Introduction to Signalling Own

Introduction to Signalling Switching Core Network Signalling M14/U4

For public use – IPR applies 1 © Nokia Siemens Networks

Presentation / Author / Date / Document Number

Signalling Concept



What is Signalling ?

Signalling is the exchange of information specifically concerned with the establishment and control of connections, and with management, in a telecommunications network.



Standardisation Bodies: The ITU (International Telecommunication Union)

UN

ITU http://www.itu.int

Secretary General For public use – IPR applies 6 © Nokia Siemens Networks

ITU-D Presentation / Author / Date / Document Number

ITU-R

ITU-T

Other Standardisation Bodies

www.3gpp.org is a collaboration agreement that was established in December 1998. The collaboration agreement brings together a number of telecommunications standards bodies which are known as “Organizational Partners”. The current Organizational Partners are ARIB, CCSA, ETSI, ATIS, TTA, and TTC

www.ietf.org Is an organised activity of Internet Society (ISOC). ISOC is a not-for-profit organization founded in 1992 to provide leadership in Internet related standards, education, and policy. ISOC is supported by more than 90 organizational members and 26,000 individual members



Advantages of following the recommendations

• Easier network integration • Compatibility between products of different vendors • Wider choice of network products from which to choose • Competition between suppliers, which leads to a reduced price and better products • For the subscriber, this results in quality, lower price and wider network coverage



Signalling Types

Signalling is divided into three types:

•signalling within the exchange see also courses CN3414 and CN3415: SCN Call Control

•signalling between subscriber and exchange

•signalling between exchanges



Simplified Signalling Between Subscriber and Exchange

a) Service Request b) Access Grant c) Setup (Digits)

d) Page e) Service Request

Exchange f) Setup

A Subscriber g) Alerting h) Connect

i) Connect Acknowledge



g) Alerting h) Connect i) Connect Acknowledge

B Subscriber

Signalling Between Exchanges Simplified PSTN

MSC Hey, I want to call number 2...

Hold on a second, who are you and what is your number? I am a priority subscriber and my number is 214-123-4567 Ok, now give the rest of digits Here theyare, 14-987-6543 Ok, he answered

Asubscriber

CONVERSATION I want to clear the call now Got it, byebye!



Bsubscriber

Historical signaling development •DC Signaling

•AC Signaling •MF Signaling (DTMF, CAS) •CCS Signaling, – Digital signalling based on data communication concept from OSI (Open System Interconnection). – Now is CCS No. 7 (called also SS7, C7, …) – This document will discuss only digital signalling



Common Channel Signalling Common Channel Signalling (CCS) is a signalling method in which signalling information is conveyed over a single channel by addressed messages.

CCS7 CCS7 is an internationally standardised Common Channel Signalling (CCS) system. It is optimised for operation in digital telecommunication networks such as GSM.



Data Communication Environment

host A

user A

application

application

Communication hardware/softwar e

Communication hardware/softwar e

transmission medium


host B


user B

OSI Protocol Stack

OSI Stack host A

host B

application

Communication hardware/software

Application Layer

application interface

6

Presentation Layer

encryption, decryption, compression, decompression

5

Session Layer

session creation

4

Transport Layer

virtual connection and multiplexing

3

Network Layer

addressing and routing

2

Data Link Layer

error detection and correction

1

Physical Layer

access to phys. medium

application

Communication hardware/software

transmission medium


7


Protocols and Interfaces

application

application

protocol

7

Application Layer

protocol

6

Presentation Layer

protocol

5

Session Layer

protocol

4

Transport Layer

protocol

3

Network Layer

2

Data Link Layer

1

Physical Layer

protocol interface

protocol

transmission medium For public use – IPR applies 16 © Nokia Siemens Networks


CCS7 protocol stack vs. the OSI reference model (level and layer)

Layer

OSI Reference Model

7

Application layer

6

Presentation layer

5

Session layer

4

Transport layer

3

Network layer

Common Channel Signalling No. 7

Application Part User Part (GSM specific part) SCCP

User Part

Level

4

(Common part) (PSTN, ISDN, GSM) 3

2 1

Data link layer

MTP (levels 1-3)

Physical layer



2 1

Landmarks in the Progress of CCS7 Signalling 1972

CCITT Recommendation No.6

1976

CCIS introduced by Bell System

1980

CCITT Recommendation SS7 (Yellow Book)

1984

Enhancement to SS7 (Red Books)

1985

ANSI specification of SS7

1988

Enhancement to SS7 (Blue Books)

1992

Modifications to SS7 Architecture (White Books)

Evolution of the SS No. 7 architecture since the Red Book (1984) increasingly has been based on the Open Systems Interconnection (OSI) reference Model. For public use – IPR applies 18 © Nokia Siemens Networks


The Yellow Book Architecture : MTP with only: • Signalling Data Link Function • Signalling Link Functions • Signalling Network Function • User Parts: TUP and DUP, with possibility for other user parts.

The Red Book Architecture • SCCP introduced • ISDN user part modified to ISDN-UP • The SCCP served OMAP, with an application service part in between, which provided services of the Presentation-, Session- and the Transport layer

The Blue Book Architecture: • Introduction of “Transaction Capabilities” • The ISDN-UP modified to ISUP • The MTP made compatible to serve other CCITT defined users

The White Book Architecture: • The present-day CCS#7. TC modified to TCAP. For public use – IPR applies 19 © Nokia Siemens Networks


Signaling protocols in 2G/3G Core Networks



2G GSM/3G Rel.99 network structure Internet (TCP/IP) GPRS + UMTS GSM mobile

GSM + UMTS Base Station Subsystem

2G SGSN GGSN

BSC SIM card

GSM BTS

Network Subsystem (GSM +UMTS) SRR

3G SGSN HLR

MSC

GSM / UMTS mobile

MGW

RNC UMTS mobile

Landline NW (PSTN/ISDN)

UMTS (WCDMA) BTS IN SCP



CCS7 protocols in GSM Network MSC/VLR BSSAP

MAP/INAP TUP TCAP NUP

PSTN Exchange

TUP NUP ISUP

ISUP SCCP

MTP

SCCP

MTP

MAP / INAP

BSSAP

BSC

TCAP SCCP

SCCP

MTP For public use – IPR applies 22 © Nokia Siemens Networks

HLR/EIR/AC


MTP

Protocol stack in MGW Rel.99 Iub

A'

Iu Media Media Gateway Gateway

MSC MSC

RANAP / BSSAP

BSSAP

BB/NB SCCP

SCCP

RNC RNC

RANAP Broadband SCCP Broadband MTP-3

BB/NB MTP-3

SSCF-NNI

SSCF-NNI

SSCOP

SSCOP

AAL5

AAL5

ATM Layer

ATM


MTP-3

MTP-2

MTP-2

ATM Layer

MTP-1

MTP-1

ATM

TDM

TDM


New Protocols in SCN Rel4 • Radio Access Network Application Part (RANAP) • SIGTRAN (M3UA and SCTP) • Media Gateway Control protocol (H.248/MEGACO) • Bearer independent call control (BICC) • Session Initiation Protocol (SIP) • AAL2SIG (AAL Type 2 Signalling) between RNC-MGW or MGW-MGW when using an ATM bearer • IPBCP (IP Bearer Control Protocol), tunnelling for MGW-MGW when using an IP bearer



GSM/UMTS Rel4 network structure IN/SCE

APSE

HLR / HSS

PSTN/ISDN

BSC MSC Server

GSM

BICC CS-2, SIP-I H.248

A

RNC

H.248

MGW

MGW

Other PLMN

IP/ATM Backbone

Iu-CS

WCDMA

MSC Server

A

Iu-PS

External IP networks GGSN SGSN For public use – IPR applies 25 © Nokia Siemens Networks


MSS System Interfaces & Protocols HLR

BICC or SIP for call control

Services

H.248 for MGW control

CAP

MAP BICC CS-2, SIP ATM/IP

MSS/ GCS

MSC Server

Nc

Mc

H.248 IP

RANAP or BSSAP towards radio network

H.248 IP

Mc

AAL2/AAL5 ATM Nb

RANAP AAL5/ATM Iu-CS MGW

RTP IP

SS7 TDM MGW

BSSAP

RNC

AAL2 ATM

A TDM

BSC For public use – IPR applies 26 © Nokia Siemens Networks


User data over ATM, TDM or IP

PSTN

RANAP ---Radio Access Network Application Part Maintains Iu-interface Control Plane, thus handling activities between the RAN and CN.

L

Broadband CCS MSS/VLR

RANAP ATM RNC For public use – IPR applies 27 © Nokia Siemens Networks

MGW Presentation / Author / Date / Document Number

RANAP

MAP RANAP ISUP

RANAP

TCAP SCCP M3UA

M3UA

SCTP

SCTP

IP

IP

MSS For public use – IPR applies 28 © Nokia Siemens Networks

SCCP MTP3B

MTP3B

SSCF

SSCF

SSCOP

SSCOP

AAL5

AAL5

ATM

ATM

MGW


RNC

BSSAP Signalling in Rel4

MAP BSSAP ISUP

BSSAP

TCAP SCCP

SCCP M3UA

M3UA

SCTP

SCTP

IP

IP

MSS For public use – IPR applies 29 © Nokia Siemens Networks

MTP

MGW


MTP

BSC

SIGTRAN - Signalling over IP SIGTRAN defines a standardized way of carrying any SS7 signalling over IP networks Defines retransmission and reordering functionalities Physical layer can be any layer 1 technology Sigtran signalling stack

Application Signalling adaptation: SIGTRAN

M3UA SCTP

Transport layer

IP

Physical layer

Ethernet/SDH/etc .



Application can be ISUP, BICC, SCCP, etc.

SIGTRAN Deployment in Rel4 MSC Server System MAP

MAP

TCAP

TCAP SMSC

SCCP M3UA

SCCP M3UA

HLR

SCTP

SCTP

IP

IP BICC

MSC Server

PSTN/ ISDN

BSSAP

RANAP

M3UA

SCCP

SCCPb

SCTP

M3UA

M3UA

IP

SCTP

SCTP

IP

IP

IP

MSC Server

ISUP MTP3 MGW

M3UA SCTP IP


RAN/BSS

ISUP


MGW MGWs act as Signalling GWs

MEGACO / H.248 ---Media Gateway Control protocol The H.248 protocol is used on the Mc interface between MSC Server and MGW Rel.4. MSC Server controls the user plane terminations and contexts in MGW Rel.4 through the Mc interface.

MSS/VLR

L

MEGACO/ H.248

ATM/IP/TDM

MGW For public use – IPR applies 32 © Nokia Siemens Networks


MGW

H.248 The MSC Server (MSS) can control the user plane Terminations and Contexts in Media Gateway (MGW), using the H.248 protocol This protocol is used to • reserve and connect terminations • connect or release echo cancellers to terminations • connect or release tones and announcements to terminations • send/receive DTMF tones Protocol stack

MGW

H.248

context C

User data

Ta

Tb

terminations



User data

SCTP

TCP

IPv4 or IPv6 L1

Bearer Independent Call Control - BICC •Specified by ITU-T, required in Rel4 networks •BICC is used for call control between two MSC servers in the Nc interface, allowing a backbone independent Control Plane and User Plane. •Based on ISUP, includes extensions to carry bearer related information; due to the fact that BICC is supposed to control calls over ATM/IP connection instead of PCM-TSLs. •The needed bearer specific information is transferred from MGW to MSS through the H.248 protocol

Bearer information carried in signalling messages MSC Server

MSC Server IAM Bearer cntr

Bearer cntr

MGW address MGW



. . MGW address Codec: AMR mode 7 . . .

Two ways to establish a bearer 1) Use separate bearer control signalling (ATM) 2) Tunnel bearer information in call control messages (IP)

MSS

Call Control Signalling BICC or SIP

H.248

MSS

H.248

In ATM backbone, bearer is established via separate bearer control signalling. In case of ATM AAL2 connections, AAL2 signalling is used.

Bearer Control Signalling E.g, AAL2 signalling

MGW



In IP backbone, no separate bearer signalling is used. Instead, the information about the bearer is tunneled in H.248 and SIP or BICC via the MSC Servers. (IPBCP)

Session Initiation Protocol - SIP •SIP specified by IETF •SIP-T defines extensions to carry ISUP messages encapsulated in SIP messages (“SIP for Telephony”) •Transport usually over UDP (can be e.g. SCTP as well) •Can establish IP bearers only Bearer information and ISUP carried in signalling messages MSC Server

MSC Server INVITE Bearer cntr

Bearer cntr

. . IP address: 192.168.3.2 Port: 5964 Codec: AMR mode 7 . . ISUP: IAM …. SIP UDP/SCTP IP

192.168.3.2/5964 For public use – IPR applies 36 © Nokia Siemens Networks

MGW


AAL Type 2 Signaling SETUP

AAL type 2 signaling protocol (Q.2630) is used between AAL2 switching capable network elements ("AAL2 switches"), e.g., RNC-MGW

AAL2 Switc h

Signaling channel AAL2 paths

AAL2 Switc h

• Dedicated signaling channel (ATM VCC with AAL5) is CID(x) Path = ATM VCC CID(x) configured between switches for (Interface,VPI/VCI) carrying Q.2630 signalling • AAL2 paths are configured (ATM AAL2 ch = AAL2 path & CID VCC) as permanent virtual CID = 8-255 channels • Signaling protocol controls AAL2 channel setup and tear down within AAL2 paths. AAL2 channel is ATM identified by AAL2 Path ID and Switc Channel Identifier (CID) h • AAL2 path can go through an intermediate ATM switch in ATM protocol level without switching in AAL2 protocol level For public use – IPR applies 37

© Nokia Siemens Networks


CCS7 in 3G Rel 4 Network MSS/VLR RANAP

MAP/INAP TCAP

GCS BICC ISUP

MAP/INAP TCAP

SCCP

PSTN Exchange BICC ISUP

SCCP

SCCP

M3UA

M3UA

MTP3

MGW MAP / INAP

RANAP

RNC

SCCP

MTP3b


HLR/EIR/AC TCAP SCCP

M3UA


ISUP

Control Plane Protocol Stacks BICC

MSC Server

BSSAP

BSSAP

SCCP

BSC

MTP

RANAP

SCCP M3UA

MSC Server

M3UA SCTP IP Ethernet H.248

SCTP IP Ethernet

ISUP H.248

M3UA SCTP IP Ethernet

RANAP

Backbone RNC

SCCP MTP3b

SCCP MTP3b

SAAL

SAAL

ATM

ATM

Phy

Phy


MGW MGW


MGW

PSTN

Signalling and protocols in MSS

MAP

CAP

INAP

TCAP

BSSAP RANAP SCCP

BICC M3UA

H.248

SCTP IPv4, IPv6

Ethernet


ISUP


TCP

SIP UDP

MSS Interfaces (1/2) Interface MGW-BSC (A) MGW-BSC (Ater), Nokia proprietary

Protocol

MGW-RNC (Iu-CS / Control Plain)

RANAP

BSSAP

MGW-RNC (Iu-CS / User Plain)

Specified by Spec. ETSI GSM 08.0X 3GPP

TS 25.410 - 415 TS 25.933

3GPP

MSS/VLR - HLR/EIR (C,D,F)

MAP -C/-D/-F

MSS/MSC-MSS/MSC (E)

MAP-E

MSS-VLR (B)

MAP-B

VLR-VLR (G) HLR - AuC (H)

MAP-G

MSS - MGW (Mc)

H.248/Megaco

MSS - IM-MGW (Mn)

H.248/Megaco

MSS-MSS (Nc)

BICC CS2 ISUP SIP, SIP-I, SIP-T

ETSI 3GPP ETSI 3GPP ETSI 3GPP ETSI 3GPP

GSM 09.02 TS 29.02 GSM 09.02 TS 29.02 GSM 09.02 TS 29.02 GSM 09.02 TS 29.02

3GPP ITU/IETF 3GPP ITU/IETF ITU-T

TS 29.232 RFC 3525 (H.248) TS 29.332 RFC 3525 (H.248) Q.1901

ITU-/ETSI Q.76x series ITU/IETF several /3GPP

MGW - MGW (Nb) / User Plain

Broadband (Mb) (User Plane) - MGW MSS - SMSC MAP SMRSE



Transport

Physical Transport STM-1 (VC11/VC12) TDM E1/T1 AAL5/ATM STM-1/VC4, E1/T1 M3UA/SCTP/IP LAN CODEC/AAL2/ATM STM-1 (VC11/VC12), E1/T1 CODEC/RTP/UDP/IP LAN TDM E1/T1 IP (Sigtran) LAN TDM E1/T1 M3UA/SCTP LAN Internal

Internal

Internal

Internal

Internal TCP/IP SCTP TCP/IP SCTP M3UA/SCTP/IP MTP3b/AAL5/ATM MTP3/MTP2

Internal LAN

UDP/IP

LAN

Codec/RTP/UDP/IP Codec/AAL2/ATM G.711/TDM Codec/RTP/UDP/IP TDM IP (Sigtran) X.25, TCP/IP

LAN (Gbit/FE) STM-1 E1/T1/STM-1 LAN E1/T1 LAN X.21, LAN

LAN LAN STM-1/VC4 E1/T1

MSS Interfaces (2/2) Interface MSS/MSCI - Voice Mail MSS/MSCI - CCBS MSS/MSCi/HLRi - NetAct

MGW - ISDN/PSTN

Protocol

Specified by

ISUP/TUP/R2

ITU-/ETSI several

TDM

FTAM FTP, GTP' Q3, FTAM, VTERM, XML over HTTP

OSI IETF

several

Several

several

ISO-IP (OSI), X25 TCP/IP X.25/TDM IP (Sigtran) TCP/IP

ISUP/TUP/R2

ITU-/ETSI several

Euro ISDN (DSS1) ITU-T DPNSS1 Core INAP ETSI CAP 3GPP ETSI MAP 3GPP SIP 3GPP

PBX ( 30B+D ) - MSS/MSC SSF - SCF HLR - SCF MSS - IMS (Mj,Mg)

ISC (SIP)

NVS AS - IMS (S-CSCF ) SBC - NVS

SIP

NVS - NVS (Nokia propriatory use) LDAP database - NVS

SIP

MAP

MSS - SMLC (Ls)

MAP

HLR - GMLS (Lh) MAP SGSN-BSC (Gb) GTP SGSN-RNC (Iu_PS) GTP Cell Broadcast Centre (CBC) - NC (Iu_BC)

ETSI 3GPP ETSI 3GPP ETSI 3GPP

Transport

TDM

Physical Transport STM-1 (VC11/VC12) E1/T1 LAN, E1/T1 LAN E1/T1 LAN LAN STM-1 (VC11/VC12) E1/T1

Q.921

TDM

E1

CS-1 and CS-2 CAMEL GSM 09.02 TS 29.02 TS. 29.163

TDM (IP) SIGTRAN TDM (IP) SIGTRAN UDP/IP

E1/T1 LAN E1/T1 LAN LAN

several

UDP/IP UDP/IP

LAN

UDP/IP IP SIP TDM (IP) SIGTRAN TDM (IP) SIGTRAN TDM (IP) SIGTRAN IP IP

LAN

several several

LDAP

MSS - GMLC (Lg)


ITU/IETF 3GPP ITU/IETF ITU/IETF 3GPP

Spec.

GSM 09.02 TS 29.02 GSM 09.02 TS 29.02 GSM 09.02 TS 29.02


LAN

LAN E1/T1 LAN E1/T1 LAN E1/T1 LAN LAN LAN

Introduction to Signalling Own

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