SIGTRAN Protocols for Next Generation Network

2003. 6.

김 부 일

㈜ 케이벨

2

목 차

SIGTRAN 개요

SIGTRAN 프로토콜

SCTP

M2PA / M2UA

M3UA/ SUA

IUA

SIGTRAN 적용

적용 망

Signaling Gateway

Intelligent Network

전개 방향

3

SIGTRAN 개요

The primary purpose

to address the transport of packet-based PSTN signaling over IP Networks

to transport signaling such as Q.931 or SS7 ISUP messages or TCAP messages between IP nodes such as a Signaling Gateway and Media Gateway Controller or Media Gateway.

applications

- Internet dial-up remote access

- IP telephony interworking with PSTN

- Other services as identified

4

SigTran Components

SCN adaptation module

Common Signaling Transport

Standard IP transport

5

Functional Nodes

Signaling Gateway

An SG is a signaling agent that receives/sends SCN native signaling at the edge of the IP network.

The SG function may relay, translate or terminate SS7 signaling in an SS7-Internet Gateway.

The SG function may also be co-resident with the MG function to process SCN signaling associated with line or trunk terminations controlled by the MG.

Media Gateway Controller

An MGC handles the registration and management of resources at the MG.

The MGC may have the ability to authorize resource usage based on local policy.

Media Gateway

A MG terminates SCN media streams, packetizes the media data, if it is not already packetized, and delivers packetized traffic to the packet network.

6

Standard Documents

RFC

Architectural Framework for Signaling Transport (RFC 2719)

Stream Control Transmission Protocol (RFC 2960)

ISDN Q.921-User Adaptation Layer (RFC 3057)

Signaling System 7 (SS7) Message Transfer Part (MTP)2 - User Adaption Layer (RFC 3331)

SS7 MTP3-User Adaptation Layer (M3UA) (RFC 3332)

Drafts

Signalling Connection Control Part User Adaptation Layer (SUA)

SS7 MTP2-User Peer-to-Peer Adaptation Layer

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SS7 프로토콜

E1 ATM

MTP Level 2

Q.SAAL

Q.2140

MTP Level 3 / MTPB Level 3

SCCP

TCAP

AP ISUP B-ISUP

SS7 Protocol Stack

8

NGN 프로토콜

TCP

SCTP

M2PA/M2UA M3UA

SIP

SUA

UDP

IP

IP over ATM Ethernet

ISUP MTP3 TCAP

SIGTRAN & Open Switch Protocol Stack

M

E

G

A

C

O

SCCP

9

SCTP 개요

to transport PSTN signaling messages over IP networks

a reliable transport protocol operating on top of a connectionless packet network such as IP

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.

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M2PA

Support seamless operation of MTP3 protocol peers over an IP network connection

MTP Level 2 Functionality

Data retrieval to support the MTP3 changeover procedure

Reporting of link status changes to MTP3

Processor outage procedure

Link alignment procedure

Peer to peer messages Message Signal Units, Link Status Signal Units

MTP Level 3 interface boundary

MTP3 Primitives BSNT Confirmation

Retrieval Request and FSNC

management of SCTP transport associations and traffic instead of MTP2 Links

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M2PA Network Model

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M2UA

Support for MTP Level 2 / MTP Level 3 interface boundary

Support for communication between Layer Management modules on SG and MGC

Support for management of SCTP active associations between the SG and MGC

Primitives

DATA

ESTABLISH

RELEASE

STATE

DATA RETRIEVAL

DATA RETRIEVAL COMPLETE

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M2UA Network Model

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Comparison between M2PA and M2UA

M2PA and M2UA are similar in that:

Both transport MTP3 data messages.

Both present an MTP2 upper interface to MTP3.

Differences between M2PA and M2UA include:

M2PA: IPSP processes MTP3/MTP2 primitives.

M2UA: MGC transports MTP3/MTP2 primitives between the SG's MTP2 and the MGC's MTP3 (via the NIF) for processing.

M2PA: SG-IPSP connection is an SS7 link.

M2UA: SG-MGC connection is not an SS7 link. It is an extension of MTP to a remote entity.

M2PA: SG is an SS7 node with a point code.

M2UA: SG is not an SS7 node and has no point code.

M2PA: SG can have upper SS7 layers, e.g., SCCP.

M2UA: SG does not have upper SS7 layers since it has no MTP3. e. M2PA: relies on MTP3 for management procedures. M2UA: uses M2UA management procedures.

15

M3UA 개요

a need for Switched Circuit Network (SCN) signalling protocol delivery from an SS7 Signalling Gateway (SG) to a Media Gateway Controller (MGC) or IP-resident Database

Support for the transfer of all SS7 MTP3-User Part messages (e.g., ISUP , SCCP, TUP, etc.)

Support for the seamless operation of MTP3-User protocol peers

Support for the management of SCTP transport associations and traffic between an SG and one or more MGCs or IP-resident Databases

Support for MGC or IP-resident Database process failover and load sharing

Support for the asynchronous reporting of status changes to management

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M3UA Network Model

Application Server Process (ASP)—MGC, IP SCP, or IP HLR

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SUA 개요

Support for transfer of SCCP-User Part messages (TCAP, RANAP, etc.)

Support for SCCP connectionless service.

Support for SCCP connection oriented service.

Support for the seamless operation of SCCP-User protocol peers.

Support for the management of SCTP transport associations between a SG and one or more IP-based signalling nodes.

Support for distributed IP-based signalling nodes.

Support for the asynchronous reporting of status changes to management.

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SUA Network Model

Relay function

Global Title

Hostname

SSN and PC or SSN and IP Address

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Primitives

Management Primitives

N-State

N-Pcstate

N-Coord

Upper Layer Primitives

N-Connect

N-Data

N-Expedited

N-Reset

N-Disconnect

N-Inform

N-Unit Data

20

Comparison between M3UA and SUA

M3UA SUA

SCCP Flavors

The signaling point is required to support different flavors of SCCP if it has to interoperate with different national systems.

This problem is eliminated using SUA.

Implementation Complexity

M3UA needs the SCCP services. One protocol layer less. The elimination of SCCP reduces the complexity of the network node (implementation as well as management), therefore reducing costs.

Routing Aspects

In M3UA the message is handled from point code to point code.

SUA allows the IP network to route the messages using global title information.

Addressing Aspects

Using M3UA each IP node is required to have both the IP address and point code assigned to it.

Using SUA each IP node does not consume scarce point-code resources.

ISUP Services

Supported Cannot be supported

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IUA

Support for transport of the Q.921 / Q.931 boundary primitives

Support for communication between Layer Management

modules on SG and MGC

Support for management of active associations between SG

and MGC ****** ISDN ****** IP *******

* EP *---------------* SG *--------------* MGC *

****** ****** *******

+-----+ +-----+

|Q.931| (NIF) |Q.931|

+-----+ +----------+ +-----+

| | | | IUA| | IUA |

| | | +----+ +-----+

|Q.921| |Q.921|SCTP| |SCTP |

| | | +----+ +-----+

| | | | IP | | IP |

+-----+ +-----+----+ +-----+

NIF - Nodal Interworking Function

EP - ISDN End Point

SCTP - Stream Control Transmission Protocol

IUA - ISDN User Adaptation Layer Protocol

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Primitives

Upper Layer Primitives

DL-ESTABLISH

DL-RELEASE

DL-DATA

DL-UNIT DATA

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SS7 망 구성도

VOIP

Internet

STP STP

SSP

SSP

PBX

PBX

SG

STP STP

SCP

IP

MGC

MG

MG

RGW

RGW

PSTN

MSC

HLR

GMSC

VLR

BSC

BSC

Mobile Network

STP

MSC

VMS/IVR

SG

IP HLR

SG

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Signaling Gateway 적용

L2 Interface

AP

1

AP

2

AP

n

… Remote

O&M

L2 Glue

Ethernet

SS7 Network IPS7 Network

IP

L

M

Internet

KSIGI7

SCCP

MTP3

M3UA

SCTP

SUA

NIF

25

Primitives

M3UA

SCTP

ASSOCIATE

INITIALIZE

SEND

DATA ARRIVE

RECEIVE

COMMUNICATION UP

REQ HEARTBEAT

SHUTDOWN

SHUTDOWN COMPLETE

NIF

MTP_TRANSFRE ind.

MTP_TRANSFRE req.

MTP_RESUME ind.

MTP_PAUSE ind.

MTP_STATUS#1 ind.

MTP_STATUS#2 ind.

LM

M-SCTP ESTABLISH ind M-SCTP RELEASE ind M-SCTP STATUS req M-SCTP STATUS conf M-NOTIFY ind M-ERROR ind M-ASP UP ind M-ASP DOWN ind M-ASP ACTIVE ind M-ASP INACTIVE ind M-AS ACTIVE ind M-AS INACTIVE ind M-AS DOWN ind

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SCTP Association Establish 및 ASP UP 절차

M3UA-MGC M3UA-SG LM-SG LM-MGC

INITIALIZE

M_SCTP ESTABLISH req

ASSOCIATE

COMMUNICATION UP COMMUNICATION UP

M_SCTP ESTABLISH ind M_SCTP ESTABLISH cfm

M_ASP UP req

SEND(ASPUP pdu)

DATA ARRIVE

RECEIVE(ASPUP pdu)

M_ASP UP ind

SEND(ASPUP Ack pdu)

DATA ARRIVE

RECEIVE(ASPUP Ack pdu) M_ASP UP cfm

SCTP

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ASP Active/Inactive 절차(Routing Key)

M3UA-MGC M3UA-SG LM-SG LM-MGC SCTP

M_ASP INACTIVE req

SEND(ASPIA pdu ) DATA ARRIVE

RECEIVE(ASPIA pdu) M_ASP INACTIVE ind

SEND(ASPIA Ack pdu)

DATA ARRIVE

RECEIVE(ASPIA Ack pdu)

M_ASP INACTIVE cfm

M_AS INACTIVE ind

M_ASP ACTIVE req

SEND(ASPAC pdu) DATA ARRIVE

RECEIVE(ASPAC pdu ) M_ASP ACTIVE ind

SEND(ASPAC Ack pdu) DATA ARRIVE

RECEIVE(ASPAC Ack pdu) M_ASP ACTIVE cfm

M_AS ACTIVE ind

SEND(REG REQ) DATA ARRIVE

RECEIVE(REG REQ pdu)

SEND(REG RSP pdu) DATA ARRIVE

RECEIVE(REG RSP pdu)

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ASP Down 및 SCTP Association Release 절차

M3UA-MGC M3UA-SG LM-SG LM-MGC SCTP

M_ASP DOWN req

SEND(ASP DOWN pdu )

DATA ARRIVE

RECEIVE(ASP DOWN pdu)

M_ASP DOWN ind

SEND(ASP DOWN Ack pdu)

DATA ARRIVE

RECEIVE(ASP DOWN Ack pdu)

M_ASP DOWN cfm

M_AS DOWN ind

M_SCTP RELEASE req

SHUTDOWN

SHUTDOWN COMPLEET SHUTDOWN COMPLEET M_SCTP RELEASE ind M_SCTP RELEASE cfm

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MTP3-User 메시지 M3UA-MGC M3UA-SG MTP3 UPPER

MTP_TRANSFER ind

MTP_TRANSFER ind

SCTP

SEND(DATA pdu ) DATA ARRIVE

RECEIVE(DATA pdu)

MTP_TRANSFER req SEND(DATA pdu)

DATA ARRIVE

RECEIVE(DATA pdu) MTP_TRANSFER req

MTP_PAUSE ind

MTP_PAUSE ind

SEND(DUNA pdu ) DATA ARRIVE

RECEIVE(DUNA pdu)

MTP_RESUME ind

SEND(DAVA pdu ) DATA ARRIVE

RECEIVE(DAVA pdu)

MTP_RESUME ind

SEND(DAUD pdu) DATA ARRIVE

RECEIVE(DAUD pdu)

MTP_STATUS ind

MTP_STATUS ind

SEND(SCON pdu ) DATA ARRIVE

RECEIVE(SCON pdu)

MTP_STATUS ind

SEND(DUPU pdu ) DATA ARRIVE

RECEIVE(DUPU pdu)

MTP_STATUS ind

SEND(DAUD pdu) DATA ARRIVE

RECEIVE(DAUD pdu)

Time Out

Time Start

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지능망 적용

IP Network

MGC

MGC

MGC

Signaling Gateway

Signaling Gateway

SS7 Network

SCP

Media Gateway

Media Gateway

Media Gateway

SSP

SSP

Subscriber

Network

SCP

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지능망 SIGTRAN 적용 프로토콜

INAP TCAP SCCP MTP3 MTP2

E1

SCP

App App

NIF SCCP MTP3 MTP2

E1

NIF SUA SCTP

IP Ether.

SG INAP TCAP SUA SCTP

IP Ether.

MGC

ISUP/ SIP

SS7 Sigtran Call domain

SSF/CCF

32

전개 방향

공중망의 인터넷 확장

공중망 신호 프로토콜의 인터넷 적용에 필수적인 SIGTRAN 의 할성화

개방형 VoIP망, IMT-2000/NGN All-IP 망에 ASP 노드 적용

개방형 구조의 Internet 망과 기존의 지능망 및 PSTN/ISDN 망과의 신호 연동에 필수적인 ALL-IP용 SG 필요

SIGTRAN 적용 고려 사항

구성 망에 따른 다양한 SIGTRAN 프로토콜 선택의 복잡성

기존 SS7 망과의 정합에 따른 복잡성

인터넷 보안의 중요성