mss overview

8/2/2019 MSS Overview

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MSC Server overview

Markus Martin

26.06.2003


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2 NOKIA MSS overview.PPT/ 27-06-2003 / MMa

MSC Server - separates user and controlplane

MSCi - M11

MGW - U1.5

A'

Iu-CS

MSS

M12

MGW - U2

Packet basedBackbone (IP/ATM)

& TDM based PSTN

TDM basedBackbone & PSTN

A

A & Iu-CS

userplane

control plane

H.248/MegacoSigtran

MSC 3GPP Rel99

MGW is a part of 3G MSC GSM and 3G Circuit Switching Transmission is TDM

MSC Server 3GPP Rel4

MGW is separate from MSS GSM and 3G Circuit Switched services Transmission is IP (also ATM can be use Voice and signaling over IP


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All interfacessupported by

same elements

WCDMA

IP/ATMBackbone

PSTN/ISDN

Other PLMN

MSC Server

GSM

BSC

RNC

A

Iu-CS

MGW

H.248

IN/SCE HLR

MSC Server system


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Interfaces & ProtocolsRel.4 Network

Iu-CS

RNC

MSCServer

AAL2ATM

TDM

H.248IP

MSCServer

Mc

MGW

Nc

AAL2/AAL5ATM Nb

Mc SigtranIP

BICCATM/IP

RANAP/BSSAP for radio accesscontrol

Nc - BICC for call control (also SIP-T)

Mc - H.248 for MGW control

Nb - AAL2 for user data

Nb- RTP for user data over IP

AAL5 for signaling over ATM

Sigtran for transmitting SS7signaling over IP

HLRServices

MAP CAP

MGWRTPIP

PSTN

RANAPAAL5/ATM SS7

BSC

SigtranIP

A

TDM

BSSAP

H.248IP


5/385 NOKIA MSS overview.PPT/ 27-06-2003 / MMa

Support for All-IP Mobility CoreIMS-CS interworking

SS7

RTP

IP

PSTN

MSS/GCS

SIP

CPS

MGW

SIGTRAN

TDM

H.248

SIP

PS CN domain

Gi

Gi

Gi

GGSNSGSN

MGW can be used in IMS

environment forinterconnecting IMS andPSTN/PLMN networks

CPS = Connection Processing ServerGCS = Gateway Control Server

M13/ U2.1



MSC Server overview

the MSC Server is a circuit-switched call controlproductoffering all GSM and 3G circuit-switched services.

the MSC Server allows operators to: provide same CS services as with an MSC combine transport of voice and data (GPRS)

in a single transport network optimize signaling and transport networks,

separatelypurchase call control and traffic capacity

have a clear evolution to IP backbone with theMGW

the MSC Server is a functionality which can beupgraded tothe MSCi and TMSCi network elements (2G or 3G)

6 NOKIA MSC Server marketing1.PPT / 26.9.2000/ATu/KN



Integrated MSC Server

Upgrade from previous MSCi release to contain also MSCServer features

Still supports full MSCi functionality

Contains Gateway MSC Functionality Visited MSC Functionality

Media Gateway Control Function

MSCi - M11 MSCi - M12 MSS1) M12 upgrade 2) MSS activation

GMSC VMSC

MGCF

GMSC VMSC

Switching IWF IWFSwitching

GMSC VMSC

Switching IWF



Standalone MSC Server

New delivery in M12 without user plane switching

Contains only MSC Server features and optimized hardware(e.g. no GSW, ET or modem pools)

Note though that same functionalities are present as inIntegrated MSC Server except MSCi user plane handling

Gateway MSC Functionality Visited MSC Functionality

Media Gateway Control Function Also possible to upgrade Integrated MSC Server to Standalone

MSC Server (MSSu) by removing user plane switching HW andfunctionality

MSS

GMSC VMSC

MGCF

New delivery



Gateway Control Server

Gateway Control Server

New product Includes GMSC and MGCF functionalities Meant for operators who need transit MSC Server or

dedicated PSTN access for IP Telephony

MSS functionality also possible in TMSCi (probably not

relevant)

GCS

GMSC

MGCF

New delivery


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Location of new functionalities

MSC Server adds more signallings

CCSU

SIGU

BSU

Sigtran (M3UA/SCTP)

H.248

BICC

SIP/SIP-T

Sigtran (M3UA/SCTP)

RANAP

ISU

Sigtran (M3UA/SCTP)

H.248

AAL2 signalling

MSC S i l i d


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MSC Server in a multivendorenvironment

Nokia philosophy on the power of open interfaces also applies

in the MSC Server system Nokia has implemented all interfaces according to

standardization with the exceptions defined in the detailedinterface specifications

Standardization in all other interfaces apart from Mc is such thatno major IOT issues are foreseen.

Variations in H.248 packages (grouping of termination characteristics) Naming convention of the Termination Identity

IOT testing has not started yet for MSC Server system specific

interfaces It should be noted that it supports the same multivendor interfaces as the

MSCi First priority in IOT/MVI will be in Nc (MSS-MSS) and Nb (MGW-MGW)

interfaces


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MSS system topology

handlingshort intro


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IP Network Topology - User Plane

Using IP an operator can build a routable user plane with no

connection configuration UPD is the lowest level information that the MSC Server knows

about the user plane (no user plane IP addresses are known)

Signaling links still need to be configured (not for SIP)

MGW

MGW

MGW MGW

MGW

MGW

IP

UPD1UPD2

UPD3


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Finding an terminating MGW

MGW_

A

MSC Server

MSC Server

MGW_B

1. ADD.req2. ADD.resp

(IP_addr_A)

3. IAM(IP_addr_A)

4. ADD.req(IP_addr_A)

5. ADD.req(IP_addr_B)

6. APM(IP_addr_B)

7. MOD.req(IP_addr_B)

IP address information is tunneled between the MGWs

MGW does not need to know anything about the user planetopology

Routers need to be configured with their own subnets

R

R

Subnet 192.168.2.0/24Subnet 192.168.3.0/24


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IP Network Topology - Signalling

Sigtran links are created between Signalling Point Codes

Sigtran STPs are possible but do not make networkconfiguration easier at MTP3 level

Configuration consists of few MMLs, planning the PCM-TSLusage not necessary

MSC Server

MSC Server

MSC ServerMGW

SPC: 600H

SPC: 400H

SPC: 500HSPC: 300H

PSTNSPC=x

Sigtran

Sigtran

Sigtran

SGW funcionalityof the MGW used


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ATM Topology - User Plane

MGW

MGW

MGW MGW

MGW

MGW

ATM

UPD1UPD2

UPD3

ATM connections between MGWs have to be preconfigured

Between MGW and the ATM switch PVCs used

In ATM core S-PVC if supported by ATM switch vendor(PNNI1.0 signalling required)

Similarly as in IP case, UPDs have to be configured to the

MSC Server


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Finding an terminating MGW

MGW_

A

MSC Server

MSC Server

MGW_B

1. ADD.req2. ADD.resp(ATM_addr_A)

3. IAM(ATM_addr_A)

4. ADD.req(ATM_addr_A)

5. ADD.req(ATM_addr_B)

6. APM(ATM_addr_B)

7. MOD.req(ATM_addr_B)

ATM address information is tunneled between the MGWs

MGW does needs to find a route towards the terminating MGW ATM switches have been configured with PVCs (S-PVCs)

S

S

Route AAL2 ERQ towards ATM_addr_B


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ATM Topology - User Plane (cont.)

In large networks, to reduce the number of VCs to be

configured, either use two MGW per call, or the AAL2 nodal function can be used

MGW

MGW

MGW

UPD2

MSC Server

MGW

MGW

MSC Server

RAN

AAL2 Nodal function used!

2.

1.

RAN

MGWWeight - 50

Weight - 30

UPD1

MGW


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AAL2 Nodal Funtionality

MGW_B

RAN

ATM PVC betweenRNC and MGW

2. AAL2 ERQ

MGW_A

MSC Server

1. RAB ESTABLISHMENT REQ (NSAP_A)

4. AAL2 ERQ

ATM PVCbetween MGWs

3. NUMBERANALYSIS

5. NUMBERANALYSIS

The MGW will analyze the called party address of the incoming

AAL2 ERQ message If it is not destined for itself, it will route it forward


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ATM Topology - Signalling

Sigtran links are created between Signalling Point Codes like

in IP case IP based signalling carried

over IP over ATM tunnels or via SGW (using MTP3b)

MSC Server

MSC Server

MGW

SPC: 600H

SPC: 400H

SPC: 500HSPC: 300H

Sigtran

SGW funcionalityof the MGW used

MGW


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Virtual MGWs

MGW

MSC Server MSC Server

Single physical MGW can be controlled by more than one MSC

Server Improved resiliency at critical points of the network

E.g. a large Point of Interconnect

MGW can be split to 50 VMGWs (each ISU unit can be split tofive VMGWs)

H.248 H.248

MGW does not know whether it is controlledby a single or many MSS.


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Virtual MGWs (cont.)

MSC Server selected at MGW startup and registration

IP and ATM resources are common for all MSC Servercontrolling the MGW

TDM resources are dedicated to MSC Servers

ISU-1

MGW

Primary MSC Server: 192.168.26.1

Secondary MSC Server: 192.168.21.1

. . .

MSC ServerMGW DB

MGW name: OuluMGW1.operator.net

IP addr: 192.168.11.1

Routes: 101-105, 110

. . .


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Protocols and stack

short intro

U Pl P l S k


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User Plane Protocol Stacks

Backbone

MSC Server

MSC +

IP Trunk

RNCMGW MGW

Nb/IPNb/ATM

Nb-UP

AAL2

ATM

Phy

Nb-UP

RTP

UDP

IP

Phy

AMR (/EFR / FR)

Iu-UP

AAL2

ATM

Phy

RTP

UDP

IP

Phy

AMR/EFR/FR/G.711

G.711Phy

PSTNBSS

Iu_CS

AMR/EFR/FR/G.711

H 248


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H.248

Master-slave protocol The MGC (Media Gateway Controller) is the master and the MG (Media

Gateway) the slave MG registers with the MGC and the association is setup a one-to-one protocol, MG is controlled by one MGC can be ASN.1 binary codes or ASCII coded, MGC must support both,

MG chooses

Specified in IETF (Megaco) and ITU-T (H.248) In 3GPP mandated between MSS and MGW for Rel.4

In Rel.5/6 it is used between MGCF and MGW, and CSCF andMRF

Connection model based on termination and contextsTa Tb

terminations

MGW

context CUser data User

data

SCTP TCP

IPv4 or IPv6

H.248

L1

Protocolstack

Si lli T t (SIGTRAN)


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Signalling Transport (SIGTRAN)

Sigtran maps SS7 addressing (Signalling Point Codes orGT addresses) into IP addresses.

SCTP (Stream Control Transmission Protocol) providesreliable and redundant transport mechanism over IPspecial features suitable for signalling

Different adaptation layers possible M2UA (MTP2 user adaptation layer), Not supported M3UA (MTP3 user adaptation layer) SUA (SCCP user adaptation layer), FFS

M3UA supported in the 1st implementation of Rel4

The main function of the T-SGW is changeMTP L1 L3 signalling to correspond IPsignalling. SCTP and adaptation layers(e.g. M3UA) can be used for this purpose in the T-SGW.

IP

SCTP

SUA

TCAP

MAP

IP

SCTP

M3UA

SCCP

TCAP

MAP

B I d d t C ll C t l BICC


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Bearer Independent Call Control - BICC

Specified by ITU-T, required in Rel4 networks

Based on ISUP, includes extensions to carry bearer relatedinformation

Two parts Call control (signalling) Bearer Control (application in MSC Server)

Can establish ATM and IP bearers Transported over Sigtran

MSC ServerMSC Server

IP

SCTP

M3UA

BICC

MGWMGW

IAM

Sigtran

.

.IP address: 192.168.3.2Port: 5964Codec: AMR mode 7...

Bearer informationcarried insignalling messages

Bearer cntr Bearer cntr

192.168.3.2/5964

S i I iti ti P t l SIP


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Session Initiation Protocol - SIP

SIP specified by IETF, required in 3GPP All-IP networks

SIP-T defines extensions to carry ISUP messagesencapsulated in SIP messages (SIP for Telephony)

Transport usually over UDP (can be e.g. TCP as well, M13candidate)

Can establish IP bearers


IP

UDP/TCPSIP

MGWMGW

INVITE

.

.IP address: 192.168.3.2Port: 5964Codec: AMR mode 7..ISUP: 84FC 03FC .

Bearer informationand ISUP carried insignalling messages

192.168.3.2/5964

Bearer cntr Bearer cntr

Basic Call Cases in MSS system


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Basic Call Cases in MSS system

The basic call cases are described in the feature:

FN1327 Basic Call Cases in MSC Server

UE UE call ATM core (1/3)


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UE-UE call, ATM core (1/3)

MSC Server

MGW

RNC

MSC Server

MGW

RNC

PSTNPSTN

TDMTDM

Forward Establishment used, BICC between MSS

ATM Core

1. SETUP2. CALL PROCEEDING

3. IAM

4. SETUP5. CALL CONFIRMED

6. Add.req7. Add.resp (mgw_addr, binding id)

8. APM (mgw_addr, binding_id

9. Add.req (mgw_addr, binding_id)10. Add.resp

11. ERQ (mgw_addr, binding_id)

12. ECF

15. Notify.ind16. Notify.resp



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MSC Server

MGW

RNC

MSC Server

MGW

RNC

PSTNPSTN

TDMTDM


ATM Core


19. RAB ASSIGNMENT REQ(mgw_addr, binding_id)

20. ERQ (mgw_addr, binding_id)

21. ECF

22. RAB ASSIGNMENT COMPLETE

23. COT


26. RAB ASSIGNMENT REQ(mgw_addr, binding_id)

29. RAB ASSIGNMENT COMPLETE

27. ERQ (mgw_addr, binding_id

28. ECF

30. ALERTING

33. ACM

31. Add.req (ringing tone)32. Add.resp

34. ALERTING



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MSC Server

MGW

RNC

MSC Server

MGW

RNC

PSTNPSTN

ATM/ AAL2

ATM/ AAL2

TDMTDM


ATM Core

35. CONNECT

36. Modify.req (cut through) and remove tone37. Modify.resp

38. ANM

39. CONNECT

UE to UE call


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RNC

WCDMA MGWMGW


UE to UE call

WCDMA

RNC

Two MSC Servers, BICC signalling, IP user plane

1. RANAP: Setup

2. Digit analysis:outgoing call ->select MGW

3. H.248:Reserve userplane resources

4. BICC: IAM

8. BICC: APM

9. Bearer established

6. RANAP: Setup

5. Digit analysis:UE terminated ->Page, select MGW

7. H.248:Reserve userplane resources


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Network migration

example scenarios

MSC Server introduction (2G)


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( )as port and coverage expansion

MGW

MGW

MGW

CommonIP/ATM backbone

MSCi upgraded to

Integrated MSS

Existing MSC coverage

BSC

BSC

New coverage

PSTN

BSC

BSC

MGWs introducedin new area toprovide local

switching

MGWs introduced inexisting area to provideadditional port capacityand BB connectivity

PSTN

IWFIWF functionality

can be provided byMSS



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as separate expansion

MGW

MGW

MGW


MSCi

Existing MSC coverage

BSC

BSC

New coverage

PSTN

BSC

BSC

MGWs introducedin new area toprovide local

switching

MGWs introduced inexisting area to provideadditional port capacity

and BB connectivity

MSS introduced

to control newMGWs

ISUPPSTN

CDS

IWF functionalityprovided by CDS



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Subrack MSC replacement

MSCi

Area1

BSC

BSC

Area 2

PSTN

BSC

BSC

MSS introduced

to control newMGWs

ISUPPSTNMSC

MSC

MSCISUP

ISUP

ISUP

3 subrack MSCs in twodifferent areas are beingreplaced by MGW andMSS

MSC Server introduction (2G)S SC


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Subrack MSC replacement

MGW

MGW

MGW


MSCiBSC

BSC

PSTN

BSC

BSC

MGWs introducedin Area 2 to providelocal switching

MSS introduced to

handle subrack MSCcontrol plane

functions as eachMSC is swapped to a

MGW

ISUPPSTN

MGWs introduced oneby one to replacesubrack MSC user

plane functions.

PBX interfaces insubracks rehomed to

MSCi

CDS

IWF functionalityprovided by CDS.CDSU boards from

subrack MSCs can bereused.

Area1Area 2

mss overview

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