Transcript NGN 19 - PTCL Training & Development

Next Generation Networks
Call Setup
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Legacy Telephone Service
Basic Service: Call setup
Phone number resolution
Call routing
Callee status detection
Resource reservation
Advanced Service: IN features and services
Authentication, admission and billing
Call rerouting, redirection, call-back and waiting
In-call application: IVR, call center, voice mail, centrix, and telephone vote
Advanced service provisioning and management based on user’s profile
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Legacy Network Service Architecture
• Basic service is provided by distributed telephone
switches
– Call setup is executed in distributed telephone switches
– A signaling network (SS7) interconnects the telephone
switches
– Call procedures in the switches are interlinked by signaling
(TUP/ISUP)
• Advanced service is offered by centralized Intelligent
Network
– An advanced service formed by a service logic (SL) and a
serious of service independent blocks (SIB)
– A management platform (SMP) supports service creation
and maintenance
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Legacy Service Architecture
•
•
•
•
•
•
Separate UNI services and network services
Make services independent of any call processing
Distributed call control and centralized services
One service control point for one service class
One service control point for one service instance
Decompose functions into small pieces and assembly
them together
• Authentication, billing and routing are basis of any
services
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Legacy Service Architecture
PSTN
2G Mobile
• The PSTN/ISDN is based on 64 kbit/s digital
connections, with a separate “common channel”
signalling system
• Access may be analogue (telephony), 64 kbit/s
digital (ISDN) or low speed digital (mobiles)
• The network establishes an end-to-end digital
connection for the duration of each call
• The PSTN/ISDN is designed for high reliability,
specified at the national level and connecting to
form a global network
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Legacy Telecom Networks:
Layer, Separate, Centralize and Sharing
UNI
Application
UNI
Layer
Service
Network
Service
Switching
Layer
Network
Transmission
Layer
NNI
NNI
Switching
Network
Transmission Network
NNI
Switching
Network
Transmission Network
CPE
CPE
NNI
Physical
Physical Network
Physical Network
NNI
Physical Network
Layer
Physical
Interface
Logical
Interface
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Service
Access
Point
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Packet based Communication
• Best effort and service-independent packet-switching
network
• User-driven application/content-independent client-server
mode
• Smart terminal, servers and network
• Transparent active application access
• Open network, open application and open access
• Open and active services on the Internet
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Packet based - Internet
• The (public) Internet is based on the set of protocols defined
by the Internet Engineering Task Force (IETF)
• The primary protocol is the Internet Protocol (IP) which
describes a simple connectionless packet protocol able
to operate over a range of media
• Other protocols work in association with the IP, for
example, TCP to assist reliable end-to-end operation
• The Internet is defined by the Internet protocols rather than
by a standardised architecture
• The Internet provides open interfaces, supporting rapid
innovation
ISP
“The Internet” (bestendeavours network)
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ISP
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Internet Service Architecture
Client
Application
Server
Server
APP
Layer
Network
Layer
CPE
Transmission
Layer
Server
Server
ISP
ISP
ISP
Applications
Applications
Applications
IP
Packet
Packet
IP
Switching Network
Physical
Interface
IP
Switching Network
NNI Transmission
Transmission
Network
APP
CPE
NNI Transmission
Network
Logical
Interface
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Network
Service
Access
Point
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H.323 Architecture
H.323 Gatekeeper
3 stages of signaling:
• RAS to Gatekeeper
• H.225 call signaling
• H.245 media stream control
(can be simplified for VoIP)
PSTN
H.323
Terminal
H.323 Zone
H.323
Gateway
H.323
Multipoint Control Unit
• Telco-centric multimedia,multiparty conferencing (initially for LANs)
• Gatekeeper for network control, heavy-weight protocols
• Widely deployed in first wave of VoIP standardization
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SIP Based Services
• Internet-centric alternative, initially for large multicast
conferences
– SIP for call signaling, SDP (Session Description
Protocol) for media
• Network servers for additional capabilities:
– Registrar for terminal registration, aliases
– Redirect returns contact address directly to end user
– Proxy forwards signaling (requests, responses)
• Evolution towards greater use of proxy/registrar for locating
users, vertical services, call tracking, network control
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SIP Call Setup
Ptcl.net.pk
ptcl.com
DNS
Location
server
Proxy
INVITE
[email protected]
INVITE
Ringing
200 OK
Proxy
ACK
INVITE
Ringing
200 OK
Shahab
Media Streams
Irfan
INVITE SDP proposes media type(s), IP & ports to send to
200 OK SDP accepts/rejects media, gives IP & ports to send to
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Where Do Services Live?
• Some implemented at the endpoints
– Last-number redial, call hold...
• Others may be better supported from the network
– Avoid need for PC or IP phone to be turned on (call forwarding)
– More complex services, such as conferencing
– Integration with web-based services (unified messaging)
• Example: SIP Proxy runs a script for each incoming call
– Parallel forking: forward INVITE to multiple endpoints
simultaneously
– Sequential forking: try his office PC first, then lab, then cell
phone, …
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SIMPLE (SIP for IM and Presence)
ptcl.net.pk
ptcl.com
Presence
server
Proxy
SUBSCRIBE
NOTIFY
NOTIFY
SUBSCRIBE
[email protected]
Proxy
Update
Presence
Linda
Peter
Linda subscribes to notifications of changes in Peter’s status:
Off-line, on-line, busy, away, available, ...
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Carrier Networks are not homogeneous
• Carrier networks consist of multiple domains
Domain 3
Service network
Service
Domain
Client
Client
Transport Network
Domain 2
Domain 1
•
•
•
Transport Network
each domain may have its own policies
each domain may have its own commercial goals
and possibly its own protocols & transport
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Relevant
interfaces
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NGN: Service layer on IP, Current Status
• Support of multiple access networks (broadband
and narrowband)
• Support of multiple access protocols (H.323,
MGCP/MEGACO)
• Support session mobility control (MAP, Mobile
IP, HLR/VLR)
• PSTN/IN interworking (ISUP, INAP, CAP, PINT,
SPIRIT, SIP-T)
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Current Approaches
of NGN Service Architecture
• Mobile telephone network (GSM, GPRS)
– Separation of Home network and serving network
– Connection mobility and roaming control
• 3G-UMTS
– Service portal and service capability feature (SCF)
– Open Service Access (OSA)
• SIP
– Distributed service control
– Open access to services and applications
• Web Service (SOAP/WSFL/WSDL/UDDI)
– Service access portal (SOAP)
– Service description, discovery, and integration (UDDI)
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Changes of Telecom Service Architecture
Off-line customer management
Extended call control and IN charging
Terminal
Terminal
Telecom basic service/call control
Access Service
Transmission
Access Service
Linear Service Architecture in Legacy Network: Static Services
A User Service
Management
A Home Service
B Home Service
B User Service
Management
Control Service
A
Terminal
A
Portal
B
Portal
Session Service
Access
Transmission
Access
B
Terminal
Two-Dimension Service Architecture in NGN: Active Services
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NGN Soft switch: Services
• Legacy telephone service is static and close
• Current soft switch experiences legacy
service architecture
• Soft switch session is going to be distributed
• Telecom service is becoming with 2-D
dynamic
• Home service portal is to support open
service access
• Service broker provides a platform for open
services
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NGN Services Characteristics
• Multiple numbering systems
• IP, Phone, Universal Numbers
• Distributed Intelligence
• Databases in central servers, Provider database,
Customer PC, Phones
• Central global database does inter-provider
translation
• Central Database is ‘shared’ by providers
• Transaction volume
• At central db, number of inter-provider calls
• At services databases (800, call-blocking lists, …)
number of subscribed services
• At Provider and endpoints
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NGN Services Characteristics cont’d
• Network Repositories
• User data (profiles, lists) in multiple devices and
databases
• Central Server provides reliability
• Updates to devices synchronized on re-connect
• Synchronization on demand or periodically:
• User mobility
• Where should translation take place
• Should cache migrate
• Real-time constraints
• Transaction volume across devices, endpoints...
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NGN Services Characteristics
• Object based services
– Calls abstracted as object
– Call models implemented within objects
– Object mobility used to implement services
• Call forwarding
• Third party call set-up
• Objects for service creation
– Tool-kit for third party service creation
– Base Objects/components upon which to build
• Device Independence
– Migrate calls across device
– Compose services across devices
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End-to-End Connectivity?
There is no shortage of possible approaches – and they
are all in use!
The problem
– How to guarantee end-to-end service with the required QoS
across multiple networks using incompatible implementations
[the subject of current international work]
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