MSS Overview
June 4, 2016 | Author: Noman Saeed | Category: N/A
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MSC Server overview Markus Martin 26.06.2003
MSC Server - separates user and control plane MSC 3GPP Rel99 • MGW is a part of 3G MSC • GSM and 3G Circuit Switching • Transmission is TDM
A
MSC Server 3GPP Rel4 • MGW is separate from MSS • GSM and 3G Circuit Switched services • Transmission is IP (also ATM can be used • Voice and signaling over IP
MSCi - M11 TDM based Backbone & PSTN
H.248/Megaco Sigtran
A'
MGW - U1.5
MGW - U2 control plane user plane
© NOKIA
Packet based Backbone (IP/ATM) & TDM based PSTN
A & Iu-CS
Iu-CS
2
MSS M12
MSS overview.PPT/ 27-06-2003 / MMa
MSC Server system IN/SCE
HLR
PSTN/ISDN MSC Server BSC
GSM
Other PLMN A
RNC
MGW Iu-CS
WCDMA
All interfaces supported by same elements 3
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MSS overview.PPT/ 27-06-2003 / MMa
H.248
IP/ATM Backbone
Interfaces & Protocols Rel.4 Network
• RANAP/BSSAP for radio access HLR control Services • Nc - BICC for call control (also SIPT) CAP MAP • Mc - H.248 for MGW control BICC MSC MSC ATM/IP Server Server • Nb - AAL2 for user data Nc • Nb- RTP for user data over IP Mc Sigtran H.248 Sigtran IP H.248 • AAL5 for signaling over ATM IP IP IP Mc • Sigtran for transmitting SS7 AAL2/AAL5 RANAP signaling over IP SS7 ATM Nb
AAL5/ATM
Iu-CS MGW BSSAP
RNC
AAL2 ATM
A TDM
BSC 4
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MSS overview.PPT/ 27-06-2003 / MMa
RTP IP
TDM MGW
PSTN
Support for All-IP Mobility Core
M13/ U2.1
IMS-CS interworking
CPS
SIP
SIP
MSS/ GCS
H.248
• MGW can be used in IMS environment for interconnecting IMS and PSTN/PLMN networks
SIGTRAN
IP SS7
Gi
PSTN
Gi
RTP Gi SGSN GGSN
PS CN domain
5
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MSS overview.PPT/ 27-06-2003 / MMa
TDM MGW CPS = Connection Processing Server GCS = Gateway Control Server
MSC Server overview • the MSC Server is a circuit-switched call control product offering 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, separately purchase call control and traffic capacity • have a clear evolution to IP backbone with the MGW • the MSC Server is a functionality which can be upgraded to the MSCi and TMSCi network elements (2G or 3G) ©©NOKIA marketing1.PPT27-06-2003 / 26.9.2000 / MMa 6 NOKIA MSC Server MSS overview.PPT/ /ATu/KN
Integrated MSC Server • Upgrade from previous MSCi release to contain also MSC Server features • Still supports full MSCi functionality • Contains • Gateway MSC Functionality • Visited MSC Functionality • Media Gateway Control Function MSCi - M11
1) M12 upgrade
MSCi - M12
2) MSS activation MSS
GMSC
VMSC
GMSC
VMSC
GMSC
Switching
IWF
Switching
IWF
Switching MGCF
7
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MSS overview.PPT/ 27-06-2003 / MMa
VMSC 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 in Integrated 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 and functionality MSS New delivery
GMSC MGCF 8
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MSS overview.PPT/ 27-06-2003 / MMa
VMSC
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)
New delivery
GCS
GMSC MGCF 9
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MSS overview.PPT/ 27-06-2003 / MMa
Location of new functionalities • MSC Server adds more signallings CCSU SIGU BSU
ISU
12
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MSS overview.PPT/ 27-06-2003 / MMa
•
Sigtran (M3UA/SCTP)
•
H.248
•
BICC
•
SIP/SIP-T
•
Sigtran (M3UA/SCTP)
•
RANAP
•
Sigtran (M3UA/SCTP)
•
H.248
•
AAL2 signalling
MSC Server in a multivendor environment • 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 detailed interface specifications • Standardization in all other interfaces apart from Mc is such that no 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 • • 13
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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 MSS overview.PPT/ 27-06-2003 / MMa
MSS system topology handling– short intro
14
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MSS overview.PPT/ 27-06-2003 / MMa
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) UPD1
UPD2
MGW
MGW
MGW
UPD3 MGW
MGW
MGW
IP
15
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MSS overview.PPT/ 27-06-2003 / MMa
Finding an terminating MGW • IP address information is tunneled between the MGWs • MGW does not need to know anything about the user plane topology
• Routers need to be configured with their own subnets MSC Server MSC Server
3. IAM(IP_addr_A) 6. APM(IP_addr_B)
1. ADD.req 2. ADD.resp (IP_addr_A)
4. ADD.req (IP_addr_A)
5. ADD.req (IP_addr_B)
MGW_ B
MGW_ 7. MOD.req A
(IP_addr_B)
R R Subnet 192.168.2.0/24 16
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MSS overview.PPT/ 27-06-2003 / MMa
Subnet 192.168.3.0/24
IP Network Topology - Signalling • Sigtran links are created between Signalling Point Codes • Sigtran STPs are possible but do not make network configuration easier at MTP3 level
• Configuration consists of few MMLs, planning the PCM-TSL usage not necessary MSC Server MSC Server Sigtran Sigtran
SPC: 600H
Sigtran
SPC: 400H MSC Server
MGW
SPC=x PSTN
SPC: 300H 17
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MSS overview.PPT/ 27-06-2003 / MMa
SGW funcionality of the MGW used
SPC: 500H
ATM Topology - User Plane • 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 MGW UPD1
UPD2
MGW
MGW
UPD3 MGW
MGW
MGW
ATM
18
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MSS overview.PPT/ 27-06-2003 / MMa
Finding an terminating MGW • 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) MSC Server MSC Server
3. IAM(ATM_addr_A) 6. APM(ATM_addr_B)
1. ADD.req 2. ADD.resp (ATM_addr_A)
4. ADD.req (ATM_addr_A) MGW_ B
MGW_ 7. MOD.req A
(ATM_addr_B)
S S Route 19
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MSS overview.PPT/ 27-06-2003 / MMa
AAL2 ERQ towards ATM_addr_B
5. ADD.req (ATM_addr_B)
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 MSC be Server used MGW
UPD1
1.
MGW
UPD2 MGW
RAN
MGW
Weight - 50 MGW
Weight - 30 MSC Server
AAL2 Nodal function used! MGW
2.
20
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RAN
MSS overview.PPT/ 27-06-2003 / MMa
MGW
AAL2 Nodal Funtionality • 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 MSC Server
1. RAB ESTABLISHMENT REQ (NSAP_A)
MGW_A
4. AAL2 ERQ
RAN
2. AAL2 ERQ
MGW_B
ATM PVC between MGWs ATM PVC between RNC and MGW 21
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
3. NUMBER ANALYSIS
5. NUMBER ANALYSIS
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 Sigtran
SPC: 600H SPC: 400H MGW MGW
SPC: 300H 22
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
SGW funcionality of the MGW used
SPC: 500H
Virtual MGWs • 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 to five VMGWs) MSC Server MSC Server
H.248 H.248 MGW
MGW does not know whether it is controlled by a single or many MSS. 23
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MSS overview.PPT/ 27-06-2003 / MMa
Virtual MGWs (cont.) • MSC Server selected at MGW startup and registration • IP and ATM resources are common for all MSC Server controlling the MGW
• TDM resources are dedicated to MSC Servers MGW DB
MSC Server
Primary MSC Server: 192.168.26.1 Secondary MSC Server: 192.168.21.1 . . . MGW
ISU-1
24
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MSS overview.PPT/ 27-06-2003 / MMa
MGW name: IP addr: Routes: . . .
OuluMGW1.operator.net 192.168.11.1 101-105, 110
Protocols and stack – short intro
25
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MSS overview.PPT/ 27-06-2003 / MMa
User Plane Protocol Stacks AMR/EFR/FR/G.711 RTP UDP
G.711 Phy
MSC Server
IP
MSC + IP Trunk
Phy
PSTN BSS Backbone RNC
MGW
MGW AMR/EFR/FR/G.711
AMR (/EFR / FR)
Nb-UP
Iu-UP AAL2
© NOKIA
RTP UDP
ATM
ATM
IP
Phy
Phy
Phy
Iu_CS 26
AAL2
Nb-UP
MSS overview.PPT/ 27-06-2003 / MMa
Nb/ATM
Nb/IP
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 and Protocol MRF MGW stack H.248
• Connection modelcontext basedC on termination and contexts SCTP
User data
Ta terminations 27
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MSS overview.PPT/ 27-06-2003 / MMa
Tb
User data
TCP
IPv4 or IPv6 L1
Signalling Transport (SIGTRAN) • Sigtran maps SS7 addressing (Signalling Point Codes or GT addresses) into IP addresses. • SCTP (Stream Control Transmission Protocol) provides reliable and redundant transport mechanism over IP special features suitable for signalling MAP
• Different adaptation layers possible TCAP • M2UA (MTP2 user adaptation layer), Not supported SCCP • M3UA (MTP3 user adaptation layer) M3UA • SUA (SCCP user adaptation layer), FFS SCTP • M3UA supported in the 1st implementation of Rel4
IP
• The main function of the T-SGW is change MTP L1 – L3 signalling to correspond IP signalling. SCTP and adaptation layers (e.g. M3UA) can be used for this purpose in the T-SGW. 28
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
MAP TCAP SUA SCTP IP
Bearer Independent Call Control - BICC • Specified by ITU-T, required in Rel4 networks • Based on ISUP, includes extensions to carry bearer related information • Two parts • Call control (signalling) • Bearer Control (application in MSC Server) . Bearer information . • Can establish ATM and IP bearers IP address: 192.168.3.2 carried in Port: 5964 signalling messages • Transported over Sigtran Codec: AMR mode 7 MSC Server
MSC Server IAM Bearer cntr
. . .
Bearer cntr BICC Sigtran
29
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
SCTP
IP
192.168.3.2/5964 MGW
M3UA
MGW
Session Initiation Protocol - SIP • SIP specified by IETF, required in 3GPP All-IP networks • SIP-T defines extensions to carry ISUP messages encapsulated in SIP messages (“SIP for Telephony”)
• Transport usually over UDP (can be e.g. TCP as well, M13 candidate) • Can establish IP bearers
Bearer information and ISUP carried in signalling messages MSC Server
MSC Server INVITE Bearer cntr
. . IP address: 192.168.3.2 Port: 5964 Codec: AMR mode 7 . . ISUP: 84FC 03FC ….
Bearer cntr SIP UDP/TCP IP 192.168.3.2/5964
MGW 30
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MSS overview.PPT/ 27-06-2003 / MMa
MGW
Basic Call Cases in MSS system The basic call cases are described in the feature: FN1327 Basic Call Cases in MSC Server
31
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
UE-UE call, ATM core (1/3) Forward Establishment used, BICC between MSS MSC Server
3. IAM
MSC Server
8. APM (mgw_addr, binding_id 1. SETUP 4. SETUP 15. Notify.ind 2. CALL PROCEEDING 16. Notify.resp 5. CALL CONFIRMED 9. Add.req (mgw_addr, binding_id) 10. Add.resp 6. Add.req 7. Add.resp (mgw_addr, binding id) RNC 11. ERQ (mgw_addr, binding_id) 12. ECF
RNC
ATM Core MGW
TDM
PSTN
32
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MSS overview.PPT/ 27-06-2003 / MMa
MGW TDM
PSTN
UE-UE call, ATM core (2/3) Forward Establishment used, BICC between MSS MSC Server 19. RAB ASSIGNMENT REQ (mgw_addr, binding_id)
23. COT 33. ACM
29. RAB ASSIGNMENT COMPLETE 30. ALERTING
22. RAB ASSIGNMENT COMPLETE 17. Add.req 18. Add.resp (mgw_addr, binding id)
34. ALERTING
MSC Server 26. RAB ASSIGNMENT REQ (mgw_addr, binding_id)
RNC 20. ERQ (mgw_addr, binding_id)
24. Add.req 25. Add.resp (mgw_addr, binding id) 31. Add.req (ringing tone) RNC 32. Add.resp 27. ERQ (mgw_addr, binding_id) 28. ECF
21. ECF
ATM Core MGW
TDM
PSTN
33
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
MGW TDM
PSTN
UE-UE call, ATM core (3/3) Forward Establishment used, BICC between MSS MSC Server
38. ANM
MSC Server
35. CONNECT
39. CONNECT
36. Modify.req (cut through) and remove tone 37. Modify.resp RNC RNC ATM/ AAL2 ATM/ AAL2 MGW
TDM
PSTN
34
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
ATM Core MGW TDM
PSTN
UE to UE call Two MSC Servers, BICC signalling, IP user plane MSC Server
2. Digit analysis: outgoing call -> select MGW
4. BICC: IAM
MSC Server
5. Digit analysis: UE terminated -> Page, select MGW
8. BICC: APM
1. RANAP: Setup
7. H.248: 6. RANAP: Setup Reserve user 3. H.248: Reserve user plane resources plane resources RNC
RNC
9. Bearer established WCDMA
35
© NOKIA
MGW
MSS overview.PPT/ 27-06-2003 / MMa
MGW
WCDMA
Network migration – example scenarios
36
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
MSC Server introduction (2G) – as port and coverage expansion PSTN BSC
MSCi upgraded to Integrated MSS
BSC
PSTN IWF
IWF functionality can be provided by MSS
MGW’s introduced in new area to provide local switching
MGW
BSC
MGW
Common IP/ATM backbone
MGW’s introduced in existing area to provide additional port capacity and BB connectivity
Existing MSC coverage
BSC
MGW
New coverage
37
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
MSC Server introduction (2G) – as separate expansion PSTN MSS introduced to control new MGW’s
MSCi
BSC
BSC
PSTN
ISUP
MGW’s introduced in new area to provide local switching
MGW
BSC
CDS
Common IP/ATM backbone
MGW
MGW’s introduced in existing area to provide additional port capacity and BB connectivity
IWF functionality provided by CDS
Existing MSC coverage
BSC
MGW
New coverage
38
© NOKIA
MSS overview.PPT/ 27-06-2003 / MMa
MSC Server introduction (2G) – Subrack MSC replacement PSTN MSS introduced to control new MGW’s
BSC
MSCi
ISUP
BSC
MSC
PSTN
ISUP ISUP BSC
MSC
3 subrack MSCs in two different areas are being replaced by MGW and MSS
Area1 39
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MSS overview.PPT/ 27-06-2003 / MMa
ISUP
BSC
MSC
Area 2
MSC Server introduction (2G) – Subrack MSC replacement PSTN MSS introduced to handle subrack MSC control plane functions as each MSC is swapped to a MGW
MSCi
BSC
ISUP
BSC
PSTN MGW’s introduced in Area 2 to provide local switching
MGW
BSC
CDS
Common IP/ATM backbone
MGW MGWs introduced one by one to replace subrack MSC user plane functions. PBX interfaces in subracks rehomed to MSCi Area1
40
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IWF functionality provided by CDS. CDSU boards from subrack MSCs can be reused.
MSS overview.PPT/ 27-06-2003 / MMa
BSC
MGW
Area 2
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