Transcript Document 7227438

Reference Models
THE OSI & TCP/IP
REFERENCE
MODELS
1
Public Switched Telephone Network (PSTN)
• The PSTN includes a number of transmission links and
nodes:
 Customer Premises Equipment (CPE) – the
equipment that is located at the customer site to
transmit and receive user information and exchange
the control information with the network, it includes
PBXs key telephone systems, and single line
telephones.
 Switching nodes – interconnect transmission
facilities at various locations and route traffic through
a network.
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Public Switched Telephone Network (PSTN)
(Continued..)
Transmission nodes – provide communication
paths that carry user traffic and network control
information between the nodes in the network,
include the transmission media, transport equipment,
amplifiers and/or repeaters, multiplexers and…
 Service nodes – handle signaling, which is the
transmission of information to control the setup,
holding, charging, and releasing of connections, as
well as the transmission of information to control
network operations and billing (SS7)
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PSTN Architecture
Long-haul
Central
Office
Central
Office
Network
Toll switch
(For routing calls to
or from other cities)
International
Gateway
Central
Office
PBX
Individual
User station
lines, or
Extensions
• Each phone user (subscriber) has a direct connection to a switch in the
central office. This is called the local loop
• The local loop has a length of 1 – 10 km
• The switches in the central office are called (local) exchange
• A company which provides local telephone service is called a4 local
exchange carrier (LEC)
How is voice transmitted?
• Voice can be transmitted in two ways:
– Analog voice transmission: each voice
channel is allocated a bandwidth of 3.5 kHz
– Digital voice transmission: analog voice
stream is converted in a digital stream:
• Standard scheme for voice call: Obtain 8000
samples per second, each with length 8 bit
5
How is voice transmitted?
• Until 1960s:
– Entire telephone network is analog
– Frequency division multiplexing
• Today:
– The local loop is analog.
– The rest of the network is digital (based on
TDM)
• All digital: When do we get an all digital network?
– ISDN (Integrated Services Digital Network ) is an all digital
circuit-switching technology. ISDN is available since the
early – 1990s (in Europe) or mid-1990s (US). No wide
deployment in US
– Another all digital – but not circuit switched - telephony6
solution is IP telephony.
All Analog telephone network
Subscriber
Subscriber
Telephone
Switch
Subscriber
•
•
Telephone
Switch
Subscriber
The telephone switch bundles (multiplexes)
multiple voice calls on a high-bandwidth link
The multiplexing method is FDM
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Analog local loop / digital network
Subscriber
Subscriber
Telephone
Switch
Subscriber
Telephone
Switch
1-byte voice
samples
Subscriber
•
The first telephone digitizes a voice call (8000 8-bit
•
samples per second)
Switching method is TDM.
- Switch bundles multiple calls, by interleaving samples in time.
Each receives one 8-bit slot every 125μs
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PBX
Long-haul
Central
Office
Central
Office
Network
Central
Office
PBX
Toll
switch
• A PBX (Private Branch Exchange) is telephone system
within an enterprise that switches calls within the
enterprise on local lines, while allowing all users to share a
certain number of external lines to the central office.
• The main purpose of a PBX is to save the cost of requiring
a line for each user to the telephone company’s central
9
office.
The long-haul network
Long-haul
Central
Office
Central
Office
Network
Central
Office
PBX
Toll
switch
• Toll or backbone switches provide
connectivity over long distance trunks.
long-distance
• There are only about 500 toll switches in the united states.
Each toll switch can run more than 100,000 simultaneous
phone calls
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Signaling
 Signaling: exchange of messages among network entities
to enable (provide service) to connection / call
 Or the communication necessary to set up a call from one
subscriber to another
 Before, during, after connection/call
o call setup and tear down
o call maintenance
o measurement, billing
 Between:
o end – user <-> network
o network element <-> network element
o end – user <-> end – user
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Telephone network: services
 point-to-point POTS calls
 special telephone numbers:
o 800 (888) number service: free call to customer
o numbers for life
 caller ID
 calling card / third part charging
 call routing (to end user): prespecified, by time-of-day
 “follow me” service – allows you to select a temporary
alternate phone on campus to receive your forwarded calls.
 incoming/outgoing call restrictions
 support for cellular roaming: “home” number routed to
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current cell location
Intelligence in the network
 Telephone companies are looking for
providing intelligent services to their
subscribers: forward, block, reverse the call
charges and record messages.
 Network programmability.
 Competence
services
by
delivering
value-added
 This competence led to the standardization
of intelligent network architecture.
 SS7 – Metanetwork for signaling.
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SS7 Network Elements
 Signaling
points
equipment that can
signaling messages.
(SPs):
network
send or receive
 Signaling Links (SLs): links that carry
signaling messages ( 56-Kbps or 64-Kbps)
 Signaling Transfer points (STPs):
intermediate nodes that route signaling
messages from one place to another.
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SS7 Network Elements
SP
SL
SL
SL
STP
SP
SL
STP
SP
STP
STP
SL
SP
Bearer Connection
Network 1
Network 2
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SS7 Protocol Stack
Telephony User Part (TUP)
Signaling Connection Control Part (SCCP)
ISDN User Part (ISUP)
IN Application
Part (INAP)
Mobile
Application Part
(MAP)
Orientation,
Administration,
and Management
Part (OAMP)
Transaction Capabilities Application Part (TCAP)
Message Transfer Part (MTP) 3
Message Transfer Part (MTP) 2
Message Transfer Part (MTP) 1
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17
SS7 Protocol Stack (Cont.)
 Message Transfer Part 1 (MTP1): Contains hardware and
firmware resources (Network Cards, Transceivers, and Cables).
 Message Transfer Part 2 (MTP2): Responsible for secure
transaction of messages between two signaling points.
 Message Transfer Part 3 (MTP3): Responsible for routing
(Through STP).
 Telephony User Part (TUP): Describes the signaling messages
for the setup of calls and connections in analog telephony
networks.
 ISDN User Part (ISUP): Describes the signaling messages for
the setup of calls and connections in Digital networks.
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SS7 Protocol Stack (Cont.)
 Signaling Connection Control Part (SCCP): Sets up and
manages signaling connections, using MTP3 to route
messages reliably from one node to another.
 Supports both Connection-Oriented and Connectionless
signaling contexts.
 Carries the information that STPs need to perform global
title translation. (800 numbers, and number portability)
 Transaction Capabilities Application Part (TCAP): allows
signaling nodes to do transactions. (e.g. Database access). It
contains two types of information: 1. Transaction Portion
(starting and ending transactions & maintains the state of the
dialog).
2. Component portion (carries the actual protocol queries
and
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responses).
SS7 Protocol Stack (Cont.)
A TCAP message can carry the signaling
message of other protocols in the component
portion:
 Operation, Administration, and Management
Part (OAMP): verification network routing
Database and diagnosing link problems.
 Mobile Application Part (MAP): Responsible
for Mobility management, GSM networks.
 IN Application Part (INAP).
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 SS7 provides a secure data network for signaling messages.
 It is easy to add special processing nodes for call processing.
 SCP – service control points allows an operator to install and
manage services like call forwarding, and call blocking
SCP
SP
SP
SL
STP
STP
SL
SP
Bearer Connection
Network 1
Network 2
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IN Standardization & Implementation
Problems:
1. Framework expanding all the time by nature.
2. Telephony switches offer more and more features with every release
and new network.
3. Technology such as GSM and the Internet are constantly changing
the environment that IN operates in.
Assumptions:
 Upward compatibility
 IN – collection of dedicated computers that perform special control
functions.
 IN – software architecture that runs services.
 IN – set of nodes as it is a software framework.
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IN Standardization & Implementation (Cont.)
ITU -> INCM – look for the IN from different angles.
1. Service Plane (SP):
Describes what features
a service is composed
of. E.g. the freephone
service consists of two
features:
1. One –
number feature: routes
incoming calls to a
single external number
from
different
telephones.
2. Reverse Charging –
The owner of the
freephone number Pays
instead of the caller.
2. Global Functional
Plane (GFP):
Identify the building
blocks out of which to
construct services.
(Looks at services
from the providers
point of view).
Describes the
software components
that a service
providers must deploy
to assemble services.
3. Distributed
Functional
Plane
(DFP):
Reflects
the
distribution
of
functions. It is
the result of
interactions
between switches
that use protocols
to decide how to
route the call
from source to
destination
4.
Physical
Plane
(PP):
Allocates
functions
to
physical
locations
or
machines. E.g. 1.
SSP contains the
switch, CCF, and
SSF. 2. SCP
contains SCF.
3. SMP contains
SMF. 4. SDP
cont. DB, SDF.
5. IP impl. SRF.
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IN Standardization & Implementation (Cont.)
Alcatel SCP Architecture
Memory Channel
FEPs –
Terminate
the SS7
connections
and run the
SS7
Protocols
BEP
BEP
BEP
BEP
FEP
DB
BEPs – Run
the actual
service
software
Ethernet
FEP
Service Control Point
FEP – BEP selected
for three reasons:
2. Scalability
SS7 Network
3. Reliability
1. Performance
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IN and the Internet
 Many operators and manufacturers already started making their IN
platforms Internet ready with proprietary solutions.
1. IP, the Internet, and the Web
2. Routers and Gateways: hubs, bridges, routers, gateways, firewalls.
3.
Connecting to the Internet using modems via an ISPs.
4.
ISDN
5.
ADSL, VDSL, and DHN
6.
Satellite Networks, LEO
7.
Cellular Networks: GSM, GPRS
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Intelligence on the Internet
IN and The Internet
 The internet is a network of networks.
 Not administered by a central operator
 Invented for data communication not for voice communication
 Communications achieved by the routing packets of data
 IP addresses and telephone numbers are differ on format, scope, and the
way that they are assigned.
IP Networks have almost the intelligence on the application layer
 The Features in IN are centralized and controlled from the SCF. In the
Internet they are completely distributed through the network.
 Some IN features do not make sense in the Internet: freephone, calling card calls
 All of this changes when we use the Internet Infrastructure for telephony.
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Intelligence on the Internet
IN and The Internet
Voice, Video, and Multimedia over the Internet
 TCP/IP – Designed for communicating data (files, e-mail, web pages)
between servers and clients. It breaks the data up into packets and routs
them to their destination, where they are reassembled and passed to the
receiving application.
 Voice and video could be translated into bits using codecs, IP routers
should be able to deal with it as they do the routing of a file or a web page.
 H323 is the standard for providing Voice and Multimedia services over
packet networks. Can involve the following components:
Gateways, Gatekeepers (address translation, call authorization,
accounting and billing, call management), Multipoint Control Units.
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The Mobile Dimension
Three types of mobility in telecommunications:
1. Terminal mobility: the terminal is connected to the network via
radio interface and can move around freely (e.g. cordless and
cellular phones)
2. User mobility: the user can move from one terminal to another
and register for incoming and outgoing calls to be made to and
from this terminal. (e.g. calling cards)
3. Service mobility: the portfolio of services that a user has
subscribed to follows the user as he or she roams to different
networks (the concept of exporting content and service to visited
location)
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Cellular Networks
The Mobile Dimension
Types of Terminal Mobility Networks:
• Cordless: DECT, CT2, …
• Cellular: GSM, DAMPS, …
• Satellite: LEO – EUTELSAT, …
GEO – SKYBRIDGE, …
A cellular network employs many radio cells of limited coverage to
cover a large area that gives the following advantages:
1. A mobile phone is always close to a network transceiver,
needs less transmission power.
2. channels can be reused in different cells, the capacity of
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network increases as the cell size shrinks.
Cellular Networks Generations
The Mobile Dimension
First Generation (1G): 1980 – analog cellular
networks (e.g. AMPS – USA, NMT – Scandinavia, C-450
– Germany, RTMS - France).
Second Generation (2G): 1990 – digital transmission,
higher capacity, Better standardization (e.g. GSM, DAMPS, IS-95, PDC) .
Third Generation (3G): 2000 – Multimedia
communications, Mobile Internet, Capacity & services
(e.g. GPRS, UMTS)
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The Mobile Dimension
GSM
GSM radio interface is a mix of Time- and Frequency-division
Multiple Access (TDMA and FDMA) with Frequency Division
Duplex (FDD).
Frequency
Channel
0.58ms
200kHz
94
10
01
93
92
…
11
11
01
01
11
00
11
01
01
10
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4…
Time Slot
Time
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GSM Architecture
The Mobile Dimension
A GSM network consists of three components:
1. Mobile Station (MS): GSM network terminals, they connect to
the network through a radio interface and require processing
power.
2. Base Station Subsystem (BSS): consists of a base station
controller (BSC) and base transceiver stations (BTS).
3. Network Switching Subsystem (NSS): the core network part of
the GSM, the key component in NSS is the Mobile Switch Center
(MSC); A Visited Location Register database (VLR) – holds the
subscriber data for visiting subscribers; A home Location
Register database (HLR) – holds the essential subscriber
information including information about the VLR to which
a
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subscriber is currently attached.
The Mobile Dimension
GSM Architecture (Cont.)
MS
HLR
BTS
BSC
BTS
MSC
BTS
To other MSC or
other Networks
BSC
BTS
Base Station Subsystem
VLR
Network Switching Subsystem
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Mobility Management and Handover The Mobile Dimension
 Procedures that enable mobile terminal when a call
arrives.
 GSM is divided into location areas, each area covers
several radio cells and has a unique identifier
transmitted on a special channel in all the cells it
contains.
 Each mobile monitors this channel. When it detects
a change in the broadcast location area identifier
(LAI), the mobile terminal knows it has crossed into
another location area’s radio cell. at that time it
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requests a location update from the network.
Mobility Management and Handover
(Continued)
The Mobile Dimension
Two ways that a location update can take place:
1. If the new location area is served by the same
MSC and VLR, then the VLR registers the move.
2. If the new location area is served by the another
MSC and VLR, then the mobile subscriber
information is moved from the old to the new
VLR. The HLR is also updated so that it can rout
all incoming calls to the new MSC and VLR as
follows:
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Mobility Management and Handover
(Continued)
The Mobile Dimension
1. The mobile terminal moves into a new cell, notice
that the location identifier for this cell is different,
and requests a location update.
2. The VLR requests the subscriber information from
the HLR.
3. The HLR sends the subscriber information to the
VLR and registers that the subscriber is now attached
to the new VLR.
4. The HLR informs the old network of the move and
orders the old VLR to remove the record for this
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subscriber.
Mobility Management and Handover
(Continued)
The Mobile Dimension
4
Location Area A
BSC
MSC
VLR
3
1
BSC
MSC
HLR
VLR
2
Location Area B
Location Update
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Mobility Management and Handover
(Continued)
The Mobile Dimension
Handover: When the network and the
mobile terminal perceive a decline in
quality of the current connection, the
network will look for a better channel in
a neighboring cell. The mobile terminal
must be detached in real time from the
radio channel of the old cell and attached
to the new channel in the new cell.
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GSM Security
The Mobile Dimension
 A subscriber identity module (SIM) stores the
subscription.
GSM
 Each subscription has a unique identifier, the international
mobile subscriber identity (IMSI).
 The dialed number is called the mobile station ISDN
number (MS-ISDN).
 The HLR stores the mapping from MS-ISDN to IMSI.
 The network authenticates the SIM in the mobile terminal
using a secret key algorithm. The visited network will
request a location update by sending the mobile station
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roaming number (MSRN) to the HLR.
GSM Security (Continued)
The Mobile Dimension
 The MSRN is an identifier composed of the IMSI and the
LAI of the cell where the mobile terminal is located.
 The VLR assigns a temporary identifier for the mobile
terminal that is locally unique, the temporary mobile station
identifier (TMSI). It is much shorter than IMSI and prevents
the IMSI from being sent over the air frequently.
 The VLR stores the relationship between IMSI and TMSI,
and also keep track of the location area of the mobile
terminal in the form of the MSRN
 when the call is established, the exchange of the digital
voice is encrypted using the same secret key as for
40
authentication, but using a different algorithm.
The Mobile Dimension
GSM Security
HLR
VLR
IMSI
TMSI
MSRN
IMSI
SIM
BSC
TMSI
MS
MS-ISDN
IMSI
MSRN
MSC
BTS
Visited Network
Home Network
Use of Identifiers in GSM
41
GSM Connection Services
The Mobile Dimension
GSM provides the following services:
1. Basic voice (using 13 kbps codec)
2. Half - rate voice (using 6.5 kbps codecs)
3. Circuit Switched data connection (9.6 kbps)
4. SMS (Store-and-forward Messages of 160
characters)
5. Cell broadcast (93 characters)
6. USSD – transfer of service data between
mobile terminal and HLR.
42
General Packet Radio Service
The Mobile Dimension
(GPRS)
 GPRS deployed by operators that already have a GSM
network; it is implemented as an extension of the
existing GSM infrastructure.
GPRS Radio Interface
 GPRS occupies free time slots only when a packet is
sent or received in a dynamic way.
 The maximum number of time slots that a terminal
can handle is called mutlislot class of the terminal. It
depends on the processing power and radio interface
43
hardware in the terminal.
The Mobile Dimension
GPRS Radio Interface
Frequency
Channel
0.58ms
200kHz
94
10
01
93
92
…
11
11
01
01
11
00
11
01
01
10
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4…
Time Slot
Time
Mobile 1 sends on channel 93 in time slot 4
Mobile 2 sends on channel 92 in time slot 2
GPRS packet transmission in free time slots
44
GPRS Radio Interface
(continued)
The Mobile Dimension
 Many terminals support more slots for the
downlink than for the uplink.
 Most terminal multislot classes commercially
available are 4+1, 3+1, …, and 2+2.
 The data rate depends on the number of slots
and the coding scheme employed to map the data
packets on the channel bit stream.
 The most frequently used scheme offers 13.4
kbps per time slot.
45
The Mobile Dimension
GPRS Architecture
MSC
BSC
BTS
Circuit GMSC
Switched
PTSN,
ISDN,
or GSM
VLR
PCU
HLR
MS
SGSN
IP
GGSN
GPRS-Specific infrastructure
Interne
t
46
GPRS Architecture
The Mobile Dimension
 Installing GPRS requires software updates in the BTS,
MSC, VLR, and HLR.
 The BSC needs to extend with a Packet Control Unit
(PCU), which inserts the packet data traffic into the
GSM channel structure.
 GPRS core network contains:
1. The serving GPRS support node (SGSN), which
routs the packets to and from the mobile terminals.
2. The Gateway GPRS support node (GGSN), which
acts as the gateway to the external packet network.
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GPRS Mobility Management
The Mobile Dimension
 The GPRS network is divided into routing areas, to find
a compromise between notifying the network of each
cell change and the broadcasting of packets for each
subscriber to the whole network.
 The routing area is the same as, or a subset of , a
location area. This gives the following advantages to the
GSM-GPRS subscribers:
1. GSM updates automatically imply routing area
updates.
2. An incoming GSM call can be paged in the GPRS
routing area. Which is smaller than a location area
that means less use of radio resources for paging. 48
GPRS Mobility Management
The Mobile Dimension
ATTACHMENT AND DETACHMENT PROCEDURE
 Before a mobile station can use GPRS services, it must
register with an SGSN of the GPRS network. The network
checks if the user is authorized, copies the user profile from
the HLR to the SGSN, and assigns a packet temporary
mobile subscriber identity (P-TMSI) to the user. This
procedure is called GPRS attach.
 For mobile stations using both circuit switched and
packet switched services it is possible to perform combined
GPRS/IMSI attach procedures. The disconnection from the
GPRS network is called GPRS detach. It can be initiated by
the mobile station or by the network (SGSN or HLR).
49
GPRS Connection model
The Mobile Dimension
 A GPRS subscriber can be in one of the following states:
State model of a GPRS mobile station.
50
GPRS Connection model
(Continued)
The Mobile Dimension
 In IDLE state the MS is not reachable.
Performing a GPRS attach, the MS gets into
READY state. With a GPRS detach it may
disconnect from the network and fall back to
IDLE state. All PDP contexts will be deleted.
 The STANDBY state will be reached when an
MS does not send any packets for a longer period
of time, and therefore the READY timer (which
was started at GPRS attach) expires.
 An MS in READY state informs its SGSN of
every movement to a new cell.
51
GPRS Connection model
(Continued)
The Mobile Dimension
 For the location management of an MS
in STANDBY state, a GSM location area
(LA) is divided into several routing areas
(RA). In general, an RA consists of several
cells. The SGSN will only be informed
when an MS moves to a new RA; cell
changes will not be disclosed. To find out
the current cell of an MS in STANDBY
state, paging of the MS within a certain RA
must be performed.
52
GPRS Connection model
(Continued)
The Mobile Dimension
 For MSs in READY state, no paging is
necessary. Whenever an MS moves to a
new RA, it sends a “routing area update
request” to its assigned SGSN.
The
message contains the routing area identity
(RAI) of its old RA. The base station
subsystem (BSS) adds the cell identifier
(CI) of the new cell, from which the SGSN
can derive the new RAI.
53
GPRS Connection model
(Continued)
The Mobile Dimension
To exchange data packets with external PDNs after a successful
GPRS attach, a mobile station must apply for one or more addresses
used in the PDN, e.g., for an IP address in case the PDN is an IP
network. This address is called PDP address (Packet Data Protocol
address). For each session, a so-called PDP context is created, which
describes the characteristics of the session. It contains the PDP type
(e.g., IPv4), the PDP address assigned to the mobile station (e.g.,
129.187.222.10), the requested QoS, and the address of a GGSN that
serves as the access point to the PDN. This context is stored in the
MS, the SGSN, and the GGSN. With an active PDP context, the
mobile station is “visible” for the external PDN and is able to send
and receive data packets. The mapping between the two addresses,
PDP and IMSI, enables the GGSN to transfer data packets between
PDN and MS. A user may have several simultaneous PDP contexts
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active at a given time.
Parlay & OSA
Distributed Intelligence
 Intelligent networks were originally designed for
telephony networks.
 Services are controlled and managed centrally by the
network operator.
 The IN model doesn’t seem prepared to deliver
value-added services in an environment that is
becoming heterogeneous and competitive.
 Several industry initiatives sought to develop more
state-of-the art software architectures for service
deployment and operation.
55
Parlay & OSA
(cont.)
Distributed Intelligence
 Parlay & OSA appear to be the technologies that are
leading the way in the evolution of IN – the key concept
in both is the distribution of service control.
Parlay Concept
 The network provider is responsible for deploying,
operating, and managing services.
 The idea of Parlay is to open this interface to third
parties, so that others beside the network operator can
create and deploy services.
56
Parlay Concept
SMF
Proprietary interface
SSF
Public interface
SCF
Parlay
Intelligent network
Proprietary interface
Third-party
application
PSTN operator
57
Parlay Concept (cont.)
Distributed Intelligence
 The Parlay interface also allows access to other
network functionalities, such as messaging, charging,
QoS negotiation, and mobility management.
 Network access to third-party applications is subject
to authentication and authorization.
 Parlay allow the network provider to set different
privilege levels (e.g. some third-party applications can
be allowed to receive only notifications from the
network while others can control calls and connections)
 Parlay also provides facilities for nonrepudiation.
58
Parlay Business Model
Distributed Intelligence
Subscription
QoS
Connectivity
Management
Enterprise
Administration
Trust and Security
Call Control
management
Client
Application
Discovery
User Interaction
Messaging
Integrity management
Framework
provider
Mobility
Parlay
framework
Parlay
Service
Service
Provider
Service factory
(Not in specified Parlay)
Registration
59
Parlay Business Model
Distributed Intelligence
 Client Application: the third-party application that
accesses network features through Parlay interface.
(deployed and operated by the enterprise administration)
 Framework Interfaces: offer all support functions for
Parlay, in particular security and management features
(administered by the service provider)
 Service Interfaces: offer access to network features,
such as call control, messaging, and mobility
management (administered by the service provider)
60
Parlay Business Model
Distributed Intelligence
 Parlay wanted to ensure complete flexibility in
mapping Parlay business roles into real-world physical
entities.
 Parlay allows the provider of the framework interface
to be different from the provider of the service interface.
From Parlay to OSA
 At the same time that Parlay began gaining momentum,
3GPP and ETSI were working on the OSA interfaces for
UMTS.
61
From Parlay to OSA
Distributed Intelligence
 Because Parlay and OSA are so similar, most manufacturers
have been combining both interfaces in one product.
 There remains some differences between the two:
a.
Parlay specifies only a business model and a set of interfaces.
b.
Parlay very explicitly refrains from specifying any requirements on the
implementation of the interfaces.
c.
Parlay is generic and stand-alone interface specification. While:
d.
OSA Specifies more than just an interface and must be seen as a service
architecture.
e.
ETSI makes recommendations for mapping OSA interface to network
protocols like MAP & CAP.
f.
OSA is an integral part of the service architecture for UMTS.
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OSA interfaces
Distributed Intelligence
 OSA and Parlay consist of 10 main interface groups:
Interface
Short description
Framework
Overall security, integrity, and management framework
Call control
Setting up, releasing, and managing calls, conferences, and
multimedia connections; notifications of call- and
connection-related events.
Data session control
Setting up, releasing and managing data sessions
User interaction
Play or display messages and retrieve user input
Mobility
Notifications of user location and user status
Generic messaging
E-mails, voice mails, SMS
Terminal capabilities
Interrogating a terminal for its capabilities
Connectivity management
Negotiation and management of QoS and service Lev agr IP
Account management
Creating, deleting, and modifying subscriber accounts
Charging
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Reservation and charging of units of volume or money
OSA interfaces
Distributed Intelligence
 Parlay offers two extra interfaces that are not parts of
OSA:
a. Policy Management: allows for the creation and
management of policy classes and their parameters; to
provide application service providers with the possibility
of defining service-level agreements (SLAs)
b. PAM. Allows subscribers and terminals in the
network to exchange information about presence and
availability (buddy lists and instant messaging).
 OSA interfaces are defined as a set of object types
(classes) – class definitions follow an inheritance hierarchy. 64
OSA interfaces
Distributed Intelligence
 Each of the OSA interfaces is specified (in UML
and IDL) in four parts:
1. Class diagrams. Provide an overview of the inheritance
structure of the interface, its classes and operations.
2. Sequence diagrams. Show key examples of use of the
interface in the form of UML message sequence charts.
3. Interface specifications. Provide the formal definition of
the interface
4. Data definitions. Provide formal data-type definition in
IDL.
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General Interface Structure
Distributed Intelligence
 OSA defines two object classes for each interface on the
network side:
1.
Ip<Interface> - is the actual interface that offers operations to control
resources in the network.
2.
Ip<Interface>manager - is a management interface that that contains the
operation to start and manage an instance of Ip<Interface>. Its also used to
request server-related event notifications like overload conditions.
 The client application also has to implement two object classes
for each interface:
1. IpApp<Interface> - is a client-side interface that contains operations for
receiving results and notifications from the Ip<Interface> interface.
2. IpApp<Interface>manager - is an interface for receiving results and
notifications from the Ip<Interface>manager interface.
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OSA Interface Structure
OSA server
Ip<Interface>Manager
Distributed Intelligence
Application
Notifications
IpApp<Interface>Manager
Creates,
manages
Ip<Interface>
Notifications,
IpApp<Interface>
results
67
General Interface Structure
Distributed Intelligence
 These client-side interfaces are often called callback
interfaces – they are just like procedure calls in
programming languages such as Pascal, operations on
objects are synchronous: a client application that requests
an operation on an object has to wait for this operation to
finish and send back the result.
 By putting a callback interface on the client it is
possible to decouple the delivery of the result from the
request.
 Callbacks are used to allow asynchronous
communication with synchronous operations.
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OSA call-control interface
Distributed Intelligence
 OSA offers several interfaces for call control,
some of these interfaces consist of several
classes with an inheritance relation.
 The figure below shows the inheritance
structure (the main classes defined at the server
side)
 A new object class is defined in a terms of an
existing one by inheriting and extending the
operations of the parent class
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OSA call-control interface
(Server side)
IpMultiPartyCall
IpMultiMediaCall
IpConfCall
1
1
0…n
Distributed Intelligence
IpCallLeg
0…n
1
IpMultiMediaCallLeg
0…n
0…n
0…n
IpMultiMediaCallLeg
1
1
0…n
1
IpSubConfCall
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OSA call-control interface

Distributed Intelligence
There are three main types of call defined in OSA:
1. Multiparty calls: calls with zero or more parties. The connections
set up within a call are represented by call-leg objects (connect
and disconnect call parties within the scope of a call)
2. Multimedia calls: multiparty calls that allow for multimedia
connections between parties. (can create and delete multimedia
call legs – each of which can have several streams)
3. Conference calls: multimedia calls in which there exists the
possibility of defining additional relationships between the parties
(the chair party has privileges to add parties, drop parties, give a
party to turn a speak, and interrupting a speaking party). It is
possible to create subconferences, and to move parties from one
subconference to another
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Using OSA
Distributed Intelligence
 The complete cycle for using an OSA service consists of
three phases:
1. Authentication: before using OSA services, the
application and the OSA framework authenticate each
other (prevents unauthorized access)
2. Service selection: the application selects the service
interface. Request the signing of agreement before
using the interface.
3. Service use: only after the authentication and service
selection the application start using the actual service.
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Application
OSA Framework
Initiateauthentication
Specify an authentication method
(1)
authentication method
(2)
Evaluate
authentication
response
Compute
authentication
response
(4)
(e.g., challenge response)
authenticationFramework
authentication response
Compute authentication response
authenticationSucceeded
authenticate Client
(3)
authentication response
authenticationSucceeded
obtainDiscoveryInterface
Evaluate authentication response
Create
Discovery
Interface reference
DiscoverServices
Services
Get
73Profile
Using OSA
Service Selection & Service Agreement
Application
(5)
Evaluate
agreement
(7)
(8)
(9)
OSA Framework
Select Service
Prepare service agreement
SignServiceAgreement
Signature
(6)
SignServiceAgreement
Signature
Create
Distributed Intelligence
IpAppCallControlManager
Evaluate agreement
(8)
Create
IpCallControlManager
setCallback
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Using OSA
Distributed Intelligence
Call Setup
IpAppCallControlManager
(10)
(11)
Create
IpCallControlManager
IpAppCall
createCall
Create
IpCall
routeReq
(12)
Party A rings
Party A answers
routeRes
(13)
routeReq
(14)
Party B rings
routeRes
Party B answers
(15)
75
OSA Applications
Distributed Intelligence
 OSA can bring the following added value:
1. Third-party service control. Allow the integration of
network features with applications external to the
network. (OSA needed to securely access the
network’s features)
2. Roaming interface. Current roaming agreements
require a high level of trust between the roaming
partners. OSA has a security framework, it offers
roaming between parties that don’t have an
established trust relationship.
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OSA Applications
Distributed Intelligence
(Continue…)
3. Protocol replacement. OSA can provide a
standard programming interface for these
network functions; OSA also provides a
framework for features that might be added in
the future.
4. Content billing. The OSA charging interface can
be used to dynamically establish relations
between volume and value.
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OSA Applications
Distributed Intelligence
Example: Taxi Dispatcher
 The idea is that when a client calls, his mobile terminal is
automatically located and a program automatically alerts the
nearest taxi. To implement this service, the taxi dispatcher
subscribes to the following three OSA service interfaces offered
by the mobile network operator:
1. Call control: to automatically notify the taxi dispatcher of
requests for taxis;
2. Mobility: to determine the position of the calling
customer and the taxis;
3. Generic messaging: to send a notification to the
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nearest taxi.
OSA Applications
Distributed Intelligence
Example: Taxi Dispatcher (Cont.)
 OSA supports two ways of locating taxis (mobile terminals):
a. To ask for the position of all taxis whenever a customer calls.
b. To have the network send periodic positioning information
for each taxi, for example every 5 minutes.
 The taxi dispatcher develops an application that automatically
receives a notification when a customer calls, then locates the
customer and finds the nearest taxi, the program send a short
message to alert the taxi to pick up the client. This includes the
following steps:
1. A customer dials a special number to request a taxi.
79
OSA Applications
Distributed Intelligence
Example: Taxi Dispatcher (Cont.)
2. The OSA interface notifies the taxi dispatcher application of
the customer’s call. Identifies the calling-party number.
3. The taxi dispatcher requests location of the calling party or
the (taxis) through the OSA interface. Forwards it to the MLC.
4. The network locates the calling party or the taxis (this may be
done periodically).
5. Receiving the caller’s coordinates, it looks up the geographic
location in a database and determines the nearest taxi.
6. The application sends a short message to the nearest taxi
through the OSA interface to pick up the customer at the
indicated location.
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OSA Applications
Distributed Intelligence
Example: Taxi Dispatcher (Cont.)
Taxi
Taxi
Taxi
Taxi Dispatcher
GMLC
(4)
(3)
(2)
MSC
Application
OSA
(6)
(1)
SMSC
(6)
Mobile network
(5)
Database
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Telecommunications InformationNetworking Architecture (TINA)
Telecommunications
Middleware

Middleware: is software that runs between machine’s operating system
and the applications.

TINA Business Model

TINA architecture

Session model

TINA Service Architecture

1.
Computational objects
2.
Access session
3.
Service session
TINA network-resource Architecture
1.
Computational objects
2.
Connection establishment
3.
Federation
82
Telecommunications
Middleware
TINA Architecture
Retailer
Consumer
Terminal
Application
Service
Service
Service
Service Architecture
Resource Management Architecture
ATM
Switch
ISDN
Switch
IP Router
Connectivity Provider
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Service session graph
Telecommunications
Middleware
Service
Session graph
Contains
Session
Session
relation
member
Is-a
Is-a
Control
Party
resource
relation
Stream
binding
84
Access session
Telecommunications
Middleware
 The procedure for starting an access session:
1. When the user requests an access session, the PA (provider
agent) in the terminal contacts the IA(initial agent) in the
network. The address of the IA is always known to any TINA
network.
2. The IA consults the subscription database, authenticates the
user, and finds the UA(user agent) for this user. (UA can be
in a remote network).
3. The UA activates an access session for the user. The PA in the
terminal is linked to the UA for the duration of the access
session and the user can start using the services.
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Access session

Telecommunications
Middleware
Through the access session, the user can do any of the
following:
1. Request a list of available services. The UA will list the
services that the user is subscribed to.
2. Request the start of a service session. The access session is
always the window through which services are started.
3. Receive invitations from other users to join a service session.
4. Join a service session that is already active.
5. Register remotely at terminals. A user can request to be
registered on a remote terminal for incoming invitations to
join sessions.
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Service session graph
Telecommunications
Middleware
 The TINA service session offers the following features that
allow parties to modify the session graph:
1. Basic features: such as starting, stopping, and suspending a
session;
2. Multiparty features: adding or dropping a party in a session;
3. Stream-binding features: adding or dropping
binding to a party in the session;
a stream
4. Voting features: voting among parties in the session
(permission of a new party to join the session);
5. Control features: for modifying control relations between
parties (transferring chairmanship of a videoconference).
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TINA network-resource Architecture
Telecommunications
Middleware
 TINA sets up connections in three main steps:
1. Negotiation. The communication session queries all
involved terminals and network entities for their
capabilities, and selects a set of common capabilities that
will allow the connection to be set up.
2. Reservation. The communication session asks all involved
terminals and network entities to reserve the selected
capabilities.
3. Commitment. If all involved terminals and networks confirm
the reservation of the necessary resources, the
communication session will then order them to commit the
resources and the connection is set up.
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Service
Application
session
TCSM
Negotiate
CSM
CC
TLA IP
M Reserve and commit
LNC IP
Terminal
Network
resources
resources
Retailer
Terminal
Connectivity provider
Consumer
TINA network-resource Architecture
Telecommunications
Middleware
89
Connection Establishment

Telecommunications
Middleware
The negotiation phase consists of the following steps:
1. The CSM queries the TCSM of each terminal for the terminal
capabilities. The terminals respond by giving a list of capabilities
they can support (4 slot GPRS)
2. The CSM matches the terminal capabilities listed by each
terminal, and defines the common set of capabilities that will
allow the requested connection to be established.
3. The CSM tells the TSCM which capabilities are needed and asks
the TSCM to select the necessary resources in the terminal.
4. The TCSM asks the TLA to identify the terminal end points that
correspond to the requested capabilities. (GSM channels, IP
addresses)
5. The selected end-point coordinates are propagated back to the
90
CSM.
Negotiation phase in TINA connection setup
TLA
TCSM
Telecommunications
Middleware
CSM
Query capabilities
Terminal capabilities
TCSM
TLA
(1)
Query capabilities
Terminal capabilities
CSM selects
Select end
points
TLA selects terminal
(2)
common capabilities
Select capabilities
Select capabilities
(3)
Terminal A
(4)
TLA selects terminal
end points that fit the
requested capabilities
End points
Select end
points
End-point address
End-point address
(5)
end points that fit the
requested capabilities
End points
Terminal B
91
Connection Establishment
Telecommunications
Middleware
 The reservation phase consists of the following steps:
1. The CC contacts the LNC for each subnetwork involved,
and asks them to set up the necessary connections within
their domain.
2. The LNC asks the terminal to reserve the resources
negotiated in the previous steps. The LNC also reserves the
necessary network resources.
3. If the selected terminal end-points are available, the LNC
asks the TLA to associate them with physical resources in
the terminal.
4. The TLA asks the TCSM to link the terminal applications to
the physical ports in the terminal that will terminate the
92
connection.
Telecommunications
Middleware
Reservation phase in TINA connection setup
TLA
TCSM
LNC
CC
LNC
TCSM
TLA
Set up
Reserve resources
Terminal
reserve
resources
Set up (1) connection
(2)
(2) connection
Network
reserve
resources
Network
reserve
resources
(4)
The TLA associates end
points with terminal ports,
and the TCSM links the
application to them
OK
OK
OK
Terminal A
Associate end points
Associate end points (4)
(3)
(3)
The TLA associates end
points with terminal ports,
and the TCSM links the
application to them
Network A
Terminal
reserve
resources
Terminal end-point settings
Terminal end-point settings
Associate end points
Associate end points
Reserve resources
OK
Network B
Terminal B
93
From SIBs to Objects
Service Creation
 The key issue is how to conduct business with the new
architectures.
 Telecommunications business is determined by the services and
offered and their price.
 Service creation is all about software engineering.
 Telecommunications software is complex, concurrent, must be
reliable and deliver high performance.
 The INCM recognizes the need for efficient creation of new
services. It defines services as compositions of features, which are
composed out of elementary building blocks, SIBs.
 An IN service-creation environment allows even inexperienced
service engineers to create services by clicking together elementary
94
building blocks in a plug-and-play fashion.
Service Creation
From SIBs to Objects
Begin
Play announcement
(1)
(2)
User Interaction
Service data
Get calling card ID from user
Look up calling card in
database
management
Play announcement
(3)
User Interaction
Get PIN from user
No match
Play error
announcement
(6)
Return to
BCP:
Release call
User Interaction
Clear call
(4)
(5)
Compare
Charge
Continue
Validate PIN against card data
Charge communication to
calling card
Return to BCP:
95
Continue setting up the call
From SIBs to Objects
Service Creation
The calling card service shows the SIB flow and performs the following
steps:
1. A message is played to the user, asking for the calling-card ID, and
user input is received in the form of DTMF tones.
2. The calling card data is retrieved from the database using the
calling-card ID input by the user in the previous step.
3. A message is played to the user, asking for the PIN code, and user
input is received in the form of DTMF tones.
4. The PIN provided by the user is verified against the PIN on the card.
5. If the PIN is correct, the call is charged to the calling card and the
call setup continues.
6. If the PIN incorrect (card number or PIN invalid), an error message
is played to the user and the call is cleared.
96