Upload
ben-duong
View
5
Download
0
Embed Size (px)
DESCRIPTION
751x MG (Media Gateway) Fundamentals Ed.02.Ce
Citation preview
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 1
Do not delete this graphic elements in here:
All Rights Reserved Alcatel-Lucent 2008
3FL 36201 AAAA Edition 02 - 04/2008
751x MG (Media Gateway)Fundamentals
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 2
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
2
Blank Page
This page is left blank intentionally
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 3
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
3
Objectives
z This training document covers basic information ofmedia gateways in an NGN environment.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 4
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
4
Objectives [cont.]
This page is left blank intentionally
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 5
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
5
Table of Contents
z Switch to notes view! Page1 NGN Overview 7
1.1 Voice over IP (VoIP) and NGN 81.2 IP Telephony (IPT) 91.3 Class 4 Application 101.4 Border Gateway 111.5 Class 5 Application 121.6 IP Multimedia Subsystem (IMS) 13
2 Gateway Functions 142.1 Classification of Gateways 152.2 Monolithic and Decomposed Gateway Concept 162.3 Codecs 172.4 Silence Supression 182.5 Fax Relay (T.38) 192.6 Hairpinning 202.7 Session Border Control 21
3 MEGACO Protocol 223.1 MEGACO Network Elements 233.2 Definitions and Commands 243.3 Call Setup Scenario 25
4 Signaling Transport (SIGTRAN) 274.1 Overview 284.2 SIGTRAN IUA Example 30
5 Summary 315.1 Gateway Applications 32
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 6
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
6
Table of Contents [cont.]
z Switch to notes view!
This page is left blank intentionally
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 7
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
7
1 NGN Overview
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 8
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
8
1 NGN Overview
1.1 Voice over IP (VoIP) and NGN
Softphone / IP-Phone(H.323, SIP)
Softphone / IP-Phone(H.323, SIP)
Data Network
Voice Communication between IP Devices
Softphone / IP-Phone(H.323, SIP)
Data Network
Voice Communication between Networks
PSTN
POTS / ISDNGateway
Data Network
Data Networks to replace Local ExchangesPOTS / ISDNGatewayGatewayPOTS / ISDN
Data Network
Data Networks to replace Long Distance Exchanges
PSTN
POTS / ISDNGatewayGatewayPSTN
POTS / ISDN
Data Network-own network-
Border Gateway ApplicationBorder GatewayGateway
PSTN
POTS / ISDN
Data Network-other provider-
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 9
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
9
1 NGN Overview
1.2 IP Telephony (IPT)
H.323,SIP
PSTN
VoiceGate-way
PRI
GatekeeperProxyServer
(IPT)
H.323, SIP
Softphone(H.323, SIP)
IP Telephone(H.323, SIP)
RTP
H.323,SIP
Softphone(H.323, SIP)
IP Telephone(H.323, SIP)
RTP RTP
ApplicationServer /Services
SIPData Network
IP Internet ProtocolIPT IP TelephonyMRF Media Resource FunctionPRI Primary Rate InterfacePSTN Public Switched Telephone NetworkRTP Real-Time Transport ProtocolSIP Session Initiating Protocol
RTP
MRF
SIP
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 10
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
10
1 NGN Overview
1.3 Class 4 Application
Data Network
SignalingGateway
MediaGate-way
MediaGateway
Controller(Class 4)
SIGTRAN
ISUP
PSTN
N7
CCS N7(ISUP)
MediaGate-way
RTP
MEGACO MEGACO
MEGACO Media Gateway Control ProtocolRTP Real-Time Transport ProtocolSIGTRAN Signaling TransportSIP Session Initiating Protocol
ISUP
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 11
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
11
1 NGN Overview
1.4 Border Gateway
Data Network
MediaGate-way
MediaGateway
Controller(IBCF)
ISUP
PSTN
BorderGate-way
RTPMEGACO
MEGACO
IBCF - Interconnection Border Control FunctionMEGACO Media Gateway Control ProtocolRTP Real-Time Transport ProtocolSIP Session Initiating Protocol
ISUP
Data Network
MediaGate-way
BorderGate-way
RTP
MEGACO
MediaGateway
Controller(IBCF)
PSTN
SIP / SIP-I SIP / SIP-I
Firewall Firewall
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 12
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
12
1 NGN Overview
1.5 Class 5 Application
MediaGateway
Controller(Class 5)
MEGACO
AccessNode
AccessGate-way
ResidentialGateway
(MTA, IAD)
PABX
SIP, MGCP,MEGACO
CentralizedAccess
Gateway
MEGACOSIGTRAN
Data Network
RTP RTP
IAD Integrated Access DeviceMEGACO Media Gateway Control ProtocolMGCP - Media Gateway Control ProtocolMTA Media Terminal AdapterRTP Real-Time Transport ProtocolSIGTRAN Signaling TransportSIP Session Initiating Protocol
Access Network
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 13
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
13
1 NGN Overview
1.6 IP Multimedia Subsystem (IMS)
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 14
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
14
2 Gateway Functions
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 15
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
15
AGW - Access GatewayAN - Access Nodec-AGW - centralized Access GatewayBGW - Border GatewayRGW - Residential GatewaySGW - Signaling GatewayTGW - Trunking Gateway
TDM Gateways
- convert TDM-voice to Packet-voice and vv.- Voice Coding, Echo Suppression, VAD, CNG- Special treatment for other traffic (Fax)
Signaling Gateways
- converts TDM Signaling (CCS N7, DSS, ...) to IP
Packet Gateways- Packet to Packet Gateways
- Voice Transcoding- Network Address Translation
- SLA Mapping of QoS-Levels
TransitBGW
Data Network other Provider
4,000..32,000EquivalentChannels
SignalingSGW
1...64CCS N7 Links
TGW
PSTN
250..32,000Channels
Data Network
Access
250..32,000Channels
1,500...100,000Subscriber
c-AGW
AN
1...8 Ports1 Subscriber+ Ethernet
RGW
250..1,500Subscriber
AGW BGW
4,000..16,000EquivalentChannels
2 Gateway Functions
2.1 Classification of Gateways
Classification of GatewaysA classification of gateways can be made via location of the gateway in the network. So we can decide between the following types of gateways:
Transit gateways Signaling gateways Access gateways
Transit GatewaysTransit gateways are gateways used between different networks. Beside border gateways (BGW), used between different packet networks, also trunking gateways (TGW) with a media conversion from circuit switched to packet switched networks and vice versa are possible.
Signaling GatewaysSignaling gateways (SGW) are used to transport TDM based signaling messages in a packet network. In an NGN environment signaling gateways are used for N7 signaling and DSS signaling (PRA interface)
Access GatewaysAccess gateways (AGW) are used to provide the access of subscribers to the telecommunication network. Depend on the function, size and physical location different types of access gateways are classified:
centralized Access Gateway (c-AGW)are used to connect TDM based concentrators to the data network
Access Gateways (AGW)contains subscriber interfaces and connect subscribers immediately the data network
Residential Gateways (RGW)are also used to connect subscribers immediately to the data network. In difference to an AGW the RGW is located on the subscriber premises and supports a small number of ports for analogue or ISDN telephone sets for one subscriber. Additionally an Ethernet interface can be supported.
Border Gateways (BGW)supports firewall functions in the access to a subscriber
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 16
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
16
Voice Gateway
Call Control
Media
H.323 Terminal
Call Control
Media
Gatekeeper /Proxy Server
PSTN
ISDN
H.323SIP
H.323SIP
H.323, SIP
RTP
Monolithic Gateway
Media Gateway
Media
Media GatewayController
Call Control
PSTN
Media Gateway
Media PSTN
Signaling GWSignaling GW
ISUPCCS N7
ISUPSIGTRAN
ISUPSIGTRAN
ISUPCCS N7
MEGACO MEGACO
RTP
Decomposed Gateway
2 Gateway Functions
2.2 Monolithic and Decomposed Gateway Concept
Monolithic GatewayA monolithic gateway is used for example in an H.323 or SIP configuration. Here the terminal contains both the media handling (coding, packetization, ...) and the call control function. A Gatekeeper or Proxy Server is used for support functions only (Registration, address-translation, ...). The monolithic gateway contains also the media handling and the call control.
Monolithic gateways are used to connect a PABX or a VPN via an Primary Rate Interface (PRI) to an existing PSTN. Its also called a Voice Gateway.
Decomposed GatewayA decomposed gateway separates the media and call control function. So the call control function is located on a central instance, the Media Gateway Controller (MGC). The gateway covers only the media handling (coding, packetization, ...). Its also called a Media Gateway.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 17
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
17
DSP... 01101100 10110100 01010101 ... 010100 101010 011011
CODEC
i.e. 64 kBit/s PCM Bitstream (G.711) i.e. G.729 Packets (5,3/6,3kBit/s)
i.e.TDM Interface
i.e.Packet Interface
Codec Name Bitrate MOS
G.711 Pulse Code Modulation (PCM) 56 / 64 kBit/s 4.1
G.726 Adaptive Differential Pulse Code Modulation(ADPCM) 16 - 40 kBit/s 3.85
G.728 Low Delay Code Excited Linear Prediction (LD-CELP) 16 kBit/s 3.61
G.729 /G.729A
Conjugate Structure Algebraic Code Excited Linear Prediction(CS-ACELP) 8 kBit/s
3.92 /3.7
G.723.1 Multiple Maximum Likehood Quantizatition(MPMLQ) 6.3 kBit/s 3.9
G.723 Algebraic Code Excited Linear Prediction(ACELP) 5.3 kBit/s 3.65
2 Gateway Functions
2.3 Codecs
Codecs (COder/DECoder)A Codec is used for coding of a video or audio stream into packets used in the IP network.The codec works bi-directional. So the codec transforms also received IP packets into a video- or audio-stream.
G.711 PCM CodeThe ITU G.711 Standard is used in nearly all PSTNs world-wide. It describes the Pulse Code Modulation (PCM) with 64 kBit/s.
G723.1Low Bitrate Codec originally developed for video telephony.Silence suppression is possible.
G.729 / G.729ALow Bit Rate Codec used for integrated speech and data applications. It is similar to G.723.1 but less delay.Silence suppression is possible.
Mean Opinion Score (MOS)Usually technical procedures are used to measure the voice quality in a objective way. But these mechanisms cant describe the real perception. So additionally a Mean Opinion Score is defined as an average over a big number of individual opinions. The MOS ranges from 1 to 5.
Processor PowerThe reduction of bitrate required processor power. So this parameter describes the effort that has to be spend in the Digital Signal Processor (DSP).
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 18
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
18
Data Network PSTN PSTN
1101 1010 0000 0000 1111 1010
1101 1010 1111 1010
without Voice Activity Detection
with Voice Activity Detection
2 Gateway Functions
2.4 Silence Supression
Voice Activity DetectionComfort Noise Generation
Voice Activity Detection (VAD)is a process used to identify presence or absence of speech data bits. The result can be used to reduce the bandwidth for a communication channel in a data network. So in case of no speech information only a no-information-but-still-alive indication is transmitted. This indication is send with one UDP packet i.e. all 300 ms. Compared with one UDP packet all i.e. 30 ms for speech data there is a reduction of up to 90% of bandwidth.
Comfort Noise Generation (CNG)To avoid the feeling of a dead line during a running Voice Activity Detection in a no-data-phase on the receiver side a quiet noise is generated.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 19
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
19
Data Network PSTN PSTN
DA
AD
AD
DA
0100 1011 1100
2 Gateway Functions
2.5 Fax Relay (T.38)
Fax Relay (T.38)
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 20
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
20
TDM Hairpinning
IP Hairpinning (RTP Hairpinning)
AN - Access NetworkLEX - Local ExchangeTEX - Toll Exchange
AN
Media Gateway
TEX / LEX
Media GatewayController
AN
MediaGateway
MediaGateway
Controller
ANAN
MediaGateway
MediaGateway
Controller
Data Network 1 Data Network 2
IP Telephone Media Gateway
IP Telephone
Data Network
MediaGateway
IP Telephone IP Telephone
Subscriber withCall Forwarding
2 Gateway Functions
2.6 Hairpinning
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 21
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
21
Data Center of Voice Application Service Providers
Hosted IP Based InteractiveCommunication Services (IC)
Peering Service Provider Networks
Serv
ice
Ass
uran
ce
Crit
ical
Sec
urit
y
Law
Enfo
rcem
ent
Requ
irem
ents
Applications for Session Border Control
2 Gateway Functions
2.7 Session Border Control
Session Border Controllers (SBC)is a new category of network equipment that provides critical control functions to enable high quality interactive communications across IP network borders.
SessionA "session" is any real-time, interactive voice, video or multimedia communication using layer 5 IP session signaling protocols such as SIP, H.323, MGCP or Megaco/H.248.
BorderThe "border" is any IP-IP network border such as those between service provider and customer/subscriber, or between two service providers.
ControlThe "control" functions span security, service assurance and law enforcement requirements.
Applications for Session Border Controllers (SBC) Peering service provider networks
Today many providers employ managed IP networks with softswitches and gateways. The next step in this network evolution entails connecting these softswitch -gateway islands to expand network reach and minimize PSTN termination costs. SBCs enable these VoIP providers to peer networks for PSTN origination and termination, IP transit and, ultimately, IP termination and origination.
Facilities-based providers offering hosted IP-based interactive communication (IC) services will also benefit from the use of SBCs at the borders to their business and residential customers.(voice, video, unified messaging, conferencing, gaming, IP-PBX transport)
Doorway to the data centers of voice applications service providers delivered to other retail providers or directly to users.(calling card, directory, messaging)
Across all of these applications, there are critical security, service assurance and law enforcement requirements that must be satisfied.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 22
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
22
3 MEGACO Protocol
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 23
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
23
3 MEGACO Protocol
3.1 MEGACO Network Elements
PSTNPSTN
Ethernet
IP
TCP UDP
MEGACOH.248
MediaGateway
MediaGatewayController
Sign GW
#7ISUP
#7ISUP
MEGACO
Sign GWDataNetwork
MediaGateway
MediaGateway
MediaGateway
Media gateway Control Protocol (MEGACO)
Is a Protocol between a Media Gateway Controller (MGC) and a Media Gateway (MG). It is used to control Media Gateways (MG).
MEGACO covers thefunctionality to set up and release cross-connection between media streams in a circuit-switched and packed-based network.
official industry-standard for Media Gateway Control Protocol cooperation of IETF (Megaco RFC3015) and ITU-T (H.248 v1.0)
important component of Next Generation Network (decomposed model)
RFC-3015
Competitive protocols: MGCP IETF only (RFC-2705) Runs over TCP and UDP
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 24
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
24
Gateway
Context
Termination
PSTN Data Network
Message
Add
Modify
Subtract
Move
AuditValue
AuditCapablities
Notify
Description
ServiceChange
Addition of a termination to a context. The first add-message creates a new context
Modification of features and signals of a termination.
Removal of a termination from a context. Removing the last termination causes the deletion of the context.
Removal of a termination from a context and addition of this termination to another context.
Requests information about features, events and signals of a termination
Requests information about all possible features, events and signals allowed for this termination
Notification on events.
Notification on changes in the status of a termination,also used for registration with an MGC
3 MEGACO Protocol
3.2 Definitions and Commands
TerminationA termination is a logical entity that sources and/or sinks media and/or control streams (virtual or logical)
ContextA context is an association between a number of terminations while a call is in progress.
PackageA package is a collection of properties, events, signals and statistics associated with a termination
Commands Add: to place a termination in a context Modify: to change the properties of a termination Subtract: to remove a termination from a context Move: to move a termination to another context (f.ex. Call Waiting) Audit value: a query for all information about a (set of) termination(s) Notify: allows the MG to inform MGC of the occurrence of an event (e.g. off-hook detected) Service change: to register with MGC and to report change to MGC (e.g. termination out of
service/in service)
Audit capabilities: to audit the capabilities of MG
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 25
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
25
Data Network
MediaGateway
MediaGateway
Media GatewayController
PSTNPSTN
#7 ISUPMEGACOSpeech, VoIP
1 Initial Address Message (IAM)2 Add
3 Add-Reply4 Add
5 Add-Reply6 Modify
7 Modify-Reply
8 Initial Address Message (IAM)
10 Addr. Complete Message (ACM)9 Addr. Complete Message (ACM)
12 Answer Message (ANM)11 Answer Message (ANM)
LocalExchange
LocalExchange
Exchange of User Data
3 MEGACO Protocol
3.3 Call Setup Scenario
(1) The Media Gateway Controller (MGC) is notified by the Local Exchange (LEX) about a new call with the ss7 message - Initial Address Message (IAM). This message contains important parameters as Called Number, Calling Number, Circuit Identification Code (identification for the ds0 reserved for this call), ...
(2) Upon reception of this IAM, the MGC will generate an ADD REQUEST, requesting the Media Gateway (MG) to create a context for this new call, and add a TDM termination link (=the reserved ds0) to the newly created context. Physically, the MG will also allocate a DSP resource for the call. With the same or a second ADD message, the MGC will request the MG to add an RTP termination to the same context. When two terminations (a TDM and an RTP in this case) are placed in the same context, they have the potential to exchange media. The MG will add an RTP termination to the context, and set-up the DSP with the appropriate values (e.g. for codec, packetization time).
(3) The MG generates an ADD-REPLY to confirm that the TDM termination has been placed in the new context, and a DSP resource has been allocated for the call. Also the RTP termination (IP address and port number) are given back to the MGC.
(4) The routing in the MGC defines the terminating media gateway. Once determined, exactly the same procedure as on the origination gateway is repeated. So the MGC generates in the next step an ADD_REQUEST to request creation of a new context for this new call. This message contains a specific TDM termination that identifies the outgoing TDM termination link (outgoing ds0). The MG generates an RTP Termination, that is linked to the RTP IP address and port of the originating MG. For the incoming RTP traffic an own IP address and port number will be created. After allocation of an DSP both terminations are through connected.
(5)The ADD_REPLY message indicates the successful context allocation to the MGC. Furthermore the RTP address information is given back to the MGC.
(6) This information has to be forwarded to the originating MG. Now both terminations can be through connected.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 26
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
26
MediaGateway
MediaGateway
Media GatewayController
PSTNPSTN Data Network
#7 ISUPMEGACOSpeech, VoIP
1 Initial Address Message (IAM)2 Add
3 Add-Reply4 Add
5 Add-Reply6 Modify
7 Modify-Reply
8 Initial Address Message (IAM)
10 Addr. Complete Message (ACM)9 Addr. Complete Message (ACM)
12 Answer Message (ANM)11 Answer Message (ANM)
LocalExchange
LocalExchange
Exchange of User Data
3 MEGACO Protocol
3.3 Call Setup Scenario [cont.]
(7) The MG sends with the MODIFY-REPLY message a successful acknowledge back to the MGC.
(8) Now the MGC indicates to the terminating exchange the seizure of a trunk circuit with an INITIAL ADDRESS MESSAGE (IAM).
(9) (12) All further messages in the call setup scenario will be transmitted via the MGC without any messages to the gateways. So the ADDRESS COMPLETE MESSAGE (ACM) indicates the successful end to end call setup. With the ANSWER MESSAGE (ANM) the conversation phase starts.
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 27
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
27
4 Signaling Transport (SIGTRAN)
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 28
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
28
4 Signaling Transport (SIGTRAN)
4.1 Overview
Ethernet, ATM, ...
IP
SCTP
M2UA M3UA IUA SUA V5UA
IUA - Q.921 User Adaptation Layer (ISDN)M2PA - MTP2 User Peer-to-Peer Adaptation LayerM2UA - MTP2 User Adaptation LayerM3UA - MTP3 User Adaptation LayerSCTP - Stream Control Transmission ProtocolSUA - SCCP User Adaptation LayerV5UA - V5 User Adaptation Layer
M2PA
SIGTRAN ModelSIGTRAN was developed by the IETF working group SIGTRAN and defines the control protocol between the Signaling Gateway, Media Gateway Controllers and IP based Signaling Points. The Sigtran protocol consists of a modular, extensible structure with a common reliable transport protocol used for all signaling transport. The protocol transports message based signaling protocols messages, usually SS7, transparently over IP networks.
Stream Control Transmission Protocol (SCTP)The Stream Control Transmission Protocol is a reliable transport protocol operating on top of a connectionless packet network such as IP. SCTP is designed to transport PSTN signaling messages over IP networks, but is capable of broader applications.It offers the following services to its users:
Acknowledged error-free non-duplicated transfer of user data.
Data fragmentation to conform to discovered path MTU size.
Sequenced delivery of user messages within multiple streams, with an option for order-of-arrival delivery of individual user messages.
Optional bundling of multiple-user messages into a single SCTP packet.
Network-level fault tolerance through supporting of multi-homing at either or both ends of an association.
Signaling Functions in SIGTRANOn top of SCTP there can be used different signaling applications depend on the network request. The most important signaling applications are the following:
- M2UA - MTP2 User Adaptation Layer- M3UA - MTP3 User Adaptation Layer- IUA - Q.921 User Adaptation Layer- SUA - SCCP User Adaptation Layer- V5UA - V5 User Adaptation Layer
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 29
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
29
4 Signaling Transport (SIGTRAN)
4.1 Overview [cont.]
ISDN User Adaptation (IUA)This layer provides functionality to transport ISDN signals from Switched Circuit Network (SCN) to IP network by back-hauling the Q.921 user messages over SCTP (Stream Control Transport Protocol) as per the IETF RFC 3057. IUA supports both ISDN Primary Rate access (PRA) as well as Basic Rate Access (BRA) including the support for both point-to-point and point-to-multi-point modes of communication.
MTP2 User Peer-to-Peer Adaptation Layer (M2PA)is a SIGTRAN protocol for transporting SS7 MTP Level 2 user part signaling messages (i.e. MTP Level 3) over IP using the Stream Control Transmission Protocol (SCTP). Unlike M2UA, M2PA is used to support full MTP Level 3 message handling and network management between any two SS7 nodes communicating over an IP network. IP signaling points function as traditional SS7 nodes using the IP network instead of the SS7 network. Each switched circuit or IP signaling point has an SS7 point code. The M2PA protocol layer provides the same set of services as MTP Level 2 provides to MTP Level 3.M2PA can be used between a signaling gateway and a media gateway controller, between a signaling gateway and an IP signaling point, and between two IP signaling points. Signaling points may use M2PA over IP or MTP Level 2 over standard SS7 links to send and receive MTP Level 3 messages.
MTP2 User Adaptation Layer (M2UA)is a protocol defined by the IETF Sigtran Working Group for transporting SS7 MTP Level 2 user (i.e. MTP Level 3) signaling messages over IP using the Stream Control Transmission Protocol (SCTP). The M2UA protocol layer provides the equivalent set of services to its users as MTP Level 2 provides to MTP Level 3.M2UA is used between the Signaling Gateway and Media Gateway Controller in VoIP networks. The signaling gateway receives SS7 messages over an MTP Level 1 and Level 2 interface from a signaling end point (SCP or SSP) or signal transfer point (STP) in the public switched telephone networks. The signaling gateway terminates the SS7 link at MTP Level 2 and transports MTP Level 3 and above to a Media Gateway Controller or other IP endpoint using M2UA over SCTP/IP. The signaling gateway maintains the Availability State of all media gateway controllers to manage signaling traffic flows across active SCTP associations.
MTP3 User Adaptation Layer (M3UA)is used for the transport of Signaling System 7 (SS7) MTP 3 user signaling messages over IP using the Stream
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 30
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
30
Q.921 Q.921
SCTP
IP IP
SCTP
IUA
Q.931
IUA
Q.931
PABX
PABX
Media Gateway
Media Gatewaywith SIGTRAN
SoftswitchSoftswitch
DataNetwork
SIGTRAN(IUA)
PRI(30B+D)
ATM - Asynchronous Transfer ModeIP - Internet ProtocolIUA - Q.921 User Adaptation Layer (ISDN)SCTP - Stream Control Transmission ProtocolPABX - Private Automatic Branch ExchangePRI - Primary Rate InterfaceQ.921 - ISDN Layer 2 ProtocolQ.931 - ISDN Layer 3 Protocol
ATM, ... ATM, ...
E1E1
4 Signaling Transport (SIGTRAN)
4.2 SIGTRAN IUA Example
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 31
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
31
5 Summary
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 32
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
32
5 Summary
5.1 Gateway Applications
VoPacketBackbone
PSTN PSTN
VoIP TrunkingVoIP TrunkingTDM-TDMHairpinningTDM-TDM
Hairpinning Alcatel7510 MG
Alcatel7510 MG
Alcatel7510 MG
Packet2PacketGateway
Packet2PacketGateway
LEX
LEXLEX
LEX
IP Phones
PBX
PBXAccessPBX
Access
Alcatel7510 MG
DLC
DLC AccessDLC Access
VoIPTermination
VoIPTermination
SCP/OSP Application Server3rd party Application Server
IP-PBX
VoPacketBackbone
Media gateway controller
DLC Digital Loop CarrierLEX Local ExchangePBX Private Branch ExchangePSTN Public Switched Telephone Network
SGWSGW
IP Hair-pinningIP Hair-pinning
3FL 36201 AAAA WBZZA Ed. 02P01.02/2008Page 33
All Rights Reserved Alcatel-Lucent 2008
Media Gateway Basics
33
Abbreviations and Acronyms
z Switch to notes view!# A AGW Access Gateway AN Access Node ATM Asynchronous Transfer Mode B BGW Border Gateway C CNG Comfort Noise Generation CODEC CODer/DECoder D DLC Digital Loop Carrier DSP Digital Signal Processor DSS Digital Subscriber Signaling E F G H I IBCF Interconnection Border Control Function IETF Internet Engineering Task Force IP Internet Protocol IPT IP Telephony ISDN Integrated Services Digital Network ISUP ISDN User Part ITU-T International Telecommunications Union IUA ISDN User Adaptation Layer J K L LEX Local Exchange M M2PA MTP Level 2 Peer to Peer Adaptation Layer M2UA MTP Level 2 Adaptation Layer MEGACO Media Gateway Control Protocol MGC Media Gateway Controller MGW Media Gateway MOS Mean Opinion Score N NGN Next Generation Network O
P PABX Private Automatic Branch Exchange PCM Pulse Code Modulation PRI Primary Rate Interface PSTN Public Switched Telephone Network Q R RGW Residential Gateway RTP Real-Time Transport Protocol S SBC Session Border Control SGW Signaling Gateway SIGTRAN Signaling Transport SLA Service Level Agreement T TCP Transmission Control Protocol TDM Time Division Multiplex TEX Tall Exchange TGW Trunking Gateway U UDP User Datagram Protocol V VAD Voice Activity Detection VoIP Voice over IP W X Y Z