gsm A接口信令分析.docx

gsm A接口信令分析.docx

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gsmA接口信令分析

AppendixA:

SCCPMessageFormatandCode

SCCPMessages

GenerallayoutofSCCPmessageisasfollows:

SCCPUDTMessageStructure

SCCPUDTSMessageStructure

SCCPParameterNameCodes

SCCPMessageType

MessageType

ProtocolClass

Code

0

1

2

3

CRConnectionRequest

X

X

ConnectionOrientedMessage

00000001

CCConnectionConfirm

X

X

ConnectionOrientedMessage

00000010

CREFConnectionRefused

X

X

ConnectionOrientedMessage

00000011

RLSDReleased

X

X

ConnectionOrientedMessage

00000100

RLCReleaseComplete

X

X

ConnectionOrientedMessage

00000101

DT1DataForm1

X

ConnectionOrientedMessage

00000110

DT2DataForm2

X

ConnectionOrientedMessage

00000111

AKDataAcknowledgment

X

ConnectionOrientedMessage

00001000

UDTUnidata

X

X

ConnectionlessMessage

00001001

UDTSUnidataService

X

X

ConnectionlessMessage

00001010

EDExpeditedData

X

ConnectionOrientedMessage

00001011

EAExpeditedDataAcknowledgment

X

ConnectionOrientedMessage

00001100

RSRResetRequest

X

ConnectionOrientedMessage

00001101

RSCResetConfirmation

X

ConnectionOrientedMessage

00001110

ERRError

X

X

ConnectionOrientedMessage

00001111

ITInactivityTest

X

X

ConnectionOrientedMessage

00010000

ThefollowingSCCPmessagesareusedfrequently:

▪ConnectRequest（CR）

▪ConnectConfirm（CC）

▪ConnectionRefused（CREF）

▪DataForm1（DT1）（Thismessage"carries"DTAP&BSSMAPmessages）

▪Released（RLSD）

▪ReleaseComplete（RLC）

▪UnitData（UDT）（Thismessage"carries"BSSMAP&MAPmessages）

SCCPProtocolClassParameters

Option

MessageHandling

ProtocolClass

1Byte

0000

Bits4321

ProtocolClass

Bits8765

MessageHandling

nospecialoptions

0000

class0

0001

class1

spare

to

0001

class2

0111

0010

0011

class3

returnmessageonerror

1000

1111

1001

to

spare

SCCPDiagnostics

Bits8thru1

Diagnostics

00000000

notranslationforaddressofsuchnature

00000010

subsystemcongestion

notranslationforthisspecificaddress

00000001

00000011

subsystemfailure

unequippeduser

00000100

00000101

to

spare

11111111

CallingPartyandCalledPartyAddress

TheCgPAandtheCdPAarecomposedofsomecombinationofthefollowing:

▪addressindicator（mandatory）

▪pointcode（optional）

▪subsystemnumber（optional）

▪globaltitle（optional）

AddressIndicator

Theaddressindicator,identifieswhichoptionalfieldsarepresentandincludestheRoutingIndicator（RI）.TheRIdetermineswhetherroutingisbasedonpointcodeandsubsystemnumberorglobaltitle.

TheCgPA/CdPAaddressindicatorbitsaredefinedasfollowsforCCITT:

Note:

GlobalTitleisnotsupportedbyGSMspecification,accordingtoSS7BasedA-InterfaceIS-651.

SCCPSignalingPointCode

APointCodeidentifiesaspecificsignalingpointwithinaCCS7network.Asshownbelow,thesignalingpointcodeisrepresentedbytwooctetsinCCITT.

87654321

1Octet

1Octet

0

0

AreaNetwork

Zone

Sig.point

SCCPSubsystemNumber

MAPLIDBQ

00100011

INAP

BSSAP

11111110

00001100

AUC

00001010

EIR

00001001

MSC

00001000

VLR

HLR

MAP

OMAP

00000111

00000110

00000101

00000100

00000011

00000010

00000001

SSNnotknown/notused

00000000

Bits8thru1

SCCPmanagement

ISDNuserpart

Spare

SCCPGlobalTitleField

GlobalTitleIndicator=0001

87654321

SignalingPointCode

2Octets

SubsystemNumber

1Octet

0=Evennumberofaddress

signal

1=Oddnumberofaddress

signal

GlobalTitle

Variable

Natureofaddressing

indicator

Bits7654321

87654321

0000000

Spare

Natureofaddressing

indicator

1octet

O/E

0000001

UserNumber

AddressInformation

noctets

0000010

Sparenational

Nationalvalidnumber

InternationalNumber

0000100

0000011

87654321

Octet2

1stAddressSignal

2ndAddressSignal

Octetm

Octet3

nthAddressSignal

Filler（ifnecessary）

3rdAddressSignal

4thAddressSignal

GlobalTitleIndicator=0010

87654321

SignalingPointCode

2Octets

SubsystemNumber

1Octet

GlobalTitle

Variable

87654321

TranslationType

1octet

noctets

AddressInformation

TranslationTypeisunderresearch.InGSMitisall0s.

GlobalTitleIndicator=0011

87654321

SignalingPointCode

2Octets

SubsystemNumber

1Octet

Variable

GlobalTitle

87654321

1octet

TranslationType

NumberingPlan

Scheme

1octet

Encoding

noctets

AddressInformation

Spare

Spare

BCD,Evennumberofdigits

BCD,Oddnumberofdigits

unknown

1111

to

1110

0011

0010

0001

0000

4321

EncodingScheme

Bits

GlobalTitleIndicator=0100

spare

noctets

AddressInformation

Encoding

NumberingPlan

Scheme

1octet

TranslationType

1octet

Natureofaddressing

indicator

1octet

GlobalTitle

SubsystemNumber

SignalingPointCode

Variable

1Octet

2Octets

87654321

87654321

8765

Bits

ISDN/MobileNumberingPlan（E.214）

LandMobileNumberingPlan（E.212）

MaritimeMobileNumberingPlan

（E.210&E.211）

TelexNumberingPlan（F.69）

DataNumberingPlan（X.121）

ISDNNumberingPlan（E.163/E.164）

unknown

NumberingPlanScheme

0000

0001

Spare

0010

0011

0100

0101

0110

0111

ConnectionRequest（CR）Message

ThismessageissentbythecallingSCCPtorequestthesetupofasignalingconnectiontothecalledSCCP.

CRMessageFormat

SCCPSignalingInformation

Field

Size（octets）

MT

MessageType（#01）

1

MandatoryFixed

SourceLocalReference

3

Protocolclass

1

MandatoryVariable

PointertoCdPA

1

Pointertooptionalpart

1

CalledPartyAddress（CdPA）

3min.

OptionalParameters

Credit

3

CallingPartyAddress（CgPA）

4min.

Data

3-130

SCCPhopcounter

3

Endofoptionalparameters

1

Note:

Creditfieldisnotused.

Protocolclass3isnotsupported.

SCCPhopcounteracceptedbutisnotused.

SCCPhopcounterisneversent.

ConnectionConfirm（CC）Message

ThismessageconfirmstothecallingSCCPthatthecalledSCCPhasperformedthesetupofthesignalingconnection.

CCMessageFormat

SCCPSignalingInformation

Field

Size（octets）

MT

MessageType（#02）

1

MandatoryFixed

DestinationLocalReference

3

SourceLocalReference

3

Protocolclass

1

OptionalParameters

Credit

3

CalledPartyAddress（CdPA）

4min.

Data

3-130

Endofoptionalparameters

1

Note:

Creditfieldisnotused.

Protocolclass3isnotsupported.

ConnectionRefused（CREF）Message

ThismessageissentbythecalledSCCPtoindicatethatthecalledSCCPhasrefusedtosetupthesignalingconnection.

CREFMessageFormat

SCCPSignalingInformation

Field

Size（octets）

MT

MessageType（#03）

1

MandatoryFixed

DestinationLocalReference

3

Refusalcause

1

OptionalParameters

CalledPartyAddress（CdPA）

4min.

Data

3-130

Endofoptionalparameters

1

Note:

Protocolclass3isnotsupported.

RefusalCause:

refusalcauseisnotused

refusalcauseisused

00000011SCCPuseroriginated

-Timeoutmessagesoftheconnectionestablishmenttimerconnectionrefusal,whenCgPAisnotvalid.

00000100Destinationaddressunknown

-ThisprocedureisusedtoreturnaCREFmessagetothefarendwheneveraCRmessagehasarrivedandthesubsystemisincorrectorthesubsysteminunavailablewhichresultsinaalocalroutingfailure.

00001100expirationoftheconnectionestablishmenttimer

-Touser,inconnectionrefusalindicationifatimeoutmessageoftheconnectionestablishmenttimer.

00001110notobtainable

-Touser,inconnectionrefusalindicationinconnection_request_primitive.

00001111unqualified

-whenwecannothandletheconnectionrequestthenwesendconnectionrefusedunqualifiedmessage.

DataForm1（DT1）Message

ThismessageissentbyeitherendofasignalingconnectiontopasstransparentlySCCPuserdatabetweentwoSCCPnodes.Theconnectionmustalreadybeestablished.

DT1MessageFormat

SCCPSignalingInformation

Field

Size（octets）

MT

MessageType（#06）

1

MandatoryFixed

DestinationLocalReference

3

Segmenting/reassembling

1

MandatoryVariable

Pointertodata

1

Data

2-256

bits

2

1

8

Segmenting/reassembling

M

Bit2-8:

spare

Bit1:

M=0Nomoredata

M=1moredata

Released（RLSD）Message

Thismessageissentintheforwardorbackwarddirection,toindicatethatthesendingSCCPwantstoreleasethesignalingconnectionandtheassociatedresourcesatthesendingSCCPhavebeenbroughtintothedisconnectpendingcondition.Italsoindicatesthatthereceivingnodeshouldreleasetheconnectionandanyotherresourcesassociatedwithit.

RLSDMessageFormat

SCCPSignalingInformation

Field

Size（octets）

MT

MessageType（#04）

1

MandatoryFixed

DestinationLocalReference

3

SourceLocalReference

3

ReleaseCause

1

Optionalparameters

Data

3-130

Endofoptionalparameters

1

Note:

Protocolclass3isnotsupported.

ReleaseCause:

releasecauseisused

00000000Enduseroriginated

-InRLSDmessagewhenCCmessagereceivedandlocaluserhadrequestedforconnectiontakedownafterCRbutbeforetheCCreceived.

-Touser,ifRLSDmessagereceivedindisconnectionindicationinresponsetoCRmessage.

-Touser,ifRLSDmessageindisconnectindicationreceivedforanactiveconnection.

-Touser,indisconnectindication,iferrormessagereceivedforanactivestate.

-TofarendinRLSDmessage,iferrorreceivedforanactivestate.

-InRLSDmessage,iflocaltodisconnectactiveconnection.

-TouserifresponsetoCRisnotCC,RLSD,CREF.

00000010Enduserfailure

-TouserifinconsistentdatareceivedinCCmessage.

00000101inconsistentconnectiondat