ET2080 7 Signaling

7/27/2019 ET2080 7 Signaling

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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

ET2080 Jaringan Telekomunikasi

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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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ET2080 7 Signaling