Owg000008 Sigtran Introduction Issue1.0

ISSUEISSUE

Fixed Network Curriculum

Development Section

Fixed Network Curriculum

Development Section

OWG000003 SIGTRAN protocolOWG000003 SIGTRAN protocol

1.01.0

Confidential Information of Huawei. No Spreading without Permission.

Security Level: Internal

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ObjectivesObjectives

SIGTRAN application in R4 network

SIGTRAN protocol structure and

message introduction

SIGTRAN signaling flow

Upon completion of this course,you will be able to:



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Course ContentCourse Content

Training.huawei.com

Chap1 overview

Chap2 SCTP protocol

Chap3 M3UA protocol introduction

Chap4 SIGTRAN application



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SIGTRAN definitionSIGTRAN definition

Two layers of protocols are included in the SIGTRAN

protocol stack, i.e., transmission protocols (such as SCTP/IP)

and adaptation protocols (such as M3UA, IUA).



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Introduction of M3UAIntroduction of M3UA

SEP MGC

ISUP

MTP3

MTP2

MTP1

ISUP

M3UA

SCTP

IP

M3UA

SCTP

IP

MTP2

MTP1

SS7 SIGTRANSG

PSTN IP

MTP3

NIF



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Training.huawei.com

Chap1 overview

Chap2 SCTP protocol





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Chap2 SCTP protocolChap2 SCTP protocol

1.1 overview1.1 overview

1.2 SCTP terms

1.3 SCTP function

1.4 SCTP message str

ucture



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SCTP protocol introductionSCTP protocol introduction

Stream Control Transmission Protocol (SCTP) is a reliable

transport protocol that operates over a potentially unreliable

connectionless packet service such as IP.

SCTP is designed to transfer SCN narrowband signaling over

IP network.

Compared with the TCP, SCTP features higher reliability,

real-time and multi-homed performance.



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SCTP features SCTP features

Support for orderly/disorderly transmission of subscriber

datagram in the flow.

Multiple streams can be established in one association, and the

data in the streams do not interfere with each other.

Multi-home can be supported at one end or both ends of the

association to improve the reliability of the link.

The association must pass the COOKIE authentication before

establishment to guarantee the security.



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1.1 overview

1.2 SCTP terms1.2 SCTP terms

1.3 SCTP function


ucture



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SCTP transmission addressSCTP transmission address

A transport address of Stream Control Transmission Protocol

(SCTP) is defined by the combination of an IP address and an

SCTP port number.

SCTP port number is used for the identification of the users at

the same address, and it is identical to that of TCP port

number in the concept.



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Host and endpointHost and endpoint

A Host is a computer, configured with one or multiple IP addresses.

It is a typical physical entity.

Endpoint is one of basic concepts of SCTP. An endpoint is the

logical sender/receiver of SCTP packets. It is a typical logical entity.



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Association and streamAssociation and stream

SCTPEndpointA

IP/SCTP-port

SCTPEndpointB

IP/SCTP-port

SCTPassociation

SCTPstream(sigleway)



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TSN and SSNTSN and SSN

TSN

Transmission Sequence Number (TSN) is a 32-bit sequence

number used internally by SCTP. One TSN is attached to each

chunk containing user data to permit the receiving SCTP

endpoint to acknowledge its receipt and detect duplicate

deliveries. TSN is maintained on the basis of association.

SSN

SSN is the acronym of Stream Sequence Number. In each strea

m of an SCTP association, a 16-bit sequence number is assigne

d to each data chunk sent in the stream by the local end, in orde

r to ensure the sequenced transmission in the stream. SSN is m

aintained on the basis of stream.



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TSN and SSNTSN and SSN

TSN is maintained on the basis of association.

For example: Endpoint A use two stream to connect endpoint B.

Now block A,B,C,D will be transmit, the sequence of transmission is

as following :block A use stream1,block B use stream2, block C use

stream3, block D use stream4. And block5 is divided into D1 and

D2.

data TSN SSN

A 1 1

B 2 1

C 3 2

D1 4 2

D2 5 2



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CWND and RWNDCWND and RWND

CWND: Congestion Window

An SCTP variable that limits the data, in number of bytes, a

sender can transmit to a particular destination transport address

before receiving an acknowledgement. SCTP is a sliding window

protocol.

RWND: Receiver Window.

An SCTP variable that a data sender uses to store the most rece

ntly calculated receiver window of its peer, in number of bytes.



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1.1 overview

1.2 SCTP terms

1.3 SCTP function1.3 SCTP function


ucture



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SCTP functionSCTP function

The functions of SCTP mainly include:

association startup and takedown

sequenced delivery within streams

user data fragmentation

acknowledgement and congestion avoidance

chunk bundling

packet validation

path management.



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1.1 overview

1.2 SCTP terms

1.3 SCTP function

1.4 SCTP message str1.4 SCTP message str

uctureucture



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SCTP messageSCTP message

（ COMMON HEADER）＋（ CHUNK）



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SCTP message typeSCTP message type

Message Name Description

DATA The payload user data

INIT This chunk is used to initiate a SCTP association between two endpoints.

INIT ACK The INIT ACK chunk is used to acknowledge the initiation of an SCTP association.

SACK This chunk is sent to the peer endpoint to acknowledge received DATA chunks and to inform the peer endpoint of gaps in the received

subsequences of DATA chunks.

HEARTBEAT An endpoint should send this chunk to its peer endpoint to probe the reachability of a particular destination transport address defined i

n the present association.

HEARTBEAT ACK An endpoint should send this chunk to its peer endpoint as a response to a HEARTBEAT chunk.

ABORT The ABORT chunk is sent to the peer of an association to close the association.

SHUTDOWN An endpoint in an association MUST use this chunk to initiate a graceful close of the association with its peer.

SHUTDOWN ACK This chunk MUST be used to acknowledge the receipt of the SHUTDOWN chunk at the completion of the shutdown process.

ERROR An endpoint sends this chunk to its peer endpoint to notify it of certain error conditions.

COOKIE ECHO This chunk is used only during the initialization of an association. It is sent by the initiator of an association to its peer to complete the

initialization process.

COOKIE ACK It is used to acknowledge the receipt of a COOKIE ECHO chunk.

SHUTDOWN COMPLETE This chunk is used to acknowledge the receipt of the SHUTDOWN ACK chunk at the completion of the shutdown process



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Startup of associationStartup of association

The startup of SCTP association is a four-way handshake process,

which has four message interactions: INIT, INIT ACK, COOKIE

ECHO and COOKIE ACK



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Termination of associationTermination of association

SCTP association can be terminated in two ways: One is

GRACEFUL close, the other is UNGRACEFUL close.

Just as their names imply, the former means that all data in

queue by either endpoint is delivered to the respective peers

before the association is shut down.

The latter means that the association is directly aborted and

the data is directly discarded.



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Training.huawei.com

Chap1 overview

Chap2 SCTP protocol





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Chap3 M3UA protocol introductionChap3 M3UA protocol introduction

3.1 overview3.1 overview

3.2 basic concept

3.3 M3UA message st

ructure



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M3UA functionM3UA function

M3UA (MTP3 User Adaptation) protocol supports the

transport of any SS7 MTP3-User signaling (e.g., ISUP and

SCCP messages) over IP using the services of the Stream

Control Transmission Protocol.

Also, provision is made for protocol elements that enable a

seamless operation of the MTP3-User peers in the SS7 and

IP domains. This protocol would be used between a Signaling

Gateway (SG) and a Media Gateway Controller (MGC) or IP-

resident Database, or between two IP-based applications.



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M3UA protocol introductionM3UA protocol introduction

SEP MGC

ISUP

MTP3

MTP2

MTP1

ISUP

M3UA

SCTP

IP

M3UA

SCTP

IP

MTP2

MTP1

SS7 SIGTRANSG

PSTN IP

MTP3

NIF

SEP： signal endpoint SG： signal gateway MGC：media control



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M3UA protocol introduction(continue)M3UA protocol introduction(continue)

RNC

RANAP

SCCP

MTP-3b

SAAL

ATM

MGW

ATM

SAAL

MTP-3b M3UA

SCTP

IP

SERVER

RANAP

SCCP

M3UA

SCTP

IP

ATM IP



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M3UA protocol introductionM3UA protocol introduction

M3UA also can be used to transfer signaling between two

IPSP

IPMGC MGC

User

M3UA

SCTP

IP

User

M3UA

SCTP

IP



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3.1 overview

3.2 basic concept3.2 basic concept

3.3 M3UA message st

ructure



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Basic conceptBasic concept

AS

A logical entity serving a specific Routing Key.

ASP

A process instance of an Application Server.

IPSP

A process instance of an IP-based application. An IPSP is

essentially the same as an ASP, except that it uses M3UA in a

point-to-point fashion. Conceptually, an IPSP does not use the

services of a Signaling Gateway node.



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M3UA link state transition

M3UA_LINK_INACTIVE

M3UA_LINK_UNESTABLISH

M3UA_LINK_DOWN

Asp Inactive/Asp Inactive Ack/

Asp Alt Notify

Asp Active/Asp Active Ack

M3UA backout successful/Sctp-CDI

M3UA_LINK_ACTIVE

SCTP-RI Asp Down orAsp Down Ackor SCTP-RI

SCTP-CDI

SCTPCDI

M3UA establish successful

Asp Up orAsp Up Ack



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Relationship among M3UA Link, Linkset, Route and Entity

SGP1

SGP2

SGP3

SGP1

SGP2

SGP3

SG1

SG2

MGC

M3UA link set

M3UA route

SP

ASP1

ASP2

ASP3

M3UA linkM3UA entity MTP link



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M3UA route

The path from source entity to destination entity is called a M3U

A route.

One M3UA route corresponds to one M3UA Linkset at the home

terminal.



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M3UA entity

The logical processing unit that accomplishes some special func

tions, such as AS, SP or a logic unit that only implements specia

l message transfer function, such as SG can be classified as M3

UA Entity. Each M3UA Entity is identified by a unique signaling p

oint code.

M3UA LOCAL ENTITY: The logical entity to accomplish speci

al function in local side.

M3UA DESTINATION ENTITY: The logic entity to accomplish

special function in peer side.



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3.1 overview

3.2 basic concept

3.3 M3UA message st3.3 M3UA message st

ructureructure



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M3UA message structureM3UA message structure

The general M3UA message format includes a common message

header followed by zero or more variable length parameters.

The protocol messages for MTP3-User Adaptation require a message

structure, which contains a version, message class, message type,

message length, and message contents.

All the parameters contained in a message are defined in a Tag

Length-Value format as shown below.

Version(8) Reserved(8) Message Class(8) Message Type(8)

Message Length(32)

Parameter Length (16)

Parameter Value(32)

Parameter Tag (16)



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M3UA message introductionM3UA message introduction

Management messages

Transfer messages

SS7 Signaling Network Management messages

ASP State Maintenance messages

ASP Traffic Maintenance messages



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Establishment procedureEstablishment procedure

SGP ASP

ASP UP

ASP UP ACK

AS INACTIVE NOTIFY

ASP ACTIVE

ASP ACTIVE ACK

AS ACTIVE NOTIFY



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Data Transfer procedureData Transfer procedure

Determine the correct Destination Entity.

If the destination Entity is Accessible, then get the Available ro

ute to that destination entity.

Get an Active Linkset belonging to this Route.

Determine an Active Link in the given Linkset.

Determine whether to complete the optional fields of the DAT

A message.

Map the MTP-TRANSFER request primitive into the Protocol

Data field of a DATA message

Send the DATA message to the remote M3UA peer at the SG

P, over the chosen M3UA link.



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MTP_TRANSFER primitive handling at ASPMTP_TRANSFER primitive handling at ASP

MTP_TRANSFER

ASP

Choose the rightlink and map

Transferprimitive to

DATA message

SGP

DATA message



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MTP_TRANSFER handling at SGPMTP_TRANSFER handling at SGP

MTP_TRANSFER

ASP

Choose the rightlink and map

Transferprimitive to

DATA message

SGP

DATA message



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Release procedureRelease procedure

SGP ASP

ASP INACTIVE

ASP INACTIVE ACK

AS PENDING NOTIFY

Pending Timer ExpiresAS INACTIVE NOTIFY

ASP DOWN

ASP DOWN ACK

AS DOWN NOTIFY



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Owg000008 Sigtran Introduction Issue1.0

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