HUAWEI TECHNOLOGIES CO., LTD. All rights reserved www.huawei.com Internal OMF001005 GSM Signaling System- SCCP(BSS) ISSUE 2.0
Oct 28, 2014
HUAWEI TECHNOLOGIES CO., LTD.
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Internal
OMF001005 GSM Signaling System-
SCCP(BSS)
ISSUE 2.0
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Upon completion this course, you are
supposed to be able to:
Understand the necessity of SCCP.
Know the services provided by SCCP.
Know the SCCP message format.
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Chapter 1 Chapter 1 GeneralGeneral
Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
Chapter 3 Chapter 3 Addressing & Routing Functions Addressing & Routing Functions
of SCCPof SCCP
Chapter 4 Chapter 4 SCCP Message FormatSCCP Message Format
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Limitation of MTP Transmission
The signaling point code is not the standard international code,
it is only effective within a certain network.
The limited capacity of the signaling point code (14-bit is
specified by CCITT) also limits the number of the signaling
point to be marked.
The 4-bit SI can not satisfy the increased requirements of the
modern communication as well, since it can only be assigned
to sixteen different user parts.
MTP can only provide the connectionless transmission.
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When SCCP and MTP are combined together, they are called
as NSP (Network Service Part).
SCCP and MTP-3 both locate in the network layer of the OSI
model.
The Location of SCCP in CCS7
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Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
1.1 1.1 Application Features of SCCPApplication Features of SCCP
1.2 1.2 Service Functions of SCCP Network Service Functions of SCCP Network
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Application Features of SCCP
Enable to transfer both circuit-related and non-circuit-related
signaling messages in telecommunication networks.
Provide enhanced addressing and routing functions, and
enable to achieve the direct transmission between different
CCS7 networks.
Enable to provide both connectionless service and connection-
oriented service.
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Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
1.1 1.1 Application Features of SCCPApplication Features of SCCP
1.2 1.2 Service Functions of SCCP Network Service Functions of SCCP Network
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Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
1.1 1.1 Application Features of SCCPApplication Features of SCCP
1.2 1.2 Service Functions of SCCP Network Service Functions of SCCP Network
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There are two kinds of service provided by the SCCP protocol:
Connectionless Service
0. Basic connectionless class
1. In-sequence delivery connectionless class
Connection-oriented Service
2. Basic connection-oriented class
3. Flow control connection-oriented class
Service Functions of SCCP Network
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In the connectionless service, the routing information
must be contained in each data packet.
No logical connection is established between the end
nodes.
Connectionless Service
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The connectionless SCCP offers two services:
The class 0 service allows the SCCP to insert SLS values randomly,
or with the aim to achieve an appropriate load sharing within the und
erlying MTP network.
The class 1 service requires the SCCP to insert the same SLS for all
the SCCP-SDUs (service data unit) associated with given parameter
s "sequence control" and "called address" .
Connectionless Service
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UDT----unit data
UDTS----unit data service
XUDT----extended unit data
XUDTS---extended unit data service
Message type UDTUDT
S
XUD
TXUDTS
Message type code 0x09 0x0A 0x11 0x12
Connectionless Service
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SCCP procedure of connectionless service
originatingSCCP
relaySCCP
terminalSCCP
UDT UDT
UDT UDT
UDT
UDTSfailure
Connectionless Service
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Connection-oriented service is a way to realize the exchange of signaling
information by establishing a logical signaling connection between the
network service users.
The logical signaling connection is achieved by distributing a local
reference number to the signaling messages belonging together.
Connection-oriented Service
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originatingSCCP
relaySCCP
terminalSCCP
CR CR
CC CC
DTDT
DT DT
AKAK
RSLD RSLD
RLC RLC
SCCP procedure of connection-oriented service
Connection-oriented Service
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Chapter 1 Chapter 1 GeneralGeneral
Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
Chapter 3 Chapter 3 Addressing & Routing Functions Addressing & Routing Functions
of SCCPof SCCP
Chapter 4 Chapter 4 SCCP Message FormatSCCP Message Format
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Address in SCCP comprises three elements:
DPC
Global Title (GT)
Sub-System Number (SSN)
Addressing and Routing Functions of SCCP
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0000 0000 SSN not known/not used
0000 0001 SCCP management
0000 0010 Reserved for ITU-T allocation
0000 0011 ISDN user part£ ISUP£ ©
0000 0100Operation, maintenance and administration part (OMAP)
0000 0101 Mobile application part£ MAP£ ©
0000 0110 Home location register£ HLR£ ©
0000 0111 Visitor location register£ VLR£ ©
0000 1000 Mobile switching centre£ MSC£ ©
0000 1001 ... ... 1111 1101 Idle
1111 1110 BSS Application Part (BSC)
1111 1111Reserved for expansion of national and international SSN
SSN
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There are two basic categories of SCCP routing
GT
DPC+SSN
Addressing and Routing Functions of SCCP
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Addressing and Routing Functions of SCCP
From SPA to SPD,
If DPC+SSN routing is adopted by SCCP, in the Called Party Address of SCCP
message, DPC is point code of SPD, while SSN depends on the different requirements.
The message is sent to STPB or STPC, the Called Party Address is not necessary to
be translated by STP.
If GT routing is adopted by SCCP, in the Called Party Address of SCCP message, GT is
the information of SPD. Because GT can’t be identified by MTP, actually, DPC should
be included in the SCCP message, in this case, DPC is point code of STP. The
message is sent to STPB or STPC, the Called Party Address is necessary to be
translated to the relevant point code and/or SSN by STP.
SPA
STPB
STPC
SPD
An example
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Chapter 1 Chapter 1 GeneralGeneral
Chapter 2 Chapter 2 Features & Functions of SCCPFeatures & Functions of SCCP
Chapter 3 Chapter 3 Addressing & Routing Functions Addressing & Routing Functions
of SCCPof SCCP
Chapter 4 Chapter 4 SCCP Message FormatSCCP Message Format
HUAWEI TECHNOLOGIES CO., LTD. Page 23All rights reserved
F C
K
SIF SIO LI FI
B
FSN BI
B
BS
N
F Mandatory parameter A
…………
Mandatory parameter I
Pointer to parameter M
…………
Pointer to parameter P
Pointer to start of optional part
Length indicator of parameter M
Parameter M
…………
Length indicator of parameter P
Parameter P
Parameter name=X
Length indicator of parameter X
Parameter X
…………
Parameter name=Z
Length indicator of parameter Z
Parameter Z
End of optional parameters
8 16 8n,n>2 8 2 6 171 7 8
Routing label
Message type
Mandatory fixed part (F)
Mandatory variable part (V)
Optional part (O)
SCCP Message Format
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F C
K
SIF SIO LI FI
B
FSN BI
B
BS
N
F
8 16 8n,n>2 8 2 6 171 7 8
Label
Message type (UDT)
Protocol class
Called party address pointer
Calling party address party
Data pointer
Called party address length
Called party address
Calling party address length
Calling party address
Data length
Data (TCAP)
MF
MV
MV
MV
Message Example
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General
Features & Functions of SCCP
Addressing & Routing Functions of SCCP
SCCP Message Format
SummarySummary
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