VoIP i2 ArchitectureVoIP i2 Architecture

Part IPart I

The IP DomainThe IP Domain

SBC – Southwest Public SafetySBC – Southwest Public Safety

The Interim VoIP Architecture for Enhanced 9-1-1 Services (i2)Interim VoIP Architecture for Enhanced 9-1-1 Services (i2) document was the primary source of information used to create this presentation.

This NENA STANDARD is published by National Emergency Number Association (NENA) as a guide for the designers and manufacturers of systems that are used for the purpose of processing emergency calls.

VoIP i2 ArchitectureVoIP i2 Architecture

The following slide has the IP Domain graphically The following slide has the IP Domain graphically depicted, where you will see several functional depicted, where you will see several functional elements and where they fit within this schema.elements and where they fit within this schema.

Click on any of the Click on any of the VoIP functional elementsVoIP functional elements to to be magically transported to a place presenting the be magically transported to a place presenting the element definition and a short explanation of how it element definition and a short explanation of how it fits in the VoIP I2 Architecture.fits in the VoIP I2 Architecture.

There is a short quiz at the end of the presentation There is a short quiz at the end of the presentation concerning some of the components of the VoIP concerning some of the components of the VoIP architecture. architecture.

To proceed to the quiz section, To proceed to the quiz section,

IP Domain

PSAP

E9-1-1 Selective Router(s)

VoIP End

Point

DBMS

IP domain Emergency Services

Provider Network

Call server/ proxy server

LIS

SRDB

ALI DB

MSAG

VPCVPC

VPC

ALI DB

ESGW(s)

VDB

ESZRDB

v1

v0

v2

v4

v5

v2

v3

v-e2

v7

v8

v4

Routing Proxy & Redirect server(s)

v6

Layer 3/Layer 7 Location Download

Used for contingency routing

v7

PSTN Gateway

PSTN

Layer 2 Location Download mechanisms

RDO

v9

v9

So Sorry!So Sorry!

This element is not a discussion item in this particular PowerPoint show.

Information concerning only the VoIP elements in the IP domain are presented in this show.

Please return and select one of those functional elements.

VoIP EndpointVoIP Endpoint

The term VoIP endpoint is used to refer to the The term VoIP endpoint is used to refer to the endpoint IP Device that is used to originate an endpoint IP Device that is used to originate an emergency call.emergency call.

To return to I/P overview click

here

Location Information ServerLocation Information Server

The LIS serves as a repository for The LIS serves as a repository for location informationlocation information. . Location information is in the form of Location information is in the form of civic addresscivic address or or geo-spatial locationgeo-spatial location attributes correlated with a particular attributes correlated with a particular physical location. physical location.

The LIS is configured with mappings between individual The LIS is configured with mappings between individual location information and a logical representation of the location information and a logical representation of the physical locations with which they are associated. physical locations with which they are associated.

This set of associations is called a This set of associations is called a “Wiremap.”“Wiremap.”

The “The “wiremapwiremap” in the LIS is assumed to be configured ” in the LIS is assumed to be configured and maintained by the entity that provides/maintains the and maintained by the entity that provides/maintains the physical or logical access facility for endpoint equipment.physical or logical access facility for endpoint equipment.

The administrator/owner of the LIS is responsible for The administrator/owner of the LIS is responsible for creating and maintaining this wiremap, and for ensuring creating and maintaining this wiremap, and for ensuring that the civic location data is MSAG-validated.that the civic location data is MSAG-validated.

Location Information Server Location Information Server (cont.)(cont.)

This might be an IT administrator for an enterprise, or an Internet Service provider or an access provider in non-

enterprise/residential VoIP markets.

A given endpoint can be associated with a physical A given endpoint can be associated with a physical location that is mapped to a particular address (civic or location that is mapped to a particular address (civic or geo), and the address is downloaded from the LIS to the geo), and the address is downloaded from the LIS to the endpoint.endpoint.

The LIS may also support assignment of a The LIS may also support assignment of a location location query key,query key, to a particular instance of an address, to to a particular instance of an address, to support subsequent queries for the address.support subsequent queries for the address.

Location Information ServerLocation Information Server (cont.)(cont.)

Validation DatabaseValidation Database

The VDB contains information that describes the The VDB contains information that describes the current, valid civic address defined by the Emergency current, valid civic address defined by the Emergency Services Network Provider’s MSAG. Services Network Provider’s MSAG.

The VDB should have the capability to receive a The VDB should have the capability to receive a validation request containing a civic address consisting of validation request containing a civic address consisting of data elements included in the civic Location Object (data elements included in the civic Location Object (LO) and be able to determine if this civic address is a valid and be able to determine if this civic address is a valid address. address.

The VDB will return a response indicating that a The VDB will return a response indicating that a given LO is a valid address or an error response. given LO is a valid address or an error response.

The VDB may be distributed across multiple The VDB may be distributed across multiple databases, for example, with different VDB’s serving databases, for example, with different VDB’s serving different regional areas; however, different regional areas; however, there will be one there will be one primary source of validation data for any given primary source of validation data for any given geographic area or addressgeographic area or address..

Validation Database Validation Database (cont.)(cont.)

Location Object (LO)Location Object (LO)

The LO is used to refer to the current position of a VoIP The LO is used to refer to the current position of a VoIP endpoint that originates an emergency call. endpoint that originates an emergency call.

The LO may be:The LO may be:Geo locationGeo location – latitude, longitude, elevation or floor, and the – latitude, longitude, elevation or floor, and the datum which identifies the coordinate system used. datum which identifies the coordinate system used. Civic locationCivic location – a set of objects that describe detailed street – a set of objects that describe detailed street address information.address information.

Call Server/Proxy ServerCall Server/Proxy Server

The term The term Call ServerCall Server is used to refer to the entity in is used to refer to the entity in a private or public IP domain that provides a private or public IP domain that provides service to service to endpointsendpoints in an emergency caller’s home domain and in an emergency caller’s home domain and that works with the servers and other elements in the that works with the servers and other elements in the IP domain used to support emergency services call IP domain used to support emergency services call routing in the i2 solution. routing in the i2 solution.

The The Call ServerCall Server may use SIP may use SIP (Switched Internet (Switched Internet

Protocol)Protocol) or some other VoIP signaling protocol within or some other VoIP signaling protocol within its own serving domain.its own serving domain.

Call Server/Proxy Server Call Server/Proxy Server (cont.)(cont.)

A proxy server primarily plays the role of A proxy server primarily plays the role of routingrouting, , which means its job is to ensure that a request is sent to which means its job is to ensure that a request is sent to another entity "closer" to the targeted user. another entity "closer" to the targeted user. Proxies are also useful for enforcing policy (Proxies are also useful for enforcing policy (for for example, making sure a user is allowed to make a example, making sure a user is allowed to make a callcall). ). A proxy A proxy interpretsinterprets, and, if necessary, , and, if necessary, rewritesrewrites specific parts of a request message before forwarding. specific parts of a request message before forwarding.

Redirect Server/Call Relay ServerRedirect Server/Call Relay Server

A call relay server is a A call relay server is a redirect serverredirect server that that generates redirect responses to requests it receives, generates redirect responses to requests it receives, redirecting the client to contact an redirecting the client to contact an alternate set of alternate set of URIs to route the call to the call center with which to route the call to the call center with which VoIP Service Provider has an arrangement. VoIP Service Provider has an arrangement.

Call Server/Proxy signals callback number as Call Server/Proxy signals callback number as calling number/ANI for the call.calling number/ANI for the call.

Uniform Resource IdentifierUniform Resource Identifier

URIURI is an Internet is an Internet protocol element consisting of a element consisting of a short string of characters that conform to a certain short string of characters that conform to a certain syntax. syntax. The string comprises a name or address that can be The string comprises a name or address that can be used to refer to a resource. It is a fundamental component used to refer to a resource. It is a fundamental component of the World Wide Web. of the World Wide Web.

For example, the URL http://www.wikipedia.org/ is a URI For example, the URL http://www.wikipedia.org/ is a URI that identifies a resource (Wikipedia's home page) and that identifies a resource (Wikipedia's home page) and

implies that a representation of that resource is obtainable implies that a representation of that resource is obtainable via HTTP from a network host named www.wikipedia.org. via HTTP from a network host named www.wikipedia.org.

Emergency Service Zone (ESZ) Emergency Service Zone (ESZ) Routing Data Base (RDB)Routing Data Base (RDB)

The ERDB contains routing information associated The ERDB contains routing information associated with each with each ESZ in a serving area.

It supports the boundary definitions for ESZs and the It supports the boundary definitions for ESZs and the mapping of civic address or geospatial coordinate mapping of civic address or geospatial coordinate location information to a particular ESZ.location information to a particular ESZ.

Emergency Service Zone Routing Emergency Service Zone Routing Data Base Data Base (cont.)(cont.)

For each ESZ, the ERDB contains:For each ESZ, the ERDB contains:1.1. one Emergency Services Routing Number (ESRN) one Emergency Services Routing Number (ESRN)

associated with the primary Selective Router (SR) associated with the primary Selective Router (SR) that serves the ESZ andthat serves the ESZ and

2.2. one routing Emergency Services Number (ESN) one routing Emergency Services Number (ESN) that uniquely identifies the ESZ in the context of that uniquely identifies the ESZ in the context of that SR. that SR.

When an emergency call is originated, and location When an emergency call is originated, and location information is received from the VoIP Positioning information is received from the VoIP Positioning Center (VPC), the ERDB will identify the ESZ and Center (VPC), the ERDB will identify the ESZ and routingrouting information associated with the received information associated with the received location information, and will provide to the VPC:location information, and will provide to the VPC:1.1. ESRN, ESRN, 2.2. the routing ESN, the routing ESN, 3.3. the Contingency Routing Number (CRN - if available) and the Contingency Routing Number (CRN - if available) and

optionally,optionally,4.4. the administrative ESN.the administrative ESN.

Emergency Service Zone Routing Emergency Service Zone Routing Data Base Data Base (cont.)(cont.)

Emergency Service ZonesEmergency Service Zones

When the response areas of the When the response areas of the agencies are overlaid, they form agencies are overlaid, they form geographic zonesgeographic zones, each served , each served by a combination of Police, Fire by a combination of Police, Fire and EMS agencies.and EMS agencies.

These Zones are called Emergency These Zones are called Emergency Service Zones (ESZ’s). Each ESZ Service Zones (ESZ’s). Each ESZ contains the set of street addresses contains the set of street addresses served by the agencies.served by the agencies.

Root Discovery OperatorRoot Discovery Operator

The RDO is responsible for:The RDO is responsible for: maintaining and making available the identities maintaining and making available the identities

of the key VDB and ERDB functions in the of the key VDB and ERDB functions in the network. network.

ensuring that updated versions of the data with ensuring that updated versions of the data with specific activation and expiry times are available. specific activation and expiry times are available.

Root Discovery OperatorRoot Discovery Operator

The RDO is also responsible for:The RDO is also responsible for: consolidatingconsolidating the discovery information as the discovery information as

received by all VDB and ERDB operators, received by all VDB and ERDB operators, negotiatingnegotiating coordinated activation and expiry coordinated activation and expiry

intervals, and intervals, and making this consolidated information available making this consolidated information available

for access over the interface. for access over the interface.

The VDB will return a response indicating that a The VDB will return a response indicating that a given Location Object (given Location Object (LO) is a valid address or an error response.

The VDB may be distributed across multiple The VDB may be distributed across multiple databases, for example, with different VDBs serving databases, for example, with different VDBs serving different regional areas; however, there will be one different regional areas; however, there will be one primary source of validation data for any given primary source of validation data for any given geographic area or address.geographic area or address.

Validation Data BaseValidation Data Base (cont.)(cont.)

The VoIP Positioning CenterThe VoIP Positioning Center

VPC is the element that provides routing information to support the routing of VoIP emergency calls, and cooperates in delivering location information to the PSAP over the existing ALI DB infrastructure.

The information provided includes: Callback information, when available and a Location Object or Location Key.

The VPC may also receive other information The VPC may also receive other information about the call, such as Voice Server Provider about the call, such as Voice Server Provider

(VSP) identification information.(VSP) identification information.

The VoIP Positioning Center The VoIP Positioning Center (cont.)(cont.)

The VPC uses the received location information with The VPC uses the received location information with

other locally stored information that enables it to other locally stored information that enables it to

determine the determine the appropriate ERDB to queryappropriate ERDB to query for the for the

routing instructions.routing instructions.The VPC uses the received location information to The VPC uses the received location information to request routing information from the ERDBrequest routing information from the ERDB that is that is associated with the caller’s location. associated with the caller’s location.

The VPC may also obtain information from the The VPC may also obtain information from the ERDB to assist in contingency routing.ERDB to assist in contingency routing.

Emergency Services GatewayEmergency Services Gateway

The ESGW uses the routing information provided The ESGW uses the routing information provided in the in the received call setup signalingreceived call setup signaling to select the to select the appropriate trunk (group) and proceeds to signal call appropriate trunk (group) and proceeds to signal call setup toward the SR using the ESQK to represent the setup toward the SR using the ESQK to represent the Calling Party Number/Automatic Number Calling Party Number/Automatic Number Identification (ANI) information.Identification (ANI) information.

The ESGW is the signaling and media interworking The ESGW is the signaling and media interworking point between the point between the IP domain and conventional trunksIP domain and conventional trunks to the E9-1-1 SR that use either Multi-Frequency to the E9-1-1 SR that use either Multi-Frequency [MF] or Signaling System #7 [SS7] signaling. [MF] or Signaling System #7 [SS7] signaling.

PSTN is the world's collection of interconnected PSTN is the world's collection of interconnected voice-oriented public telephone networks, both voice-oriented public telephone networks, both commercial and government-owned. commercial and government-owned. PSTN is the aggregation of circuit-switching PSTN is the aggregation of circuit-switching telephone networks that has evolved from the days of telephone networks that has evolved from the days of Alexander Graham Bell. Alexander Graham Bell.

Public Switched Telephone NetworkPublic Switched Telephone Network

The following five review questions are designed to help you remember some of the important components of the IP Domain and their function within the VoIP architecture.

Quick QuizQuick Quiz

Click on the response that you feel best answers Click on the response that you feel best answers the question. The correct answer will highlight.the question. The correct answer will highlight.

1. The term VoIP endpointVoIP endpoint is used to refer to:

a) the termination point of a VoIP call.

b) a repository for location information..

c)c) the element that provides routing information to the element that provides routing information to support the routing of VoIP emergency calls.support the routing of VoIP emergency calls.

d)d) the endpoint IP Device that is used to originate an the endpoint IP Device that is used to originate an emergency call.emergency call.

2. A serverserver is a network element that receives requests in order to service them and sends back responses to those requests.

One of these is NOT an example of a server used in SIP domains :

a)a) proxies,proxies,

b)b) VoIP Positioning Centers VoIP Positioning Centers

c)c) redirect servers, redirect servers,

d)d) registrarsregistrars

3.3. The Emergency Routing Database (ERDB) The Emergency Routing Database (ERDB) is the element that provides routing information to support the routing of VoIP emergency calls, and cooperates in delivering location information to the PSAP over the existing ALI DB infrastructure.

a)a) TRUETRUE

b)b) FALSEFALSE

The ERDB contains the routing information associated with each ESZ in a serving area.

The VoIP Positioning Center (VPC) is the element that provides routing information to support the routing of VoIP emergency call. The VPC supports access to the routing data in the ERDB.

4.4. The VoIP Positioning Center (VPC) The VoIP Positioning Center (VPC) is a key element in the VoIP architecture. The following statements are all true about the function of the VPC except for one. Which statement is not a function of the VPC?

a. The VPC uses the received location information with other

locally stored information that enables it to determine the

appropriate ERDB to query for the routing instructions.

b. The VPC uses the routing information provided in the received

call setup signaling to select the appropriate trunk (group).

c. If the VPC receives a Location Key, the VPC obtains the

location information from the identified LIS.

The Emergency Services Gateway (ESGW)Emergency Services Gateway (ESGW) uses the routing information provided in the received call setup signaling to select the appropriate trunk.

5.5. The Validation Database (VDB) The Validation Database (VDB) contains information that describes the current, valid civic address space defined by the Emergency Services Network Provider’s MSAG.

“Once queried, The VDB will return a response Once queried, The VDB will return a response indicating that a given location is a valid address indicating that a given location is a valid address or reply with an error response”.or reply with an error response”.

a)a) TRUETRUE

b)b) FALSEFALSE

VoIP i2 Architecture The IP DomainThe IP Domain is Part 1 in the VoIP i2 Architecture PowerPoint series.

See VoIP i2 Architecture 9-1-1 Call 9-1-1 Call RoutingRouting for an explanation of the basic routing of a VoIP call.

Frank Abbenhaus

SBC – Southwest Public SafetySBC – Southwest Public Safety