VoIP i2 Architecture Part I

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VoIP i2 ArchitecturePart I
The IP Domain
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• The 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.

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VoIP i2 Architecture

• The following slide has the IP Domain graphically
  depicted, where you will see several functional
  elements and where they fit within this schema.
• Click on any of the VoIP functional elements to
  be magically transported to a place presenting
  the element definition and a short explanation of
  how it fits in the VoIP I2 Architecture.
• There is a short quiz at the end of the
  presentation concerning some of the components of
  the VoIP architecture.

To proceed to the quiz section,
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(No Transcript)
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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.

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VoIP Endpoint

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

To return to I/P overview click here
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Location Information Server

• The LIS serves as a repository for location
  information.
• Location information is in the form of civic
  address or geo-spatial location attributes
  correlated with a particular physical location.
• The LIS is configured with mappings between
  individual location information and a logical
  representation of the physical locations with
  which they are associated.

This set of associations is called a Wiremap.
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Location Information Server (cont.)

• The wiremap in the LIS is assumed to be
  configured and maintained by the entity that
  provides/maintains the physical or logical access
  facility for endpoint equipment.
• The administrator/owner of the LIS is responsible
  for creating and maintaining this wiremap, and
  for ensuring that the civic location data is
  MSAG-validated.

This might be an IT administrator for an
enterprise, or an Internet Service provider or an
access provider in non-enterprise/residential
VoIP markets.
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Location Information Server (cont.)

• A given endpoint can be associated with a
  physical location that is mapped to a particular
  address (civic or geo), and the address is
  downloaded from the LIS to the endpoint.
• The LIS may also support assignment of a location
  query key, to a particular instance of an
  address, to support subsequent queries for the
  address.

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Validation Database

• The VDB contains information that describes the
  current, valid civic address defined by the
  Emergency Services Network Providers MSAG.
• The VDB should have the capability to receive a
  validation request containing a civic address
  consisting of data elements included in the civic
  Location Object (LO) and be able to determine if
  this civic address is a valid address.

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Validation Database (cont.)

• The VDB will return a response indicating that a
  given LO is a valid address or an error response.
  
• The VDB may be distributed across multiple
  databases, for example, with different VDBs
  serving different regional areas however, there
  will be one primary source of validation data for
  any given geographic area or address.

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Location Object (LO)

• The LO is used to refer to the current position
  of a VoIP endpoint that originates an emergency
  call.
• The LO may be
• Geo location latitude, longitude, elevation or
  floor, and the datum which identifies the
  coordinate system used.
• Civic location a set of objects that describe
  detailed street address information.

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Call Server/Proxy Server

• The term Call Server is used to refer to the
  entity in a private or public IP domain that
  provides service to endpoints in an emergency
  callers home domain and that works with the
  servers and other elements in the IP domain used
  to support emergency services call routing in the
  i2 solution.
• The Call Server may use SIP (Switched Internet
  Protocol) or some other VoIP signaling protocol
  within its own serving domain.

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Call Server/Proxy Server (cont.)

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

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Redirect Server/Call Relay Server

• A call relay server is a redirect server that
  generates redirect responses to requests it
  receives, redirecting the client to contact an
  alternate set of URIs to route the call to the
  call center with which VoIP Service Provider has
  an arrangement.
• Call Server/Proxy signals callback number as
  calling number/ANI for the call.

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Uniform Resource Identifier

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

For example, the URL http//www.wikipedia.org/ is
a URI that identifies a resource (Wikipedia's
home page) and implies that a representation of
that resource is obtainable via HTTP from a
network host named www.wikipedia.org.
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Emergency Service Zone (ESZ) Routing Data Base
(RDB)

• The ERDB contains routing information associated
  with each ESZ in a serving area.
• It supports the boundary definitions for ESZs and
  the mapping of civic address or geospatial
  coordinate location information to a particular
  ESZ.

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Emergency Service Zone Routing Data Base (cont.)

• For each ESZ, the ERDB contains
• one Emergency Services Routing Number (ESRN)
  associated with the primary Selective Router (SR)
  that serves the ESZ and
• one routing Emergency Services Number (ESN) that
  uniquely identifies the ESZ in the context of
  that SR.

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Emergency Service Zone Routing Data Base (cont.)

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

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Emergency Service Zones
When the response areas of the agencies are
overlaid, they form geographic zones, each served
by a combination of Police, Fire and EMS agencies.
These Zones are called Emergency Service Zones
(ESZs). Each ESZ contains the set of street
addresses served by the agencies.
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Root Discovery Operator

• The RDO is responsible for
• maintaining and making available the identities
  of the key VDB and ERDB functions in the network.
  
• ensuring that updated versions of the data with
  specific activation and expiry times are
  available.

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Root Discovery Operator

• The RDO is also responsible for
• consolidating the discovery information as
  received by all VDB and ERDB operators,
• negotiating coordinated activation and expiry
  intervals, and
• making this consolidated information available
  for access over the interface.

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Validation Data Base (cont.)

• The VDB will return a response indicating that a
  given Location Object (LO) is a valid address or
  an error response.
• The VDB may be distributed across multiple
  databases, for example, with different VDBs
  serving different regional areas however, there
  will be one primary source of validation data for
  any given geographic area or address.

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The 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 about
the call, such as Voice Server Provider (VSP)
identification information.
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The VoIP Positioning Center (cont.)

• 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.
• The VPC uses the received location information to
  request routing information from the ERDB that is
  associated with the callers location.

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

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

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

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Public Switched Telephone Network

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

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Quick Quiz

• 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.

Click on the response that you feel best answers
the question. The correct answer will highlight.
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• The term VoIP endpoint is used to refer to
• the termination point of a VoIP call.
• a repository for location information.
• the element that provides routing information to
  support the routing of VoIP emergency calls.
• the endpoint IP Device that is used to originate
  an emergency call.

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A server 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

• proxies,
• VoIP Positioning Centers
• redirect servers,
• registrars

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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.

• TRUE
• FALSE

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.
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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?

• 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.
• The VPC uses the routing information provided in
  the received call setup signaling to select the
  appropriate trunk (group).
• If the VPC receives a Location Key, the VPC
  obtains the location information from the
  identified LIS.

The Emergency Services Gateway (ESGW) uses the
routing information provided in the received call
setup signaling to select the appropriate trunk.
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The Validation Database (VDB) contains
information that describes the current, valid
civic address space defined by the Emergency
Services Network Providers MSAG. Once
queried, The VDB will return a response
indicating that a given location is a valid
address or reply with an error response.

• TRUE
• FALSE

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• VoIP i2 Architecture The IP Domain is Part 1 in
  the VoIP i2 Architecture PowerPoint series.
• See VoIP i2 Architecture 9-1-1 Call Routing for
  an explanation of the basic routing of a VoIP
  call.

Frank Abbenhaus