ngn

NGN StructureNGN Structure

10th Annual Conference of Computer Society of Iran, CSICC'2005 2

• Today’s network is divided into: • The Public Switched Telephone Network,• The Packet Switched Networks and • The Mobile networks (PLMN). • Convergence is the process of

interconnection of traditional switched circuit networks (PSTN and PLMN) and packet-switched networks based on the Internet Protocol (IP) for routing.

Existing Network Infrastructure


Key drivers of NGN developmentOne network for everything

TodayToday TomorrowTomorrow

Telephonenetwork

Mobile radionetwork

IP-Network

Multimedia Access - Advantages:• easy to handle• reliable• mobile

Internet


NGN Outline

• NGN Architecture• NGN Layers• NGN Main Components• SG (Signaling Gateway)• MG (Media Gateway)• MGC (Media Gateway Controller)• Servers


NGN

Outline (cont.)

• NGN and Protocols• Call Control & Signaling Protocols• Gateway Control Protocols• Media Transfer Protocols• NGN Migration • Conclusion


NGN Outline



NGN Architecture

• The architecture basically comprises of :– Network Elements needed for the provision of

traditional Telephony services.

• NGN has a layered architecture.• The layers of NGN :

– Access layer,– Core layer,– Control layer and– Service layer.


NGN Architecture

• Each element :– has distinct roles within the network,– designed to integrate :

• horizontally with other elements in the same layer,• vertically with the function-based elements of the

other layers.


NGN Architecture

Packet NetworkPacket Network

WANWAN UTRANUTRAN

Mobile Mobile PSTNPSTN

COCOCableCableDSLDSL

BroadbandBroadband

WLLWLLAccess

Edge

Core

Control

Applications

Management

Content

MediaGatewa

y

Management system

ResidentialUsers

Remote Office/SOHOEnterprise Customers MobileUsers

Softswitches

Application Servers


What is NGN?

AG MG SG

SIP-T / BICC

DSS1 over SCTP / SIGTRAN

SS7 overSCTP / SIGTRAN

MEGACO/H.248

MediaServer

Appl.Server

H.323/ SIP

SIPProxy

SIP

SIP

SIP

SIP /SIP-T

SIP

MG SG

PLMNPSTN

PABX

SS7 SS7TDMTDMDSS1

GSMSoft

Phone

ENUMServer

MGC MGC

SIP Telephone

BB-RAS

Fire-wall

SIPBIND

PacketNetwork

H.323

H.323-Network

AGAG MGMG SGSG

SIP-T / BICC

DSS1 over SCTP / SIGTRAN

SS7 overSCTP / SIGTRAN

MEGACO/H.248

MediaServerMediaServer

Appl.ServerAppl.Server

H.323/ SIPH.323/ SIP

SIPProxySIP

ProxySIP

SIP

SIP

SIP /SIP-T

SIP

MGMG SGSG

PLMNPSTN

PABX

SS7 SS7TDMTDMDSS1

GSMSoft

Phone

ENUMServer

MGC MGC

SIP Telephone

BB-RAS

Fire-wall

SIPBIND

PacketNetwork

H.323

H.323-NetworkH.323-

Network

NGN protocols


NGN architecture, IP-oriented NGN model

IP network

SoftswitchContent server

NOC

Transit gatewayGateway

PSTN, GSM, ATM, ...

Services

Transport


NGN Outline



NGN Layers

• Characters of Layers :–Open Architecture;

• open Interface and

• Open Protocols between layers.


NGN layers

• The Next Generation Networks architecture is based on four layers:Access layer,Core layer,Control layer andApplication & Service layer.


1. Access layer includes :– Traditional networks;

• PSTN, ISDN, PLMN, …

– Specialized packet networks.

Access layer elements include different Media Gateways that support connection to and from the access network with the core network.

NGN layers


NGN layers

2. Core layer is the network handling converged services based on IP.

– Includes high capacity switches and routers, in addition high capacity links.

3. Control layer is the Call Server that provides:

– Call Control functions and– The Control of the Media Gateway.


NGN Control Layer

• Provide capabilities of:– Call Control, – Connection Control,– Protocol Handling and– Other management issues

• The primary part of this layer is: Softswitch.


NGN Ctrl Layer

Softswitch• Is the core of NGN,• Independent of Transport Layer.• Main functions are included:

– Call control– Resource distribution– Protocol handling– Routing– Authentication and – Charging


• handles signaling and management entities.

• Never concerns with detailed routing procedures and controlling network partial components.

• its other tasks are:– Providing Security for connections and– Network Management.

NGN Ctrl Layer


NGN layers

4. Application & Service layer :– plays the role of an IN-SCE (Intelligent Network

Service Creation Environment) extending their functionality in order to cover the new network scenarios.


NGN App. & Service Layer

Appl i ca ti on Crea ti on En vi ron men t

Appl i ca ti onServer

Ca l lServer

Ca l lServer

Med i aGa tewa y

Med i aGa tewa y

AccessNetwork

AccessNetwork

Pa cketNetwork


NGN Outline



NGN main components

Networkcontroller

MGCP

H.323

Gatekeeper NOCSOFTSWITCH

MG

CP

Multiservice access

АDSLPOTSISDN

PRIV5.x (VoIP)

Gateway

SS7


Softswitch combines the advantages of both networks

Voiceservices for IP-users

PSTN

Switch

Switch

Switch

Switch

Services

QoS

VoIP

Data networks

Flexible bandwidth

Effective transmission

SOFTSWITCH


Media Server in a Softswitch Architecture

Media Server

MGCP,Megaco,SIP,VoiceXML

RTP

RTPVoATM

MGCP/Megaco

Traditional Phone

SoftswitchApplication

Server

Media Gateway(xDSL, cable, PSTN,

wireless)

MGCP/Megaco

H.323/SIP

H.323/SIP/MGCP

Basic Services Enhanced Services

IP Phone

http://www.cisco.com/logo/


NGN Components

• The Softswitch

• The Packet core Network

• The Access Networks

• The Media & signaling Gateways

• The Call Server

• The application Server

• The Application Creation Environment


NGN Outline



SG, Signaling Gateway

SignalingGateway

IP/ATM

SS7Network

SS7 over IPSIGTRAN / TALI / Q.2111

MTP2

MTP3

Protocol

MTP2

MTP3

IPUDP

IPUDP

Protocols

SS7Device

SS7 - > IP protocol Translation

Protocols

IP TelephonyApplication

Protocol


NGN Outline



NGN Media Gateway

Provides Translations between circuit switched networks and packet switched networks.

Sends notification to the call agent about endpoint events.

Execute commands from the call agents.


NGN Media Gateway Media Gateway Functionality

• Bearer Interworking Function– Interworking Between Multiple Interface

Protocols: ATM,TDM, Frame Based (IP, FR)– QoS, Traffic and Congestion Management

• Congestion Management– Using Priorities based on Traffic Parameters


• Different QoS For Different Services

• Traffic Policing per Connection

• Traffic Shaping per Connection– Flat Shaping

– Hierarchical Shaping (shaped VCs in shaped VPs)

NGN Media Gateway


Media Gateway Architecture


MG Types

According to capacity and access level to the core network, Media Gateway is categorized to 3 groups:

• Trunking Gateway

• Access Gateway

• Residential Gateway


NGN Outline



NGN MGC

Media Gateway Controller Functionality

• Provides End-to-End Call Control

• Supports Call Control Signaling (ISUP, BICC, IN/TCAP, ISDN)

• Supports Signaling Interworking Between Different Signaling Protocols (e.g., ISDN-ISUP-BICC)


NGN MGC

• Correlates Between Call Control Signaling and Bearer Control Signaling (BICC)

• Communicates With Feature Servers to Determine Service and Some Call Parameters (TCAP)

• Coordinates Call Progress and Resources Management with the Bearer Control Function (H.248/MEGACO)


Media Gateway

Controller

SIP-BCP-T

H.323

MEGACOMGCP

SIGTRAN

TALI

SIP

Control SwitchCall Agent Media Gateway Controller (MGC)

CallHandling

MTP2IP

UDPSIGTRAN

PSTN Switch Media Gateway Controller

Signaling Gateway

ProtocolMTP3

MTP2

MTP3

ISUP

IPUDP

SIGTRANProtocol

ISUP

CallHandling

Protocol Translation and addressing

Media Gateway Controller


NGN Outline



Servers

• Application Server

• Media Server

• Call Server

• Feature Server


Application Server

App. Server functionality :

• No. 800 service• No. 900 service• Billing services• VPN• Calling Card services• IN services


Media Server

Media Server functionality :

• Voice Mail services• Fax Mail Box• Voice Recognition• Video Conferencing• Voice to Text• Unified Messaging• Fax over IP by means of T.38


NGN Outline (cont.)

• NGN and Protocols

• Call Control & Signaling Protocols

• Gateway Control Protocols

• Media Transfer Protocols

• NGN Migration

• Conclusion


NGN and Protocols

NGN requires new protocols to support converged networks.

Requirements• Support for

– Legacy PSTN interworking,– Migration Plan from legacy to NGN,– High Availability,– Lifeline services and– Scalability


NGN and Protocols

• With so many protocols, which one to choose? – H.323,– SIP (Session Initiation Protocol),– MGCP,– H.248/MEGAco and– SIGTRAN


NGN Protocols


NGN

Outline (cont.)



RTCPRTP

IP

MGCP

Call Control and Signaling Signaling and Gateway Control

Media

H.225

Q.931

H.323

H.323 Version 1 and 2 supports H.245 over TCP, Q.931 over TCP and RAS over UDP.

H.323 Version 3 and 4 supports H.245 and Q.931 over UDP/TCP and RAS over UDP.

SIP supports TCP and UDP.

TCP

RAS

UDP

SIPH.245

Audio/Video

RTSP

SIP, H.323 and MGCP


NGN Signaling Protocols

Session Initiation ProtocolSIP


“

”

An application layer signaling protocol that defines

• Initiation,

• Modification and

• Termination

of interactive, multimedia communication sessions between users.

IETF RFC 2543 Session Initiation Protocol

What is SIP?


SIP components• User Agent Client (UAC)

– End systems– Send SIP requests

• User Agent Server (UAS)– Listens for call requests– Prompts user or executes program to

determine response

• User Agent– UAC plus UAS


SIP components (cont.)

• Redirect Server– Network server - redirects users to try other

server

• Proxy Server– Network server - a proxy request to another

server can “fork” request to multiple servers, creating a search tree

• Registrar– Receives registrations regarding current user

locations


User Agents

• An application that initiates, receives and terminates calls. – User Agent Clients (UAC) – An entity that

initiates a call. – User Agent Server (UAS) – An entity that

receives a call.

– Both UAC and UAS can terminate a call.


– An intermediary program that acts as both a server and a client to make requests on behalf of other clients.

– Requests are serviced internally or by passing them on, possibly after translation, to other servers.

– Interprets, rewrites or translates a request message before forwarding it.

Proxy Server


• A location server is used by :– Redirect Server or– Proxy Server

• To obtain information about a called party’s possible location(s).

Location Server


• A server that :– Accepts a SIP request,– maps the address into zero or more new addresses

and– Returns these addresses to the client.

• Unlike a proxy server, the redirect server does not initiate its own SIP request.

• Unlike a user agent server, the redirect server does not accept or terminate calls.

Redirect Server


– A server that accepts REGISTER requests.

– The register server may support authentication.

– A registrar server is typically co-located with a proxy or redirect server and may offer location services.

Registrar Server


SIP architecture

SQL/LDAP/?

Proxy Farm

INVITE

DB

Registrar

RE

GIS

TER

• On Startup, SIP UA Sends REGISTER to Registrar

• Registration Data Provides Addresses to Reach User

• Registration Database Forms a Dynamic Routing Database of Users

• Centralized Store is Desired for Scalability


Redirect Server

Location Server

Registrar Server

User Agent

Proxy Server

Gateway

PSTN

SIP Components

Proxy Server

SIP Distributed Architecture


• The SIP address is identified by a SIP URL, in the format: user@host. – Examples of SIP URLs:

• sip:[email protected]• sip:[email protected]• sip:[email protected]

SIP Addressing


SIP MessagesMethods and Responses

SIP components communicate by exchanging SIP messages:

• SIP Methods:– INVITE – Initiates a call by inviting

user to participate in session.– ACK - Confirms that the client has

received a final response to an INVITE request.

– BYE - Indicates termination of the call.

– CANCEL - Cancels a pending request.

– REGISTER – Registers the user agent.

– OPTIONS – Used to query the capabilities of a server.

– INFO – Used to carry out-of-bound information, such as DTMF digits.

• SIP Responses:– 1xx - Informational

Messages.– 2xx - Successful

Responses.– 3xx - Redirection

Responses.– 4xx - Request Failure

Responses.– 5xx - Server Failure

Responses.– 6xx - Global Failures

Responses.


Establishing communication using SIP usually occurs in sixsteps:

1. Registering, initiating and locating the user.2. Determine the media to use – involves delivering a

description of the session that the user is invited to.3. Determine the willingness of the called party to

communicate – the called party must send a response message to indicate willingness to communicate – accept or reject.

4. Call setup.5. Call modification or handling – example, call transfer

(optional).6. Call termination.

Process for Establishing Communication


SIP

Protocols related to SIP


Session Description Protocol (SDP)

• Used to specify client capabilities

• Example: (client can support MPEG-1 video codec, and MP3 codecs)


Session Announcement Protocol (SAP)

• Originated around same time as SIP

• Used to announce multimedia sessions– Announcement goes to users in a multicast

group– Announcements can contain :

• Start Time of session,• Duration of session, etc.


–Session initiation.

–Multiple users.

–Interactive multimedia applications.

SIP Framework


• SIP was designed for:–Integration with existing IETF

protocols.

–Scalability,

–Simplicity,

–Mobility and

–Easy feature and service creation.

SIP – Design Framework


• Other IETF protocol standards can be used to build a SIP based application. SIP can works with existing IETF protocols, for example:– RSVP - to reserve network resources.– RTP Real Time Protocol -to transport real

time data and provide QOS feedback.– RTSP Real Time Streaming Protocol - for

controlling delivery of streaming media.– SAP Session Advertisement Protocol - for

advertising multimedia session via multicast.

Integration with IETF Protocols (1)


– SDP Session Description Protocol – for describing multimedia sessions.

– MIME – Multipurpose Internet Mail Extension – defacto standard for describing content on the Internet.

– HTTP – Hypertext Transfer Protocol - HTTP is the standard protocol used for serving web pages over the Internet.

– COPS – Common Open Policy Service.– OSP – Open Settlement Protocol.

Integration with IETF Protocols (2)


• The SIP architecture is scalable, flexible and distributed.

– Functionality such as proxying, redirection, location, or registration can reside in different physical servers.

– Distributed functionality allows new processes to be added without affecting other components.

Scalability


• SIP is designed to be: – “Fast and simple in the core.”

– “Smarter with less volume at the edge.”

– Text based for :• Easy implementation and• Debugging.

Simplicity


• SIP supports user mobility by proxying and redirecting requests to a user’s current location.

• The user can be using a :– PC at work,– PC at home, – Wireless phone, – IP phone or– Regular phone.

• The user must register their current location.• The proxy server will forward calls to the user’s current

location.• Example mobility applications include presence and call

forking.

Mobility


• A SIP based system can support rapid feature and service creations.

• Features and services can be created using:– Call Processing Language (CPL).– Common Gateway Interface (CGI).

Feature Creation


• SIP can support these features and applications:– Basic call features

• Call waiting,• Call forwarding,• Call blocking.

– Unified messaging.– Call forking.– Click to talk.– Presence.– Instant messaging.– Find me / Follow me.

Feature Creation


NGN Signaling Protocols

H.323


What is H.323?

• H.323 is a standard that specifies– Protocols,– Components and– Procedures

• That provide multimedia communication services, real-time audio, video, and data communications over packet networks, including IP based networks.

• H.323 is part of a family of ITU-T recommendations called H.32x that provides multimedia communication services over a variety of networks.

“

,,


H.323 Framework

H.323 defines:

– Call establishment and termination.– Audio visual or multimedia conferencing.


Terminal Gateway

Packet Based

Networks

Multipoint Control

Unit

Gatekeeper

Circuit Switched

Networks

H.323 Components

TerminalsGatewaysGatekeepersMultipointControl Units(MCUs)


H.323 terminals are client endpoints that

must support:– H.225 call control signaling.– H.245 control channel signaling.– RTP/RTCP protocols for media packets.– Audio codecs.

Video codecs support is optional.

H.323 Terminals


A gateway provides translation:– Gateway translates the messages that

belongs to the two different networks with different protocol stacks.

– Gateways can also provide :• Transmission formats translation,• Communication procedures translation,• H.323 and non-H.323 endpoints translations or• Codec translation.

H.323 Gateway


• Gatekeepers provide these functions:– Address translation.– Admission control.– Bandwidth control.– Zone management.– Call control signaling (optional).– Call authorization (optional).– Bandwidth management (optional).– Call management (optional).

• Gatekeepers are optional but if present in a H.323 system, all H.323 endpoints must register with the gatekeeper and receive permission before making a call.

H.323 Gatekeepers


• MCU provide support for conferences of three or more endpoints.

• An MCU consist of:– Multipoint Controller (MC) – provides control

functions.– Multipoint Processor (MP) – receives and

processes audio, video and/or data streams.

H.323 Multipoint Control Unit(MCU)


H.323 is an “Umbrella” Specification

Media H.261 and H.263 – Video codecs.G.711, G.723, G.729 – Audio codecs.RTP/RTCP – Media.

Data/FaxT.120 – Data conferencing.T.38 – Fax.

Call Control and SignalingH.245 - Capabilities advertisement, media channel establishment, and conference control.H.225Q.931 - call signaling and call setup.RAS - registration and other admission control with a gatekeeper.

Call Control and

Signaling

Data/FaxMedia

IP

UDP

RTP

Audio

Codec

G.711

G.723

G.729

Video

Codec

H.261

H.263RTCP

H.225

Q.931

H.225

RASH.245T.120 T.38

TCP TCPUDPTCP

H.323


• Establishes logical channels for transmission of H.323 data – Negotiates:

• channel usage• master/slave configuration• flow control • Codec used (capability exchange)

H.323 – H.245


• Master/Slave Determination– Determines which terminal will be master which will

be slave in the call

• Terminal Capability Set– Contains information on a terminal’s ability to send

and receive multimedia streams

• Open Logical Channel– Opens logical channel for transport of multimedia data

• Close Logic Channel– Closes the logical channel between two endpoints

H.323 – H.245 Messages


• Request Mode– Receive terminal requests type of

transportation from a transmit terminal– Types of Modes:

• Video• Audio• Data• Encryption



• Send Terminal Capacity Set– Instructs far-end terminal to send transmit and

receive capabilities

• End Session Command– Indicates the end of the H.245 session



Other ITU H. Recommendation that work with H.323

Protocol Description

H.235 Specifies security and encryption for H.323 and H.245 based terminals.

H.450.N H.450.1 specifies framework for supplementary services. H.450.N recommendation specifies supplementary services such as call transfer, call diversion, call hold, call park, call waiting, message waiting indication, name identification, call completion, call offer, and call intrusion.

H.246 Specifies internetworking of H Series terminals with circuit switched terminals.


NGN Signaling protocols

Comparing

SIP and H.323


• Functionally, SIP and H.323 are similar.Both SIP and H.323 provide:– Call control, call setup and teardown.– Basic call features such as :– Call waiting,– Call hold,– Call transfer,– Call forwarding,– Call return,– Call identification or– Call park.– Capabilities exchange.

Comparing SIP and H.323 Similarities


• H.323 – Defines sophisticated multimedia conferencing. H.323 multimedia conferencing can support applications such as:

– Whiteboarding,– Data Collaboration and– Video Conferencing.

• SIP – Supports flexible and intuitive feature creation with SIP using SIP-CGI (SIP-Common Gateway Interface) and CPL (Call Processing Language).

• SIP – Third party call control is currently only available in SIP. Work is in progress to add this functionality to H.323.

Comparing SIP and H.323 Strengths


NGN

Outline (cont.)



Gateway Control Protocols

MGCP (Media Gateway Control Protocol)

H.248/MEGAco


MGCP• RFC 2705• Controlling VoIP Gateways from External Call Control

Elements• History:

– Simple Gateway Control Protocol (SGCP): Bell core / Cisco

– IP Device Control (IPDC): extended work of XCOM, Ascend & others.

– Media Gateway Control Protocol (MGCP): Merged IPDC + SGCP

– Media Device Control Protocol (MDCP): Lucent– H.GCP: ITU SG16 Functional Decomposition

Control Protocol


What is MGCP?

“

”

•Media Gateway Control Protocol – A

protocol for :

– Controlling Telephony gateways from external call control elements called media gateway controllers or call agents.

IETF RFC 2705 Media Gateway Control Protocol


• Decompose gateway into :– A controlling signalling component and– A controlled media component.

• Can be used in phones or gateways in conjunction with SIP

MGCP


MGCP Call agent or media gateway

controller– Provides call signaling,

control and processing intelligence to the gateway.

– Sends and receives commands to/from the gateway.

Call Agent or Media Gateway

Controller(MGC)

Call Agent or Media Gateway

Controller(MGC)

SIPH.323

MGCP MGCP

Media Gateway(MG)

Media Gateway(MG)


• Call Agent Commands:– EndpointConfiguration– NotificationRequest– CreateConnection– ModifyConnection– DeleteConnection– AuditEndpoint– AuditConnection

MGCP Commands

• Gateway Commands:– Notify– DeleteConnection– RestartInProgress


MGCP– A master/slave protocol.

• Assumes limited intelligence at the edge (endpoints) and intelligence at the core (call agent).

• Used between call agents and media gateways.• Differs from SIP and H.323 which are peer-to-peer

protocols.

– Interoperates with SIP and H.323.

Characteristics of MGCP


– MGCP divides call setup/control and media establishment functions.

– MGCP does not replace SIP or H.323. SIP and H.323 provide symmetrical or peer-to-peer call setup/control.

– MGCP interoperates with H.323 and SIP. For example,

• A call agent accepts SIP or H.323 call setup requests.

• The call agent uses MGCP to control the media gateway.

• The media gateway establishes media sessions with other H.323 or SIP endpoints.

Call Agent/Media

Gateway Controller

Media Gateway

MGCP

H.323 Gateway

H.323Gateway

H.323

Media RTP/RTCP

In this example, an H.323 gateway is “decomposed” into:

–A call agent that provides signaling.

–A gateway that handles media.

MGCP protocol is used to control the gateway.

MGCP, SIP and H.323


H.323 1. A user picks up analog phone and dials

a number.

2. The gateway determines how to route the call.

3. The two gateways exchange capabilities information.

4. The terminating gateway rings the phone.

5. The two gateways establish RTP/RTCP session with each other.

MGCP1. A user picks up analog phone and dials a

number.

2. The gateway notifies call agent of the phone (endpoint) event.

3. The Call agent determines capabilities, routing information, and issues a command to the gateways to establish RTP/RTCP session with other end.

H.323Gateway

H.323Gateway

AnalogPhone

AnalogPhone

Gateway A Gateway B

AnalogPhone

Call Agent/Media

Gateway Controller

RTP/RTCP

AnalogPhone

5.RTP/RTCP1

3

4

1

2

Example Comparison


• A protocol that is evolving from MGCP and developed jointly by ITU and IETF:

–Megaco - IETF.–H.248 or H.GCP - ITU.

What is Megaco?


MEGAco


• SIP and H.323 are comparable protocols that provide– Call Setup,– Call Teardown,– Call Control,– Capabilities Exchange and– Supplementary features.

• MGCP is a protocol for controlling media gateways from call agents. In a VoIP system, MGCP can be used with SIP or H.323.

• SIP or H.323 will provide the call control functionality and MGCP can be used to manage media establishment in media gateways.

Summary


NGN

Outline (cont.)



IETF standard: RFC 3550• Provides end-to-end delivery services for

data with real-time characteristics, such as interactive audio and video

• Specifies a packet structure for packets carrying audio and video data

• RTP packet provides – payload type identification– packet sequence numbering– time stamping

Real-Time Transport Protocol (RTP)


• RTP runs in the end systems

• RTP packets are encapsulated in UDP segments

• Provides a transport-layer interface(“OSI-Layer 4b”)

• Attempts to avoid jitter

RTP (2)


• RTP does not provide:– Any mechanism to ensure timely delivery of data– Any quality of service guarantees

• RTP encapsulation is only seen at the end systems– Not recognized by routers as a special kind of

datagram– Routers providing best-effort service do not make any

special effort to ensure that RTP packets arrive at the destination in a timely matter

• Allows for each voice or video device to have its own RTP stream

• Supports unicast as well as multicast applications

RTP (3)


• Works in conjunction with RTP

• It’s Main function is Echo Cancellation

• Each participant in RTP session periodically transmits RTCP control packets to all other participants

• Transfers necessary information to synchronize transmitter & receiver

Real-Time Control Protocol (RTCP)


RTCP

• Each RTCP packet contains sender and/or receiver reports– Report statistics useful to application

• Statistics include :– Number of packets sent,– Number of packets lost,– Interarrival jitter, etc.

• Feedback can be used to control performance– Sender may modify its transmissions based

on feedback (incl. Bandwidth scaling)


• For an RTP session there is typically a single multicast address; all RTP and RTCP packets belonging to the session use it

• RTP and RTCP packets are distinguished from each other through the use of distinct port numbers (RTCP port = RTP port + 1)

• To limit traffic, each participant reduces its RTCP traffic as the number of conference participants increases

RTCP (2)


NGN

Outline (cont.)



• EUROSCOM

• SIEMENS

• ALCATEL

• LUCENT

• ZTE

Migration Strategies


One of the migration scenarios which breaks theproblem into smaller part.The following network diagrams represent how thearchitectural model may be instantiated for somescenarios of interest to a network operator. Eachfigure displays the functions and interfacesrequired of each network scenario. For eachinterface, suggestions are provided as examples oftypical inter-working protocols.

EUROSCOM Migration Scenario



PSTN to IP network interface scenario


GSM PLMN (Mobile) to IP network



• Alcatel presents a step-by-step migration scenario from a TDM-based public switched telephone network to a packet based next generation network. Six steps consolidation and expansion scenario is elaborated.

Alcatel Migration Scenario


Alcatel Migration Scenario

1. PSTN for Voice and Internet Access.

2. PSTN Consolidation.

3. Voice over Packet Trunking (IP or ATM).

4. Voice over Packet Access (ADSL, LMDS or cable)

5. Introduction of Multimedia

6. Migration to Full NGN


Alcatel Full NGN


Siemens Migration Scenario• Siemens proposed a Next Generation Network

migration Strategy based on class 4 and 5 softswitch replacement.

First: migrate the transit level


Siemens Migration Scenario

Then, introduce IP-based services


Siemens Migration Scenario

Finally, replace local switches


•First Scenario: Focus on Voice over BroadBand and minimize risk

Step 1:–Start with VoBB solutions based on voice gateway–Reuse existing TDM network and OAM infrastructure–QoS is manageable, avoid risks of softswitch technology–Get experience with various customer premises

equipment (CPE)–Get experience with commercial packaging and market

acceptance

Step2:–Migrate to full NGN solution Get cost advantages of end-

to-end VoIP solution Introduce more advanced NGN applications (SIP, application severs).

Lucent Migration Scenarios


• Second scenario: Focus on traffic offload and cost-effective gateways

Step1: – Start with LSS-based ICD application for internet

offload– Reuse dial-in gateways also for VoIP– Introduce VoIP backbone network

Step2:– Add VoIP endpoint support for Voice over

Broadband– Introduce more advanced NGN applications (SIP,

application servers)

Lucent Migration Scenario


• ZTE produced two strategies for PSTN evolution based on softswitch network solutions.– Strategy 1: Softswitch device together with Trunking

Gateway carries out the functions of legacy tandem and toll exchanges whilst the Class 5 terminal exchange remains the same .

– Strategy 2: Softswitch devices together with Access Gateway carries out the functions of legacy terminal exchange while twisted pair user interface remains the same.

ZTE Migration Scenario



ZTE Evolution Strategy 1 of existing PSTN/ISDN



ZTE Evolution Strategy 2 of Existing PSTN/ISDN


NGN

Outline (cont.)



• The ultimate requirement of the NGN is to handle packetized voice and data in a converged manner.

• Next generation networks are not just a PSTN replacement but at a minimum they must provide the equivalent voice quality and reliability of today’s PSTN.

• The NGN will be the foundation for the creation of a new range of multimedia applications that take full advantage of the characteristics of the broadband network and the “always on” capability.

Conclusion


The users that are most ready to embrace the new opportunity will be the first to be migrated to the NGN model, this will then be a commercial migration with the emphasis being placed on new revenue opportunities.

The creation of the NGN is no overnight transformation, but it is an evolution that is already underway and gathering pace.

Conclusion


Thanks for your

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ngn

Technology

layers of ngn

ngn control layer

core of ngn

ngn ctrl layer softswitch

ngn ctrl layer handles

ngn str ucture

core layer

core network