Next Generation Network

ZTE-University

By: Jay Shankar Singh

Topic Covered1. NGN Overview2. NGN Architecture3. Media Gateway Overview4. MSG9000 Architecture5. Softswitch/Media Gateway Controller Overview6. Softswitch Architecture7. NGN Protocols1. SIP 2. H.248 3. SIGTRAN8. Advantages of NGN.Next Generation NetworkThe Next Generation Network (NGN) is a popular phrase used to describe the network that will replace the current PSTN network around the world today used to carry voice, fax, modem signals, etc. By definition, the NGN is essentially a managed IP-based network that enables a wide variety of services. Among those services are VOIP, videoconferencing, Instant Messaging, e-mail, and all other kinds of packet-switched communication services. Its a concept for defining and deploying networks, which due to their formal separation into different layers and planes and use of open interfaces, offers service providers and operators a platform which can evolve in a step-by-step manner to create, deploy and manage innovative services.International Telecommunication Union (ITU) in its recommendation Year 2001 has defined NGN as a packet based network able to provide services including Telecommunication Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It offers unrestricted access by users to different service providers. It enables unfettered access for users to networks and to competing service providers and/or services of their choice. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.

Above all we can say NGN is:

Separation of call and services

Separation of call control and bearer

Next Generation Services Converged (quad-play, voice, data, video, mobile) i.e. Service-driver Network. Base on IP, including voice, fax, data, video and multimedia.

Next Generation Access High speed (Broadband) IP based connectivity (ADSL,VDSL, Wi-Max, FTTH. Standard Protocol Next Generation Architecture Service oriented, layered (transport, control, application) Next Generation Interconnect Capacity and Quality basedNGN ArchitectureThe NGN architecture incorporates:

Support for multiple access technologies: The NGN architecture offers the configuration flexibility needed to support multiple access technologies.

Distributed Control: This will enable adaptation to the distributed processing nature of packet-based networks and support location transparency for distributed computing.

Open Control: The NGN control interface is open to support service creation, service updating, and incorporation of service logic provision by third parties.

Independent service provisioning: The service provisioning process is separated from transport network operation by using the above mentioned distributed open control mechanism. This is intended to promote a competitive environment for NGN development in order to speed up the provision of diversified NGN services.

Support services in a converged network: This is needed to generate flexible, easy-to-use multimedia services, by tapping the technical potential of the converged, fixed-mobile functional architecture of the NGN.

Enhanced security and protection: This is the basic principle of an open architecture. It is imperative to protect the network infrastructure by providing mechanisms for security and survivability in the relevant layers.

Functional entity characteristics: Functional entities incorporate the following principles:

Functional may not be distributed over multiple physical units but may have multiple instances.

Functional entities have no direct relationship with the layered architecture. However, similar entities may be located in different logical layers.

NGN ArchitectureAccess LayerAccess layer of the NGN architecture has following functions:

Connecting subscribers (Legacy/IP based), AN & PABX and trunks from PSTN, ISDN, and PLMN etc.

Converting the formatting of information (circuit to packet or packet to circuit) before transmitting it.

The components of the access layer are:

TG (Trunk Media Gateway): It resides between circuit switched (CS) network and the IP network. It converts format between pulse code modulation (PCM) signal flow and IP media flow. It supports functions such as packetisation, echo control etc. It can have integrated signaling gateway functionality also, The MGW can connect devices, such as the PSTN exchange, private branch exchange (PBX), access network device and base station controller (BSC).AG (Access Gateway): It acts as the line side interface to the core IP network and connects subscribers with analog subscriber access, integrated services digital network (ISDN) subscriber access, PABX and x digital subscriber (xDSL) access.

IAD (Integrated access device): It is a devices used to access subscribers (Analog, ADSL, IP) in the NGN. It access data of subscriber terminals, voice services and video services to the packet network. It works as Access Gateway local exchange.

SG (Signaling Gateway): Its works to accomplishing signaling translation to IP. The SG provides the signaling interface between the IP network and the PSTN signaling network. It terminates SS7 links and provides Message Transport Part (MTP) Level 1 and Level 2 functionality. Each SG communicates with its associated circuit switch (CS) to support the end-to-end signaling for calls.BGW (Broadband Gateway): BGW interconnecting public network and private network. The access network provides connectivity between the customer premises equipment and the access gateways in the service providers network.Multi Services Gateway/Media Gateway (MSG/MG):

A node that works as a facilitating adapter for the user plane between different networks, in a layered network architecture.

Connects the Mobile Core Network with other networks e.g. WCDMA, GSM, PSTN

Bridges different transmission technologies

Process the connectivity layer, adding services to end-user connections.

In the next generation network based on Softswitch technology, ZXMSG 9000 can be used as trunk gateway (TG), signaling gateway (SG) ,access gateway (AG) and media resource server (MRS). It can also act as an integrated gateway (TG/SG/AG/MRS) by deploying different circuit boards on the same equipment.

ZXMSG 9000ZXMSG 9000 Functions As a carrier-class, high capacity integrated media gateway ZXMSG 9000 includes:

TG(As TG, maximum capacity = 336000 ports) Can be used as major TG node. In charge of inter-connecting PSTN network via trunk cable with IP core network via Ethernet cable and accomplishing voice translation from PSTN/ISDN to IP and vice versa

Can be used as the Transit Switch and Toll Switch in the existing fixed network

SG(As SG, maximum signal transaction capacity > 2M MSU/s. maximum 64Kbits/s signaling link = 6144maximum signaling networks= 255; maximum SCTP LINKS=2560; maximum DPC number=2048; maximum signaling route number=4096 ;) Support SS7 MTP message processing and network management in the SCN

Support SIGTRAN, signal adaptation protocol M3UA, M2UA,M2PA,SUA,IUA,V5UA

Support SCTP, ensuring message transferring reliability

multiple No.7 signaling network Support

ITU-T,ANSI,CHINA SS7 Support

Support STP function

AG(As AG, maximum capacity = 1,000,000 ports) Support access to analog subscriber

Support access to traditional PBX

Support standard V5.2 interface

Support access to remote module Support access to xDSL, ISDN subscriberZXMSG 9000 Hardware ArchitectureZXMSG9000 device can be divided into three major units according to their functions: Backplane Central Control Unit (BCTC), Backplane Circuit Switch Network (BCSN), and Backplane Universal Management/Service Access unit (BUSN/BUMA)

ZXMSG 9000 System operating principleBackplane Central Control Unit (BCTC)As the control center, BCTC unit monitors system function unit/circuit boards, establishes message links and provides the software operating platform to satisfy various service requirements. It could also process the signal transactions. Its a control shelf in MGW i.e. carries the signaling processing circuit, control circuit, carries out the call control logic transaction.

Standard BCTC configurationBCTC consists of operating management processor (OMP), call control processor (CMP), universal interface management circuit (UIMC), IP-side interface (SIPI) and control hub (HUB).

Main control slot9, 10which can not be used by other service circuit but UIMC, carrying the communication inside the BCTC. Normal slot1~811~14, which can be used by many control circuits, including CMP, OMP, or SIPI. And Switching control slot15~16, which can be used by either CHUB or CLKG.Card Detail: OMP (Operating Main processor)2 CPUs, standby/active mode, Data configurations stored in build-in hard driver, provide alarm management ,net management. Its CPU2 work as Route Processing Unit; OMPs back board-RMPB configuration as below:OMC1: The primary OMC network interface (used for interface operation and maintenance of external networks) OMC2: The secondary OMC network interface (used for interface operation and maintenance of external networks) GPS485: Full duplex GPS485 interface (used to manage the GPS in the system and is connected to the GPS)

PD485: Semi-duplex PWRD485 interface (used to manage the power supply in the system and is connected to the PWRD)

RS232: The management interface 232

DEBUG1-232: The DEBUG 232 interface of the primary CPU system

DEBUG2-232: The DEBUG 232 interface of the secondary CPU system CMP (Call management processor): 2 CPUs, standby/active mode, provide the transaction for control protocol and signal protocol, such as H.248,m3ua

UIMC (universal interface management card) standby/active mode, provide the Ethernet communication for all of the functional cards in the same shelf; No T-NET/TFI interface, It provides two 24+2 switching HUBs. The back boards corresponding to the UIMC include RUIM2 and RUIM3. CHUB (Call HUB) standby/active mode, Every resource shelf provides 2 FE connecting with CHUB; CHUB itself provides 46 FE interfaces for external frames and 1 GE interface to connect with UIMC

SIPI (Signaling IP Interface): IP interface for signaling, standby/active mode, providing several FE interfaces for external IP network. It provides four 100M Ethernet interfaces for external networks.Backplane Universal Management/Service Access unit (BUSN/BUMA)BUSN sub-system provides the functionality of processing service unit (with protocols), implements the translation of internal media stream and signal streams which can get access to subscriber unit and E1/T1 trunk/signaling link

Standard Configuration of BUSNNote: Main control slot 9, 10can not be used by any other service board but UIMT.

UIMT: Provide LAN switch & synthesized TDM circuits; 2 FE interfaces connecting with CHUB in control frame; a pair of 8K fiber cable connecting with BCSN. It provides two 24+2 switching HUBs, one 16K switched network, two pairs of TDM optical fibers. And the backboard corresponding to the UIMT is RUIM1. DTB: 32E1/T1 (Leads out RS232 transceiver signals and 8KBase clock signals) VTCA: 960VOIP, It implements media stream conversion between the PSTN side and IP Side. SPB: SS7 process board,128 NO7 signal links, It implements Narrowband signaling processing, MTP1, MTP2 signaling processing and it provides 4 sub-card, 32 link / sub-card. SDTB: STM-1interface, one card can provide 84T1/63 E1 interfaces

NIPI: IP interface for media,1000M,Fiber ,10000 RTP port

MRB: It provides 480 channels of Tone/Voice, DTMF Detection/Generation, MFC Detection/Generation, and Conference Call, which can be configured as TONE/ CONF/ DTMF/MFC/CID. And Its include 120 Channels constitute one basic sub-element.Backplane Circuit Switch Network (BCSN):The major function of BCSN is to implement the inter-connection of TDM switching network. Adapting 3G platform BCSN frame to this unit and can support up to 256Kx256K capacity. Can also be configured with different capacity according to customers requirements (from 64K to 256k)

BCSN StructureIn BCSN shelf, TSNB board can be configured according to different requirements. Its a resource shelf i.e. Its a TDM switching unit with capacity from 64k to 256k. This unit can occupy TSNB, TFI, CLKG, UIM.BCSN Standard Hardware Architecture TSNB(T-Net switching network board): 64K-256K; It provides 64K circuit/timeslot switching function and it can be expanded to 256K and It works in active/standby mode TFI (T-Net fiber interface)It provides 8 pairs of optical fibers connected to the active or standby UIMT and 8K time slot connecting with resource shelves; it requires 4 pairs of TFIs to serve a 256K T-Net board

UIMC (Universal Interface management card)It provides 2 FE interfaces connecting the control signals with control shelf

CLKG (clock board): Its mostly used in BCSN to clock synchronizationCore Layer: The core layer functions provide the connectivity for all components and physically separated functions within the NGN. These functions provide support for the transfer of media information, as well as the transfer of control and management information.

The core layer is composed of devices, such as routers and layer 3 switches that are located in the backbone network and in the MAN. The primary function of the IP core network is to provide routing and transport of IP packets. It adopts the packet switching technology and provides subscribers with a common, integrated platform of data transport which ensures: High reliability, QoS assurance, High capacity.Control Layer

The network control layer adopts the software switching or soft-switching technology to achieve: Primary real-time call control

Connection control

Softswitch (SS/MGC): In NGN Softswitch is a programmable device that control Voice over IP (VoIP) calls. It enables correct integration of different protocols within NGN. The most important function of the Softswitch is creating the interface to the existing telephone network, PSTN, through Signaling Gateway (SG) and Media Gateway (MG). However, the Softswitch as a term may be defined differently by the different equipment manufacturers and have somewhat different functions. It control one or more gateways.

The softswitch, also known as Media Gateway Controllers (MGC), Call Servers (CS) and Call Agents is the core device in the NGN. The softswitch is located in the service providers network and handles call control and signaling functions, typically maintaining call state for every call in the network. A softswitch interacts with Application Servers to provide services that are not directly hosted on Softswitch. Important functions of Softswitch are: Call Control

Media Gateway Access Control

Signaling Gateway Control

Border Gateways Control Resource allocation

Protocol Processing Routing

Authentication

Charging

Softswitches also act as Signaling Switching Point (SSP) to provide access to IN services to SIP users.The softswitche also provides services such as: Basic voice services

Multimedia servicesSoftswitch(ZXSS10 SS1b) hardware architecture as below:SS Standard Hardwar Archtecture

SS Board Details:SC (System Control Card): It includes CPU (MPC7410, MPC750), RAM, IDE, Ethernet Interface, Serial bus (RS-485/RS-232), and Power Supply. SC card monitor the hardware and software status of other boards, it control the other board in the shelf. It takes file backup i.e. Software version, CLI script etc. It has a HD with min. capacity of 20 Gb and upgraded till 40 Gb. It act as active-reserve switch.SSN board (System Switching Network): There is CPU, RAM and Switching Chip contain in this card. It has 24 Ethernet Interface with speed of 100M, in which 13 for SPC cards, 2 for SC cards, 6 for NICs and others are for DB server and shelf cascading. And It provides Ethernet switching platform.NIC (Network Interface Card): It has CPU, RAM and Ethernet Interface for IP network. Ethernet Interface in NIC used to connect with outer network with Softswitch. It distributes the Protocol and other packet among SPCs.

SPC (System Protocol Card): It has CPU, RAM and one 10Base-T Ethernet Interface and It functioning to control Protocol and call processing. Its capacity is 60K i.e. 60,000 subscribers per SPC. SSNI board (System Switching Network Interface): This board is using to connect DB Server /Billing Server and CDR Server.

SS1B Shelf Cascading:CSN (Cascade Switching Network): Its inserted in Slot 7 and Slot 8 of the main shelf of SS. It provides 24 Fast Ethernet and 2 GE for Ethernet Switching. And works in the active/standby mode.

Master Shelf Card Slot PositionCSNI (Cascade Switching Network Interface): It provides Ethernet connection for CSN board.

GNIC (Gigabit Network Interface Card): It provides 1 GE and 4 FE ports used to connect to the external network.CDR Generation: Call flow to Softswitch i.e. CDR generates to SPC card and subscriber information save at SC & SPC cards of Softswitch.CDR GenerationService LayerThe service layer provides value-added services (VAS) and operation support functions, The components of the service layer are:

SHLR: Smart Home Location Register is storing subscribers data.Application Server: It produces and manages logics of value-added services (VAS) and intelligent network (IN) services, providing a platform for a third party to develop services through open APIs. The application server is the result of separating service from call control. It helps to develop supplementary services.

NGN Protocols:

In NGN environment the media stream consist of audio, video or data, or a combination of any of them. It is transported through RTP/RTCP (Real time control protocol). Control signaling messages are transported by control streams using signaling protocols like SIGTRAN, H.248, H.323 & SIP etc.

SIP: Designed by the IETF, the Session Initiation Protocol (SIP) is an application-layer control protocol for multimedia communication over IP network. It is used for creating, modifying and terminating two party sessions, multiparty sessions and multicast sessions (one sender and many receivers). These sessions include audio, video and data for multimedia conferences, instance messaging, and Internet telephone calls etc. It works between Softswitches.

Session Initiation Protocol (SIP) is an application-layer control protocol that can establish, modify and terminate multimedia sessions or calls. It is the core protocol of IETF multimedia data and control architecture. It can be easily expanded, conveniently achieved, and suitable to implement Internet-based multimedia conference systems. The NGN Soft-Switch system interconnects with other Soft-Switch systems and SIP domain devices via SIP signaling, achieving the call control functions between them. E.g. Window live Messenger, Skype

SIP Messages Request/ReplySIP components rely on the interaction of SIP messages to communicate with each other, the messaging mechanism is based on Client/Server, and can be divided into two categories (request and reply)

SIP uses the following request methods:

INVITEIndicates that a user or service is being invited to participate in a call session.

ACKConfirms that the client has received a final response to an INVITE request.

BYETerminates a call and can be sent by either the caller or the callee.

CANCELCancels any pending searches but does not terminate a call that has already been accepted.

OPTIONSQueries the capabilities of servers.

REGISTERRegisters the address listed in the To header field with a SIP server.

REFERIndicates that the user (recipient) should contact a third party for use in transferring parties.

NOTIFYNotifies the user of the status of a transfer using REFER. Also used for remote reset.

The following types of responses are used by SIP:

SIP 1xxInformational Responses

SIP 2xxSuccessful Responses

SIP 3xxRedirection Responses

SIP 4xxClient Failure Responses

SIP 5xxServer Failure Responses

SIP 6xxGlobal Failure Responses

SIP Call flow:The call flow scenario is as follows:

1. User A calls User B.

2. User B answers the call.

3. User B places User A on hold.

4. User B takes User A off hold.

5. The call continues.

H.248: H.248 is an ITU recommendation that defines Media Gateway Control Protocol. It is the result of a joint collaboration between the ITU and the IETF. It is also referred to as IETF MEGACO, which defines a centralised architecture for creating multimedia applications, including VOIP. In many ways, H.248 builds on and extends MGCP. It is used as a media gateway control protocol between Softswitch (MGC) and a Media Gateway (MG). Compared to the MGCP protocol, the H.248 protocol is more flexible and can support more types of access technologies and mobility of terminations.

H.248 DiagramH.248 Protocol Stack:The H.248 application in NGN supplies a framework for building gateways and controllers on the top of the H.248 protocol stack. Some key features are: Carrier-class high availability, process supervision, soft code upgrade etc.

Scalable distributed implementation with ability to distribute an MG or MGC over several NGN nodes

Flexible architecture dynamic run-time configuration in order to select encoding methods, transport mechanisms, timers etc.

H.248 stack supports interactive multimedia communication using decomposed gateway architectures.Terminology Interpretation: a) Termination: Termination is logical entity on the MGW, which initiates/receives media stream. Termination is identified with Termination ID. There are 3 types of termination:

Semi-permanent termination: Semi-permanent termination represents the physical entity. For example, for a TDM channel, as long as this channel exists in the MGW, the termination exists.

Temporary termination: Temporary termination only exists during the calling procedure, such as RTP media stream. Once the calling ends, the termination eliminates.

Root termination: Refer to the entire MGW (from Softswitch to MGW)b) Context: means the relationship between groups of terminations. If context involves more than two terminations, it describes the topology (receiver/sender), media blending and/or switching parameters. And a null context represents terminations that havent relationship with others.

When a call is originated, the H.248 protocol can use commands to add terminations corresponding to calling and called parties in the contextH.248 Commands

Above commands are running between Softswitch (MGC) and Media Gateway. Six commands i.e. Add, Modify, Subtract, Move, AuditValue, and AuditCapability are running from Softswitch and for every command from Softswitch, the Notify command is responded by Media Gateway. And ServiceChange command is running from both Media Gateway and Softswitch to get registered once in the scenario.i. Add: To Add the termination to the contextii. Modify: To change the property, event or signal parameter of Termination

iii. Subtract: To delete the termination from context and delete the context as well if there is no more termination.

iv. Move: Move a termination from one context to another i.e. call waiting turn to answering mode.

v. AuditValue: To obtain the all possible event, current status, signal information of a termination.

vi. AuditCapabilities: To check the MGW connectivity with Softswitch and obtain the possible capacity i.e. characteristics, event, signal of a MGW.

vii. Notify: After every command executed from SS, MGW sends an acknowledgement to SS through Notify command. viii. Service Change: Its the command which used by both MGW and Softswitch to register each other.

H.248 Call Flow Scenario:The call establishment between two residential users is considered in this example. The all two IAD (Residential gateways) controlled by MGC/Softswitch. The call scenario assumes the implementation of analog line supervision package, RTP package, generic package, DTMF detection package, call progress generator package, and the Network package in the successful call between two residential gateways.

In all the telephone scenarios explained in this draft, once the call is terminated by either the calling party or the called party, the other user hears a busy tone. A dial tone can be applied for the user to initiate another call. But for simplicity busy tone is applied so that the user goes onhook before initiating another call. It is assumed in the call scenarios that the registration of the MG with the Softswitch/MGC is done already. SIGTRAN: SIGTRAN (Signaling Transport) is a protocol stack defined by the SIGTRAN workgroup of the IETF (Internet Engineering Task Force) for transport of switched circuit network (SCN) signaling over IP networks.

This protocol stack supports the inter-layer standard primitive interface defined in SCN signaling protocol hierarchy model so as to ensure utilization of the existing SCN signaling application without modification. It uses the standard IP transport protocol as the transmission bottom layer, and satisfies the special transmission requirements of SCN signaling by adding its own functions.

SIGTRAN is a protocol stack that mainly includes three protocols: SCTP,M2UA, and M3UA.

SIGTRAN supports transmission of SCN (Switched Circuit Network) signaling via IP network. SIGTRAN is responsible for the communication between SG and MGC, with such two functions as adaptation transmission In NGN softswitch system, SIGTRAN is used to bear and adapt interworking between SS7 of SCN and IP network softswitch control system, acting as a bridge for signaling conversion.Advantages of NGN:NGN makes use of best of both the worlds (flexibility, efficiency & Innovativeness of IP and QOS, Security, Reliability, Customer-friendly features of proven PSTN

Advantages for service providers Reduced CAPEX due to integrated and efficient IP-based technology (Packetized Network) Reduced OPEX due to transmission cost saving, less power consumption, less space requirement, less O&M costs Ability to offer increased range of services More flexibility increasing market penetration by offering personal service customization and management There is no need for separate voice and data networks Advantages for subscribers Reduced call charges New innovative services Single connection and bill for voice, data, video, mobile (Quad play) Better QoS Faster speedNote: As discussed with Faculty, its observed that to configure a fresh NGN site it will take Min 15-17 days and its including Media Gateway and Softswitch configuration only except hardware installation. This is only an assumption.Supporting Platform

Service

Softswitch

Softswitch

APPS

SHLR

OAM

Control

NMS

IP Network

Core

Billing

BGW

AG

SG

TG

BAC-N

Intelligent

Terminal

Access

Other NGN

PSTN/PHS

Broadband

Access

IP TV

IP Phone

HG

EMBED Excel.Sheet.8

EMBED Visio.Drawing.11

NIC

External Network

SSN

SPC

MAC

IP

UDP

SIP

User Part

MTP

MG

MGC

Add

Modify

Subtract

Move

AuditValue

AuditCapability

Notify

ServiceChange

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BCTC

Sheet2

Sheet3

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32MHW

TSNB

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LVDS

DTU/TCU

LVDS

LVDS

LVDS

TFI

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TFI

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BCSN

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