSAP A
PSAP SIP Proxy
.
.
.
Location-to-Service Translation (LoST)
Server
.
.
.
Call Takers
PSAP Z
PSAP SIP Proxy
.
.
.
Call TakersCall DistributorSIP Back-to-back
User Agent
Public Safety Answering Points (PSAP)
Conference Server
RTP
LoST
Telematics
Access Network
SIP
9-9-1-19-1-9-1-1
Crash Data
Emergency Services Network (ESN)
Emergency Services Routing Proxy (ESRP) Call Distributor
SIP Back-to-back User Agent
PSAP A
PSAP SIP Proxy
.
.
.
Location-to-Service Translation (LoST)
Server
.
.
.
Call Takers
PSAP Z
PSAP SIP Proxy
.
.
.
Call TakersCall DistributorSIP Back-to-back
User Agent
Public Safety Answering Points (PSAP)
Conference Server
RTP
LoST
Access Network
SIP
“All call takers are busy…”
All Busy
9-9-1-19-1-9-1-1
24
Calltaker screen• Columbia SIPc as SIP UA
• Mapping software to display caller’s location– Geolynx– Google Maps
25
NG911 trial: Lessons learned• Tested NG911 prototype in 3 PSAPs in TX and VA• Surprise: PSAP is really a conferencing system
– LanguageLine, first responders, …
• Surprise: no uniform incident description– every jurisdiction uses their own variation and level of detail
• What is desirable behavior– rather than current behavior– e.g., for transfer, overflow
• Need to integrate call taker management– presence (availability)– a specialized call center
• Special requirements: partial mute– not typically supported on conference servers
26
Challenges for NG911
• Technically, much simpler than E911 Phase II– hopefully, cheaper, too– but security challenges: location and identity verification– co-existence between E911 and NG911– integrating external data (e.g., OnStar) -- from silo to NG911
SOA
• Logistical challenges– deployment of new infrastructure
• location and LoST servers
• Legal and regulatory challenges– will ISPs give out location information to VSPs or customers?– liability for misrouted calls?
Final Comments
• We are beginning to understand what an emergency response system should look like
• Lots of interesting network problems in emergency communication systems– Geographic Location of network devices– “Call setup time (dialing of last digit to ring at the
PSAP), under expected peak load shall be less than 2 seconds.”
– Reliable communications in large scale disasters
mDNS?