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ET2080 JARINGANTELEKOMUNIKASI
Tutun Juhana – Program Studi Teknik TelekomunikasiSTEI -
ITB
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Definition
The IEEE defines signaling as the exchange of
information specifically concerned with the
establishment and control of connections and
the transfer of user-to-user and managementinformation in a telecommunication network
Conventional signaling has evolved with the
telephone network
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Supervisory Signaling
Supervisory signaling provides information on
line or circuit condition
It informs a switch whether a circuit (internal to
the switch) or a trunk (external to the switch) isbusy or idle, when a called party is off-hook or
on-hook, and when a calling party is on-hook
or off-hook
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Address Signaling
Address signaling directs and routes a telephone call to
the called subscriber
It originates as dialed digits or activated push-buttons
from a calling subscriber
The local switch accepts these digits and, by using theinformation contained in the digits, directs the call to the
called subscriber
If more than one switch is involved in the call setup,
signaling is required between switches (both addressand supervisory)
Address signaling between switches is called
interregister signaling
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Call Progress: Audible-Visual
This type of signaling we categorize in the
forward direction and in the backward direction
In the forward direction there is alerting
This provides some sort of audible-visual means
of informing the called subscriber that there is a
telephone call waiting
This is often done by ringing a telephone’s bell
A buzzer, chime, or light may also be used for
alerting.
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In the backward direction, among these are audible
tones or voice announcements that will inform the calling
subscriber the following: Ringback
This tells the calling subscriber that the distant telephone is ringing. Busyback
This tells the calling subscriber that the called line is busy
ATB-All Trunks Busy There is congestion on the routing. Sometimes a recorded voice
announcement is used here.
Loud Warble on Telephone Instrument—Timeout This occurs when a telephone instrument has been left off-hook
unintentionally
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Signalling
Subscriber - exchange Exchange - exchange
Channel associated Common channel
Klasifikasi Signaling8
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Areas of Signaling
There are mainly three areas of signaling during a telephone call :
between subscribers and exchanges.
within exchanges.
between exchanges.
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Exchange A Exchange B
between
Subscriber
and exchangewithin
exchange
between
exchanges
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Subscriber – Exchange Signaling
• Dari pelanggan ke sentral
– Informasi kondisi off-hook
– Informasi nomor B (nomor tujuan)
– Informasi jumlah uang yang dimasukkan (khusus untuk payphone)
– Informasi kondisi on-hook ketika panggilan usai
• Dari sentral ke pelanggan A (nomor pemanggil)
– Informasi bahwa sentral siap menerima nomor B
– Informasi mengenai status B (busy atau tidak)
– Informasi kongesti atau interception
– Sinyal charging (khusus untuk payphone)
• Dari sentral ke pelanggan B
– Sinyal ringing untuk menarik perhatian pelanggan B
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• Pelanggan A mengangkat telepon,hal ini dapat berarti
– A ingin menghubungi seseorang
– Pesawat A berbunyi lalu menjawab
• Sentral dapat mendeteksi keadaantelepon apakah merupakanpanggilan atau jawaban
• Sentral menanggapi panggilandengan mengirimkan dial tone
• A mengirimkan digit nomor B (Bnumber)
• Sentral menganalisa digit lalumencek apakah B ada dan tidakbusy. Ringing tone dikirimkan ke Asedangkan sinyal ringing ke B
• B mengangkat handset, sentralmendeteksinya sebagai jawaban
• Ketika A dan B menyimpan handset,sentral mendeteksi sebagai sinyalclear lalu koneksi diputuskan
Bsentral
Off-hook
Dialling tone
conversation
A
N
OM
O
R
Ringing tone Ringing signal
~425Hz ~90V, 20-25 Hz
answer
Clear forward
Clear back
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Off-Hook Signaling (Analog) Loop Start (almost all telephones)
Seizure is detected when current flows through local loop, due to off-hook
Ground Start (antar PBX (Private Branch Exchange) atau antara PBXdengan Sentral Lokal)
Seizure (upaya pendudukan kanal komunikasi) is detected when one wireis grounded
Seizure can be initiated in both directions
Untuk mengindikasikan status on/off-hook ke sentral lokal
Ground Start
Source: Cisco Interactive Mentor
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Switch Switch
Loop Start Ground Start
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Exchange – exchange
Signaling
Channel Associated Signalling (CAS)
Common Channel Signalling (CCS)
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Channel Associated Signaling
Signaling dilakukan menggunakan kanal yang
juga digunakan untuk mentransfer informasi
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Channel Asociated Signalling
• Informasi speech dan informasi signallingmengalir melalui jalur yang sama
• Beberapa macam CAS
– Signalling dilakukan secara bersama padakanal untuk speech (DC signalling, inband)
– Signalling dilakukan pada kanal yang sama
dengan speech tetapi menggunakan
frekuensi yang berbeda (out-band)• Contoh: Signalling dilakukan melalui timeslot 16 (PCM signalling)
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Seizure acknowledgment
Pelanggan A Pelanggan B
sentral sentral
seizure
B number
answer
conversation
Clear forward
Clear backB- hangs up
A- hangs up
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Forward and Reverse direction
Forward signal mengalir dari sentral telepon
tempat A berada menuju sentral telepon tempat
B berada
Backward signal mengalir pada arah yangberlawanan dengan forward signal
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Common Channel Signaling
Signaling menggunakan kanal yang terpisah
dari kanal untuk mentransfer informasi Terdapat
jaringan signaling tersendiri
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Signaling System Number 7 (SS #7)
Signaling System NO. 720
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Signaling System No. 7 (SS No. 7) was
developed to meet the stringent signaling
requirements of the all-digital network based
on the 64-kbps channel It is a data network entirely dedicated to
interswitch signaling
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SS No. 7 is described as an international
standardized general-purpose common-channel
signaling system that:
Is optimized for operation with digital networks whereswitches used stored-program control (SPC)
Can meet present and future requirements of
information transfer for interprocessor transactions
with digital communications networks for call control,
remote control, network database access andmanagement, and maintenance signaling
Provides a reliable means of information transfer in
correct sequence without loss or duplication
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CCS7 Network Components
The CCS7 Network consists of the followingComponents :
SP -Signaling Point : The SP is the source or originatingentity of the signaling message.
STP-Signaling Transit Point : These entities transfer thesignaling message to another SP or STP without processingthe signaling message.
SRP – Signaling Relay Point : These are STPs with abilitytp process the signaling message.
SEP –
Signaling End Point : The SEP is defined to be theterminating point of the signaling message
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CCS7 Network Architecture
A typical SS7 network is a mixture of various SPs STPs SRPs and
SEPs, As shown below :
SP
(SPC=100)SRP
(SPC=400)
STP
(SPC=300)
STP
(SPC=200)
SEP
(SPC=500)
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CCS7 Terminologies
SPC : SPC is defined as signaling point code which uniquelyidentifies each element within the SS7 network.
Signaling Links : The signaling links transmit signaling messagesbetween the communicating entities.
Signaling Link Set : A signaling link set is a collection of signalinglinks between two signaling entities.
Signaling Route : A signaling route is defined to be the paththrough which signaling messages are exchanged between twoentities. There can be multiple signaling routes between two SPCs,wherein there will be one primary route and several alternateroutes.
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SS7 Routing Modes
Associated Mode :
In the associated mode, the signaling link is routed together with thecircuit group belonging to the link. In other words, the signaling linkis directly connected to signaling points which are also the terminalpoints of the circuit group. This mode of signaling is recommended
when the capacity of the traffic relation between the signaling points A and B is heavily utilized.
Associated Mode of Signaling
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SS7 Routing Modes
Quasi associated mode :
In the quasi-associated mode of signaling, the signaling link and thecircuit group run along different routes, the circuit group connectingthe signaling point. A is directly connected with the signaling point B.For this mode the signaling, the circuit group is carried out via one
or more defined signaling transfer points. This signaling mode isfavorable for traffic relations with low capacity utilization, as thevarious signaling links can be used for several destinations.
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SS7 Network Structure
SPC=100
SPC=200
SPC=300
SPC=100
SPC=400
SPC=500
SPC=600
SPC=400
SPC=900SPC=800
SPC=700
SPC=800
SPC=100
SPC=100
SPC=300
SPC=200
INAT 0
NAT 0
NAT 1
NAT 1NAT 1
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SS7 Protocol Structure
SS7 protocol stack can be broadly divided into two maincategories :
A ) MTP – Message Transfer Part : The message transfer parthas three levels , namely MTP Layer 1, Layer 2 and Layer 3.The message transfer part (MTP) represents a user-neutralmeans of transport for messages between the users.
B ) User Parts (UP) : Each user part (UP) encompasses the
functions, protocols and coding for the signaling via SS7 for aspecific user type (e.g. data service, ISDN). In this way, the user parts control the set-up and release of circuit connections, theprocessing of facilities as well as administration andmaintenance functions for the circuits.
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SS7 Protocol Structure
MTP Layer 3 (Network Management)
MTP Layer 1 (Signaling Data Link)
MTP Layer 2 (Signaling Link)
SCCP
B
S
S
A
P
I
S
U
PTCAP
TCAP
Users
SS7 Users
M
U
P
Other
User Parts
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Contoh signaling CCS#7
IAM: Paket pertama yang membawa informasi nomor B
Sisa nomor berikutnya dibawa oleh SAM
ACM: Paket yang berisi
konfirmasi dari sentral B
bahwa seluruh digit sudah
diterima; selain itu paket ini
berisi pula informasi apakah
panggilan dapat di-charge
atau tidak juga apakah
pelanggan tujuan sibuk atau
tidak
Ketika pelanggan B off-
hook, sentral B
mengirimkan
sinyal ACN untuk
mengaktifkan charging
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