VVT-420 5305 05 2002 c1 - Cisco网络技术(Net130.Com) · Corba/Telnet/FTP/SNMP FTP Front-end server ... CNAM 800 LNP CNAM 800 LNP SS7 IN FSIN FS Element ... VVT-420 5305_05_2002_c1

1© 2002, Cisco Systems, Inc. All rights reserved.VVT-4205305_05_2002_c1


Deploying Advanced Softswitch Applications

Session VVT-420


Prerequisites of this Session

• Basic understanding of VoIP (MGCP, H.323, and SIP) and PSTN protocols

• Basic understanding of the functions of the Softswitch/Call Agent


Agenda

• SP Voice Network Evolution and Challenge

• Softswitch Overview• Integrated Access Solutions• Challenges and Design Issues• Summary


SP Voice Network Evolution and Challenge

777© 2002, Cisco Systems, Inc. All rights reserved.VVT-4205305_05_2002_c1 222Kevin Yin, 2003 APSM © 2002, Cisco Systems, Inc. All rights reserved.

The Typical PSTN NetworkCPE Access Local Local &

BSC

Access CPEToll/Long distance, International

TDM Local Loop

LE/COC5

LocalTandem

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

MSC


333Kevin Yin, 2003 APSM © 2002 Cisco Systems Inc All rights reserved


BSC


TDM Local Loop

LE/COC5

LocalTandem

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

H-S TP

L-S TPL-S TP

H-S TP

MSC



BSC


TDM Local Loop

LE/COC5

LocalTandem

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

SCP

SCEDB

H-S TP

L-S TPL-S TP

H-S TP

MSC


GKGK

GK

GKGK

GK

Add H323 Transit/Tandem SolutionCPE Access Local Local &

BSC


TDM Local Loop

MSC

LE/COC5

LocalTandem

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

SCP

SCEDB

H-STPL-STPL-STP

H-STP

111111© 2002, Cisco Systems, Inc. All rights reserved.VVT-4205305_05_2002_c1 141414Kevin Yin, NGN Architecture © 2002, Cisco Systems, Inc. All rights reserved.

H323 VoIP vs Class 4 Softswitch

GKGK

GK

GKGK

GK

PGW2200 PGW2200

Billing Billing

IP

ITPITPITPITP

MGMGMGMG

MGMGMGMG

MGMGMGMG

Billing Billing

IP/ATM

Router Server


IP/ATM

MGMGMGMG

MGMGMGMG

MGMGMGMG

MGMGMGMG

ITP ITPITPMGMGMGMG

ITP

Add Class 4 SoftswitchCPE Access Local Local &

BSC


TDM Local Loop

MSC

LE/COC5

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

SCP

SCEDB

H-S TP

L-S TPL-S TP

H-S TP


SP Voice Business Challenges

ARPU is going down for PSTN local serviceThe separate access for data/voice are costly to maintain & operateNeed to develop new value added services over same infrastructure architecture easily!

Only converged data/voice/video infrastructure are commercially viable.

In low density in country, PSTN access remains expensiveCore transmission costs falling rapidly. We have to focus on access again.

SPs need the access to and to own the end subscribersCopper(PSTN, PBX, SDH) , Wireless, Broadband IP (ETTX)

SPs desperately looking for differentiation from other competitorsPSTN will only provide the vendor-based vertical solution but similar voice service

Want to leverage new technology for deployment advantage(Not PSTN Replacement), Softswitch based solutions are the only way for SPs to go


Multi-Mode Endpoints with Voice driving converged IP infrastructure

VideoTelephony

VoicePortals

PC toPhone

IP PhonesPDA

UnifiedMessaging Voice-enabled

Websites

InstantMessenger


7960

7910

7940

SoftPhone

7935

7960+7914

7920

Cisco IP Phone Product Line

9x23 line screen4 soft keys6 programmable line keysFull-duplex speaker phoneLine/Local power2-port Ethernet switch

9x23 line screen4 soft keys2 programmable line keysFull-duplex speaker phoneLine/Local power2-port Ethernet switch

2x23 line screen4 hard feature buttonsOn-hook dialing, call monitorLine/Local power2-port Ethernet switch7905

4x26 line screen4 soft keysLocal power standard

(line power dongle option)


ITP

MGMGMGMG

MGMGMGMG

ITP

MGMGMGMG

MGMGMGMG

IP

MGMGMGMGMGMGMGMG

Add Class5/Classless SoftswitchCPE Access Local Local &

BSC


TDM Local Loop

MSC

LE/COC5

LocalTandem

TandemC4

TandemC4

Toll

Int. GW

RSM

AN/DLC

SCPSCEDB

H-S TPL-S TPL-S TP

H-S TP


Executive Summary

• An Open Standard based Softswitch Architecture provides a Foundation for Converged Networks and Bundled Services Offerings

• The Long Term Market for NGN is real: IP has won the ‘theology’ debate, but it must surmount the ‘mass production’ scale

• As NGN helps Service Providers to transform their networks—new sources of revenue will become available to them from entertainment services, content and storage networks


Softswitch Overview


Definitions of the Softswitch

• Call & feature Control platform for SP voice service • Examples of what it does:

VoIP signaling interfacesPSTN signaling interfacesBearer controlling interfacesBasic digit analysis and manipulationBasic call processingBuilt-in enhanced servicesExternal interfaces or APIs for enhanced servicesCall Detail Record (CDR) generationElement management system and northbound interfaces

• Call Agent (CA) and Media Gateway Controller (MGC) usually provide a subset of these functions complementary with external EMS and enhanced service servers


PSTN/PLMN/GSM/

CDMA

MGCP/H248EndPoints

H323/SIPMulti-Media

Endpoints

Conference

VmailUM

Multi-Media

ApplicationServer

TUP/ISUP

SIP

AccessGW

Internet

OSSBillingServer

InternationalVoIP

Corba/Telnet/FTP/SNMPFTP

Front-end server

A-Link

F-Link

SIP/SIP-T/BICC

Cisco GW H323

International PC to Phone Traffic

Call Agents

Feature Server

SG

GW

EMS

Network/trunk

TrunkMG

Cisco Softswitch System

SIP/H.323 Network

Open Standard based Softswitch System


PSTNPSTN--TDM Switch and TDM Switch and SoftSwitchSoftSwitch

EP

PSTN+Valued Added Service

NMS/OSS

FeatureServer

ServicePortal H323/SIP

MGCP/H248SIP/H323

Centralize Control/Distributed Aggregation

SS7

TDM PSTN Voice Only Feature

EP

R2, SS7

Centralize Vertical Platform

TDM based

PSTN Switch Applicationserver

Centralized Call ControlDistributed Edge/AccessLocal PSTN interconnect

Softswitch


Interfaces of Softswitch

Network ManagementFTP, SNMP, Telnet

COBRA, HTTPPSTN

ISUP/M3UA/SCTP (SS7 and C7),

Q.931/IUA, QSIG,

CAS, Analog

PSTNISUP/M3UA/SCTP

(SS7 and C7),Q.931/IUA,

QSIG,CAS, Analog

VoIPH.323, SIP, SIP-TSignaling Interop,

Bearer Interop,Feature

Transparency

VoIPH.323, SIP, SIP-TSignaling Interop,

Bearer Interop,Feature

Transparency

Media GatewayControl

MGCP / H.248, MGCP NAS,NCS, TGCP

Media GatewayControl

MGCP / H.248, MGCP NAS,NCS, TGCP


Key Characteristics of Softswitch

• Separate Call Control from media bear • Open Hardware Platform• International standard based interface.• Interface PSTN with standardized transport methods (i.e.

SIGTRAN)• Multi-protocols interworking (e.g. MGCP ↔ H.323,H248 ↔H323, H.323 ↔ SIP)

• Bearer interoperability between different protocols• Inter-Softswitch communication


TDM Switch“IP board”

“IP board”

“SoftSwitch”

“GW”

Technical Trap: “SoftSwitch”

Inheritage all PSTN weakness. TDM switch, Closed/Vertical System.Only provide PSTN service. VoIP is fragile & incomplete and can only be used as demo purpose.No value/real invest for architecture! Temp Solution for more time to develop real SoftSwitch.

ATM 4x155MProprietary


Phonograph or DVD?


Softswitch Software Architecture800 LNPCNAM

CNAM 800 LNP

SS7

IN FSIN FS

Element Management

System

Element Management

System

CLISNMP

CORBA

ISUP/SS7 ISDN PRI SIP

Tandem FSTandem FS

POTS FSPOTS FSCentrex FSCentrex FS

CACACACA

800/cDNIS

FCP InterfaceFCP Interface

TCAPTCAP

CNAMCNAM ININ

JMS

MGCP

SG STP STP


Signaling Adapter Architecture

• Uniform primitives for all interactions between different protocol stacks and BTS modules.• Uniform data structures containing common Information elements from different protocols.• Call control primitives for exchanging all signaling messages between BTS & signaling network.• Primitives for Signaling Link hardware Maintenance and Signaling Protocol Stack Provisioning.

Basic Call Module (BCM)

MaintenanceModule (MNM)

ResourceManagement

(RSM)

ISDN PRI Protocol

Stack

SIP Protocol

Stack

MGCP Protocol

Stack

ConnectionControl

Module (CNM)

Signaling Adapter Interface

Signaling Adapter N-ISDN

Signaling Adapter

SIP

Signaling Adapter

MGCP inband

Signaling Adapter

SS7

SS7 Protocol

Stack

FutureSignaling Adapter

TBDProtocol

Stack

Signaling Adapter

CAS

H323 Signaling

H3A

Symphony IOS H323

Stack


Carrier-based Routing AddressCarrierCarrier--based based Routing AddressRouting Address

800 ServiceLocal Number Portability800 800 ServiceServiceLocal Number PortabilityLocal Number Portability

Vertical ServicesCOS ScreeningCustomized Dialing Plan

Vertical ServicesVertical ServicesCOS ScreeningCOS ScreeningCustomized Dialing PlanCustomized Dialing Plan

Public DP OnlyPrefix AnalysisNo A DeterminationDestination Identified

Public DP OnlyPublic DP OnlyPrefix AnalysisPrefix AnalysisNo A DeterminationNo A DeterminationDestination IdentifiedDestination Identified

Warm Line FeatureSpeed CallingWarm Line FeatureWarm Line FeatureSpeed CallingSpeed Calling

Hot Line FeatureDenied OriginationHot Line FeatureHot Line FeatureDenied OriginationDenied Origination

FeatureServer

FeatureFeatureServerServer

FeatureServer


FeatureServer


SCPSCPSCP

TranslationsServer

TranslationsTranslationsServerServer

RoutingServer

RoutingRoutingServerServer

Auth_Call_SetupAuth_Call_SetupAuth_Call_Setup

Select_RouteSelect_RouteSelect_RouteDPDPDP

Analyze_InformationAnalyze_InformationAnalyze_Information

Collect_InformationCollect_InformationCollect_Information

Authorize_Origination_Attempt

Authorize_OriginationAuthorize_Origination_Attempt_Attempt

O_NullO_NullO_Null

DPDPDP

DPDPDP

DPDPDP

Origination_Origination_Attempt_Attempt_AuthorizedAuthorized

Setup (OffSetup (Off--hook)hook)

Origination_AttemptOrigination_Attempt

Provide Dial ToneProvide Dial ToneRQNT (Request Digits)RQNT (Request Digits)

Digits/TimeoutDigits/Timeout

Collected_InformationCollected_Information

Analyzed_InformationAnalyzed_Information

BCM and Its Trigger


Other possible FSs:• Click to dial• IM integration services• Call center features

Tandem

POTS Call Waiting, Call Transfer, Call Forwarding, Caller ID

Call Waiting, Call Transfer, Call Forwarding, Caller ID

CENTREX

IN

Feature Server

Feature Examples

Multiple Line Hunting, Custom Dial Plan, DIDMultiple Line Hunting, Custom Dial Plan, DID

IN Screening, Account Code, Authorization. Code

IN Screening, Account Code, Authorization. Code

LNP, 8xx, 900LNP, 8xx, 900

POTS FS

CENTREX FS

IN FS

Tandem FS

MGCP

Call Agent

Media Gateways

Architecture for All Possibilities


Softswitch Feature & Services

International Local ServicesE.164 Dial Plan Support (incl. China)Provisionable International TonesFlexible Announcements Access Basic Services:

Call Forward UnconditionalCall Forward Busy Line (to be verified for phase 1)Call Forward on No ReplyCalling Line Identification Presentation (CLIP)Calling Line identification Restriction (CLIR)Call Waiting Deluxe (CWD)Three Way Call Deluxe (TWCD)

Outgoing Call Barring (based on destination type: international, domestic long distance)

Automatic Callback (inter-office using TCAP)Automatic Recall (inter-office using TCAP)Support T108 test line 800 enhancement with NOAProvisionable CLLI code per BTS

H.323 & SIP Trunk Features• Hairpin• Auto Reattempt (Route Advance)• Call Redirection• Cause Code Mapping Analysis• Carrier Sensitive Routing• Modem/Fax Pass through• IVR Support by TDM• Calling Number Information Delivery (Octet 3A)H.323 Specific Features• Resource Availability Indicator (RAI+IRR)• Alternate GatekeeperSIP Specific Features• Proxy Registration• SIP-TRegulatory

Lawful InterceptInterfaces

Subscriber provisioning GUIH.323 Line and Trunk Side SupportMGCP Line Side SupportInterworking with Cisco Call ManagerInterworking with Cisco PGW2200Corba / XML for OAM&P


EMS Architecture for OAM&P

CommandLine

Adapter

CorbaAdapter

FTPAdapter

SNMPAdapter

SQLStore

Flat FileStoreJMS HUB

JMS HUB

OSSProcessManager

Faul

tM

anag

er

Dia

gnos

ticM

anag

er

MyS

QL

Age

nt

Aud

itM

anag

er

Prov

.M

anag

er

Bill

ing

Man

ager

Stat

us/C

ntrl

Man

ager

Traf

ficM

anag

er

Secu

rity

Age

nt

Even

tM

anag

er

Ora

cle

Age

nt

Commercial Unix PlatformCommercial Oracle DB


System Redundancy

KAM/RDM

EMS(Active)

BDMS(Standby)

CA (Active)

BDMS(Active)

FS (Active)

NS (Active)

CA (Standby)

NS (Standby)

EMS(Standby)

FS (Standby)KAM/RDM

KAM/RDM

KAM/RDM

Ethernet Switch 1 Ethernet Switch 2

KAM/RDM

EMS(Active)

BDMS(Standby)

CA (Active)

BDMS(Active)

FS (Active)

FS (Active)

CA (Standby)

FS (Standby)

EMS(Standby)

FS (Standby)KAM/RDM

KAM/RDM

KAM/RDM

Ethernet Switch 1 Ethernet Switch 2

Call Agent 1

Active

PMG

KAMOAM

BCM DB

RDM



Integrated Access Solutions


What Are Access Solutions?• Provide integrated voice, data, and video services to

enterprises, SMB, SOHO, telecommuters, and residential subscribers

• Voice services can range from basic dial tone to residential supplementary services, IP PBX, Voice VPN, and Centrex

• Data services can range from basic Internet connectivity to web hosting, data VPN, and storage

• CPEs are managed by service providers• Access technologies can vary from leased lines to cable

to Metro Ethernet• Softswitch is only responsible for voice services• Access voice solution is never offered as a full Class 5

replacement


Architecture Layers for Access Voice Solutions

V V Residential

GWResidential

GW

IntegratedAccessDevice

IntegratedAccessDevice

AccessGatewayAccess

Gateway

IP PhoneIP Phone

CPECPE

SiSi

Transport—Aggregation Transport—Core

SoftswitchSoftswitch

EnhancedFeature Server

EnhancedFeature Server

Call ControlElements

Call ControlElements

VM/UMServer

VM/UMServer

Annc.ServerAnnc.Server

IVRServer

IVRServer

CALEAServerCALEAServer

MediaServersMedia

Servers

GKGKGatekeeper/Directory GKGatekeeper/Directory GKDGKDGK

SIP Proxy/Redirect/B2B

Servers

SIP Proxy/Redirect/B2B

Servers

MM Trunking GW/Media GWTrunking GW/Media GW

PSTN InterconnectPSTN Interconnect

SIP Network InterconnectSIP Network Interconnect

H.323 Network InterconnectH.323 Network Interconnect

Operation Support System (OSS)/Element Management System (EMS)Operation Support System (OSS)/

Element Management System (EMS)


Catalyst 2950Catalyst 2950

72007200


IAD2421IAD2421--FXSFXS

Internet

RouterRouter

AnnouncementServer

Catalyst 2950Catalyst 2950

IAD2421IAD2421--FXSFXS

72007200

MGCPMGCP PSTNPSTN

AS5xxxAS5xxx

Signaling GatewaySignaling Gateway

TDM SwitchTDM Switch

IMTIMT

Soft-switch for Integrated Broadband AccessH.323 or SIP-T for Interconnect

SS7SS7

NetMeetingNetMeetingClientClient

NetMeetingNetMeetingClientClient

H.323v1H.323v1CiscoCisco

Call ManagerCall Manager

SCCPSCCP

SG


Architecture of Access Voice Solution over E1

PoP

Voice MailServer

PSTN

Class 4/5Switch

Router

CoreRouter

911 AT

OPS

SiSi

Multi-Layer

Switch

Super PoP

IMT

TGW

AnnouncementServer

SS7

TGW

Aggregator

PPP/E1

Customer Premises

PBXPBX

Company CCompany C

Company ACompany A

Company BCompany B

Company DCompany D

Internet

SS7

Aggregator

IMT

Aggregator

TGW

MF, FGD

SONET

DS3

MF, FGD

SoftswitchIADIAD

IADIAD

IADIAD

IADIAD

E1 CAS/PRIE1 CAS/PRI

SG


Architecture of Access Voice Solution over ETTx

Service ProviderNetwork

Residential Gateway

Access Switch

Access Switch

IAD

InternetInternet

Router

MxU

MxU

Ethernet/FEGE

AnnouncementServer

Voice MailServer

Softswitch

CALEAServer

IMT

MMTrunking GW C4/C5

MMPSTN

F-LinkV V

IVRServer

M3UA/SCTP

STPV V

SG


Physical Layout for Residential Gateway per Dwelling Unit

Wiring Closet Ethernet Switch

Softswitch

Floor Ethernet Switch

V V V V

V V V V

V V V V

ResidentialGateways

Ethernet/FEFE/GE

Metro/Backbone

V V

V V

V V


Physical Layout for Access Gateway per Floor

Punch-down Block

IAD

RJ-21 Telco Cable

Metro/Backbone

Softswitch

Cat 5 CablePinout

1,2,3,6 Ethernet4,5 RJ-117,8 RJ-11

RJ-11RJ-11

RJ-45

Wall Plate/Splitter

Wiring Closet Ethernet Switch

Floor EthernetSwitch

Ethernet/FEFE/GE


PacketCable 1.0 Reference Architecture

ManagedIP Network

Call ManagementServer (CMS)

Back Office Servers and Apps

Provisioning ServerDHCP Server

TFTP/HTTP ServerSyslog Server

Record Keeping ServerTicket Granting Server

DNS Server

HFC Plant(DOCSIS)

Cable Modem

(CM)

MultimediaTerminalAdapter(MTA)

EmbeddedMultimediaTerminalAdapter(EMTA)

Cable Modem Termination

System (CMTS)

MM

LNPSCP

800SCP

PSTN

IMT

Media GW (MG)

SignalingGW (SG)

Media GWController

(MGC)

STP

SG

PSTN

Gat

eway

Annc.Controller Annc.

Player

Ann

c. S

erve

r


Basics about PacketCable

• Data over Cable Service Interface Specification (DOCSIS) –defines interface requirements for cable modems involved in high-speed data distribution over cable television system networks

• CableLabs – non-profit R&D consortium formed by the cable TV industry

• PacketCable – specifications defined CableLabs for delivery multimedia across DOCSIS compliant Hybrid Fiber Cable (HFC); voice is the initial focus

• PacketCable standards cover call signaling, QoS, media transport and encoding, event messaging for billing settlement, security and privacy, & OSS

• CMS and MGC functionality can be combined as a single Softswitch

• http://www.packetcable.com/


Softswitch

MMMM

LNPSCP

800SCP

PSTN

IMT

MG

SG

CMTSHFC Plant(DOCSIS)

CMMTA

EMTA

Back Office Servers and Apps

MediaServers

STP

Signaling Interfaces for Residential Voice over Cable (Not All Covered Here)

COPS

TGCPNCS

SIP

ManagedIP Network

M3UA/SCTP

Provisioning ServerDHCP Server

TFTP/HTTP ServerSyslog Server

Record Keeping ServerTicket Granting Server

DNS Server

Announcement

CALEA

CCC/CDC

Voice Mail


Interfaces Defined by PacketCable

• Network-Based Call Signaling (NCS) – Interface between MTA and CMS, a MGCP profile

• Trunking Gateway Control Protocol (TGCP) – Interface between MG and MGC, a MGCP profile

• Event Messages Interfaces – event message carries network info over RADIUS for CDR (from CMS, CMTS, & MGC to RKS) & CALEA (from CMS, CMTS, & MGC to DF)

• DOCSIS QoS Specification (DQoS) – various QoS interfaces defined between PacketCable components. Handled at application (SDP), network (RSVP), & data-link layers (DOCSIS 1.1)

• Common Open Policy Service (COPS) – Transports DQoS between Gate Controller (QoS management component in CMS) and CMTS (IETF RFC 2748)

• Many more interfaces….• Reference: http://www.packetcable.com/specifications.html

Recommended: pkt-tr-arch-v01-991201, pkt-tr-arch.2-V01-001229


Softswitch

MG

AS

MGCP

RTP

Media Server—Announcement Server

• Plays informational messages/tones to the originator in response to network events

• SS sends MGCP RQNT to instruct the AS what audio file to be played

• MGCP package options for AS: Script, announcement server (A), PacketCable audio server (BAU)

• AS/BAU package allows playing dynamic announcements

• Deploy multiple ASs for redundancy

This # Has Been Disconnected;

Please Check Your # Again


Media Server—Interactive Voice Response (IVR) Server

• Provide enhanced media applications to SS solutions• Two models: MGCP & SIP (H.323 also, but less

common)• MGCP Based:

–The SS determines and controls the call logic–The IVR server is the slave–Application example: Remote Activation Call Forwarding

• SIP based:–The IVR server determines the call logic–No SS is involved except for call setup and release–“Bermuda Triangle”: MGCP-SIP DTMF relay interworking–Application example: Voice Mail


MGCP Based IVR Server VersusSIP Based IVR Server

MGCP GW

MGCP Based IVR

Server

Softswitch 2. RQNT(Playing “Greeting & Enter PIN” Message)

1. Cut-thru

3. “Welcome to Cisco.Please Enter You PIN.”

5. 12345

6. NTFY(12345)

4. Subscriber Enters 12345

Softswitch

MGCP GW

SIP Based IVR

Server

Softswitch

1. Cut-thru

2. “Please Enter YourVoice Mail Box #.”

4. 12345

3. Subscriber Enters 12345


Call Flow of Call Forward on Busy to Voice Mail Server

IMT

Softswitch VM Server

MGCP SIP

TGW

IAM (CdPN = 5252000)

IAM (CdPN = 5252000)

200 (SDP_TGW (RFC2833))

200 (SDP_TGW (RFC2833))

Invite (Diversion:[email protected]; reason=user-busy

SDP_TGW(RFC2833))

Invite (Diversion:[email protected]; reason=user-busy

SDP_TGW(RFC2833))

The Originator Calls 525-2000. The SS finds out the CdPN is busy and has CFB activated. It then determines the forwarded-to number is the voice mail box of the CdPN.

The SS sends up the call with the VM server. It sends a SIP Invite, which includes:• the info from who the call was diverted from • the reason why the call is forwarded• the TGW’s SDP It receives an ack from the VM server. Then, the SS sends an ACM to the PSTN.

The SS requests the TGW to create a receive only voice path. The TGW acks back with its SDP, which includes its RFC 2833 DTMF relay capabilities.

CO

SS7 Link

MM

CRCX (Recvonly)CRCX (Recvonly)

100 Trying100 TryingACMACM


Call Flow of Call Forward on Busy to Voice Mail Server (Continued)

IMT

Softswitch VM Server

MGCP SIP

TGW

The SS passes the VM’s SDP to the TGW and instructs it to change the voice path to 2-way. The TGW acks. The SS acks back to the VM server.

CO

SS7 Link

MM

200200

MDCX (Sendrecv,SDP_VM

(RFC2833))

MDCX (Sendrecv,SDP_VM

(RFC2833))

ANMANM The SS sends an ANM to the PSTN to inform that the call was answered.

Voice Path Established The caller hears the greeting message of the subscriber, presses “1” to skip it, leaves a message, and hangs up.

RELREL

RLCRLC

250250DLCXDLCX

ByeBye

200200

AckAck

The SS releases both call legs. It then sends a RLC to the PSTN.

200 OK (SDP_VM(RFC2833))

200 OK (SDP_VM(RFC2833))

The VM server answers the call and sends its SDP to the SS. Its SDP states that it can also support RFC 2833 DTMF relay.


Lawful Intercept (LI)• Process by which law enforcement agencies (LEA) conduct

electronic surveillance of circuit and packet-mode communications as authorized by judicial or administrative order

• Communications Assistance for Law Enforcement Act (CALEA) –legislation passed in 1994 describes how LI is supported in US

• Call Data (CD) – call identifying information (e.g. dialed number, time when the call was made) about the intercept subject sent tothe LEA

• Call Content (CC) – tapped conversation (i.e. RTP in VoIP) involved the intercept subject sent to the LEA

• Three types of interceptions:–Pen register (CD): Call data for calls originated by the intercept subject –Trap and trace (CD): Call data for calls terminated at the intercept subject–Surveillance (CC): Allows law enforcements to listen the conversations involved the intercept subject


PSTN

CALEA Architecture

EMTA(Intercept Subject)

IAD(Intercept Subject)

CMTS (IAP)

Aggregator/Edge Router

(IAP)

TrunkingGateway

(IAP)

Softswitch

Delivery Function (DF)

HFC

T1

LEA

Secure Provision Interface over

IPSec/SSH

COPS for CC WiretapRequests

Duplicated RTP Packets in CCC

Call Info in CDC

J-STD-025

Demarcation Point

MM

MGCP/TGCPfor CC WiretapRequest


CALEA Architecture Basics

• Based on PacketCable surveillance architecture• Terminology:

Call Data Connection (CDC): Channel over which CD is sent from SS or to LEA. CD is transported over PacketCable Event Messages over RADIUS VSACall Content Connection (CCC): Channel over which CC is sent to LEA. RTP (CC) is encapsulated in the CCC identifier over UDP over IP Delivery Function (DF)/CALEA Server: Collects CD and CC and delivers to LEAIntercept Access Point (IAP): Entity where CC originates.Trunking gateway/media gateway and aggregation/access/edge/CMTS


CALEA Call Flow for On-Net Subscriber under Surveillance

MMEMTA(Intercept Subject)

CMTS

TrunkingGateway

Softswitch

DF

LEA

2. Request forPen/Trap

4a. Call Info(e.g. Sig-Start,

Answer, Disconnect)

3b. MGCP for CallControl

3a. NCS for Call

Control

5. RTP

4b. Call Info

1. Request forPen/Trap

PSTN


MMEMTA(Intercept Subject)

CMTS

TrunkingGateway

Softswitch

DF

LEA

PSTN

CALEA Call Content Call Flow for On-Net Subscriber Under Surveillance

6. RTP

5. DQoS/COPs for Call Content

Request

7b. Call Content

7a. Call Content w/

Duplicated RTP

4a. Call Info

4b. Call Info

3a. NCS for Call Control

3b. TGCP/MGCP for Call Control

Wire-Tap on Line Side at Edge Router/CMTS instead of CPE because the Tap Has To Be Undetectable by the Intercept Subject

1. Request forIntercept2. Request for

Intercept


MM

CMTS

Softswitch

DF

LEA

PSTN

CALEA Call Content Call Flow for Subscriber under Surveillance with Call Redirected to Off-Net

EMTA(Intercept Subject)

7b. Call Content

7a. Call Content w/

Duplicated RTP

5a. Call Info

5b. Call Info

4. MGCP for CallControl and Request

for Call Content

Wire-Tap on Trunking Side for Call Forward/Transfer Case by CPE Subscriber to Off-Net

2. Request forIntercept3. Request for

Intercept

6. TDM Hairpin

1. Call Forwardedto Off-Net Trunking

Gateway


Subscriber Provisioning

Customer Service

Workflow Inventory,Topology,

Tel. Number

Provision,DHCP, DNS,

TFTP

Billing,Rating

Softswitch Residential CPE

LAN Switch

ReceiveSubscriber

OrderPlaceOrder

Into SystemCheck Service

and Port Available

Credit CheckCheck Available

Tel. Number.CheckSuccessfulService Order Enter Device and

Subscriber Data Provision for Port, Subscriber, Features

Enable Switch PortConfiguration Successful

Sub. PicksUp CPE

V V

CPE Powered Up

Get IP and Download ConfigurationGet IP and Download Configuration


SuperPoP Architecture for Access Solutions

CA-A CA-B

AccessSwitch

EMS-A EMS-B

Softswitch ComplexCALEA ServersCALEA Servers Announcement/

IVR ServersAnnouncement/

IVR Servers

VM/UMServersVM/UMServers

SiSiSiSiISL

MGCP and H.323Networks

GE

Multi-layerSwitch

VLAN 1VLAN 2

VLAN 3VLAN 4

VLAN 5VLAN 6

VLAN 7VLAN 8

VLAN 9

Border Router

FE


• Strict priority queuing

• Strict priority queuing

QoS Strategy—ETTx as an Example

SiSiCore

Network

Access Layer Switch

Multi-layer Switch

SiSi

Softswitch

AnnouncementServer

Voice Mail Server

Residential GW

V V

IAD

Distribution Layer Router/

Switch

• From access: CoS-ToS mapping

• From core: ToS-CoS mapping

• Egress: Priority queuing

• WRED within data queue

Access GW

• L2 CoS/L3 ToS marking

RTP—5MGCP—3Data—0

• L2/L3 classification• LLQ on uplink

interface

• L2 CoS/L3 ToS marking

RTP—5MGCP—3Data—0

• L2/L3 classification• LLQ on uplink

interface

• From PoP: L3 classification/marking



• From PoP: L3 classification/marking




Transit Voice Options for Access Solutions

• Options:1. Trunking GW to TDM2. Interconnect with H.323 LD3. Interconnect with SIP LD

• Can interconnect with more than one of these options for subscribers to choose their preferred LD carriers


Transit via TDM

Softswitch

MGCPAccess GW

TDM Switch

MGCPRTP

MGCPTrunking GW

TDM Transit/Long Distance

SS7 SignalingGateway

SS7 Link

IMT

SG


Transit via VoIP (Local PSTN Termination Not Shown Here)

GKGK

DGKDGK

GKGK

Softswitch

H.323Transit

H.323 GWMGCP

Access GW

H.323 GK, DGK

TDM Switch

MGCPH.323RTP

Softswitch

SIPTransit

SIP GWMGCP

Access GW

SIP Proxies

TDM Switch

MGCPSIPRTP


Softswitch Challenges and Network Design Issues


Interoperability

Signaling Interoperability • Interworking between PSTN and VoIP protocols• PSTN signaling protocols: SS7, ISDN PRI, CAS

and E1 R2• VoIP protocols: H.323, SIP, MGCP / H.248

Bearer InteroperabilityMedia Stream transparence


Softswitch Call Flows – Basic & Advanced

BasicBasic AdvancedAdvanced

MGCP/H248

CPE

Softswitch

MGCP to MGCPMGCP to MGCP

V V V V CPE

MGCP/H248

RTP

MGCP/H248

PBX

Softswitch

IP PhoneIAD

SIP

SIP to MGCPSIP to MGCP

RTP

H.323

EO

Softswitch

H.323 to SIPH.323 to SIP

Voice MailServerH.323 GW

SIP

RTP


“Bermuda Triangle”

MMAnalog, CAS, PRI, IMT

Analog, CAS, PRI, IMT

MGCP/

H248

SIP, H.323

RTP

SS7 Link

H.323/SIP GatewayH.323/SIP GatewaySoftswitch Provides PSTN

and VoIP Protocol Interworking and Media

Gateway Control

H.323/SIP Gateway with Built-In Call Control

MGCP Gateway without Built-In Call Control;

Provides ISDN Backhaul


MMAnalog, CAS, PRI, IMT

Analog, CAS, PRI, IMT

SS7 Link

What Makes the Triangle Mysterious?

SIP/H.323-to-PSTN and MGCP

Interworking

MG

CP/SDP to

SIP/H.323

Interworking

Bearer InteroperabilityBearer Interoperability

SS Needs to Support Call Flows for Setup, Release, and Supplementary

Services amongst H.323/SIP, MGCP/H248, and PSTN Protocols

SS Needs to Properly

Exchange Bearer Capabilities (Codec, Fax, Modem, and

DTMF) between MGCP/H248 GW and SIP/H.323

GW

GWs Provide Reliable Mechanisms to Transport Fax,

Modem, and DTMF Digits


Signaling Interoperability—Basic MGCP H.323 Call Flow

FXSSoftswitch H.323 GW

MGCP

RAS

H.225, H.245CPE

The Originator Goes Off-Hook

GKGK

The CPE Reports the Off-Hook Event to the SS; It acks

Off-HookOff-Hook

The SS Requests the CPE to Notify It upon Detection of On-Hook or Digit Collection and Plays Dial Tone

The CPE Reports the Called Party Number Entered by the Originator

The SS Requests for Notification upon Detection of On-Hook

DigitsDigits

ARQARQ

ACFACF

The SS Sends an ARQ to the GK to Query for the IP of the Terminating H.323 GW Based on the CdPN; Meanwhile, the SS Requests the CPE to Create a Receive Only Voice Path; the CPE acks with Its Only SDP

V V

H.323 GK

NTFY (O:hd)NTFY (O:hd)200200

RQNT (R:hu, Digit Map S:dl)RQNT (R:hu, Digit Map S:dl)

200200

NTFY (O:Digits)NTFY (O:Digits)200200

RQNT (R:hu)RQNT (R:hu)200200

CRCX (recvonly)CRCX (recvonly)

200 (SDP_CPE)200 (SDP_CPE)



Setup (FS= SDP_CPE)Setup (FS= SDP_CPE)

Call Proc.Call Proc.Alerting (FS=SDP_GW)Alerting (FS=SDP_GW)

MDCX (recvonly, SDP_GW)

MDCX (recvonly, SDP_GW)

200200

Upon Receipt an ACF from the GK, the SS Sends Setup to the Remote GW. It Encapsulates the CPE’s Capabilities in the FastStart Element. The Remote GW Replies with Its Capabilities in the FS in the Incoming Alerting Message

The SS Maps the Remote Capabilities in the FS Into the SDP of the MDCX Sent to the CPE

Ringback

Connect (FS=SDP_GW)Connect (FS=SDP_GW) The Terminator Answers the Call and Sends the Connect Back


MGCP

RAS

H.225, H.245CPE

V V

H.323 GKGKGK

MDCX (sendrecv,SDP_GW)

MDCX (sendrecv,SDP_GW)

200200

The SS Sends a MDCX to Instruct the CPE to Change to the Voice Two Way Path



Voice Path Established

On-HookOn-Hook NTFY (O:hu)NTFY (O:hu)200200

The Originator Hangs Up; the CPE Reports the On-Hook Event to the SS

RQNT (R:hd)RQNT (R:hd)

200200The SS Requests for Notification Upon Detection of an Off-Hook Event

Release CompleteRelease Complete The SS Sends a Release Complete to H.323 and a Delete Connection to Release the Respective Call LegsThe SS Sends a DRQ the GK to Disengage the Call

DLCXDLCX250250

DRQDRQDCFDCF


MGCP

RAS

H.225, H.245CPE

V V

H.323 GKGKGK

RQNT (R:hu,hf)RQNT (R:hu,hf)

200200

The SS Requests for Notification upon Detection of an On-Hook or Flash-hook Event

H.245 TCS, MSDH.245 TCS, MSD


Bearer Interoperability

• In this context, bearer only includes: fax, modem, and DTMF digits

• Bearer traffic needs to be transported end to end like regular voice

• Cannot use voice codec to transport bearer faithfully across VoIP network because:

–Bearer traffic is sensitive to network impairments such as packet loss, jitter, and lack of clock synchronization–High compression codec cannot reproduce bearer signals faithfully at the terminating gateway


Procedures for DTMF Interoperability

1. Advertise/Negotiate DTMF Method at Call Setup

2. DTMF Digits Are Sentover RTP or VoIP Channel

5255000

5255000

5255000

1. Advertise in H.245 Terminal Capability Message

to Use Alphanumeric

2. DTMF Digits Are Sentover H.245 User Input Message

5255000 5255000

H.245 UI(5255000)

H.245 AlphanumericH.245 Alphanumeric

H.323 GWH.323 GW

1. Advertise in SIP SDP to Use RFC 2833

2. DTMF Digits Are EncodedPer RFC 2833 and Sent over

RTP Channel

5255000 52550005255000

SIP RFC 2833SIP RFC 2833

SIP GW SIP GW


Procedures for Fax, Modem Interoperability

1. Advertise/Negotiate Fax, Modem Transmission Method at Call Setup (Not All Cases)

3. Transmit Fax or Modem

PC

Fax Fax

NAS

2. Signal GW via VoIP Signalingor RTP Channel to Change Codec Upon Tone Detection

3. Transmit Modem Tone

PC NAS

2. Send Special RTP, Named Signaling Event (NSE) to Change from Audio Codec to MR Codec Upon Modem Tone Detection

1. Exchange Modem Relay Capabilitiesin MGCP SDP at Call Setup b/w GWs

MGCP Modem RelayMGCP Modem Relay


Bearer Interoperability in “Bermuda Triangle”

• Softswitch performs bearer capability exchange between MGCP/H248 and H.323/SIP

• In OOB DTMF relay, the SS also needs to perform digit exchange between the MGCP/H248 and H.323/SIP channels

• No standards have been defined by ITU or IETF on call procedures for bearer interoperability between unlike VoIP protocols


Bearer Interoperability Examples in “Bermuda Triangle”

MM

MGCP GW

Softswitch

5255000 RTP (5255000) 5255000

1. Exchange RFC 2833 Capabilitiesin SIP SDP and MGCP SDP via SS at Call Setup RFC2833 DTMF RelayRFC2833 DTMF Relay

SIP GW

2. DTMF Digits areEncoded Per RFC 2833 in RTP

Softswitch

MM

H.323 GW

H.245 Request Mode, CLC, OLC NTFY, MDCX

1. Exchange T.38 Capabilities between MGCP and H.323 GWs at Call Setup

2. Perform Switchover from Voice to T.38 Codecupon Fax Detection

UDPTL

T.38 Fax RelayT.38 Fax Relay H.245 TCS (T.38)

3. H.323 GW Encodes Fax in T.38to Send to MGCP GW

MGCP GW


Trust Boundaries in Softswitch Network

GKGK

Softswitch

TransitTransitVoiceVoice

CarrierCarrierNetworkNetwork

H.323 GWs

H.323 GK, DGK

TDM Switch

DGKDGK

GKGK

Aggregator

RGWV V

V V

RGW

AccessAccessVoiceVoice

CarrierCarrierNetworkNetwork

DistributionDistributionNetworkNetwork

Enterprise 2Enterprise 2NetworkNetwork

Enterprise 1Enterprise 1NetworkNetwork

VM, VM, AnncAnnc, &, &IVR ServersIVR Servers

NetworkNetworkManagementManagement

NetworkNetwork


PrivateIP Addresses

PrivateIP AddressesV V

10.1.1.1:242710.1.1.1:2427

VoIP Traversal of NAT/PAT

IP: 10.1.1.1

VoIP: 10.1.1.1:2427VoIP: 10.1.1.1:2427UDP: 2427UDP: 2427

IP: 171.70.1.1

VoIP: 10.1.1.1:2427VoIP: 10.1.1.1:2427UDP: 2427UDP: 2427

NAT DeviceNAT Device

VoIP VoIP Signaling ProtocolSignaling Protocol

NonNon--routableroutableAddressesAddresses

• Why need NAT in VoIP? Lack of public IPv4 addresses

• Problems with NAT for VoIP:NAT device does not look into embedded IPs in layers 5 and

up (e.g. H.323, MGCP, SIP, SDP)These IPs become un-routable VoIP apps break


VoIP Traversal of Firewalls• Why need FW?

Hides the inside network from the outside networkOnly allows authorized traffic to enter and leave the inside network based on security policies on the FW

• Default FW behaviors:Inside originated packets can get to the outsidePackets from the outside associated with an inside originated connection are allowed back in.Outside originated packets are not allowed to get to the inside

• These behaviors can be overridden with static configuration (e.g. static pinhole)

• Problems with FW for VoIP: RTP / RTCP uses dynamic UDP ports (16384-32767). Negotiated in call setupInbound VoIP calls fail, and RTP / RTCP port holes aren’t dynamically opened


PrivateIP Addresses

Application Layer Gateway (ALG) for NAT/PAT

• Add software functions to perform NAT for H.323, MGCP, SIP, & SDP natively on the NAT device

• Pros:Software upgrade only at NAT device

• Cons: Doesn’t work with encrypted signaling (e.g. IPSec)Lack of NAT binding sharing across multiple NAT devicesSingle point of failureLimited # of simultaneous calls per NAT device

PrivateIP AddressesV V

IP: 10.1.1.1

VoIP: 10.1.1.1:2427VoIP: 10.1.1.1:2427UDP: 2427UDP: 2427

IP: 171.70.1.1

VoIP: 171.70.1.1:8000VoIP: 171.70.1.1:8000UDP: 8000UDP: 8000

ALG Enhanced ALG Enhanced NAT DeviceNAT Device

10.1.1.1:242710.1.1.1:2427

VoIP VoIP Signaling ProtocolSignaling Protocol

Routable AddressesRoutable Addresses


ALG for Firewalls

• Provide Context-based Access Control (CBAC) to inspect VoIPsignaling messages to learn about the dynamic UDP/TCP connection (e.g. RTP & RTCP) for traffic from Outside to Inside

• Create dynamic access control list (ACL) entries to open the RTP/RTCP ports in the FW

• When the connection is terminated, CBAC removes the entries from the ACL

• Pros:Software upgrade only at FW device

• Cons:Doesn’t work with encrypted signaling (e.g. IPSec)Lack of policy sharing across multiple FW devicesSingle point of failureLimited # of simultaneous calls due to CPU-intensive stateful inspection for every packet


Other Solutions for VoIP Traversal of NAT/PAT/FWs

1. STUN/TURN • Created by IETF’s Middlebox Communication (MIDCOM)

Workgroup• STUN – Simple Traversal of UDP through NAT

http://search.ietf.org/internet-drafts/draft-rosenberg-midcom-stun-00.txt

• TURN – Traversal Using Relay NAThttp://search.ietf.org/internet-drafts/draft-rosenberg-midcom-turn-00.txt

2. IPv6• Primarily solves the issue of IPv4 address shortage

3. Proprietary


Centralized Softswitch

软交换机

STP STPSS7 Network

SG

MGMGPSTN

IAD

GW

MGMG PSTN

GW

IAD IADMGMG

H248

MGCP/H248

Softswitch

FeatureServer

ApplicationServer


Multiples Cities/POPs Under One Softswitch Solution

H.323 VoIP

GK

Cisco BTS 业务控制设备

智能增值业务服务器应用服务器

运维系统网管系统营帐系统

PSTN/PLMN

H.323 VoIP

Toll Trafficescity1

Cisco BTS Cisco BTS CCMApplication Server

OSS/NMS/

city2

city3

city4

city5 city6city7

city8

city9

city10

city0


Softswitch in NGN

软交换机

STP STPC7 Network

SG

MGMGPSTN

IAD

GW

MGMG PSTN

GW

IAD IADMGMG

H248SIP-T/BICC


Technical Trap: Full Mesh NGN?Full Mesh NGN?

Transport MGCP

MGMG MGMG

信令网关

MGMG


PSTNPSTN


Inter-Softswitch Communication• Protocols for SS

interconnect: H.323, SIP, SIP for Telephones (SIP-T), CMS-to-CMS Signaling (CMSS)

• SIP-T carries ISUP messages encoded as PSTN-MIME in SIP for ISUP transparency

• CMSS is SIP plus extensions• As the number of SSs

increases, H.323 GKs or SIP Proxies are necessary for scalable dial plan management

• Beware of “Bermuda Triangle” issues

GKGKGKGK

DGKDGK


LNFN

HNFN

ITSP ITSP

PSTNLE

PSTNLE

IP Conference Enum

DB

IP IN ServiceIP-800 VVPNNMSOSS

LNFN LNFN LNFN

LocalDB

LocalDB

HNFN

Video Conference

LNFN

HNFN

Complete Architecture of NGN

Layered Signaling, Flat Media stream ,

Routingpoicy

MGMGMGMGMGMGMGMGMGMGMGMG

MGMGMGMG


Summary


Conclusions• IP won the ‘Theology’ Debate for SP Converged

services. Classless Softswitch is the solution platform for SP NGN architecture.

• The long term connections to new devices will be via Ethernet and Wireless (3G & 802.11).

• Solving the “Bermuda Triangle & interworkingbetween different protocols” is a big challenge.

• A SS application is all about an end-to-endsolution, from access to core, from bearer to enhanced services

• The Challenge for SP is to execute profitably onthe integration of their Networks over softswitch: PSTN & 2G Wireless & Video Call.


References

• Recommended Networkers sessionsVVT-200: Building Correct Voice and Video for Your OrganizationVVT-220: Deploying Wholesale VoIP Using SIP and H.323VVT-222: Designing and Deploying IP-based Signaling GatewaysVVT-223: Designing IP-Based Managed Services for SMB and Enterprise Networks

• ReferencesBTS 10200 Softswitchhttp://www.cisco.com/warp/public/cc/pd/unco/10200/index.shtmlhttp://www.cisco.com/warp/public/cc/pd/unco/10200/prodlit/index.shtmlATA186 Analog Telephone Adaptorhttp://www.cisco.com/univercd/cc/td/doc/product/voice/ata/ata186/IAD2421 Integrated Access Devicehttp://www.cisco.com/univercd/cc/td/doc/product/access/iad/iad2420/


Deploying Advanced Softswitch Applications

Session VVT-420


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Session VVT-420


Documents

VVT-420 5305 05 2002 c1 - Cisco网络技术(Net130.Com) · Corba/Telnet/FTP/SNMP FTP Front-end server ... CNAM 800 LNP CNAM 800 LNP SS7 IN FSIN FS Element ... VVT-420 5305_05_2002_c1